自发性低颅压综合征脑脊液间隙显像的影像学特征分析

目的 探讨自发性低颅压综合征（SIH）患者放射性核素脑脊液间隙显像（RNC）的影像学特点及其临床意义。 方法 回顾性分析2012年5月至2017年1月福建省立医院收治的19例SIH患者,均经腰椎穿刺脊髓蛛网膜下腔注射99Tcm-DTPA,行多时相脑脊液间隙显像,对99Tcm-DTPA异常分布处加做SPECT/CT断层融合显像及MRI扫描。综合分析RNC的影像学特点。计数资料的组间比较采用 χ 2 检验。 结果 RNC可通过显示脊髓或鼻部脑脊液漏点等直接征象诊断SIH;也可通过观察脑脊液循环过程异常,如:显像剂上升缓慢,难以抵达脑池、大脑凸面、上矢状窦等及膀胱、肾脏早期显像等间接征象诊断SIH。RNC检出脑脊液漏17例。直接脑脊液漏患者12例,其中颈、胸段9例,脑脊液鼻漏2例,大流量脑脊液漏（腰段）患者1例。RNC正常者2例。MRI[阳性率为58.8%（10/17）]与RNC[阳性率为88.2%（15/17）]对SIH低颅压诊断的差异无统计学意义（χ2=0.101,P>0.05）;12例RNC检出漏口的相应部位MRI仅检出1例。 结论 RNC可通过直接或间接征象协助SIH的病因诊断,在脑脊液漏口检出上明显优于MRI,并可反映脑脊液漏的流量,便于个体化治疗,在SIH的诊疗中有重要的应用价值。     

Vascular hydraulics associated with idiopathic and secondary intracranial hypertension

BACKGROUND AND PURPOSE: The radiologic diagnosis of idiopathic intracranial hypertension (IIH) is one of exclusion, with no reproducible positive features described in the imaging literature. Because MR venography is prone to flow artifacts, diagnosis of secondary intracranial hypertension (SIH) can also be problematic. Vascular hydraulics can be useful for diagnosis of these conditions when measured by invasive or sonographic means. The purpose of this study was to measure vascular flow and pulsatility characteristics with a noninvasive MR imaging method. METHODS: Twelve patients with clinical and lumbar puncture findings of IIH or SIH and 12 control subjects were examined with MR venography and MR flow quantification studies of the cerebral arteries and veins. Total cerebral, superior sagittal sinus (SSS), and straight sinus blood flows were measured. Pulsatility indices from the arterial and venous flow for all patients were compared using the Student t test. RESULTS: MR venography confirmed that seven of the 12 patients had venous outflow obstruction, and thus, SIH. The remaining five patients had IIH. All patients showed reduced sinus pulsatility compared with that of the control group; reductions of 42% in the SSS and 32% in the straight sinus were noted (P =.0001 and.005, respectively). In the IIH group, total blood flow was 46% higher than that in the control group (P =.0002), and SSS flow was normal. In the SIH group, total blood flow was normal; however, SSS flow was reduced by 25% (P =.003). CONCLUSION: Reduced venous sinus pulsatility is a marker of intracranial hypertension secondary to raised venous sinus pressure. When suspicion of IIH or SIH exists and the MR venogram is difficult to interpret, raised total blood flow indicates IIH, whereas reduced SSS flow indicates SIH.     

Diameter of the superior ophthalmic vein in relation to intracranial pressure

BACKGROUND AND PURPOSE: Bilateral engorged superior ophthalmic veins (SOV) have been reported in patients with diffuse brain swelling. We investigated the relationship between the diameter of the SOV on brain MR images and the intracranial pressure (ICP). METHODS: We reviewed the medical records of neurologic inpatients who had undergone both MR imaging of the brain and lumbar puncture. MR imaging had to have been performed before lumbar puncture, and the two studies had to have occurred within 2 days. The diameters of the SOV were measured on coronal contrast-enhanced fat-saturated T1-weighted MR images. For this, the image nearest the rear of the globe of the eye was chosen. RESULTS: Sixty-nine patients (32 male, 37 female; mean age, 46 years +/- 19) were included. The average diameters of the SOV and the ICP were positively correlated (r = 0.58, P <.001), if an SOV diameter of <1 mm was treated as 0.5 mm for calculations. In patients with increased ICP (CSF pressure >200 mm H(2)O), SOV diameters were larger than those of patients with a normal CSF pressure (3.0 vs 1.6 mm, P <.001). Frequencies of increased ICP were 3% among patients with an average SOV diameter of 0.5-1 mm, 15% for 1.5-2 mm, and 58% for 2.5-5 mm (P <.001). CONCLUSION: This study showed that the SOV diameter, determined on the basis on MR imaging, was positively correlated with ICP. Dilatation of the SOV should alert physicians to the possibility of increased ICP.     

Symptomatic spinal epidural collections after lumbar puncture in children

BACKGROUND AND PURPOSE: Complications from lumbar puncture (LP) include headache; mild puncture-site pain; and, rarely, subdural, epidural, or subarachnoid hemorrhage. In infants, asymptomatic leakage of CSF documented with ultrasound is common. We report the MR imaging findings and clinical course of 25 symptomatic patients with spinal epidural collections after LP. MATERIALS AND METHODS: MR imaging and clinical records of 25 children with new symptoms following LP were retrospectively reviewed. RESULTS: All patients had abnormal dorsal spinal epidural collections. Signal-intensity characteristics of the collections were most commonly isointense to CSF on all pulse sequences. Significant anterior displacement of the dura with effacement of the subarachnoid space was frequently noted. All patients had fluid surrounding small foci of epidural fat, elevating them from their native interspinous fossa, resulting in a "floating" appearance. Eighteen collections involved the thoracic and lumbar spine; 4 involved the thoracic, lumbar, and sacral spine; 2 extended from the lumbar to the cervical level; and 1 was isolated to the lumbar spine. Five patients had follow-up MR imaging showing complete resolution of collections. The size of the collections was not directly related to the number of puncture attempts. Clinical symptoms resolved with time in all patients with conservative management. CONCLUSION: Symptomatic epidural fluid collections after LP are often extensive and may compromise the thecal sac. These collections are not usually the result of a difficult LP and have signal intensity characteristics most consistent with CSF leak rather than hemorrhage. Signs and symptoms typically resolve with time, without treatment and with no serious sequelae.     

Detection of cerebrospinal fluid leakage in intracranial hypotension with radionuclide cisternography and blood activity monitoring

Radionuclide cisternography is an indispensable examination to detect cerebrospinal fluid (CSF) leakage in patients suspected of having spontaneous intracranial hypotension (SIH). However, it sometimes fails to demonstrate the site of CSF leakage, and in such cases, early bladder visualization is utilized for the diagnosis of SIH as an indirect finding. The aim of this work is to improve the diagnostic ability of radionuclide cisternography and to reevaluate the reliability of early bladder visualization as an indirect finding of CSF leakage. METHODS: We obtained serial images during the first hour after injection as well as the following time points in 4 patients with SIH and 5 with normal pressure hydrocephalus (NPH) as a control. We also performed blood sampling over time to measure blood radioactivity concentrations. RESULTS: All 4 patients with SIH demonstrated leakage, 2 of 4 within one hour after injection. Bladder visualization was observed falsely in 4 of 5 patients with NPH, considered to be the result of a lumbar puncture complication. In this false bladder visualization, blood radioactivity showed a more rapid raise and fall than in CSF leakage of SIH. CONCLUSIONS: The combination of radionuclide cisternography, including early time points and blood sampling, may enable accurate diagnosis of SIH.     

Fluid-attenuated inversion recovery MR imaging and subarachnoid hemorrhage: not a panacea

BACKGROUND AND PURPOSE: Subarachnoid hemorrhage (SAH) constitutes an important neurologic emergency. Some authors have suggested that fluid-attenuated inversion recovery (FLAIR) MR imaging can detect SAH that may not be apparent on CT scans but may be revealed by lumbar puncture. We sought to determine how often FLAIR MR imaging findings are positive for SAH in cases with negative CT findings and positive lumbar puncture results. METHODS: The CT scans and FLAIR MR images of all patients with suspected SAH during a 3-year interval (2000-2002) were retrospectively reviewed by a blinded reader. Among these cases, we identified 12 with CT findings that were negative for SAH, lumbar puncture results that were positive for SAH, and FLAIR MR imaging findings that were available for review. Eleven of the 12 patients had undergone FLAIR MR imaging within 2 days of CT and lumbar puncture. The 12 patients with negative CT findings were comprised of six male and six female patients with an age range of 7 to 69 years. We evaluated the true and false negative and positive FLAIR MR imaging findings for SAH by using the lumbar puncture results as the gold standard. The FLAIR MR imaging findings of 12 additional patients without SAH (as revealed by lumbar puncture) were used as control data for a blinded reading. RESULTS: For all 12 control cases without SAH, the FLAIR MR imaging findings were interpreted correctly. Of the 12 cases that had positive lumbar puncture results but false-negative CT findings for SAH, FLAIR MR imaging findings were true-positive in only two cases and were false-negative in 10. One of the two true-positive cases had the highest concentration of RBC in the series (365 k/cc), and the other had the second highest value of RBC (65 k/cc). CONCLUSION: FLAIR MR imaging cannot replace lumbar puncture to detect the presence of SAH. FLAIR MR imaging findings are infrequently positive (16.7%) when CT findings are negative for SAH. This is likely because there is a minimum concentration of RBC/cc that must be exceeded for CSF to become hyperintense on FLAIR MR images.     

Detection of cerebrospinal fluid leakage: initial experience with three-dimensional fast spin-echo magnetic resonance myelography

Background: The pathogenesis of cerebrospinal fluid (CSF) hypovolemia is supposed to be caused by CSF leakage through small dural defects.

Purpose: To compare source three-dimensional (3D) fast spin-echo (FSE) images of magnetic resonance (MR) myelography with radionuclide cisternography findings, and to evaluate the feasibility of MR myelography in the detection of CSF leakage.

Material and Methods: A total of 67 patients who were clinically suspected of CSF hypovolemia underwent indium-111 radionuclide cisternography, and 27 of those who had direct findings of CSF leakage were selected for evaluation. MR myelography with 3D FSE sequences (TR/TE 6000/203 ms) was performed at the lumbar spine for all patients. We evaluated source images and maximum intensity projection (MIP) images of MR myelography, and the findings were correlated with radionuclide cisternography findings. MR myelography of five healthy volunteers was used as a reference. The MR visibility of the CSF leakage was graded as definite (leakage clearly visible), possible (leakage poorly seen), or absent (not shown).

Results: CSF leakage was identified with source 3D FSE images in 22 (81.5%) of 27 patients. Of the 22 patients, 16 were graded as definite and six were graded as possible. For the definite cases, 3D FSE images clearly showed the extent of the leaked CSF in the paraspinal structures. In the remaining five patients with absent findings, radionuclide cisternography showed only slight radionuclide activity out of the arachnoid space.

Conclusion: Source 3D FSE images of MR myelography seem useful in the detection of CSF leakage. Invasive radionuclide cisternography may be reserved for equivocal cases only.     

Diffuse pachymeningeal hyperintensity and subdural effusion/hematoma detected by fluid-attenuated inversion recovery MR imaging in patients with spontaneous intracranial hypotension

BACKGROUND AND PURPOSE: Fluid-attenuated inversion recovery (FLAIR) MR imaging has advantages to detect meningeal lesions. FLAIR MR imaging was used to detect pachymeningeal thickening and thin bilateral subdural effusion/hematomas in patients with spontaneous intracranial hypotension (SIH).MATERIALS AND METHODS: Eight patients were treated under clinical diagnoses of SIH. Chronologic MR imaging studies, including the FLAIR sequence, were retrospectively reviewed.RESULTS: Initial MR imaging showed diffuse pachymeningeal thickening as isointense in 6 cases, hypoisointense in 1 case, and isohyperintense in 1 case on the T1-weighted MR images, and hyperintense in all cases on both T2-weighted and FLAIR MR images. Dural (pachymeningeal) hyperintensity on FLAIR MR imaging had the highest contrast to CSF, and was observed as linear in all patients, usually located in the supratentorial convexity and also parallel to the falx, the dura of the posterior fossa convexity, and the tentorium, and improved after treatment. These characteristics of diffuse pachymeningeal hyperintensity on FLAIR MR imaging were similar to diffuse pachymeningeal enhancement (DPME) on T1-weighted imaging with gadolinium. Initial FLAIR imaging clearly showed subdural effusion/hematomas in 6 of 8 patients. The thickness of subdural effusion/hematomas sometimes increased transiently after successful treatment and resolution of clinical symptoms.CONCLUSION: Diffuse pachymeningeal hyperintensity on FLAIR MR imaging is a similar sign to DPME for the diagnosis of SIH but does not require injection of contrast medium. FLAIR is useful sequence for the detection of subdural effusion/hematomas in patients with SIH.

Spontaneous intracranial hypotension (SIH) syndrome is characterized by low CSF pressure and positional headache caused by leakage of spinal CSF.^1,2 MR imaging has revolutionized the identification, diagnosis, management, and understanding of SIH. The characteristic MR signs of SIH include diffuse pachymeningeal (dura mater) enhancement (DPME), bilateral subdural effusion/hematomas, downward displacement of the brain, enlargement of the pituitary gland, prominence of the spinal epidural venous plexus, engorgement of cerebral venous sinuses (“venous distension sign,” etc),³ venous sinus thrombosis,⁴ and isolated cortical vein thrombosis.⁵ DPME after gadolinium administration may be the most common and indicative sign^1,2 and forms the basis of the proposed “syndrome of orthostatic headache and diffuse pachymeningeal gadolinium enhancement.”⁶The cause of DPME remains unclear. Histologic examination of meningeal biopsy specimens consistently demonstrates a thin layer of fibroblasts as well as small, thin-walled, dilated blood vessels without evidence of inflammation on the subdural surface, the so-called dural border cell layer.⁷ These findings strongly suggest that dural venous dilation following the Monro-Kellie rule is the most likely explanation of DPME associated with SIH, which states that decreased CSF volume caused by CSF leakage requires volume compensation resulting in meningeal venous hyperemia and subsequent pachymeningeal enhancement.⁸ However, previous studies did not include detailed neuroradiologic evaluations of the pachymeninges in patients with SIH without artificial contrast materials to evaluate the transient and functional changes of the dura mater.⁹Bilateral subdural effusion/hematomas are also classic intracranial signs in the diagnosis of SIH, which again may be explained by the Monro-Kellie rule.^1,6,8 The incidence of subdural effusion/hematomas associated with SIH is 10% to 50% with use of conventional neuroradiologic techniques.^10,11 Subdural effusion/hematomas associated with SIH tend to be thin (typically 2–7 mm), do not cause appreciable mass effect, occur typically over the convexities of the brain, and appear as variable MR signal intensities depending on the fluid protein concentration or presence of blood.¹The fluid-attenuated inversion recovery (FLAIR) pulse sequence cancels the signal intensity from CSF and causes heavy T2 weighting because of the very long TE, resulting in excellent definition of anatomic detail, such as brain surface sulci, and high lesion contrast in areas close to the CSF.¹² This method is commonly used to detect meningeal lesions such as subarachnoid hemorrhage and meningitis.^13–15 Therefore, FLAIR MR imaging may be the optimum sequence to evaluate the thickened dura associated with SIH and to detect the very thin subdural effusion/hematomas located close to the subarachnoid CSF space.Our study used FLAIR MR imaging to examine the thickened dura and subdural effusion/hematomas in patients with SIH.     

Imaging Signs in Spontaneous Intracranial Hypotension: Prevalence and Relationship to CSF Pressure

BACKGROUND AND PURPOSE:Patients with spontaneous intracranial hypotension often exhibit low CSF pressure and changes on brain MR imaging and/or evidence of CSF leak on myelography. We investigated whether individual imaging signs of spontaneous intracranial hypotension correlate with measured CSF pressure and how frequently these 2 markers of spontaneous intracranial hypotension were concordant.MATERIALS AND METHODS:We performed a retrospective, cross-sectional study of 99 subjects with spontaneous intracranial hypotension. Prevalence of brain and myelographic imaging signs of spontaneous intracranial hypotension was recorded. CSF pressure among subjects with or without individual imaging signs was compared by using a 2-tailed t test and ANOVA. Concordance between low CSF pressure (≤6 cm H₂O) and imaging was defined as the presence of the sign in a subject with low CSF pressure or absence of the sign when pressure was not low.RESULTS:Dural enhancement, brain sagging, and venous distension sign were present in 83%, 61%, and 75% of subjects, respectively, and myelographic evidence of CSF leak was seen in 55%. Marginal correlations between CSF pressure and brain sagging (P = .046) and the venous distension sign (P = .047) were found. Dural enhancement and myelographic evidence of leak were not significantly correlated with CSF pressure. Rates of concordance between imaging signs and low CSF pressure were generally low, ranging from 39% to 55%.CONCLUSIONS:Brain and myelographic signs of spontaneous intracranial hypotension correlate poorly with CSF pressure. These findings reinforce the need to base the diagnosis of spontaneous intracranial hypotension on multiple diagnostic criteria and suggest the presence of patient-specific variables that influence CSF pressure in these individuals.

Low CSF pressure (P_CSF) is a well-known feature of spontaneous intracranial hypotension (SIH) and is one of several diagnostic criteria for the disorder.^1,2 The fact that SIH is categorized by the International Classification of Headache Disorders, 3rd edition, as a “headache attributed to low cerebrospinal fluid pressure”² underlines the historical strength of the association between SIH and abnormally low pressure.Given this association, it would be expected that low CSF pressure would also be associated with other diagnostic criteria of SIH, including typical brain imaging findings and the presence of CSF leak on myelography.¹ There is some evidence to the contrary, however. Previous investigators have recognized that patients with brain imaging findings of SIH or myelographic evidence of CSF leak may not exhibit low CSF pressure.^3,4 This observation would seem to call into question whether low CSF pressure is the fundamental cause of SIH and has prompted the alternate hypothesis that SIH is actually primarily a disorder of low CSF volume rather than low pressure.⁵ To our knowledge, the frequency of discordance between imaging and CSF pressure and, by inference, the likelihood of this alternate hypothesis have not been previously explored.The purpose of this investigation is to describe the prevalence of brain imaging and myelographic signs of SIH from a large retrospective series of patients with confirmed SIH and to determine the correlation between these imaging signs and CSF pressure measurements, with a particular focus on reporting how commonly imaging signs of SIH and low CSF pressure are concordant or discordant.     

Wave-like appearance of diffuse pachymeningeal enhancement associated with intracranial hypotension

Diffuse pachymeningeal enhancement on magnetic resonance (MR) imaging is important in identifying spontaneous and secondary intracranial hypotension (IH) [cerebrospinal fluid (CSF) hypovolemia] in patients with postural headache, because CSF pressure at lumbar puncture is variable. We examined the pachymeningeal enhancement pattern in patients with IH. MR imaging findings of pachymeningeal enhancement were examined before and after treatment in seven consecutive patients with spontaneous IH and one patient with IH after lumbar puncture. Diffuse non-nodular dural enhancement was observed in all patients. Characteristic thick, uninterrupted, enhancement was observed, mainly in the dura of the frontal, temporal, and retroclival regions, and the tentorium. Thin and uninterrupted, or partially interrupted, enhancement was observed, mainly in the parieto-occipital region and cerebellar convexity. Curved linear enhancement was observed along the calvarium of all patients. A wave-like appearance, a clear pattern of dural unevenness parallel to the brain, was detected in the frontal and temporal regions, near the base, in all patients. A wave-like appearance, especially in the frontal and temporal base, may be a characteristic MR imaging indicator of IH.     

Gadolinium-enhanced MR cisternography to evaluate dural leaks in intracranial hypotension syndrome

Background and PURPOSE: We evaluated the use of MR cisternography after intrathecal administration of gadopentetate dimeglumine to detect the presence and localization of CSF leaks in 19 patients diagnosed with spontaneous intracranial hypotension syndrome according to the criteria of International Headache Society.MATERIALS AND METHODS: Lumbar puncture with an injection of 0.5 mL of gadopentetate dimeglumine into the subarachnoid space in the lumbar area was performed. MR images of the cervical, thoracic, and lumbar regions in axial, coronal, and sagittal planes with fat-saturated T1-weighted images were acquired.RESULTS: We observed objective CSF leakage in 17 (89%) of 19 patients. In 14 of these 17 patients, the site of dural tear was demonstrated accurately. In 3 of these 17 patients, the contrast leakage was diffuse, and site of the leak could not be located accurately. No leakage was observed in 2 patients. No complications were detected in any of the patients during the first 24 hours after the procedure or during the 6- to 12-month follow-up.CONCLUSION: The current results demonstrate the relative safety, accuracy, and feasibility of intrathecal gadolinium-enhanced MR cisternography to evaluate dural leaks.

The spontaneous intracranial hypotension (SIH) syndrome was originally described by the German neurologist Schaltenbrand^1,2 in 1938 as hypoliquorrhea. The Headache Classification Subcommittee of the International Headache Society has proposed diagnostic criteria for SIH.³ Evidence of CSF leakage was accepted as one of the main criteria for SIH diagnosis according to International Classification of Headache Disorders.³ Although many patients with SIH recover without intervention, many do not.^4,5 Some of these patients do not respond to multiple epidural blood patches and may require more targeted epidural injections, infusions, or surgical repair.^4–6 In these patients, confirmation of CSF leak, localization of the actual site or sites of CSF leak, and characteristics of the dural leaks become important. Despite advances in imaging and the availability of several different and potentially useful diagnostic modalities, accurate demonstration of the site of the CSF leakage remains a challenge for radiologists and clinicians. The purpose of our study was to evaluate and report our initial experience in analyzing CSF leaks in SIH using MR imaging combined with intrathecal administration of a gadolinium-based contrast agent, that is, gadolinium-enhanced MR cisternography.     

Spinal MR findings in spontaneous intracranial hypotension

Whole spine magnetic resonance (MR) imaging was used to evaluate the shape, size, signal intensity, and enhancement of the spinal spaces in a series of six patients with spontaneous intracranial hypotension (SIH). In all patients varying degrees of shrunken dural sacs, expanded extradural spaces with delayed homogeneous enhancement, and distended epidural venous plexuses were noted. In 83% (5/6) of patients, the MR signal of the expanded extradural space was similar to that of cerebrospinal fluid; 17% (1/6) showed an excessive fat deposit in the epidural space. Sixty-seven percent (4/6) of patients had a visible peridural membrane. After relief of the symptoms, one patient (1/4) showed persistence of the spinal abnormalities even though the brain abnormalities disappeared. In conclusion, the spinal MR findings of SIH, like its brain counterpart, are characteristic. In cases with clinical suspicion but without support from brain MR imaging, spinal MR imaging may be helpful in establishing the diagnosis.     

Proton MR spectroscopy in the diagnostic evaluation of suspected mitochondrial disease

PURPOSE AND BACKGROUND: Mitochondrial diseases are a group of inherited disorders caused by a derangement of mitochondrial respiration. The clinical manifestations are heterogeneous, and the diagnosis is often based on information acquired from multiple levels of inquiry. MR spectroscopy has previously been shown to help detect an abnormal accumulation of lactate in brain parenchyma and CSF in association with mitochondrial disorders, but the frequency of detection is largely unknown. We sought to examine the frequency of detectable elevations of CNS lactate by proton MR spectroscopy in a population of children and young adults with suspected mitochondrial disease. METHODS: MR spectroscopy data evaluated for the presence or absence of abnormal brain or CSF lactate were compared with other clinical indicators of mitochondrial dysfunction for 29 patients with suspected mitochondrial disease during the years 1990 to 2000. Based on an independent review of the final diagnoses, the patients were divided into groups based on the probability of mitochondrial disorder. RESULTS: A total of 32 scans from 29 patients were reviewed. Of eight patients thought to have a definitive mitochondrial disorder on the basis of genetic, biochemical, or pathologic features, five were found to have abnormal brain or CSF lactate levels revealed by MR spectroscopy (for one patient in whom two images were acquired, one was negative and the other positive). Among the studies conducted using a multisection spectroscopic imaging technique, five of six showed elevated lactate in the brain parenchyma, six of six showed elevated lactate in the CSF, and five of six showed elevated lactate in both brain and CSF. Of 16 patients who were highly suspected of having mitochondrial disorders on the basis of clinical grounds alone but who were lacking genetic, biochemical, or pathologic confirmation, four had abnormal lactate levels shown by MR spectroscopy. Mitochondrial disorder was excluded for five patients, none of whom had CNS lactate shown by MR spectroscopy. CONCLUSION: Detection of CNS lactate by MR spectroscopy is useful in the diagnosis of mitochondrial disease. In our series of patients with confirmed mitochondrial disease, a high level of lactate shown by MR spectroscopy correlated well with other markers of mitochondrial disease. As with all other means used to diagnose mitochondrial disorders, MR spectroscopy does not depict elevated lactate in all cases. Abnormal CNS concentrations of lactate may be undetected by MR spectroscopy because of differences in the type of mitochondrial disorder, timing, severity, or location of the affected tissues and the site of interrogation.     

Spontaneous intracranial hypotension: morphological findings and CSF flow dynamics studied by MRI

We report on a case of spontaneous intracranial hypotension (SIH) presenting with classic MR findings, such as diffuse smooth thickening and intense contrast enhancement of the dura matter, increased size of the pituitary gland and downward displacement of the brain. In this case an engorgement of the cavernous sinuses is reported as an additional imaging finding of SIH. Moreover, phase-contrast MR study of the CSF flow dynamics revealed at the level of the aqueduct a decrease of the systolic and diastolic flow volume of CSF. A normalization of the flow volume was observed when SIH subsided.     

Ganglion cysts of the cruciate ligaments

Purpose:
To evaluate the MR findings of ganglion cysts of the cruciate ligaments in correlation with clinical findings. Material and Methods:
We reviewed 12 patients with ganglion cysts of the cruciate ligaments obtained from a medical record of 4153 consecutive patients referred for knee MR examinations. All patients presented with chronic knee pain and 4 had restriction of knee motion. The MR imaging findings of the cysts were evaluated and correlated with clinical manifestations. Results:
Seven ganglion cysts were found in the posterior cruciate ligaments and 5 in the anterior cruciate ligaments. All cysts were lobulated (n=7) or fusiform (n=5) in shape, 1.8-4.5 cm in size, along the posterior surface in the proximal or distal end of the ligaments. Ten patients had arthroscopic resection or aspiration of their cysts, became symptom free and had no recurrence on follow-up MR examinations. Two cysts reduced in size spontaneously by conservative treatment. Conclusion:
MR imaging can offer useful information in detection and diagnosis of patients with chronic knee pain due to ganglion cysts of the cruciate ligaments. The size and location of the ganglion cysts can attribute to the clinical manifestations.     

空泡蝶鞍综合征MRI诊断（附72例分析）

目的探讨MRI对本病的诊断价值。方法分析72例空泡蝶鞍综合征的临床表现及MRI表现,并对其病因,发病机理进行探讨。结果总结出空泡蝶鞍综合征的MRI征象有：(1）蝶鞍扩大;(2)鞍内被脑积液充填;(3)垂体受压变扁紧贴鞍底矢状位呈弧线样或新月彤;(4)垂体柄延长,伸向鞍底;(5)可伴有脑积水等脑脊液压力增高征象;(6)可伴有脑肿瘤,脑囊虫等脑脊液压力增高病变。结论MRI对空泡蝶鞍综合征的诊断准确可靠,是影像学的最佳检查手段。     

Contrast-enhanced MR myelography in spontaneous intracranial hypotension: description of an artefact imitating CSF leakage

In contrast-enhanced (CE) MR myelography, hyperintense signal outside the intrathecal space in T1-weighted sequences with spectral presaturation inversion recovery (SPIR) is usually considered to be due to CSF leakage. We retrospectively investigated a hyperintense signal at the apex of the lung appearing in this sequence in patients with SIH (n = 5), CSF rhinorrhoea (n = 2), lumbar spine surgery (n = 1) and in control subjects (n = 6). Intrathecal application of contrast agent was performed in all patients before MR examination, but not in the control group. The reproducible signal increase was investigated with other fat suppression techniques and MR spectroscopy. All patients and controls showed strongly hyperintense signal at the apex of the lungs imitating CSF leakage into paraspinal tissue. This signal increase was identified as an artefact, caused by spectroscopically proven shift and broadening of water and lipid resonances (1–2 ppm) in this anatomical region. Only patients with SIH showed additional focal enhancement along the spinal nerve roots and/or in the spinal epidural space. In conclusion CE MR myelography with spectral selective fat suppression shows a reproducible cervicothoracic artefact, imitating CSF leakage. Selective water excitation technique as well as periradicular and epidural contrast collections may be helpful to discriminate between real pathological findings and artefacts.     

Neurobrucellosis: clinical and neuroimaging correlation

BACKGROUND AND PURPOSE: Manifestation of nervous system involvement by neurobrucellosis, a treatable infection, is not well documented. We investigated patterns of nervous system involvement and determined if neuroimaging abnormalities correlated with clinical manifestations of neurobrucellosis. METHODS: We reviewed 23 MR imaging studies (17 of brain, six of spine) and seven CT scans of brain in 23 patients (14 male and nine female patients; age range 17-71 years) with positive Brucella titers in their serum and CSF. RESULTS: Twelve patients had central nervous system (CNS) involvement, four had peripheral nervous system (PNS) involvement, two had combined PNS and CNS involvement, and five had isolated hearing loss. Imaging findings were variable: five of seven brain CT studies were normal, and 10 of 23 MR studies were normal (eight brain, one thoracic, one lumbar). One brain CT study showed subthalamic hemorrhage, mild perivascular enhancement, left caudate lacunae, and diffuse white matter changes. One other brain CT study showed enhancement of the tentorium in addition to white matter changes. Abnormal MR findings were basal meningeal enhancement (n = 3), lumbar nerve root enhancement (n = 3), granuloma of the suprasellar region (n = 1), diffuse white matter changes (n = 7), and spinal cord atrophy (n = 1). All patients improved after treatment with three antimicrobial drugs for 3-12 months. Seven patients had follow-up imaging; the enhancement disappeared but the white matter and ischemic changes persisted despite almost complete clinical recovery. CONCLUSION: Clinical-radiologic correlation in neurobrucellosis varies from a normal imaging study despite positive clinical findings, to a variety of imaging abnormalities that reflect either an inflammatory process, an immune-mediated process, or a vascular insult.     

Fluoroscopy-guided lumbar puncture: decreased frequency of traumatic tap and implications for the assessment of CT-negative acute subarachnoid hemorrhage

BACKGROUND AND PURPOSE: In patients with suspected subarachnoid hemorrhage (SAH) and negative CT findings, the iatrogenic introduction of RBCs into the CSF during lumbar puncture may lead to a misdiagnosis. We tested the hypothesis that the risk of traumatic lumbar puncture is lower with the fluoroscopy-guided technique than with the standard bedside technique. METHODS: Data were collected retrospectively from two populations: adult inpatients undergoing standard bedside lumbar puncture for any reason and adult patients undergoing fluoroscopy-guided lumbar puncture for myelography. Patients with SAH and CSF samples with significant abnormalities other than erythrocytosis (ie, CSF leukocytosis, xanthochromia, or elevated protein) were excluded. In all, 1489 bedside procedures and 723 fluoroscopy-guided procedures met the criteria. RESULTS: We found a significant difference in the level of iatrogenic CSF erythrocytosis produced by the two procedures. Using a cutoff of 1000 cells/mm(3), the frequency of traumatic lumbar puncture was 10.1% for bedside lumbar puncture and 3.5% for fluoroscopy-guided lumbar puncture. With fluoroscopic guidance, the frequency of a traumatic tap varied significantly with the operator, ranging from 0% to 24%. CONCLUSION: The use of fluoroscopy-guided lumbar puncture in patients with suspected SAH and negative CT findings should reduce the frequency of false-positive diagnoses of acute SAH as well as the number of unnecessary angiograms for patients with suspected SAH but no underlying intracranial vascular malformation.     

Abnormalities on brain MR images during the course of familial haemophagocytic lymphohistocytosis in a child. A case report

Purpose:
To describe and report the neuroradiological findings and clinical features in a patient with familial haemophagocytic lymphohistocytosis (FHL), a rare hereditary immune dysregulation in early childhood characterised by multisystem involvement, including in approximately 30% of cases also the central nervous system (CNS).
Material and Methods:
Serial brain MR examinations were carried out in a 4.5-year-old boy with FHL, finally complicated with Epstein-Barr virus (EBV)-driven posttransplantation lymphoma.
Results:
Multiple brain MR examinations before and after contrast enhancement showed discrete perivascular non-enhancing areas of high signal intensity on T2 images, and later also an enhancing lesion in the right caudate nucleus.
Conclusion:
FHL should be included in the differential diagnosis of patchy white matter abnormalities in young patients. EBV-driven post-transplantation lymphoma, which may present as meningial and/or parenchymal CNS infiltration, is a differential diagnostic problem.