Temporal bone fractures and complications: Correlation between high-resolution computed tomography and audiography

Acute head trauma in the emergency room is managed primarily by the trauma surgeon or neurosurgeon. Temporal bone fractures with the complications of hearing loss and facial nerve paralysis may not be promptly evaluated. The otolaryngologist may not be consulted until late in the hospitalization. Traditionally, longitudinal fractures have been associated with conductive hearing loss and transverse fractures with sensorineural hearing loss. The purpose of this study was to correlate the type of fracture with audiometric findings of hearing loss. We also studied the incidence of facial nerve paralysis and its associated fracture types. A total of 2906 head trauma patients admitted to the emergency room from March 1994 to May 1996 were reviewed. All patients had a head computed tomographic (CT) examination. High-resolution CT of the temporal bones was performed in patients suspected of having a temporal bone fracture. Temporal bone fractures were found in 48 patients (2%) and were classified as longitudinal, transverse, or mixed. Audiometry was performed by the Department of Otolaryngology in 23 of the patients with temporal bone fractures. Patients with longitudinal fractures had conductive hearing loss in 43% and sensorineural loss in 23%. Of patients with transverse fractures, 57% had conductive hearing loss, and 29% had sensorineural loss. Facial nerve paralysis was found in 11% of patients. Patients with transverse fractures were found to have facial paralysis in 2 of 11 (18%), whereas those with longitudinal fractures had paralysis in 3 of 36 (8%). Our study found conductive hearing loss to be more frequent than sensorineural loss in patients with longitudinal and transverse fractures. This finding differs from traditional associations. We found the fracture orientation as defined by high-resolution CT scanning of the temporal bones to be a poor predictor of associated hearing loss. Facial nerve paralysis can occur with both transverse and longitudinal fractures, and extension of fractures to the geniculate ganglion should be sought on high-resolution CT scans of the temporal bone. The emergency room physicians should be notified of this potential complication. This paper was presented at the annual meeting of the American Society of Emergency Radiology, March 1997.     

Hearing loss in skull fractures

One hundred three cases of skull fractures in or around the temporal bone were reviewed for hearing loss. Of these, 100 patients had skull series, 66 had computed tomographic head scans, and 44 had polytomographic studies of the temporal bone. Hearing loss in head trauma can be grouped into four categories: conductive hearing loss, peripheral sensorineural hearing loss, central sensorineural hearing loss, and combinations of these hearing losses. The cause of conductive hearing loss and peripheral sensorineural hearing loss was usually identified by the type of temporal bone fracture. However, the cause of the central sensorineural hearing loss was more difficult to correlate with the brain lesions shown in the computed tomographic scans.     

Temporal bone fractures

Temporal bone injury is frequently associated with severe brain injury which limits the clinical evaluation and detracts from the clinical signs of temporal bone fracture such as sensorineural hearing loss, conductive hearing loss, and facial nerve paralysis. Radiologists are often the first to note the presence of temporal bone fractures and should be familiar with common types of injuries and their clinical implications. We review the traditional classification systems of temporal bone fractures with respect to clinical findings and management and suggest that radiologists should be familiar with the classification systems and, more importantly, focus their attention to identifying all critical temporal bone structures and describing their status of involvement to better the individual care.     

Fracture of the temporal bone. Evaluation of 123 cases

Out of 2,888 blunt head injuries that were treated at the Hermann Hospital Trauma Center of the University of Texas at Houston, only 123 temporal bone fractures were diagnosed in 110 patients. The clinical diagnosis was confirmed with high resolution computerized tomography of the temporal bones. Three main categories of fractures were identified: oblique in 74%, longitudinal in 13% and transverse in 13%. The clinical manifestations included hemotympanum in 83%, cerebrospinal fluid otorrhea in 21% and Battle's sign in 10.6%. One third of the patients had conductive hearing loss, 1/2 had mixed hearing loss and the rest sensorineural loss. On exploration, the most frequent middle ear pathology was incudostapedial joint dislocation. Immediate facial paralysis was observed in 64 patients. Only 11 patients needed facial nerve exploration following signs of denervation, the rest recovered spontaneously. Thirteen patients who had delayed facial paralysis also recovered spontaneously. One third of the patients had persistent unsteadiness 6 weeks following the injury. Other unusual complications encountered include 6 cases of abducent paralysis, 2 cases of trigeminal paralysis and 2 cases of aseptic sigmoid sinus thrombosis.     

Use of CT in the evaluation of cochlear otosclerosis

Otosclerosis (otospongiosis) occurs when the hard endochondral bone of the otic capsule is replaced by spongy vascular foci of haversian bone. Using computed tomography (CT), we studied the ears of 32 selected patients with mixed or sensorineural hearing loss (one patient had normal hearing); 24 were suspected of having otosclerosis. CT proved valuable in detecting cochlear otosclerosis, foci of demineralization, and changes in bony texture and enables the easy recognition of subtle radiographic findings. Our paper also reports the CT findings of temporal bones in osteogenesis imperfecta and Paget disease.     

Temporal bone trauma and imaging

Summary Fractures of the temporal bone result from direct trauma to the temporal bone or occur as one component of a severe craniocerebral injury. Complications of temporal trauma are hemotympanon, facial nerve paralysis, conductive or sensorineur hearing loss, and leakage of cerebrospinal fluid. Early recognition and an appropiate therapy may improve or prevent permanent deficits related to such complications. Only 20–30 % of temporal bone fractures can be visualized by plain films (7). CT has displaced plain radiography in the investigation of the otological trauma because subtle bony details are best evaluated by CT which even can be reformatted in multiple projections, regardless of the original plane of scanning. Associated epidural, subdural, and intracerebral hemorrhagic lesions are better defined by MRI.      

Multidetector CT of the kidney

The technological development of multidetector CT offers new possibilities for better imaging of organic structures that can be used in diagnosis of the kidney. The thinner slices allow a better spatial resolution, and slice fusion allows improved contrast resolution. The isotropic voxel has been realized in the latest 64-channel scanners. The image quality of arbitrarily reconstructed planes has arrived at the image quality of the scan plane. Faster scanning allows studies in different contrast phases, which is helpful for better discrimination of benign or malignant lesions especially in the highly vascularized kidney. Different phases of contrast uptake can be differentiated (arterial, cortico-medullary, nephrographic, and excretory phase). Multidetector CT brings along the risk of increased dose due to thinner slice collimation and overranging phenomena. Indications for CT investigation of the kidney include urolithiasis, tumor diagnosis and staging, renal trauma, and vascular disease. Even in children, special indications for CT of the kidney remain in polytrauma and tumor staging. Multidetector CT of the kidney has become a very valuable tool in urology, but a careful protocol strategy is mandatory.     

Virtual autopsy: preliminary experience in high-velocity gunshot wound victims

PURPOSE: To retrospectively assess virtual autopsy performed with multidetector computed tomography (CT) for the forensic evaluation of gunshot wound victims. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and did not require informed consent of the next of kin. Thirteen consecutive male gunshot wound victims (mean age, 27 years) were scanned with 16-section multidetector CT prior to routine autopsy. Retrospectively, the total-body nonenhanced scans were interpreted at a three-dimensional workstation by radiologists blinded to autopsy findings. Images were evaluated for lethal wound, number and location of wound tracks, injured structures, and metal fragment location. After image review, autopsy reports and photographs were compared with the images and interpretations to validate the multidetector CT determinations. RESULTS: Multidetector CT aided in correct identification of all lethal wounds, and metallic fragment location was always precise. In four cases, multidetector CT aided in accurate assessment of organ injuries and lethal wounds but led to underestimation of the number of wounds if comingling paths occurred. In two cases of a chest wound, multidetector CT aided in accurate assessment of the chest as having the lethal wound but failed to help identify specific sites of hemorrhage. In two cases of craniofacial injury, the path of the wound was not clear. Autopsy revealed a total of 78 wound tracks (mean, 6; range, 1-24). Ten (13%) wound tracks were not identified at multidetector CT (six upper extremity wounds and four thigh wounds). In two cases, findings missed at autopsy (fracture of the cervical spine, bullet fragments in the posterior area of the neck) were identified at multidetector CT. CONCLUSION: Multidetector CT can aid prediction of lethal wounds and location of metallic fragments.     

CT of the temporal bone in achondroplasia

In an attempt to better define the changes affecting the temporal bone that might predispose achondroplastic dwarfs to otitis media, nine achondroplastic subjects who were evaluated for hearing loss underwent high-resolution CT scanning of the temporal bone. Comparisons were made with 10 nonachondroplastic subjects. A number of morphologic changes were seen, including (1) poor development of mastoid air cells, (2) foreshortening of the carotid canals, (3) narrowing of the skull base, (4) "towering" petrous ridges, and (5) relative "rotation" of the cochlea and other temporal bone structures. The most significant change was the rotational effect, which was more pronounced medially, resulting in an abnormal orientation of inner ear structures relative to middle ear structures and of middle ear structures relative to the external auditory canal. There was a notable lack of evidence for otitis media or its sequelae in any of the achondroplastic subjects. Audiograms were obtained in six of the nine achondroplastic subjects (two adults and four children). There was evidence of mixed hearing loss in the four children, but only of sensorineural hearing loss in the adults. We believe that the persistent hearing loss in achondroplasia is not due to sequelae of otitis media as some authors have suggested. Intrinsic vestibulocochlear changes below the limits of resolution of high-resolution CT scanning may be responsible.     

Temporal bone fractures.

High-resolution technique is essential to the evolution of temporal bone fractures. Axial and coronal scan planes are optimal but may not be possible in acutely traumatized patients. A knowledge of normal temporal bone anatomy is important and can be obtained from standard texts, so it will not be considered in detail in this article. Classically, petrous temporal bone fractures have been classified as longitudinal, transverse, or mixed. Recent publications have emphasized the importance of describing fractures in terms of planes rather than lines. According to this concept, most temporal bone fractures are actually oblique, and true longitudinal fractures are rare. Petrous temporal bone fractures may be associated with cranial nerve or vascular injuries when the fracture extends to the skull base. This is particularly true of the oblique fracture, which characteristically extends anteromedially to the skull base through weak places in that area, thus avoiding the compact bone of the otic capsule surrounding the labyrinth. The most common associated injury is to the facial nerve in its geniculate or proximal tympanic segment. Transverse fractures frequently involve the labyrinth. A careful search for various types of ossicular dislocation should be performed in association with temporal bone fractures, because this may result in conductive hearing loss. The site of cerebrospinal fluid otorhinorrhea resulting from temporal bone fractures can usually be defined on plain high-resolution temporal bone images, but intrathecal contrast may be helpful. Temporal bone fractures caused by gunshot wounds are frequently complex and may be limited by metallic streak artifacts. Pediatric patients have different proportions of facial nerve injury and types of hearing loss as compared with adults.     

Cross-Sectional Imaging Evaluation of Congenital Temporal Bone Anomalies: What Each Radiologist Should Know

Hearing loss in pediatric age group is associated with many congenital temporal bone disorders. Aberrant development of various ear structures leads into either conductive or sensorineural hearing loss. Knowledge of the embryology and anatomical details of various compartments of the ear help better understanding of such disorders. In general, abnormalities of external and middle ears result in conductive hearing loss. Whereas abnormalities of inner ear structures lead into sensorineural hearing loss. These abnormalities could occur as isolated or part of syndromes. Temporal bone disorders are a significant cause of morbidity and developmental delays in children. Imaging evaluation of children presented with hearing loss is paramount in early diagnosis and proper management planning. Our aim is to briefly discuss embryology and anatomy of the pediatric petrous temporal bones. The characteristic imaging features of commonly encountered congenital temporal bone disorders and their associated syndromes will be discussed.     

High-resolution CT of temporal bone trauma

Computed tomographic (CT) findings in 18 patients with temporal bone trauma were reviewed. Eight patients suffered longitudinal fractures of the petrous bone, which were associated with ossicular dislocation in two patients. Transverse fractures were detected in six patients, with a contralateral mastoid fracture in one patient. In four patients, the fractures were restricted to the mastoid region. Of the 14 patients in whom adequate neurologic evaluation was available, seven had a permanent facial nerve or hearing deficit while five suffered at least a transient neurologic deficit related to the temporal bone trauma. Routine head CT (10 mm sections) demonstrated only eight of 19 petrous bone injuries. Clues to such injury included opacification of the mastoid air cells (10 patients), sphenoid sinus (11 patients), external canal and middle ear air space (10 patients), and local pneumocephalus (five patients). Evidence of brain trauma or extraaxial hematoma was seen in 12 patients. In 13 cases, high-resolution CT was also performed, demonstrating temporal bone injuries in all. This latter technique allows rapid and detailed evaluation of temporal bone trauma. Reports of radiographic evaluation of temporal bone trauma tend to deal with a somewhat skewed population, selected on the basis of clinical symptomatology. In a major trauma center equipped with high-resolution CT, it was found that temporal bone fractures may be seen incidentally, or in patients in whom symptomatology related to temporal fracture is obscured by much more serious neurologic compromise.     

Vestibular pneumolabyrinth: why assessment with temporal bone computed tomography utilizing dynamic focal spot mode is important for the diagnosis

We present an interesting and relatively uncommon case of vestibular pneumolabyrinth in a young child post-trauma. His initial clinical exam and imaging studies of the head and cervical spine were negative. He subsequently developed nystagmus and a dedicated temporal bone study demonstrated a subtle fracture and vestibular pneumolabyrinth. Temporal bone fractures can be difficult to appreciate, and therefore, associated findings of fluid in the middle ear, stapes dislocation, or vestibular pneumolabyrinth must be carefully evaluated. Temporal bone computed tomography is a high resolution study, utilizing dynamic focal spot mode which leads to increased sampling and resolution, thereby reducing aliasing artifacts but a longer scan time and increased radiation dose. CT head and cervical spine normally obtained without using this technique leads to aliasing artifacts where even the normal endolymph in the inner ear structures appear hypodense mimicking pneumolabyrinth, thereby obscuring true pneumolabyrinth. It is important to be aware of this finding and technique-related artifact, if a temporal bone injury is suspected, to ensure an earlier diagnosis and optimum management.     

儿童先天性感音神经性聋的影像学评估

目的:研究先天性感音神经性聋(SNHL)患儿的颞骨影像,分析内耳畸形的发生率及其类型,了解内耳畸形与耳蜗神经发育的关系,探讨部分患者是否仅行CT检查即可而无需进行MRI检查.方法:回顾性分析101例临床拟诊先天性SNHL的儿童颞骨CT和MRI影像资料,观察其内耳、蜗神经的结构.101例中,95例为重度或极重度双侧性SNHL,6例为单侧性SNHL.结果:196例患耳中,内耳畸形66耳:耳蜗不发育3耳;耳蜗发育不良5耳;不完全分隔I型7耳,不完全分隔II型10耳;前庭导水管扩大24耳;蜗神经不发育或发育不良19耳.10耳内听道狭窄均伴有蜗神经畸形.单侧性聋的6例患者中,均有蜗神经畸形.130例CT示内耳正常者,MRI也示蜗神经正常.结论:影像学诊断先天性重度或极重度双侧性SNHL内耳畸形发生率(31.6%)较单侧性SNHL者(100%)低,较为常见的畸形是前庭导水管扩大和耳蜗畸形,内耳畸形严重程度与蜗神经发育异常的发生率有一定相关性;对于双侧性耳聋者,CT诊断有严重内耳畸形者必须行MRI扫描,以排除蜗神经发育畸形;CT示耳蜗结构正常且内听道无狭窄者可无需行MRI扫描;单侧性耳聋者必须同时行CT和MRI扫描.     

Complication of cochlear implantation surgery

After experiencing gradual, progressive sensorineural hearing loss, a patient underwent cochlear implant (CI) surgery. Postoperatively, the patient experienced vestibular symptoms with no improvement in hearing. High-resolution temporal bone CT scanning demonstrated extracochlear positioning of the CI electrode in the superior semicircular canal.     

Occult scaphoid fractures: comparison of multidetector CT and MR imaging--initial experience

PURPOSE: To compare the diagnostic performance of multidetector computed tomography (CT) and magnetic resonance (MR) imaging in patients clinically suspected of having a scaphoid fracture and who had normal initial radiographs, with radiographs obtained 6 weeks after trauma as the reference standard. MATERIALS AND METHODS: The ethics committee approved the study, and all patients gave written informed consent. Twenty-nine patients (17 male, 12 female; age range, 17-62 years; mean age, 34 years +/- 13) underwent multidetector CT and MR imaging within 6 days after trauma. CT data were obtained with 0.5-mm collimation. For image review, 0.7-mm-thick multiplanar reformations were performed in transverse, coronal, and sagittal planes relative to the wrist. The 1.0-T MR examination consisted of coronal and transverse short inversion time inversion-recovery, coronal and transverse T1-weighted spin-echo, and coronal volume-rendered T2-weighted gradient-echo sequences. Two radiologists analyzed the CT and MR images. A binomial test was used to evaluate the significance of the differences between MR imaging and CT in detection of scaphoid fractures and cortical involvement (P < .05). RESULTS: The 6-week follow-up radiographs depicted a scaphoid fracture in 11 (38%) patients. Eight patients had a cortical fracture, while three patients had only a bandlike lucency within the trabecular portion of the scaphoid. MR imaging depicted all 11 fractures but only three [corrected] cortical fractures. Multidetector CT depicted all eight cortical fractures but failed to depict trabecular fractures. No false-positive fractures were seen on MR or CT images. Differences between MR imaging and CT were not significant for the detection of scaphoid fractures (P = .25) but were significant for cortical involvement (P = .03). CONCLUSION: Multidetector CT is highly accurate in depicting occult cortical scaphoid fractures but appears inferior to MR imaging in depicting solely trabecular injury. MR imaging is inferior to multidetector CT in depicting cortical involvement.     

Cervical spine trauma: evaluation by multidetector CT and three-dimensional volume rendering

Multidetector-row computed tomography (CT) offers important advantages over conventional imaging modalities in the evaluation of the post-trauma cervical spine. It allows for faster scanning times, critical for triaging post-trauma patients as well as for eliminating motion artifacts, and allows for thinner collimation and the ability to achieve an isotropic data set which can be reformatted in any plane without loss of spatial resolution. In addition, three-dimensional volume-rendered reconstructions of images obtained using multidetector scanners can provide additional information in defining extent of injury, allowing neurosurgeons to see the fractures in any plane, simulating intraoperative views. 3D multidetector-row CT represents an advance in CT technology and can help ensure rapid, accurate evaluation of cervical spine injuries. Electronic Publication     

Patología traumática de peñascos,un diagnóstico complejo. Claves para el informe

Fractures of the petrous part of the temporal bone are a common lesion of the base of the skull; most of these fractures result from high-energy trauma. In patients with multiple trauma, these injuries can be detected on CT scans of the head and neck, where the direct and indirect signs are usually sufficient to establish the diagnosis. It is important to these fractures because the temporal bone has critical structures and the complexity of this region increases the risk of error unless special care is taken. This article reviews the key anatomical points, the systematization of the imaging findings, and the classifications used for temporal bone fracture. We emphasize the usefulness of identifying and describing the findings in relation to important structures in this region, of looking for unseen fractures suspected through indirect signs, and of identifying anatomical structures that can simulate fractures. We point out that the classical classifications of these fractures are less useful, although they continue to be used for treatment decisions.     

Normal canals at the fundus of the internal auditory canal: CT evaluation.

PURPOSE: Knowledge of the normal anatomy of the four bony canals located at the fundus of the internal auditory canal (IAC) is necessary during evaluation of temporal bone trauma, congenital anomalies affecting the individual nerves, and some neuro-otologic surgeries. The purpose of this work was therefore to characterize the normal appearance of the four bony canals and to measure their dimensions. METHOD: A retrospective study was performed using CT studies of the temporal bones in 50 patients to identify and characterize the bony canals for the labyrinthine segment of the facial nerve (BCFN), superior vestibular nerve (BCSVN), cochlear nerve (BCNC), and the inferior vestibular nerve (singular canal; SC) located at the fundus of the IAC. All the patients underwent high resolution temporal bone CT for evaluation of uncomplicated inflammatory (n = 49) and neoplastic (n = 1) diseases involving the temporal bone. CT studies were done using 1-mm-thick contiguous sections in axial and coronal planes. Measurements of the canals were performed by one radiologist. No patient had a prior history of trauma, vertigo, and sensorineural hearing loss or facial nerve paralysis. RESULTS: The BCFN, BCSVN, and BCNC were identified in all studies, whereas the SC was seen in 93% of studies. The BCFN, BCSVN, and BCNC arise from the fundus of the IAC, whereas the SC arises medial to the fundus. Mean +/- SD measurements (in mm) of the length and width were as follows: BCFN = 2.92+/-0.48 and 0.91+/-0.28; BCSVN = 2.36+/-0.53 and 0.89+/-0.28; BCNC = 0.93+/-0.21 and 2.13+/-0.44; and SC = 3.22+/-0.73 and 0.50+/-0.14. CONCLUSION: These small canals are routinely visualized on thin section (1 mm) CT of the temporal bone and should not be confused with fractures. This study provides baseline measurements that may be used to evaluate congenital anomalies of these canals. These data may also be helpful in the presurgical evaluation of patients undergoing singular neurectomies for benign positional vertigo.