Diseases of the intracranial meninges: MR imaging features

Assessing Nordihydroguaiaretic Acid Therapeutic Effect for Glioblastoma Multiforme

In this study, we demonstrate that Raman microscopy combined with computational analysis is a useful approach to discriminating accurately between brain tumor bio-specimens and to identifying structural changes in glioblastoma (GBM) bio-signatures after nordihydroguaiaretic acid (NDGA) administration. NDGA phenolic lignan was selected as a potential therapeutic agent because of its reported beneficial effects in alleviating and inhibiting the formation of multi-organ malignant tumors. The current analysis of NDGA's impact on GBM human cells demonstrates a reduction in the quantity of altered protein content and of reactive oxygen species (ROS)-damaged phenylalanine; results that correlate with the ROS scavenger and anti-oxidant properties of NDGA. A novel outcome presented here is the use of phenylalanine as a biomarker for differentiating between samples and assessing drug efficacy. Treatment with a low NDGA dose shows a decline in abnormal lipid-protein metabolism, which is inferred by the formation of lipid droplets and a decrease in altered protein content. A very high dose results in cell structural and membrane damage that favors transformed protein overexpression. The information gained through this work is of substantial value for understanding NDGA's beneficial as well as detrimental bio-effects as a potential therapeutic drug for brain cancer.

Orbitofrontal approach for the fenestration of a symptomatic sellar arachnoid cyst

Background

Sellar arachnoid cysts (SACs) are rare lesions and incidentally found on brain imaging. The pathophysiology is poorly understood. Some authors suggested that SACs develop as a herniation of arachnoid membrane through the diaphragma sellae followed by cyst formation. Furthermore, Meyer et al. postulated that SACs are formed by splitting of the arachnoid layers. Symptomatic SACs present with headache, visual field deficit, or pituitary dysfunction. The data are limited on the indications and timing for intervention. We present a case of symptomatic SAC that was fenestrated using orbitofrontal approach.

Case Description

A 64-year-old female presented with chronic headaches and blurriness of vision. She was previously diagnosed with diabetes insipidus (DI) that was treated with desmopressin, magnetic resonance imaging (MRI) of her brain at that time was normal. Later on, she developed severe headaches that were managed medically. A year later, she had an episode of generalized seizure that led to the discovery of SAC on brain MRI. On examination, she had a left-sided monocular temporal hemianopia. The patient underwent an orbitofrontal craniotomy for fenestration of the SAC. At 6-month follow-up, her headaches had significantly improved with the resolution of the visual deficit. In addition, the DI had resolved, and the desmopressin was discontinued.

Conclusion

SACs are rare with no consensus on the indications for surgery. Our experience suggests that fenestration of SAC through transcranial approach is a valid option for patients with visual deficit and/or pituitary dysfunction.

Contrast-enhanced modified 3D T1-weighted TSE black-blood imaging can improve detection of infectious and neoplastic meningitis

OBJECTIVES

To evaluate the diagnostic value of a contrast-enhanced 3D T1-weighted-modified volumetric isotropic turbo spin-echo acquisition sequence (T1-mVISTA) in comparison with a conventional 3D T1-weighted magnetization-prepared rapid gradient-echo (T1-MP-RAGE) sequence for the detection of meningeal enhancement in patients with meningitis.

METHODS

Thirty patients (infectious meningitis, n = 12; neoplastic meningitis, n = 18) and 45 matched controls were enrolled in this retrospective case-control study. Sets of randomly selected T1-mVISTA and T1-MP-RAGE images (both with 0.8-mm isotropic resolution) were read separately 4 weeks apart. Image quality, leptomeningeal and dural enhancement, grading of visual contrast enhancement, and diagnostic confidence were compared using the Kruskal-Wallis rank sum test.

RESULTS

Image quality was rated to be good to excellent in 75 out of 75 cases (100%) for T1-mVISTA and 74 out of 75 cases (98.7%) for T1-MP-RAGE. T1-mVISTA detected significantly more patients with leptomeningeal enhancement (p = 0.006) compared with T1-MP-RAGE (86.7 vs. 50.0%, p < 0.001), each with specificity of 100%. Similarly, sensitivity of T1-mVISTA for the detection of dural and/or leptomeningeal enhancement was also significantly higher compared with that of T1-MP-RAGE (96.7 vs. 80.0%, p = 0.025) without significant differences regarding specificity (97.8 vs. 95.6%, p = 0.317). No significant differences were found for dural enhancement alone. Diagnostic confidence in T1-mVISTA was significantly higher (p = 0.01). Visual contrast enhancement was tendentially higher in T1-mVISTA.

CONCLUSIONS

T1-mVISTA may be an adequate and probably better alternative to T1-MP-RAGE for detection of leptomeningeal diseases.

KEY POINTS

• Black-blood T1-mVISTA showed a significant higher sensitivity for the detection of leptomeningeal enhancement compared with MP-RAGE without losses regarding specificity. • Diagnostic confidence was assessed significantly higher in T1-mVISTA. • T1-mVISTA should be considered a supplement or an alternative to T1-MP-RAGE in patients with suspected leptomeningeal diseases.

MRI Findings of Spontaneous Intracranial Hypotension: Usefulness of Straight Sinus Distention

OBJECTIVE. Spontaneous intracranial hypotension (SIH) shows various characteristic MRI findings. We evaluated the usefulness of straight sinus distention compared with transverse sinus distention and also evaluated other MRI findings of SIH. MATERIALS AND METHODS. Forty-three consecutive patients (28 female and 15 male patients) treated for SIH and 43 age- and sex-matched control subjects at two institutions from 2012 through 2014 were included in this study. Two reviewers determined whether the transverse sinus distention sign and straight sinus distention sign were present on MRI. Diagnostic performance values and interobserver agreement were calculated. Reviewers also assessed MRI examinations in consensus for the presence of the following findings: pachymeningeal enhancement, subdural effusion or hematoma, enlargement of the pituitary gland, and downward displacement of the brainstem and tonsils. RESULTS. The sensitivity, specificity, and diagnostic accuracy of the transverse sinus distention sign for SIH were 76.7%, 83.7%, and 80.2%, whereas those of the straight sinus distention sign were 79.1%, 95.4%, and 87.2%, respectively. The specificity of the straight sinus distention sign for SIH was significantly higher (p = 0.025) than that of the transverse sinus distention sign. In addition, the straight sinus distention sign showed substantial agreement (κ = 0.79), whereas the transverse sinus distention sign showed moderate agreement (κ = 0.60). The diagnostic accuracy of the presence of either transverse or straight sinus distention (83.7%) was significantly higher than that of pachymeningeal enhancement (80.2%, p = 0.032). CONCLUSION. The straight sinus distention sign could be helpful for the diagnosis of SIH because it has sensitivity comparable to other imaging findings and higher specificity and higher level of interobserver agreement than other imaging findings.

Contrast-enhanced FLAIR (fluid-attenuated inversion recovery) for evaluating mild traumatic brain injury

PURPOSE

To evaluate whether adding a contrast-enhanced fluid-attenuated inversion recovery (FLAIR) sequence to routine magnetic resonance imaging (MRI) can detect additional abnormalities in the brains of symptomatic patients with mild traumatic brain injury.

MATERIALS AND METHODS

Fifty-four patients with persistent symptoms following mild closed head injury were included in our retrospective study (M ∶ F =  32 ∶ 22, mean age: 59.8 ± 16.4, age range: 26-84 years). All MRI examinations were obtained within 14 days after head trauma (mean: 3.2 ± 4.1 days, range: 0.2-14 days). Two neuroradiologists recorded (1) the presence of traumatic brain lesions on MR images with and without contrast-enhanced FLAIR images and (2) the pattern and location of meningeal enhancement depicted on contrast-enhanced FLAIR images. The number of additional traumatic brain lesions diagnosed with contrast-enhanced FLAIR was recorded. Correlations between meningeal enhancement and clinical findings were also evaluated.

RESULTS

Traumatic brain lesions were detected on routine image sequences in 25 patients. Three additional cases of brain abnormality were detected with the contrast-enhanced FLAIR images. Meningeal enhancement was identified on contrast-enhanced FLAIR images in 9 cases while the other routine image sequences showed no findings of traumatic brain injury. Overall, the additional contrast-enhanced FLAIR images revealed more extensive abnormalities than routine imaging in 37 cases (p<0.001). In multivariate logistic regression analysis, subdural hematoma and posttraumatic loss of consciousness showed a significant association with meningeal enhancement on contrast-enhanced FLAIR images, with odds ratios 13.068 (95% confidence interval 2.037 to 83.852), and 15.487 (95% confidence interval 2.545 to 94.228), respectively.

CONCLUSION

Meningeal enhancement on contrast-enhanced FLAIR images can help detect traumatic brain lesions as well as additional abnormalities not identified on routine unenhanced MRI. Therefore contrast-enhanced FLAIR MR imaging is recommended when a contrast MR study is indicated in a patient with a symptomatic prior closed mild head injury.

Appearance of the canine meninges in subtraction magnetic resonance images

The canine meninges are not visible as discrete structures in noncontrast magnetic resonance (MR) images, and are incompletely visualized in T1-weighted, postgadolinium images, reportedly appearing as short, thin curvilinear segments with minimal enhancement. Subtraction imaging facilitates detection of enhancement of tissues, hence may increase the conspicuity of meninges. The aim of the present study was to describe qualitatively the appearance of canine meninges in subtraction MR images obtained using a dynamic technique. Images were reviewed of 10 consecutive dogs that had dynamic pre- and postgadolinium T1W imaging of the brain that was interpreted as normal, and had normal cerebrospinal fluid. Image-anatomic correlation was facilitated by dissection and histologic examination of two canine cadavers. Meningeal enhancement was relatively inconspicuous in postgadolinium T1-weighted images, but was clearly visible in subtraction images of all dogs. Enhancement was visible as faint, small-rounded foci compatible with vessels seen end on within the sulci, a series of larger rounded foci compatible with vessels of variable caliber on the dorsal aspect of the cerebral cortex, and a continuous thin zone of moderate enhancement around the brain. Superimposition of color-encoded subtraction images on pregadolinium T1- and T2-weighted images facilitated localization of the origin of enhancement, which appeared to be predominantly dural, with relatively few leptomeningeal structures visible. Dynamic subtraction MR imaging should be considered for inclusion in clinical brain MR protocols because of the possibility that its use may increase sensitivity for lesions affecting the meninges.

Cranio cervical tuberculous hypertrophic pachymeningitis

Background:

Hypertrophic pachymeningitis is a unique clinical entity characterized by fibrosis and thickening of dura mater resulting in neurological dysfunction. It could be idiopathic or due to variety of inflammatory and infectious conditions. Tuberculous hypertrophic pachymeningitis involving cranio cervical region is rarely reported.

Case Description:

A 50-year-old female presented with history of progressive quadriparesis and stiffness of neck for 2 years, dysphagia to liquid for past 3 months. Her condition rapidly deteriorated when another physician prescribed her corticosteroid. Physical examination revealed high cervical compressive myelo-radiculopathy with lower cranial nerve palsy and neck rigidity. Series of serum analysis, cerebrospinal fluid (CSF) study and contrast magnetic resonance imaging (MRI) clinched the diagnosis. She improved on antitubercular treatment.

Conclusion:

In case of multilevel cervical compressive myelo-radiculopathy with lower cranial involvement, possibility of hypertrophic pachymeningitis should be kept in mind. Before diagnosing it as idiopathic, infectious causes should be excluded otherwise prescription of corticosteroid will flare up the disease process.

Medulloblastoma presenting with tentorial "dural-tail" sign: is the "dural-tail" sign specific for meningioma?

To the best of our knowledge, the association of a medulloblastoma with a "dural-tail" sign has not been previously reported. A 24-year-old male developed severe headaches and right-sided dysmetria that worsened over 1 month. Magnetic resonance (MR) imaging of the brain demonstrated a heterogeneously enhancing lesion in the posterior fossa. The lesion appeared to be tentortally-based and exhibited a characteristic "dural-tail" sign, which is considered pathognothonic for meningioma. Cerebellar tonsil ectopia and hydrocephalus were also present. The presumptive diagnosis of tentorial meningioma was made. The lesion was resected by a posterior fossa approach. At surgery, the appearance of the tumor was inconsistent with the diagnosis of meningioma, and histopathologic evaluation yielded the diagnosis of medulloblastonia. This case and the literature demonstrate that malignant tumors can present with the characteristic MR imaging appearance of a meningioma. This possibility must be considered when treatment is planned, especially if a nonoperative course is favored.

Emergent neuroimaging of intracranial infection/inflammation

Infectious and inflammatory processes of the intracranial compartment often result in acute clinical presentations. The possible causes are legion. Clues to the diagnosis involve clinical presentation, laboratory analysis, and neuroimaging. This article reviews some of the salient factors in understanding intracranial infection/ inflammation, including pathophysiology and neuroimaging protocols/findings, and provides some examples and a few "pearls and pitfalls."

Imaging of the meninges and the extra-axial spaces

The separate meningeal layers and extraaxial spaces are complex and can only be differentiated by pathologic processes on imaging. Differentiation of the location of such processes can be achieved using different imaging modalities. In this pictorial review we address the imaging techniques, enhancement and location patterns, and disease spread that will promote accurate localization of the pathology, thus improving accuracy of diagnosis. Typical and unusual magnetic resonance (MR), computed tomography (CT), and ultrasound imaging findings of many conditions affecting these layers and spaces are described.

Meninges in cancer imaging

Primary malignant tumours arising from the meninges are distinctly uncommon, and when they occur, they are usually sarcomas. In contrast, metastatic meningeal involvement is increasingly seen as advances in cancer therapy have changed the natural history of malignant disease and prolonged the life span of cancer patients. The meninges can either be infiltrated by contiguous extension of primary tumours of the central nervous system, paranasal sinuses and skull base origin or can be diffusely infiltrated from haematogenous dissemination from distant primary malignancies. Imaging in these patients provides crucial information in planning management. This article reviews the pertinent anatomy that underlies imaging findings, discusses the mechanism of meningeal metastasis and highlights different imaging patterns of meningeal carcinomatosis and the pitfalls.

Magnetic resonance imaging of miliary tuberculosis of the central nervous system in children with tuberculous meningitis

BACKGROUND

Tuberculous meningitis (TBM) is closely associated with miliary tuberculosis and a pathogenetic relationship is suspected, although it has been proposed that the two processes are unrelated.

OBJECTIVE

To describe miliary tuberculosis of the central nervous system (CNS) on MRI in children with TBM.

MATERIALS AND METHODS

A retrospective descriptive study of 32 paediatric TBM patients referred for MRI. The presence of miliary nodules in the CNS was recorded. Lesions were categorized according to their distribution, enhancement pattern, size and signal characteristics.

RESULTS

A miliary distribution of nodules was present in 88% of patients. All patients with a miliary distribution had leptomeningeal nodules and 18% of these patients had deep parenchymal nodules in addition. At least one tuberculoma with central T2 hypointensity was identified in 39% of patients.

CONCLUSION

The high prevalence of miliary leptomeningeal nodules in the CNS of children with TBM is significant because it points to a pathogenetic relationship that has long been suspected on epidemiological grounds. Our findings challenge the concept that miliary tuberculosis is only an incidental finding in TBM patients and suggest that it plays an integral part in the pathogenesis.

INTRASELLAR ARACHNOID CYSTS

OBJECTIVE

To evaluate the clinical, endocrinological, and radiological presentation of nine cases of surgically verified intrasellar arachnoid cysts and to discuss the physiopathological mechanisms of formation of these cysts.

METHODS

Among 1540 patients presenting with pituitary lesions, nine presented with an intrasellar arachnoid cyst. Their charts were retrospectively reviewed.

RESULTS

Presenting symptoms included headache (n = 2), visual symptoms (n = 3), menstrual irregularities (n = 2), rapid weight gain (n = 1), vertigo (n = 1), and/or confusion (n = 1). Two cysts were discovered incidentally. T1-weighted magnetic resonance imaging scans showed an intrasellar cystic lesion in all cases, with a huge suprasellar extension in six cases. The cyst was of the same intensity as the cerebrospinal fluid (CSF) in only two patients. A transsphenoidal approach allowed the transdural aspiration of fluid and injection of a water-soluble contrast agent under mild pressure. In three patients, the contrast infiltrated along the pituitary stalk toward the subarachnoid spaces; in the other patients, it remained in the intrasellar compartment. Cyst membranes were removed as completely as possible with fenestration toward the subarachnoid spaces in communicating cysts. In spite of tight packing of the sella and sphenoid sinus, CSF fistulae requiring reoperation developed in two patients.

CONCLUSION

The clinical picture of an intrasellar arachnoid cyst resembles that of a nonfunctional pituitary adenoma. Magnetic resonance imaging scans typically show a cystic intrasellar lesion with suprasellar extension, containing isointense or, more often, hyperintense fluid on T1-weighted sequences. In spite of the risk of CSF fistulae, the preferred surgical approach is transsphenoidal. A physiopathological mechanism is proposed according to anatomic variations of the sellar diaphragma allowing penetration of subarachnoid spaces into the sellar compartment and their enlargement by a ball-valve mechanism.

MRI findings of eosinophilic myelomeningoencephalitis due to Angiostrongylus cantonensis

AIM

To study the imaging characteristics of eosinophilic myelomeningoencephalitis due to Angiostrongylus cantonensis using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Seventeen MRI examinations of the brain and spinal cord in five patients with angiostrongyliasis cantonensis of the central nervous system were performed. The final diagnosis was based on typical clinical symptoms, results of blood and cerebrospinal fluid (CSF) tests, and the presence of nematode larvae in the CSF. The sequential MRI follow-up examinations were carried out at a different stage for every patient from 1 to 28 weeks after the onset of symptoms. The features of the lesions in the brain, spinal cord, meninges and nerve roots on MRI were studied, moreover, the development of the lesions was analysed on follow-up MRI.

RESULTS

Abnormalities were demonstrated on MRI in all five cases. They included three cases of meningoencephalitis, one case of encephalitis and one myelomeningitis. The locations and appearances of the lesions were as follows: (1) brain involvement in four cases (including cerebrum in four, cerebellum in two and brain stem in three), and spinal cord involvement in one case. These lesions were diffuse or scattered and appeared as similar or slightly reduced signal intensity on T1-weighted images (T1WI), high signal intensity on T2-weighted images (T2WI) and turbo fluid attenuated inversion recovery pulse sequence (FLAIR) images. After administration of gadolinium chelate (Gd-DTPA), multiple round or oval enhancing nodules, with diameters ranging from 3 to 10 mm, were seen on T1WI, a few lesions appeared as stick-shaped enhancement whose longest measurement was 14 mm. Diffuse or local oedema around the lesion could be seen. (2) Meningeal involvement in four cases, a case of ependymal involvement and a case of nerve root involvement were among them. These lesions appeared as linear or nodular enhancement of the leptomeninges and ependyma, as well as nerve root enhancement. (3) There was a mild ventricular enlargement in two cases. On follow-up MRI lesions were most severe from the 5th week to the 8th week and it took at least 4-8 weeks (1-2 months) for a lesion to resolve completely, the resolution of larger lesion needed more than 22 weeks.

CONCLUSION

Multiple enhancing nodules in the brain and linear enhancement in the leptomeninges were the main features; stick-shaped enhancement was the characteristic sign of the disease on Gd-DTPA enhanced-T1 weighted images.

Extra-axial brain tumors

Meningiomas, schwannomas, metastases, maldevelopmental cysts, epidermoids, dermoids and bone tumors represent the vast majority of extra-axial brain tumors. The location of extra-axial brain tumors affects treatment planning and predicts their prognosis. Computed tomography and particularly magnetic resonance imaging are used for diagnosis and localization. In this article, the imaging findings of the extra-axial brain tumors are discussed.

Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.

Céphalées isolées révélatrices d’une méningite carcinomateuse

INTRODUCTION

Carcinomatous meningitis reveals a solid cancer in 10 percent of cases.

OBSERVATION

Our patient developed isolated headache which progressively worsened. Cranial Computerized Tomography (CT) was normal. Brain MRI showed multiples areas of contrast enhancements meningeal tissue associated with small nodulars deposits. Repeated cerebrospinal fluid (CSF) examinations revealed elevated tumor markers suspect cells. The diagnosis of pulmonary adenocarcinoma was established during systematic follow-up.

CONCLUSION

The diagnosis of carcinomatous meningitis can be difficult to establish because of the non-specific clinical presentation and the absence of suggestive context; negative CSF-cytology is frequent. MRI and elevated tumor markers in the CSF compared with the serum level contribute significantly to diagnosis.

Delayed post-contrast fluid-attenuated inversion recovery image for depicting meningeal carcinomatosis

We present a case of intracranial meningeal carcinomatosis that was visualized more clearly on a delayed contrast-enhanced fluid-attenuated inversion recovery (FLAIR) MRI than on other regular post-contrast MRI.

Infectious meningitis: prospective evaluation with magnetization transfer MRI

The study was performed with the aim of prospectively characterizing infectious meningitis of different aetiology using magnetization transfer (MT) MRI. Spin-echo (SE) T(1), T(2) and pre- and post-contrast T(1) weighted MT images in 100 patients with aetiologically proven meningitis were evaluated for the visibility and enhancement of the meninges on pre- and post-contrast T(1) weighted MT images, respectively. The MT ratio (MTR) was calculated from the thickened meninges in tuberculous meningitis. In addition, the percentage difference in the mean signal intensity (SI) of the meninges and adjacent brain parenchyma was calculated and compared between different groups using 2-tailed student's t-test. T(1) weighted MT images were highly sensitive (96%) in the detection of abnormal meningeal enhancement. Meninges were visible on pre-contrast T(1) weighted MT images only in patients with tuberculous meningitis. The MTR from meninges in tuberculous infection was 19.10+/-1.02, and the percentage difference in the mean SI of the meninges and the adjacent T(2) normal brain parenchyma was significantly higher (p<0.05) in the tuberculous group compared with that in the non-tuberculous group. MT MRI is an important technique for the detection and characterization of infectious meningitis of different aetiology. Visibility of the meninges on pre-contrast T(1) weighted MT images may be considered highly suggestive of tuberculous meningitis.

Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.

Imaging evaluation of sensorineural hearing loss

The imaging evaluation of patients with sensorineural hearing loss (SNHL) focuses on the acoustic pathways from the cochlea to the auditory cortex. Magnetic resonance imaging (MRI) is the modality of choice for most patients with SNHL, though computed tomography (CT) also plays an important role in the evaluation of bony changes and in patients for whom MRI is contraindicated. Conventional enhanced MRI is the most commonly used technique in this clinical setting. High-resolution fast spin-echo T2 MRI is an adjunctive technique that provides exquisite evaluation of the cerebellopontine angle (CPA), internal auditory canal (IAC), cranial nerves, and membranous labyrinth, and plays a significant role in the diagnosis and surgical evaluation of SNHL. Categories of lesions that cause SNHL include brain lesions involving central auditory pathways; neoplasms of the CPA and IAC, the most common being schwannoma; other neoplastic, congenital, and cystic masses of the CPA and IAC; congenital anomalies of the inner ear; intrinsic cochlear nerve defects, inflammatory processes of the inner ear; and temporal bone trauma.

A case of Streptococcus pneumoniae meningitis showing a marked contrast enhancement effect of whole arachnoid membrane on MRI

We have experienced the adult case of meningitis caused by the Streptococcus pneumoniae, which showed the most aggressive clinical course. The peculiar and unique magnetic resonance images are reported. The whole arachnoid membrane was prominently enhanced following the contrast material injection, however, no contrast enhancement was observed in subarachnoid space, ependyma, intraventricular cerebrospinal fluid, and dura mater. This implies the superacute phase of the bacterial meningitis, in which inflammation is localized in the whole arachnoid membrane. The contrast enhancement effect in the meningitis may vary depending on the phase and severity, because it is a time-progressive disease.

Neoplastic meningitis: diagnosis and treatment considerations

Neoplastic meningitis is an increasingly recognized complication of advanced metastatic cancer and, if left undiagnosed or untreated, is characterized by rapid neurologic deterioration and death. Thus, the diagnosis and treatment of neoplastic meningitis present challenges for the clinical oncologist. The diagnosis of neoplastic meningitis is based on clinical signs and symptoms, laboratory analysis of cerebrospinal fluid to determine cell count and cytology, and analysis of neuroimaging studies for evidence of leptomeningeal or cranial nerve enhancement. Once diagnosed, conventional treatment regimens may include radiotherapy combined with systemic or intrathecal chemotherapy, often with the antimetabolites cytarabine and/or methotrexate. However, the prognosis for neoplastic meningitis secondary to an underlying solid tumor or recurrent leukemia is poor with conventional treatment regimens. Therefore, novel agents for intrathecal administration, including DepoCyttrade mark, mafosfamide, and topotecan, or novel therapeutic approaches, including conjugated monoclonal antibodies and immunotoxins or gene therapy, are currently under investigation. Such new agents and therapeutic approaches will facilitate the development of effective treatment strategies and will ultimately improve the outcome for patients with this devastating disease. This article provides an overview of the approaches to the diagnosis, evaluation, and treatment of neoplastic meningitis.

Magnetic resonance imaging of intracranial hypotension syndrome with pathophysiological correlation

OBJECTIVE

To correlate the pathophysiology of intracranial hypotension syndrome with abnormalities in the brain and spine found through magnetic resonance imaging.

METHODS

In a series of 11 patients with intracranial hypotension syndrome, brain magnetic resonance scans were evaluated for the thickness, distribution, morphology, and pattern of meningeal enhancement coincident with subdural fluid collections and the descent of the brain toward the skull base. Spinal magnetic resonance studies were reviewed for extra-arachnoid fluid collections, meningeal enhancement, and distended epidural veins.

RESULTS

Diffuse, continuous dural-arachnoid enhancement was present in all patients with abnormal brain studies. The dura was thickest in patients with very low intracranial pressures. Subdural fluid collections and descent of the brain were seen in patients with the thickest meninges and were not present in the absence of meningeal enhancement. Extra-arachnoid or paraspinal fluid collections were found in all patients who had spinal magnetic resonance scans.

CONCLUSIONS

In the brain, diffuse dural-arachnoid enhancement is the most common imaging abnormality and is probably the earliest magnetic resonance manifestation of intracranial hypotension syndrome, while subdural fluid collections and descent of the brain are indicators of a more severe hypotensive state. Extra-arachnoid fluid collections are common spinal imaging abnormalities.

Infectious meningitis mimicking recurrent medulloblastoma on magnetic resonance imaging. Case report

This report and the accompanying review of the literature address the challenges, when using surveillance magnetic resonance (MR) imaging, of establishing the origin of newly detected central nervous system lesions. Routine surveillance MR imaging in a 16-year-old boy, whose medulloblastoma had been successfully treated, demonstrated asymptomatic nodular leptomeningeal enhancement of the brain and spinal cord, which was consistent with recurrent disease. Examination of the cerebrospinal fluid, however, led to the diagnosis of bacterial meningitis. Two weeks after completion of antibiotic therapy, the original MR imaging findings were seen to have resolved. This case illustrates the importance of considering clinical and laboratory data, including results from a complete examination of the cerebrospinal fluid, when interpreting the origin of new lesions revealed by MR imaging.

Leptomeningeal carcinomatosis from carcinoma of the palatine tonsil

Distant metastases from carcinoma of the palatine tonsil are very uncommon. We encountered a case of a carcinoma involving the tonsillar region that resulted in subarachnoid mestastases following local radical radiotherapy. Metastases were diagnosed following magnetic resonance imaging and spinal fluid cytology. The patient succumbed to the disease after a rapid downhill course, 1 month following diagnosis of the secondary deposit. The present paper describes the rare site of distant metastasis and reviews the relevant literature.

Neuroimaging of meningeal disease

In the past two decades, the advent of CT and MRI has made a considerable impact on the evaluation of meningeal diseases, conditions once regulated to cytological, histopathological, or postmortem analyses alone. This article reviews the imaging findings in various meningeal processes with particular attention to the anatomic definition of the meningeal layers and their relationship to the development of meningeal pathology and consequent imaging characteristics.