Clinical Significance of an Increased Cochlear 3D Fluid-Attenuated Inversion Recovery Signal Intensity on an MR Imaging Examination in Patients with Acoustic Neuroma

BACKGROUND AND PURPOSE:The increased cochlear signal on FLAIR images in patients with acoustic neuroma is explained by an increased concentration of protein in the perilymphatic space. However, there is still debate whether there is a correlation between the increased cochlear FLAIR signal and the degree of hearing disturbance in patients with acoustic neuroma. Our aim was to investigate the clinical significance of an increased cochlear 3D FLAIR signal in patients with acoustic neuroma according to acoustic neuroma extent in a large patient cohort.MATERIALS AND METHODS:This retrospective study enrolled 102 patients with acoustic neuroma, who were divided into 2 groups based on tumor location; 22 tumors were confined to the internal auditory canal and 80 extended to the cerebellopontine angle cistern. Pure tone audiometry results and hearing symptoms were obtained from medical records. The relative signal intensity of the entire cochlea to the corresponding brain stem was calculated by placing regions of interest on 3D FLAIR images. Statistical analysis was performed to compare the cochlear relative signal intensity between the internal auditory canal acoustic neuroma and the cerebellopontine angle acoustic neuroma_. The correlation between the cochlear relative signal intensity and the presence of hearing symptoms or the pure tone audiometry results was investigated.RESULTS:The internal auditory canal acoustic neuroma cochlea had a significantly lower relative signal intensity than the cerebellopontine angle acoustic neuroma cochlea (0.42 ± 0.15 versus 0.60 ± 0.17, P < .001). The relative signal intensity correlated with the audiometric findings in patients with internal auditory canal acoustic neuroma (r = 0.471, P = .027) but not in patients with cerebellopontine angle acoustic neuroma (P = .427). Neither internal auditory canal acoustic neuroma nor cerebellopontine angle acoustic neuroma showed significant relative signal intensity differences, regardless of the presence of hearing symptoms (P > .5).CONCLUSIONS:The cochlear signal on FLAIR images may be an additional parameter to use when monitoring the degree of functional impairment during follow-up of patients with small acoustic neuromas confined to the internal auditory canals.

The fluid of the inner ear is normally suppressed on 3D fluid-attenuated inversion recovery MR images. Increased signal intensity of the fluid on FLAIR MR images has been reported in various diseases, including sudden sensorineural hearing loss, labyrinthine hemorrhage, otosclerosis, Ramsay Hunt syndrome, and acoustic neuromas (ANs).^1–6 The increased cochlear signal on FLAIR images in patients with ANs is explained by an increased concentration of protein in the perilymphatic space.^7–12FLAIR MR imaging is sensitive to fluids with a high protein content.^13–17 Furthermore, 3D-FLAIR imaging can minimize the undesired inflow artifacts of CSF flow, has a higher signal-to-noise ratio and spatial resolution, and allows recognition of subtle compositional changes of the inner ear fluid.^18–21 Therefore, one can assume that the increased protein content in the cochlear perilymph of patients with ANs can be detected on 3D FLAIR imaging with a high sensitivity and good spatial resolution.Several researchers recently investigated whether there was a correlation between the increased cochlear FLAIR signal in patients with ANs and the degree of their hearing disturbance.^2,5 However, no such correlation was found, nor was there any difference in the cochlear FLAIR signal according to AN extent.Accordingly, the purpose of this study was to investigate the clinical significance of an increased cochlear 3D FLAIR signal in a large number patients with ANs by correlating imaging results with audiometric findings and hearing symptoms according to the extent of ANs after dividing the auditory neuromas into 2 groups: those confined to the internal auditory canal (AN_IAC) and those extending into the cerebellopontine cistern (AN_CPA).     

How Common Is Signal-Intensity Increase in Optic Nerve Segments on 3D Double Inversion Recovery Sequences in Visually Asymptomatic Patients with Multiple Sclerosis?

BACKGROUND AND PURPOSE:In postmortem studies, subclinical optic nerve demyelination is very common in patients with MS but radiologic demonstration is difficult and mainly based on STIR T2WI. Our aim was to evaluate 3D double inversion recovery MR imaging for the detection of subclinical demyelinating lesions within optic nerve segments.MATERIALS AND METHODS:The signal intensities in 4 different optic nerve segments (ie, retrobulbar, canalicular, prechiasmatic, and chiasm) were evaluated on 3D double inversion recovery MR imaging in 95 patients with MS without visual symptoms within the past 3 years and in 50 patients without optic nerve pathology. We compared the signal intensities with those of the adjacent lateral rectus muscle. The evaluation was performed by a student group and an expert neuroradiologist. Statistical evaluation (the Cohen κ test) was performed.RESULTS:On the 3D double inversion recovery sequence, optic nerve segments in the comparison group were all hypointense, and an isointense nerve sheath surrounded the retrobulbar nerve segment. At least 1 optic nerve segment was isointense or hyperintense in 68 patients (72%) in the group with MS on the basis of the results of the expert neuroradiologist. Student raters were able to correctly identify optic nerve hypersignal in 97%.CONCLUSIONS:A hypersignal in at least 1 optic nerve segment on the 3D double inversion recovery sequence compared with hyposignal in optic nerve segments in the comparison group was very common in visually asymptomatic patients with MS. The signal-intensity rating of optic nerve segments could also be performed by inexperienced student readers.

MR imaging contributes to not only the diagnosis and differential diagnosis of MS but also the monitoring and follow-up of patients.¹ T1-weighted postcontrast, T2-weighted, proton-density, FLAIR, and double inversion recovery (DIR) images are recommended to detect acute and chronic demyelinating lesions in typical locations.^1–9Acute optic neuritis is an inflammatory demyelination of the optic nerve causing acute visual loss.^10–13 After recovery, patients are often visually asymptomatic, but careful visual testing by visually evoked potentials, optical coherence tomography, and visual disability evaluation may reveal persistent slight visual deficits.^14–17 These deficits are also observed in patients without any history of previous acute optic neuritis due to a suspected subclinical disease known as subclinical optic nerve demyelination.^14–17Acute optic neuritis is easily diagnosed on MR imaging by focal nerve swelling and segmental T2-weighted hyperintensity, especially on STIR images or on fat-suppressed T2-weighted images and by segmental gadolinium enhancement on T1-weighted fat-suppressed images.^10,18–22 The enhancement is present for a mean of 30 days after the onset of visual symptoms.^21,23–31Subclinical optic nerve demyelination, however, is not easily visible on MR imaging. Routine T2-weighted images without fat suppression and contrast-enhanced T1-weighted FSE images do not show any signal abnormality in the affected optic nerve. Fat-suppressed T2-weighted FSE images, especially STIR T2-weighted images, may detect a signal-intensity abnormality in subclinical optic nerve demyelination.^23,32,33 The highly diagnostic value of fat-suppressed FLAIR images and fat-suppressed 3D DIR images in the detection of any pathologic signal intensity in the optic nerve has been evaluated in acute optic nerve demyelination.^10,34,35 In a few patients with subclinical optic nerve demyelination, signal-intensity abnormalities have been reported on 3D FLAIR.³⁴ However, there are few data about the use of the 3D DIR sequence in the evaluation of subclinical optic nerve demyelination.³⁶In our department, patients with MS are routinely and regularly monitored for disease progression by a standard protocol with 3D FLAIR, 3D DIR, T2-weighted FSE, and 3D T1-weighted postcontrast images. 3D DIR is added to our standard protocol for improved detection of juxtacortical, cortical, and infratentorial demyelinating lesions.^1–9 On the basis of postmortem and clinical studies having already shown a high percentage of subclinical optic nerve demyelination with ongoing axonal loss in patients with MS,^37–41 we wanted to test 2 hypotheses: first, that it is possible to detect signal-intensity changes in optic nerve segments on the 3D DIR sequence without the additional application of a STIR T2-weighted sequence over the orbits in patients with MS without a history of clinically obvious visual loss and without a history of acute optic neuritis during the previous 3 years; and second, that the signal-intensity changes on 3D DIR are so obvious that even inexperienced readers can detect them. This second hypothesis is important because in our department, MR imaging examinations of patients with MS are evaluated not only by trained neuroradiologists but also general radiologists. Therefore, it is desirable that the lack of neuroradiologic experience be compensated by the application of an easily readable MR image, and the 3D DIR sequence is routinely acquired in our department for the follow-up of patients with MS.For comparison, the signal intensities of normal healthy optic nerve segments in patients evaluated by the identical 3D DIR sequence for different diseases (ie, epileptic seizures and posttraumatic sequelae) were analyzed as well.     

Comparison of Inner Ear Contrast Enhancement among Patients with Unilateral Inner Ear Symptoms in MR Images Obtained 10 Minutes and 4 Hours after Gadolinium Injection

BACKGROUND AND PURPOSE:Recently 4-hour delayed-enhanced 3D-FLAIR MR imaging has been used in pathophysiologic analysis of the inner ear in many auditory diseases, including sudden sensorineural hearing loss, but comparison among different time points is not clear in patients with unilateral inner ear symptoms. We compared the signal-intensity ratios of the inner ears in patients with unilateral inner ear symptoms on 10-minute delayed-enhanced and 4-hour delayed-enhanced 3D-FLAIR MR images after IV gadolinium injection.MATERIALS AND METHODS:The 10-minute delayed-enhanced and 4-hour delayed-enhanced 3D-FLAIR MR images were retrospectively analyzed. Signal-intensity ratios between the cerebellum and inner ear structures, such as the cochleae, vestibules, and vestibulocochlear nerve were assessed. Multiple comparisons were performed.RESULTS:Signal-intensity ratios of the affected cochleae, vestibules, and vestibulocochlear nerve were higher than those of unaffected sides in both 10-minute delayed-enhanced and 4-hour delayed-enhanced images. At the affected side, signal-intensity ratios of the vestibulocochlear nerve were higher in patients with nonsudden sensorineural hearing loss than in those with sudden sensorineural hearing loss on both 10-minute delayed-enhanced and 4-hour delayed-enhanced images. The signal-intensity ratios of some affected inner ear structures were higher than those of the unaffected sides in a group of 30 patients with sudden sensorineural hearing loss and 20 patients with nonsudden sensorineural hearing loss on 10-minute delayed-enhanced and 4-hour delayed-enhanced images.CONCLUSIONS:Signal-intensity ratios of the inner ear show statistically significant increases in many diseases, especially neuritis, in 10-minute delayed-enhanced and 4-hour delayed-enhanced images. The 4-hour delayed-enhanced images may be superior in neural inflammatory–dominant conditions, while 10-minute delayed-enhanced images may be superior in neural noninflammatory–dominant conditions.

3D fluid-attenuated inversion recovery MR imaging has recently been applied to the inner ear to investigate inner ear pathology. The increased signal intensity of diseased inner ears can also be observed on 3D-FLAIR imaging after intravenous gadolinium injection. This technique is useful for the pathophysiologic analysis of the inner ear in many auditory diseases, such as sudden sensorineural hearing loss (sSNHL), cholesteatoma, cochlear otosclerosis, and vestibular schwannoma.^1–4 Compared with intratympanic gadolinium injection, 3D-FLAIR MR imaging after IV gadolinium injection is less invasive and enables observation of the bilateral cochleae and other inner ear structures.⁵The signal-intensity ratio of the inner ear to other parts of the brain allows semiquantitative expression of the signal intensity and may be useful for comparing results among patients or among ears. Recent articles have reported that the signal-intensity ratio of the inner ear and other parts of the brain is useful in patients with sudden deafness, Ménière disease, and vestibular schwannoma.^4,6–8The signal-intensity ratio of the inner ear and brain stem may indicate disruption of the blood-labyrinthine barrier in patients with inner ear disease with 4-hour enhancement after gadolinium injection.⁷ To our knowledge, the difference in inner ear signal intensity between 10-minute and 4-hour delayed MRI has not been evaluated in most patients with unilateral symptoms, however, including those with sSNHL.The purpose of this study was to compare signal intensities of the inner ear among patients with unilateral symptomatic ear diseases. Comparisons were made between the affected and unaffected sides, between patients with sSNHL and nonsudden sensorineural hearing loss (nsSNHL), and between 10-minute and 4-hour delayed intravenous gadolinium-enhanced 3D-FLAIR MR imaging.     

Prevalence of Internal Auditory Canal Diverticulum and Its Association with Hearing Loss and Otosclerosis

BACKGROUND AND PURPOSE:Focal low-attenuation outpouching or diverticulum at the anterolateral internal auditory canal is an uncommon finding on CT of the temporal bone. This finding has been described as cavitary otosclerosis in small case reports and histology series. The purpose of this study was to establish the prevalence of internal auditory canal diverticulum and its association with classic imaging findings of otosclerosis and/or hearing loss.MATERIALS AND METHODS:Temporal bone CT scans of 807 patients, obtained between January 2013 and January 2016, were retrospectively reviewed to identify internal auditory canal diverticula and/or classic imaging findings of otosclerosis. Clinical evaluations for hearing loss were reviewed for patients with internal auditory canal diverticula and/or otosclerosis.RESULTS:Internal auditory canal diverticula were found in 43 patients (5%); classic otosclerosis, in 39 patients (5%); and both findings, in 7 patients (1%). Most temporal bones with only findings of internal auditory canal diverticula (91%) demonstrated hearing loss, with 63% of this group demonstrating sensorineural hearing loss. The hearing loss classification distribution was significantly different (P < .01) from that in the classic otosclerosis group and in the group with both diverticula and otosclerosis.CONCLUSIONS:Internal auditory canal diverticula are not uncommon on CT examinations of the temporal bone and most commonly occur without classic imaging findings of otosclerosis. These lesions are associated with sensorineural hearing loss, and referral for hearing evaluation may be appropriate when present.

A focal low-attenuation notch or diverticulum within the temporal bone continuous with the internal auditory canal (IAC) is an unusual finding on imaging studies of the temporal bone. Several histologic and imaging case reports refer to this finding as a form of cavitary otosclerosis^1–4 and even suggest that the presence is associated with advanced disease.³Otosclerosis is an osteodystrophic disorder of the otic capsule, resulting in abnormal resorption of endochondral bone and deposition of abnormal vascular bone. Otosclerosis usually appears in the third-to-fifth decades of life, and most commonly affects women. Clinical otosclerosis is present in <1% of the population, though it has been reported in up to 11% of the population on histology performed at postmortem examination.⁵ On CT of the temporal bone, otosclerosis commonly appears as lucent or hypodense bone surrounding the otic capsule, often limited to the region anterior to the oval window. This process results in either conductive hearing loss (CHL) due to fixation of the stapes footplate or mixed conductive and sensorineural hearing loss (SNHL) due concomitant otic capsule involvement. Otosclerosis presenting with only SNHL in the absence of CHL is rare and is often called “cochlear otosclerosis.”^5–9Establishing the significance of the IAC diverticulum or notch is important for both the radiologist and referring physician in guiding clinical management. Determining the relationship of this lesion to classic imaging findings of otosclerosis could also be helpful in the understanding of otosclerosis and the spectrum of clinical presentations. Therefore, the purpose of this study was the following: 1) to determine the prevalence of IAC diverticula at our institution, and 2) to explore potential associations with otosclerosis and hearing loss in patients identified with an IAC diverticulum.     

Ultrasound of the Hypoglossal Nerve in the Neck: Visualization and Initial Clinical Experience with Patients

BACKGROUND AND PURPOSE:The hypoglossal nerve, providing motor innervation for the tongue, can be affected in many diseases of the neck and skull base, leading to dysarthria, dysphagia, and ultimately atrophy of the tongue. We determined the feasibility of direct visualization of the hypoglossal nerve in the neck with ultrasound, testing this technique on healthy volunteers and evaluating it in clinical practice.MATERIALS AND METHODS:The study consisted of 4 parts: first, ultrasound-guided perineural ink injections along the course of the hypoglossal nerve at 24 sides of 12 fresh, nonembalmed cadaver necks. Subsequently, the specimens were dissected to confirm the correct identification of the nerve. The second part was examination of healthy volunteers with ultrasound and measurement of cross-sectional areas for generating reference data. The third part was scanning of healthy volunteers by 2 resident physicians with little and intermediate experience in ultrasound. Fourth was examination with ultrasound of patients with motor symptoms of the tongue.RESULTS:The hypoglossal nerve was correctly identified bilaterally in all cadaveric specimens (24/24) and all volunteers (33/33). The cross-sectional area ranged from 1.9 to 2.1 mm². The resident physicians were able to locate the nerve in 19 of 22 cases, demonstrating that locating the nerve is reproducible and feasible even with intermediate experience in ultrasound. Finally, alterations of the hypoglossal nerve in disease states could be depicted.CONCLUSIONS:Direct, reliable, and reproducible visualization of the extracranial hypoglossal nerve with ultrasound is feasible.

The hypoglossal nerve provides motor innervation for the entire tongue with the exception of the palatoglossal muscle. The nerve leaves the medulla oblongata between the olive and the pyramid in the preolivary groove, passes through the premedullary cistern, and exits the skull through the hypoglossal canal. Inferior to the skull base, the nerve descends lateral to the carotid artery, traveling with the glossopharyngeal, vagal, and accessory nerves; the carotid artery; and the internal jugular vein within the carotid space. At the level of the mandibular angle, the nerve courses anteriorly, caudal to the posterior belly of the digastric muscle, toward the hyoid bone. Here, the nerve enters the submandibular space, passes between the mylohyoid and the hyoglossal muscles into the sublingual space, and finally enters the body of the tongue.¹A lesion of the hypoglossal nerve can cause dysarthria, dysphagia, and tongue paralysis, and unilateral atrophy of the tongue muscles may result. Denervation of the tongue can be secondary to radiation therapy due to formation of fibrotic tissue around the nerve, infection, lymphadenopathy, tumor entrapping or infiltrating the nerve, neurogenic tumors arising within the nerve, or trauma, with iatrogenic trauma resulting from carotid endarterectomy, neck dissection, or tonsillectomy being among the more common causes of hypoglossal nerve dysfunction. There are also reports of carotid and vertebral artery dissections leading to hypoglossal nerve injury.^2–18 In a large case series of hypoglossal nerve palsies, the site of the lesion could not be localized in 6%.⁹In the radiologic diagnostic work-up, a segmental imaging approach is advised.^19–21 The medullary, cisternal, and skull base segments can be well examined with the existing protocols of MR imaging and CT. In the carotid and submandibular spaces, these imaging modalities are also recommended, but the nerve itself is usually not depicted.^19,20,22 We are not aware of any study of the feasibility of the direct visualization of the extracranial hypoglossal nerve, though ultrasound (US) has been increasingly used to visualize peripheral nerves to diagnose and localize pathologies affecting them.^23,24The aim of our study was to test the feasibility of direct visualization of the extracranial hypoglossal nerve with US in fresh cadavers, healthy volunteers, and patients with a suspected lesion of the hypoglossal nerve. A secondary objective was to provide data on the cross-sectional area of the hypoglossal nerve in our volunteer sample as a reference.     

The Diagnostic Value of CT Myelography,MR Myelography,and Both in Neonatal Brachial Plexus Palsy

BACKGROUND AND PURPOSE:Although most infants with brachial plexus palsy recover function spontaneously, approximately 10–30% benefit from surgical treatment. Pre-operative screening for nerve root avulsions is helpful in planning reconstruction. Our aim was to compare the diagnostic value of CT myelography, MR myelography, and both against a surgical criterion standard for detection of complete nerve root avulsions in birth brachial plexus palsy.MATERIALS AND METHODS:Nineteen patients who underwent a preoperative CT and/or MR myelography and subsequent brachial plexus exploration were included. Imaging studies were analyzed for the presence of abnormalities potentially predictive of nerve root avulsion. Findings of nerve root avulsion on surgical exploration were used as the criterion standard to assess the predictive value of imaging findings.RESULTS:Ninety-five root levels were examined. When the presence of any pseudomeningocele was used as a predictor, the sensitivity was 0.73 for CT and 0.68 for MR imaging and the specificity was 0.96 for CT and 0.97 for MR imaging. When presence of pseudomeningocele with absent rootlets was used as the predictor, the sensitivity was 0.68 for CT and 0.68 for MR imaging and the specificity was 0.96 for CT and 0.97 for MR imaging. The use of both CT and MR imaging did not increase diagnostic accuracy. Rootlet findings in the absence of pseudomeningocele were not helpful in predicting complete nerve root avulsion.CONCLUSIONS:Findings of CT and MR myelography were highly correlated. Given the advantages of MR myelography, it is now the single technique for preoperative evaluation of nerve root avulsion at our institution.

Brachial plexus palsy occurs in approximately 1 in 1000 neonates.^1,2 Downward traction on the shoulder girdle produces stereotyped patterns of plexus injury.³ Nerve lesions occur first at higher levels, with more severe traction resulting in progressive inferior extension.^3,4 More superior nerve injury is typically extraforaminal, at the level of the superior trunks, because a well-developed investing fascia protects the upper nerve roots from proximal traction. In contrast, inferior lesions are more often intraforaminal, manifesting as either partial or complete avulsion of the nerve root.⁴Clinical manifestations and spontaneous recovery depend on the extent, location, and type of nerve lesions. The clinical presentation can generally be grouped into 1 of 4 patterns outlined by Narakas⁵: Type I involves C5 and C6 deficits (Erb-Duchenne type) with loss of shoulder abduction, shoulder external rotation, elbow flexion, and forearm supination. Type II involves C5 to C7/C8 deficits, resulting in a “waiter''s tip” posture from additional loss of wrist extension. Type III involves C5 to C8/T1 deficits, resulting in an arm that is generally paralyzed. Type IV involves C5 to T1 and the sympathetic chain, resulting in a flail arm with Horner syndrome. Upward traction on the brachial plexus can result in isolated lower plexus deficits that manifest as paralysis of the hand only.^6,7 This pattern is known as Klumpke palsy.The decision to proceed with surgical exploration and reconstruction is based on the clinical presentation and progression. While 70%–90% of infants are treated with therapy alone, 10%–30% have indications for surgical treatment.^8–11 Nerve injuries distal to the intervertebral foramen can be reconstructed by using nerve grafts, whereas intraforaminal nerve root avulsions require nerve transfer. While both partial and complete nerve root avulsions are described,^12,13 there is no clear consensus on the surgical approach to partial nerve root avulsions. Preoperative imaging capable of accurately identifying complete nerve root avulsions and distinguishing them from extraforaminal nerve injuries is, therefore, critical for optimal surgical planning.The current standard for preoperative assessment of nerve root avulsions in infants is CT myelography.^12,14–19 A pseudomeningocele is suggestive of nerve root avulsion, and the additional finding of absent rootlets traversing the pseudomeningocele greatly increases the specificity of this finding.¹⁴ CT myelography requires a lumbar puncture for injection of intrathecal contrast, with attendant risks of infection and seizure.^20–22 Recent studies have also raised concern for malignancy with early exposure of children to radiation.^23,24 MR myelography can be performed without injection of contrast and is a promising alternative.^17,25 However, the performance of MR myelography for predicting nerve root avulsion is not yet established²⁶ in neonatal brachial plexus injury, and the diagnostic value of MR myelography has yet to be compared with CT myelography in this setting.The purpose of this study was to determine the predictive value of CT myelography, MR myelography, and both CT and MR myelography for detecting complete nerve root avulsions in neonatal brachial plexus palsy, by using a surgical criterion standard.     

Tympanic Plate Fractures in Temporal Bone Trauma: Prevalence and Associated Injuries

BACKGROUND AND PURPOSE:The prevalence of tympanic plate fractures, which are associated with an increased risk of external auditory canal stenosis following temporal bone trauma, is unknown. A review of posttraumatic high-resolution CT temporal bone examinations was performed to determine the prevalence of tympanic plate fractures and to identify any associated temporal bone injuries.MATERIALS AND METHODS:A retrospective review was performed to evaluate patients with head trauma who underwent emergent high-resolution CT examinations of the temporal bone from July 2006 to March 2012. Fractures were identified and assessed for orientation; involvement of the tympanic plate, scutum, bony labyrinth, facial nerve canal, and temporomandibular joint; and ossicular chain disruption.RESULTS:Thirty-nine patients (41.3 ± 17.2 years of age) had a total of 46 temporal bone fractures (7 bilateral). Tympanic plate fractures were identified in 27 (58.7%) of these 46 fractures. Ossicular disruption occurred in 17 (37.0%). Fractures involving the scutum occurred in 25 (54.4%). None of the 46 fractured temporal bones had a mandibular condyle dislocation or fracture. Of the 27 cases of tympanic plate fractures, 14 (51.8%) had ossicular disruption (P = .016) and 18 (66.6%) had a fracture of the scutum (P = .044). Temporomandibular joint gas was seen in 15 (33%) but was not statistically associated with tympanic plate fracture (P = .21).CONCLUSIONS:Tympanic plate fractures are commonly seen on high-resolution CT performed for evaluation of temporal bone trauma. It is important to recognize these fractures to avoid the preventable complication of external auditory canal stenosis and the potential for conductive hearing loss due to a fracture involving the scutum or ossicular chain.

There are many reports in the literature describing CT of temporal bone trauma,^1–4 detailing fracture plane orientations,^4–6 ossicular disruptions, otic capsule involvement,^4,5 associations with air in the temporomandibular joint (TMJ),⁷ facial nerve injury,^4–6 and fracture mimics, to name a few broad categories.⁸ Temporal bone fractures involving the tympanic plate (Figs 1 and ​and2),2), however, are under-recognized and have received little attention beyond isolated case reports involving mandibular trauma.^8–15 The tympanic plate of the temporal bone is a U-shaped structure forming the anterior wall, floor, and part of the posterior wall of the external auditory canal. The limited literature concerning tympanic plate fracture (TPF) suggests that these types of fractures are uncommon.^4,10,11,16 Most literature on direct and indirect CT findings of temporal bone trauma was published in the pre-/early multidetector CT era^1,3,7,17,18 or was based solely on non-high-resolution CT (HRCT) imaging,¹⁹; however, it is possible that posttraumatic TPFs are under-recognized or overlooked by the inexperienced observer. TPFs are important to identify, given the potential for the clinically significant long-term complications of external auditory canal stenosis and trismus.²⁰ The purpose of this study was to retrospectively review acute posttraumatic HRCT temporal bone studies to determine the true incidence of TPF and to identify other associated temporal bone injuries.Open in a separate windowFig 1.External sagittal view of the left temporal bone depicting the tympanic plate as it forms part of the anterior wall of the external auditory canal.Open in a separate windowFig 2.Oblique 3D view of the skull, including the external portion of the left temporal bone and the Pöschl plane for CT reformatting superimposed. This Pöschl plane view is depicted in the inset along with a TPF and some of the possible associated traumatic injuries.     

DTI Analysis of Presbycusis Using Voxel-Based Analysis

BACKGROUND AND PURPOSE:Presbycusis is the most common sensory deficit in the aging population. A recent study reported using a DTI-based tractography technique to identify a lack of integrity in a portion of the auditory pathway in patients with presbycusis. The aim of our study was to investigate the white matter pathology of patients with presbycusis by using a voxel-based analysis that is highly sensitive to local intensity changes in DTI data.MATERIALS AND METHODS:Fifteen patients with presbycusis and 14 age- and sex-matched healthy controls were scanned on a 3T scanner. Fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were obtained from the DTI data. Intergroup statistics were implemented on these measurements, which were transformed to Montreal Neurological Institute coordinates by using a nonrigid image registration method called large deformation diffeomorphic metric mapping.RESULTS:Increased axial diffusivity, radial diffusivity, and mean diffusivity and decreased fractional anisotropy were found near the right-side hearing-related areas in patients with presbycusis. Increased radial diffusivity and mean diffusivity were also found near a language-related area (Broca area) in patients with presbycusis.CONCLUSIONS:Our findings could be important for exploring reliable imaging evidence of presbycusis and could complement an ROI-based approach.

Age-related hearing loss, also known as presbycusis, is the most common sensory deficit in the aging population. Presbycusis is usually characterized by progressive hearing loss at high frequencies, which are particularly important for speech recognition. Hypofunction of the inner ear is the main reason for the peripheral component of presbycusis.¹ However, poor speech discrimination and deteriorated temporal sound processing reflect a possible central component of presbycusis.^2,3 Moreover, many animal studies have showed the existence of a central component of presbycusis.^4,5Recent studies of multiple MR imaging modalities have demonstrated their capabilities of offering reliable imaging markers for recognizing presbycusis. In a structural MR imaging study, the volume and surface area were decreased in the auditory cortex areas of patients with presbycusis compared with young healthy controls.⁶ In a functional MR imaging study, patients with presbycusis showed higher blood oxygen level–dependent activation in response to acoustic stimuli in the temporal lobes compared with young healthy controls.⁷The aforementioned imaging markers were mainly explored in gray matter, whereas white matter integrity, as one of the most sensitive indicators of axon damage or demyelination, requires further study. A widely used technique, DTI, has been considered as the most effective method for characterizing white matter organization. Multiple scalar measurements, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (DA), and radial diffusivity (DR), can be calculated from DTI data through tensor calculation. These measurements are useful indicators for characterizing various types of pathology in the human brain.Many DTI studies have reported changes in the auditory pathway and auditory cortex in patients with sensorineural hearing loss.^8,9 To our knowledge, only 1 study has reported a lack of white matter integrity in patients with mild presbycusis by applying an intergroup statistic on the ROI-based features, which was in the form of reconstructed auditory tracts.⁶ Besides that, the study showed no obvious differences in any measured DTI parameters between mild presbycusis and expressed presbycusis. Although promising, a more reliable imaging marker of presbycusis could be established by designing more sophisticated experiments. First, the reconstructed auditory pathway was partly obscured by the optic radiation. This so-called “fiber-crossing issue” could be mitigated by using probabilistic tractography; however, the “gold standard” for validating the tractography, especially in the fiber-crossing area, has not been established. In addition, though using the average characteristic with an ROI is an effective manner of dimensional reduction and noise filtering,¹⁰ a limitation is its reduced sensitivity to localized anatomic alterations that only affect parts of a predefined structure.¹¹ Therefore, we used a voxel-based analysis, which might be considered as an alternative way to explore the imaging makers of presbycusis in the white matter.     

The Role of MRI in Diagnosing Neurovascular Compression of the Cochlear Nerve Resulting in Typewriter Tinnitus

BACKGROUND AND PURPOSE:Typewriter tinnitus, a symptom characterized by paroxysmal attacks of staccato sounds, has been thought to be caused by neurovascular compression of the cochlear nerve, but the correlation between radiologic evidence of neurovascular compression of the cochlear nerve and symptom presentation has not been thoroughly investigated. The purpose of this study was to examine whether radiologic evidence of neurovascular compression of the cochlear nerve is pathognomonic in typewriter tinnitus.MATERIALS AND METHODS:Fifteen carbamazepine-responding patients with typewriter tinnitus and 8 control subjects were evaluated with a 3D T2-weighted volume isotropic turbo spin-echo acquisition sequence. Groups 1 (16 symptomatic sides), 2 (14 asymptomatic sides), and 3 (16 control sides) were compared with regard to the anatomic relation between the vascular loop and the internal auditory canal and the presence of neurovascular compression of the cochlear nerve with/without angulation/indentation.RESULTS:The anatomic location of the vascular loop was not significantly different among the 3 groups (all, P > .05). Meanwhile, neurovascular compression of the cochlear nerve on MR imaging was significantly higher in group 1 than in group 3 (P = .032). However, considerable false-positive (no symptoms with neurovascular compression of the cochlear nerve on MR imaging) and false-negative (typewriter tinnitus without demonstrable neurovascular compression of the cochlear nerve) findings were also observed.CONCLUSIONS:Neurovascular compression of the cochlear nerve was more frequently detected on the symptomatic side of patients with typewriter tinnitus compared with the asymptomatic side of these patients or on both sides of control subjects on MR imaging. However, considering false-positive and false-negative findings, meticulous history-taking and the response to the initial carbamazepine trial should be regarded as more reliable diagnostic clues than radiologic evidence of neurovascular compression of the cochlear nerve.

Arterial compression of the cochleovestibular nerve complex has been suggested as a potential cause of hearing deficit, typewriter tinnitus, and equilibrium disturbance or vertigo.^1–4 Among these clinical symptoms, typewriter tinnitus, which was first described by a pediatric cardiologist as “ear-clicking tinnitus responding to carbamazepine,”⁵ is characterized by paroxysmal attacks. It is either spontaneous or precipitated by positioning or sounds and occurs with staccato sounds described as “Morse code,” “machine gun,” “coins in a can,” “crackling,” or “typewriter” sounds.^6–8 Typewriter tinnitus is considered the result of dysmyelination and demyelination of the contact point between the arterial loop and the cochlear nerve that transmits an abnormal signal to the auditory cortex.⁹ As in other vascular compression syndromes such as trigeminal neuralgia, typewriter tinnitus is highly responsive to carbamazepine.^6–8,10,11 Complete suppression of tinnitus with carbamazepine treatment, in addition to its paroxysmal character, has led to the hypothesis that typewriter tinnitus results from neurovascular compression of the cochlear nerve (NVC-C), for which microvascular compression would be an effective treatment.^6,7However, because typewriter tinnitus is a relatively rare condition and was only recently described, few studies have been performed investigating the relationship between radiologic evidence of cochlear nerve compression on MR imaging and the presence of typewriter tinnitus, to our knowledge. A few previous studies investigating subjects with typewriter tinnitus with carbamazepine responsiveness showed evidence of NVC-C on T2-weighted CISS images; however, the sample sizes were relatively small (4 and 5 subjects, respectively), and no control subjects without tinnitus were included.^6,10 Moreover, signs of neurovascular compression have frequently been detected on MR imaging in asymptomatic patients, which raises questions about the role of MR imaging in the diagnosis of typewriter tinnitus.^7,12Thus, in this study, we aimed to evaluate MR imaging findings of subjects with typewriter tinnitus with regard to the presence of radiologic evidence of cochlear nerve compression by performing a 3D T2-weighted volume isotropic turbo spin-echo acquisition (T2-VISTA; Phillips Healthcare, Best, the Netherlands) sequence on 3T MR imaging to effectively visualize neurovascular compression. In other words, the purpose of the current study was to examine whether radiologic evidence of cochlear nerve compression is pathognomonic in subjects with typewriter tinnitus.     

Pretreatment ADC Values Predict Response to Radiosurgery in Vestibular Schwannomas

BACKGROUND AND PURPOSE:The response rate of vestibular schwannomas to radiation therapy is variable, and there are surgical options available in the event of treatment failure. The aim of this study was to determine whether pre- and posttreatment ADC values can predict the tumor response to radiation therapy.MATERIALS AND METHODS:From a data base of 162 patients with vestibular schwannomas who underwent radiation therapy with gamma knife, CyberKnife, or fractionated stereotactic radiation therapy as the first-line therapy between January 2003 and December 2013, we found 20 patients who had pretreatment ADC values. There were 108 patients (including these 20) had serial MR images that included DWI allowing calculated ADC values from 2–132 months after radiation therapy. Two reviewers measured the mean, minimum, and maximum ADC values from elliptical ROIs that included tumor tissue only. Treatment responders were defined as those with a tumor total volume shrinkage of 20% or more after radiation therapy.RESULTS:The pretreatment mean minimum ADC for nonresponders was 986.7 × 10⁻⁶ mm²/s (range, 844–1230 × 10⁻⁶ mm²/s) and it was 669.2 × 10⁻⁶ mm²/s (range, 345–883 × 10⁻⁶ mm²/s) for responders. This difference was statistically significant (P < .001). Using a minimum ADC value of 800 × 10⁻⁶ mm²/s led to the correct classification of 18/20 patients based on pretreatment ADC values. The intraclass correlation between reviewers was 0.61. No posttreatment ADC values predicted response.CONCLUSIONS:Pretreatment ADC values of vestibular schwannomas are lower in responders than nonresponders. Using a minimum ADC value of 800 × 10⁻⁶ mm²/s correctly classified 90% of cases.

Tumors localized in the cerebellopontine angle comprise 5%–10% of all intracranial tumors.¹ Vestibular schwannomas (VSs) are the most common tumors in the cerebellopontine angle, accounting for 80% of all tumors there.^2,3 Epidemiologic data of VSs suggest the most common patients to be white and aged 50–60 years, with equal distribution between the sexes.⁴The diagnosis of VS is suggested by symptoms that may include tinnitus, hearing loss, trigeminal neuropathy, facial nerve palsy, unstable gait, or increased intracranial pressure.^5,6 High-resolution MR imaging has led to a greater number of smaller VSs being diagnosed in recent decades.⁷Few studies have evaluated the appearance of vestibular schwannomas on DWI. Chuang and colleagues⁸ have proposed that high ADCs of VSs may correlate with Antoni type B, which is associated with a cystic tumor pattern. However, this correlation is still controversial because the reviewed literature has not proved the correlation between Antoni type dominance and cystic composition.⁹ Tumors with sparse cellularity (Antoni B type) are associated with higher ADC values compared with tumors with an attenuated cellularity.¹⁰The options for managing VS include observation, surgery, and radiation therapy.^11–14 Usually, newly diagnosed and small VSs are managed expectantly with serial imaging follow-up and observation because many tumors remain stable over long periods of time. However, up to half of the tumors grow within 5 years of follow-up.¹⁵ Studies also state, however, that a wait-and-see policy is not recommended for patients with cystic tumors^16,17 because they tend to be larger and usually have a more rapid clinical evolution.^6,18 Specifically, for cystic VS, surgical treatment is the best option, and it is associated with better results than radiosurgery.¹ Other than in this cystic VS scenario, where the recommendation is firm, patient preference becomes paramount in the selection between surgery and radiosurgery for treatment. Both are considered appropriate, with similarly acceptable side effects and long-term success. The decision may be guided by multiple variables, such as the size at initial diagnosis, tumor growth rate on serial imaging, or patient symptoms.^7,19 More reliable patient-specific predictors of outcome with therapy are needed to guide patients and physicians in this important decision.ADC is a measure of the random motion of water molecules within a tissue, and it is calculated by using data from DWI or DTI.^20,21 ADC values have been shown to be correlated with astrocytoma tumor grading and tumor cellularity.^19,20 ADC measurements may serve as diagnostic and prognostic biomarkers as well as predictors of tumor response to treatment in glial tumors.^22,23 Thus, ADC values are often used in treatment planning.²⁴The aim of this study was to determine whether the pre- and posttreatment ADC values may be associated with the response of VS to radiosurgery and to provide guidance for further study.     

Symptom Differences and Pretreatment Asymptomatic Interval Affect Outcomes of Stenting for Intracranial Atherosclerotic Disease

BACKGROUND AND PURPOSE:Different types of symptomatic intracranial stenosis may respond differently to interventional therapy. We investigated symptomatic and pathophysiologic factors that may influence clinical outcomes of patients with intracranial atherosclerotic disease who were treated with stents.MATERIALS AND METHODS:A retrospective analysis was performed of patients treated with stents for intracranial atherosclerosis at 4 centers. Patient demographics and comorbidities, lesion features, treatment features, and preprocedural and postprocedural functional status were noted. χ² univariate and multivariate logistic regression analysis was performed to assess technical results and clinical outcomes.RESULTS:One hundred forty-two lesions in 131 patients were analyzed. Lesions causing hypoperfusion ischemic symptoms were associated with fewer strokes by last contact [χ² (1, n = 63) = 5.41, P = .019]. Nonhypoperfusion lesions causing symptoms during the 14 days before treatment had more strokes by last contact [χ² (1, n = 136), 4.21, P = .047]. Patients treated with stents designed for intracranial deployment were more likely to have had a stroke by last contact (OR, 4.63; P = .032), and patients treated with percutaneous balloon angioplasty in addition to deployment of a self-expanding stent were less likely to be stroke free at point of last contact (OR, 0.60; P = .034).CONCLUSIONS:More favorable outcomes may occur after stent placement for lesions causing hypoperfusion symptoms and when delaying stent placement 7–14 days after most recent symptoms for lesions suspected to cause embolic disease or perforator ischemia. Angioplasty performed in addition to self-expanding stent deployment may lead to worse outcomes, as may use of self-expanding stents rather than balloon-mounted stents.

Intracranial atherosclerotic disease (ICAD) causes considerable morbidity and mortality, accounting for up to one-third of ischemic strokes in some series, particularly in certain populations.^1–3 Some lesions prove recalcitrant to first-line medical management, and, in recent decades, endovascular treatments have emerged and evolved as complementary therapies.^4,5 Early series demonstrated technical feasibility and acceptable safety for percutaneous transluminal angioplasty (PTA) and then stent placement of lesions in ICAD.^5–17 Initially, intracranial procedures were performed with devices designed and approved for coronary interventions, with subsequent release of angioplasty balloons specifically engineered for intracranial use.^5,12,17–33 In 2005, the Wingspan stent system with Gateway PTA balloon catheter (Stryker, Kalamazoo, Michigan) became the first stent approved for treatment of ICAD in the United States.^{5,12,18–22,25,34} Numerous studies reported progressively improved outcomes and low complication rates, but randomized data proving efficacy were lacking.^{5,12,18,20,24,25,35,36} In 2011, enrollment in the first randomized, controlled trial to evaluate stent placement versus medical management of ICAD, the Stent placement and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial, was halted early due to high complication rates in the stent placement group as compared with the medical management group.⁴The results of SAMMPRIS have elicited strong responses from both proponents and detractors of stent placement, with clinical decisions now changing.⁵ This current study retrospectively analyzes results of stent placement procedures performed for ICAD at 4 centers, with attention given to factors not specifically assessed in SAMMPRIS that may help guide further investigations of endovascular ICAD management.     

Cranial Arachnoid Protrusions and Contiguous Diploic Veins in CSF Drainage

BACKGROUND AND PURPOSE:Studies have suggested that arachnoid villi or granulations found in the walls of the cranial dural sinuses, olfactory mucosa, and cranial nerve sheaths function as outlets for intracranial CSF. However, their role as CSF outlets has not yet been verified. Here we show that arachnoid protrusions and contiguous diploic veins provide an alternative drainage route for intracranial CSF.MATERIALS AND METHODS:Four hundred patients with intact skull, dura mater, and dural sinuses underwent MR imaging to explore arachnoids protruding into the skull and diploic veins. Patients with symptoms of increased intracranial pressure or intracranial hypotension were excluded. For 15 patients undergoing craniotomy, both peripheral and diploic venous blood was collected. Albumin and the CSF-specific biomarkers were measured by enzyme-linked immunosorbent assay.RESULTS:With MR imaging, arachnoid protrusions into the skull and contiguous diploic veins were consistently identified throughout the cranium with their characteristic appearance depending on the cranial region. In addition, elevated amounts of prostaglandin D synthase and cystatin C were confirmed in diploic veins compared with peripheral venous blood.CONCLUSIONS:Diploic veins are distributed ubiquitously throughout the cranium. A portion of the intracranial CSF may be drained through arachnoid protrusions and contiguous diploic veins.

It has been suggested that arachnoid villi or granulations found in the walls of the cranial dural sinuses, olfactory mucosa, and cranial nerve sheaths function as outlets for intracranial CSF.^1–4 Arachnoid granulations located adjacent to or in the cranial dural sinuses have been explored by using a variety of methods, including neuroimaging,^5–15 postmortem dissection,^5,16,17 investigations by using casting material,¹⁸ and ex vivo studies.¹ However, no report has actually shown the process of CSF absorption in vivo. Diploic veins (DVs) are present throughout the cranium; however, their distribution and functional implications have rarely been documented.^1,19 One previous MR imaging study proposed the hypothesis that major pathways of the DVs function as CSF drainage routes.¹⁹Lipocalin-type prostaglandin D synthase (PGDS) is a major endogenous β chaperone that is present in the brain and secreted into the CSF.^20,21 It is thought to be a CSF-specific biomarker and sensitive to inflammatory demyelinating disease,²² Alzheimer disease,²³ and normal pressure hydrocephalus.¹⁹ Cystatin C (CysC), a low-molecular-weight cysteine proteinase inhibitor, is known to be expressed in greater amounts in CSF compared with plasma.²⁴ The purpose of the present study was to demonstrate that arachnoid pouches protruding into the skull (APs) and contiguous diploic veins provide an alternative CSF drainage route by high-resolution MR imaging; and we also aimed to measure CSF-specific biomarkers, PGDS, and CysC.     

Localizing the L5 Vertebra Using Nerve Morphology on MRI: An Accurate and Reliable Technique

BACKGROUND AND PURPOSE:Multiple methods have been used to determine the lumbar vertebral level on MR imaging, particularly when full spine imaging is unavailable. Because postmortem studies show 95% accuracy of numbering the lumbar vertebral bodies by counting the lumbar nerve roots, attention to lumbar nerve morphology on axial MR imaging can provide numbering clues. We sought to determine whether the L5 vertebra could be accurately localized by using nerve morphology on MR imaging.MATERIALS AND METHODS:One hundred eight cases with full spine MR imaging were numbered from the C2 vertebral body to the sacrum with note of thoracolumbar and lumbosacral transitional states. The origin level of the L5 nerve and iliolumbar ligament were documented in all cases. The reference standard of numbering by full spine imaging was compared with the nerve morphology numbering method. Five blinded raters evaluated all lumbar MRIs with nerve morphology technique twice. Prevalence and bias-adjusted κ were used to measure interrater and intrarater reliability.RESULTS:The L5 nerve arose from the 24th presacral vertebra (L5) in 106/108 cases. The percentage of perfect agreement with the reference standard was 98.1% (95% CI, 93.5%–99.8%), which was preserved in transitional and numeric variation states. The iliolumbar ligament localization method showed 83.3% (95% CI, 74.9%–89.8%) perfect agreement with the reference standard. Inter- and intrarater reliability when using the nerve morphology method was strong.CONCLUSIONS:The exiting L5 nerve can allow accurate localization of the corresponding vertebrae, which is essential for preprocedure planning in cases where full spine imaging is not available. This neuroanatomic method displays higher agreement with the reference standard compared with previously described methods, with strong inter- and intrarater reliability.

Accurate and reliable spine numbering is important for the diagnosis of pathology and preprocedure planning. This can be challenging in patients with vertebral numeric variation (VNV) or lumbosacral transitional vertebrae (LSTV), particularly when full spine imaging is unavailable. VNV refers to the variation of the total number of presacral vertebrae (PSV). Approximately 89% of the population have 24 PSV (5 lumbar-type vertebrae), 8% have 25 PSV (6 lumbar-type vertebrae), and 3% have 23 PSV (4 lumbar-type vertebrae).¹ LSTV are congenital spinal anomalies in which an elongated transverse process of the last lumbar vertebra fuses with the “first” sacral segment to varying degrees.² The morphologic variation of LSTV can range from partial/complete L5 sacralization to partial/complete S1 lumbarization.^3,4 The prevalence of LSTV in the population varies throughout the literature because of differences in definition and diagnostic modalities.^1,4–6 LSTV can also vary with sex, with lumbarization of S1 seen more commonly in women and sacralization found to be more common in men.³ A person can have VNV without LSTV, or conversely, one can have LSTV without VNV.¹ Approximately 5% of subjects have been found to have both.¹Multiple anatomic landmarks have been used to determine the lumbar vertebral level in cases without full spine imaging. A leading method of localizing the iliolumbar ligament, most frequently arising from L5, has been found less accurate in the setting of LSTV and VNV.^7–11 Other landmarks, including the level of the conus, right renal artery, superior mesenteric artery, aortic bifurcation, and iliac crest height, are also less accurate.^9,12–14 Choosing the appropriate level for surgical or interventional procedures is essential and relies on accurately and reliably numbering the spine in patients with “normal” anatomy as well as those with variant or transitional anatomy.^4,15 This is especially important in patients with LSTV and/or VNV undergoing surgical planning, as up to 32% of neurosurgeons have reported an event of wrong-level spinal surgery occurring at least once in their careers.¹⁶ LSTV can also create challenges for approach in interventional pain procedures and can increase the risk of iatrogenic vascular injury.¹⁷Multiple imaging modalities have been used to evaluate LSTV and VNV, with MR imaging found to be most reliable.¹⁸ Anteroposterior radiographs have demonstrated high intermodality agreement with MR imaging.¹⁹ Studies show that one can accurately number the vertebrae by counting down from C2 to the sacrum on sagittal MR imaging by using a cross-referencing tool.^1,8,19,20 Although most counting methods have focused on the ossified structures, 1 postmortem study numbered the vertebrae by dorsal spinal nerve morphology and found up to 95% probability that the lower spinal nerves correspond to their respective spinal segment.²¹ We hypothesized that nerve morphology on lumbar spine MR imaging would aid in L5 vertebra localization, particularly when full spine imaging was not available. We aimed 1) to determine whether MR imaging morphologic features of the lumbar nerves could be used to distinguish the lower lumbar levels and 2) to apply these characteristics in localizing the L5 vertebra.     

Cranial Nerve Abnormalities in Oculo-Auriculo-Vertebral Spectrum

BACKGROUND AND PURPOSE:Cranial nerve abnormalities might be observed in hemifacial microsomia and microtia (oculo-auriculo-vertebral spectrum), but the rate, features, and relationship with functional impairment or phenotype severity have not yet been defined. This study aimed at investigating absence/asymmetry, abnormal origin, morphology and course of cranial nerves, and presence/asymmetry of the foramen ovale and inferior alveolar nerve canal in a cohort of oculo-auriculo-vertebral spectrum patients.MATERIALS AND METHODS:Twenty-nine patients with oculo-auriculo-vertebral spectrum (mean age, 7 years; age range, 0.2–31 years; 12 females) underwent brain MR imaging, CT, and neurologic evaluation; 19 patients had a more severe phenotype (Goldenhar syndrome).RESULTS:Cranial nerve abnormalities were detected only in patients with Goldenhar syndrome (17/19, bilaterally in 8) and were involved the second (4/19), third (1/18), fifth (11/19), sixth (8/16), seventh (11/18), and eighth (8/18) cranial nerves. Multiple cranial nerve abnormalities were common (11/17). Eleven patients showed bone foramina abnormalities. Trigeminal and facial nerve dysfunctions were common (44% and 58%, respectively), especially in patients with Goldenhar syndrome. Trigeminal abnormalities showed a good correlation with ipsilateral dysfunction (P = .018), which further increased when bone foramina abnormalities were included. The facial nerve showed a trend toward correlation with ipsilateral dysfunction (P = .081). Diplopia was found only in patients with Goldenhar syndrome and was associated with third and sixth cranial nerve abnormalities (P = .006).CONCLUSIONS:Among patients with oculo-auriculo-vertebral spectrum, cranial nerve morphologic abnormalities are common, correlate with phenotype severity, and often entail a functional impairment. The spectrum of cranial nerve abnormalities appears wider than simple hypo-/aplasia and includes an anomalous cisternal course and partial/complete fusion of diverse cranial nerves.

Oculo-auriculo-vertebral spectrum (OAVS) (Online Mendelian Inheritance in Man, 164210)¹ is a rare heterogeneous congenital condition (incidence, 1:3500–5600 live births; male/female ratio, 3:2),^2–4 in which the head structures originating from the first and second pharyngeal arches are incompletely developed on 1 (85% of cases) or both sides.^3,5 The disease mostly results in ear (microtia) and jaw (hemifacial microsomia) abnormalities (On-line Fig 1). Nonetheless, the abnormality spectrum might be fairly wide, from mild external and medium ear involvement or isolated facial asymmetry to anotia with complex facial deformity. The most severe cases also present with eye or spine involvement and are known as Goldenhar syndrome from the French ophthalmologist who first described the syndrome in 1952.⁶ Familial history suggestive of both autosomal recessive and dominant inheritance has been reported, and genes on chromosomes 5, 12, 14, and 22 have been implicated.^7–10 However, most cases of OAVS are sporadic and without a known etiology. Abnormal embryonic vascular supply,¹¹ hematomas, and drug use during the early phases of gestation have been reported to cause the disruption of mesodermal migration, leading to defective formation of bone and soft-tissue structures.¹²Most interesting, a few case reports and small series studies have shown a concomitant impairment of cranial nerves (CNs),^13–26 highlighting the possible involvement of neural structures in OAVS and addressing its potentially relevant clinical impact. To date, the underlying anatomic and structural CN abnormalities have been poorly investigated because the available data rely on anecdotal postmortem examination¹⁷ or neuroimaging findings.¹⁹ Additionally, the overall frequency of CN abnormalities, their association with CN dysfunction, and the relationship with the OAVS phenotype severity have not yet been defined, to our knowledge.In the past few years, MR imaging has become a powerful tool for investigating in vivo the cisternal segment of the CNs. With routinely available 1.5T MR imaging scanners and dedicated high-resolution sequences, it is possible to verify the presence and characterize the morphology, diameter, and cisternal course of most CNs. CN MR imaging evaluation has, therefore, become helpful for diagnosing several conditions such as Kallmann syndrome, optic neuritis, septo-optic dysplasia, neurovascular conflicts, and so forth. Moreover, the evaluation of the intrameatal branches of CN VIII is included in the diagnostic work-up of implant planning in patients with congenital profound hearing loss. Besides, because skull base foramina and bone canal development is induced by the presence of the corresponding CN branch,²⁷ CN abnormalities might be also indirectly inferred by bone CT. Absence or hypoplasia/stenosis of the facial canal, internal acoustic canal, foramina ovalia and rotundum, hypoglossal canal, or inferior alveolar canal might indicate hypoplasia or aplasia of the relative nerves and branches.Therefore, MR imaging and CT might help to detect or raise the suspicion of morphologic CN abnormalities providing relevant information, especially when the CN impairment is difficult to evaluate due to early age, concomitant facial bone and soft-tissue asymmetry, or poor compliance of patients with OAVS.The present study aims at investigating, in patients with OAVS, the rate of CN abnormalities, the type (eg, agenesia, hypoplasia, abnormal origin, or cisternal course), the association with functional impairment, and the side of hemifacial microsomia as well as the relationship with the phenotype severity.     

Immunoglobulin G4–Related Disease of the Orbit: Imaging Features in 27 Patients

BACKGROUND AND PURPOSE:Immunoglobulin G4–related disease is a systemic fibroinflammatory process of unknown etiology, characterized by tissue infiltration by immunoglobulin G4 plasma cells. The purpose of this study was to retrospectively identify the spectrum of imaging features seen in immunoglobulin G4–related disease of the orbit.MATERIALS AND METHODS:This study included 27 patients with biopsy-proved immunoglobulin G4–related disease of the orbit and either a CT or MR imaging of the orbits. These CT or MR imaging examinations were evaluated for the following: extraocular muscle size, extraocular muscle tendon enlargement, lacrimal gland enlargement, infiltrative process in the orbital fat (increased attenuation on CT or abnormal signal on MR imaging), infraorbital nerve enlargement, mucosal thickening in the paranasal sinuses, and extension of orbital findings intracranially.RESULTS:Extraocular muscles were enlarged in 24 of 27 (89%) patients, 21 (88%) bilaterally. In 32 of 45 (71%) affected orbits, the lateral rectus was the most enlarged muscle. In 26 (96%) patients, the tendons of the extraocular muscles were spared. Nineteen (70%) patients had lacrimal gland enlargement. Twelve (44%) patients had an infiltrative process within the orbital fat. Infraorbital nerve enlargement was seen in 8 (30%) patients. Twenty-four (89%) patients had sinus disease. Cavernous sinus or Meckel cave extension was seen in 3 (11%) patients.CONCLUSIONS:In patients with extraocular muscle enlargement, particularly when the tendons are spared and the lateral rectus is the most enlarged, and even more so when other noted findings are present, immunoglobulin G4–related disease should be a leading differential consideration, even over more commonly known etiologies of extraocular muscle enlargement.

Immunoglobulin G4 (IgG4)-related disease is a systemic inflammatory process of unknown etiology, characterized by tissue infiltration by IgG4 plasma cells and sclerosing inflammation.^1–5 Although initially described in association with autoimmune pancreatitis, manifestations of IgG4-related disease are now reported in nearly every organ system.^1–3,5–10Multiple case reports and small case series of orbital manifestations of IgG4-related disease have noted involvement of the extraocular muscles, lacrimal glands, and infraorbital nerve,^1,2,4,7–19 but these small series do not allow evaluation of the typical patterns of imaging findings in IgG4-related disease. The purpose of this study was to retrospectively identify the spectrum of imaging features seen in IgG4-related disease of the orbit. Ideally, these characteristics will help clinicians and radiologists recognize IgG4-related orbital disease among a broad differential of orbital pathologies.     

High-Resolution MRI of the Intraparotid Facial Nerve Based on a Microsurface Coil and a 3D Reversed Fast Imaging with Steady-State Precession DWI Sequence at 3T

BACKGROUND AND PURPOSE:3D high-resolution MR imaging can provide reliable information for defining the exact relationships between the intraparotid facial nerve and adjacent structures. The purpose of this study was to explore the clinical value of using a surface coil combined with a 3D-PSIF-DWI sequence in intraparotid facial nerve imaging.MATERIALS AND METHODS:Twenty-one healthy volunteers underwent intraparotid facial nerve scanning at 3T by using the 3D-PSIF-DWI sequence with both the surface coil and the head coil. Source images were processed with MIP and MPR to better delineate the intraparotid facial nerve and its branches. In addition, the SIR of the facial nerve and parotid gland was calculated. The number of facial nerve branches displayed by these 2 methods was calculated and compared.RESULTS:The display rates of the main trunk, divisions (cervicofacial, temporofacial), and secondary branches of the intraparotid facial nerve were 100%, 97.6%, and 51.4% by head coil and 100%, 100%, and 83.8% by surface coil, respectively. The display rate of secondary branches of the intraparotid facial nerve by these 2 methods was significantly different (P < .05). The SIRs of the intraparotid facial nerve/parotid gland in these 2 methods were significantly different (P < .05) at 1.37 ± 1.06 and 1.89 ± 0.87, respectively.CONCLUSIONS:The 3D-PSIF-DWI sequence combined with a surface coil can better delineate the intraparotid facial nerve and its divisions than when it is combined with a head coil, providing better image contrast and resolution. The proposed protocol offers a potentially useful noninvasive imaging sequence for intraparotid facial nerve imaging at 3T.

3D high-resolution MR imaging can provide reliable information for depicting normal intraparotid facial nerve anatomy and defining the exact relationship of the intraparotid facial nerve and adjacent structures; this information could assist in the planning of parotid tumor surgery.¹ Imaging the intraparotid course of the facial nerve is a challenge due to the fine structure and complex anatomy of the nerve.^1–4 With recent advances in MR imaging technology, especially the use of surface coils combined with 3D high-resolution MR imaging technology, increased attention has been directed to intraparotid facial nerve imaging.^1–4 The inherent resolution of a surface coil itself is significantly better than that of a head coil, ensuring high-quality imaging for fine structures, particularly in superficial organs such as the parotid gland or eye.^1,5 Recently, 3D high-resolution sequences such as 3D gradient-recalled acquisition in the steady state sequence and 3D FIESTA have been applied to intraparotid facial nerve imaging.^2–4 These sequences rely mainly on the fat within the parotid gland as a high signal background to show the facial nerve because both the intraparotid facial nerve and the parotid duct are visualized as linear structures of low intensity.^2–4 In another report, the intraparotid facial nerve showed low signal compared with the high intensity of the parotid duct by using a balanced turbo-field echo, thus avoiding confusion between these 2 structures; however, no volumetric images were obtained,⁶ and MPR or curved planar reconstruction was not available. Thus, although there are several MR imaging sequences that can delineate the intraparotid facial nerve and parotid duct, limitations remain. The aim of this study was to explore the capabilities of simultaneously displaying the intraparotid facial nerve and parotid duct by using a surface coil combined with 3D-PSIF-DWI on a 3T MR imaging scanner.     

Vision Outcomes and Major Complications after Endovascular Coil Embolization of Ophthalmic Segment Aneurysms

BACKGROUND AND PURPOSE:As aneurysms arising from the ophthalmic segment of the internal carotid artery increase in size, they can compress the optic nerve, prompting patients to present with visual disturbances. The purpose of this article is to describe the clinical and angiographic results with an emphasis on visual outcomes following the endovascular treatment of ophthalmic segment ICA aneurysms.MATERIALS AND METHODS:The records of 1254 patients who presented for endovascular treatment of a cerebral aneurysm were retrospectively reviewed to identify 65 consecutive patients who underwent coil embolization of an ophthalmic segment ICA aneurysm. The clinical records, treatment reports, and imaging were reviewed with a focus on visual outcomes.RESULTS:Twenty-two of the 65 patients (34%) who presented for treatment of an ophthalmic aneurysm reported a visual disturbance at presentation. Fifteen of the 22 patients (68%) experienced an improvement in their symptoms after treatment. Overall, patients with visual symptoms were significantly more likely to benefit from treatment than to have a decline in vision (P = .03). The overall morbidity was 4%, and mortality was 0%. The retreatment rate was high at 30%, though this was disproportionately weighted by an 86% retreatment rate in patients with ruptured aneurysms.CONCLUSIONS:Patients with visual symptoms attributable to ophthalmic segment ICA aneurysms undergoing endovascular coil embolization were statistically more likely to experience an improvement in their vision than to have worsening or unchanged vision. Coiling was associated with a low morbidity rate, though an elevated retreatment rate.

Aneurysms arising from the ophthalmic segment of the internal carotid artery account for approximately 5% of all intracranial aneurysms.^1,2 As these aneurysms increase in size, they can compress the optic nerve, prompting the patient to present with visual disturbances, often involving the inferior and/or nasal fields first.^2,3 Both surgical and endovascular treatment of these aneurysms have shown the potential to improve visual disturbances if occurring early.^2,4–11 However, treatment of these aneurysms is not without its own set of inherent risks. Retinal artery occlusion or delayed optic ischemia may occur after either surgical or endovascular repair.^12–14 A review of recent surgical literature suggests a permanent morbidity ranging from 3% to 38% following treatment of an ophthalmic segment ICA aneurysm.^{3,5,6,10,15–18} This morbidity includes a risk of new or worsened visual disturbance in 2%–30% of surgically treated patients and 3%–8% of endovascularly treated patients.^3,5,6,15,16This article assesses the angiographic and clinical outcomes of 65 consecutive patients who presented for initial treatment of an ophthalmic segment ICA aneurysm via an endovascular approach. Our goal is to describe the clinical and angiographic outcomes with an emphasis on visual outcomes following the endovascular treatment of ophthalmic segment aneurysms.     

Cortical Activation Through Passive-Motion Functional MRI

BACKGROUND AND PURPOSE:Functional brain mapping is an important technique for neurosurgical planning, particularly for patients with tumors or epilepsy; however, mapping has traditionally involved invasive techniques. Existing noninvasive techniques require patient compliance and may not be suitable for young children. We performed a retrospective review of our experience with passive-motion functional MR imaging in anesthetized patients to determine the diagnostic yield of this technique.MATERIALS AND METHODS:A retrospective review of patients undergoing passive-motion fMRI under general anesthesia at a single institution over a 2.5-year period was performed. Clinical records were evaluated to determine the indication for fMRI, the ability to detect cortical activation, and, if present, the location of cortical activation.RESULTS:We identified 62 studies in 56 patients in this time period. The most common indication for fMRI was epilepsy/seizures. Passive-motion fMRI identified upper-extremity cortical activation in 105 of 119 (88%) limbs evaluated, of which 90 (86%) activations were in an orthotopic location. Lower-extremity cortical activation was identified in 86 of 118 (73%) limbs evaluated, of which 73 (85%) activations were in an orthotopic location.CONCLUSIONS:Passive-motion fMRI was successful in identifying cortical activation in most of the patients. This tool can be implemented easily and can aid in surgical planning for children with tumors or candidates for epilepsy surgery, particularly those who may be too young to comply with existing noninvasive functional measures.

The criterion standard for presurgical brain mapping has typically been intraoperative cortical stimulation mapping and the Wada test.^1–4 Both methods are invasive procedures, and their efficacy and superiority over other mapping procedures have become less clear with advances in noninvasive brain-mapping techniques,^4–12 with some studies showing that these alternative methods are comparable to stand-alone and/or adjunct techniques.^9–18 Blood oxygen level–dependent functional MR imaging is an increasingly used imaging technique in the clinical setting. Since the early 1990s, it has been used to study brain function in healthy individuals and particularly for surgical planning in patients with brain tumors or epilepsy.^{2,4,17,19–22} This imaging technique maps areas of cortical activation via changes in blood flow to metabolically active brain regions during cortical activation, typically secondary to specific motor, language, and visual tasks. fMRI provides a number of benefits: it is noninvasive, it is a useful tool for presurgical evaluation for invasive procedures that involve high risk,^{2,4,17,19,20,23,24} and it can also assess the current function of patients with brain lesions or previous brain surgery.^20,25 Clinically, it is performed as a task-based technique that requires the patient to cooperate and keep all other body movements to a minimum. Incomplete compliance limits the utility of this technology and introduces risk for spurious results. Compliance with the tasks and remaining still is a particular concern in young children and patients with developmental or acquired cognitive deficits.^26,27 Even children who can perform the task during training sessions may not be able to comply in the MR imaging scanner.²⁷A strategy that allows this information to be obtained from subjects who are unable to cooperate is to perform a similar fMRI task under sedation. fMRI of sedated patients performed with passive motion of the extremities has been successful in some reports.^{15,23,24,28,29} The goal is to map the motor cortex while removing the need for task compliance and reducing or eliminating concerns for patient motion.^23,24,28 We performed a retrospective review of our institution''s 2.5-year experience with passive-motion fMRI to assess the feasibility and reliability of this imaging technique.     

CT-guided injection of the anterior and middle scalene muscles: technique and complications

BACKGROUND AND PURPOSE:Anterior scalene block is a helpful diagnostic test for NTOS and a good predictor of surgical outcome. The purpose of this study was to describe the technique, success rate, and complications associated with CT-guided anesthetic and botulinum toxin injection of the ASM/MSM in patients with NTOS symptoms.MATERIALS AND METHODS:One hundred six participants (mean age, 41.5 ± 10 years; 80 women) were identified via a retrospective review of medical records for CT-guided scalene blocks. The procedure was evaluated regarding the technical success, defined as satisfactory detection of the ASM/MSM; intramuscular needle placement; intramuscular injection of contrast; appropriate delivery of medication; and frequency of unintended BP block or other complications. We also determined the outcome of patients who underwent surgery following the block.RESULTS:Study participants underwent 146 scalene injections, 83 blocks, and 63 chemodenervations, which were included in this investigation. In all cases, detection of the ASM/MSM and intramuscular needle placement was satisfactory. Postprocedural complications included 5 (3.4%) temporary BP blocks, 1 patient with (0.7%) Horner sign, 7 (4.8%) needle-induced pain reports, 1 (0.7%) case of dysphagia, and 2 (1.4%) instances of muscle weakness. There were no major complications reported. The rate of good outcome following surgery was the same in patients with positive versus negative blocks, 30/43 (70%) versus 5/7 (71%), respectively.CONCLUSIONS:CT guidance is a useful adjunct in performing accurate ASM/MSM blocks with a low rate of minor complications.

Estimates of TOS incidence vary widely, with rates ranging from 3 to 80 cases per 1000 people.^1,2 TOS is caused by compression of the neurovascular structures passing through the superior thoracic outlet, and it results from neck trauma (often from auto crashes), repetitive stress injury, congenital abnormalities (eg, cervical ribs), or a combinations of these.^3,4 There are 3 types of TOS: venous, arterial, and neurogenic. NTOS comprises almost 95% of TOS cases^5–7 and is mostly seen in the third and fourth decades of life, with a female/male ratio of 3:5–4:1.^2,6–8 Symptoms of NTOS include paresthesias; pain on the affected side of the neck, shoulder, or arm; discoloration and cold intolerance of fingers in cases involving sympathetic fibers; and, less commonly, weakness of the upper extremity. Venous TOS commonly presents with acute effort thrombosis of the subclavian vein, also known as Paget-Schroetter syndrome.^2,6 Patients usually are athletes who present with an acutely swollen discolored upper extremity; pain due to subclavian vein obstruction, with or without thrombosis; and visible subcutaneous veins over the involved shoulder and chest wall.^2,3,5,6 Arterial TOS is associated with hand ischemia caused by either external compression of the subclavian artery or from emboli arising from a subclavian artery aneurysm.^3,5,6 The symptoms of arterial TOS include digital ischemia, claudication, pallor, coldness, paresthesia, and pain in the hand but seldom in the shoulder or neck. Occasionally, the neurologic and vascular components may coexist in the same patient.²If ergonomic modifications, exercise, and physiotherapy do not improve the symptoms, anesthetic injection of the anterior scalene muscle, as a diagnostic test, is often performed.⁹ The anesthetic injection allows the first rib to descend by relaxing the scalene muscle and thereby decompressing the BP.^6,9–11 The anterior scalene block has been the most helpful test to confirm the diagnosis of NTOS^5,6,11–15 and to predict the response to surgery, because it may mimic the results of first-rib resection and anterior scalenectomy.^{6,10–12,14,16} However, to be predictive, the injection should avoid anesthesia of the BP and sympathetic chain, and the patient should be both medically and psychologically stable.¹³Different methods have been used to guide the scalene injection, including the use of anatomic landmarks,^13,17 EMG,¹² sonography,¹¹ combinations of EMG and sonography,¹⁸ EMG and fluoroscopy,¹⁸ and CT most recently.^9,10CT-guided injection of the scalene muscle is a novel technique,⁹ which has not been previously evaluated in the radiology literature, to our knowledge. The purpose of this study was to describe the technique, findings, and complications associated with CT-guided injection of the ASM/MSM in patients being evaluated or treated for NTOS. We also assessed the predictive value of the CT-guided scalene block by determining the outcome of patients who underwent surgical decompression following the block.