Atypical CT and MRI aspects of an epidermoid cyst.

We report a case of an unusual epidermoid cyst (EC) of the cerebellopontine angle that appeared hyperdense on computed tomography (CT) scanning, hyperintense on T1-weighted MR images and hypointense on T2-weighted magnetic resonance (MR) images. Diffusion-weighted imaging showed a hypointense lesion. We discuss imaging characteristics of ECs, explain the atypical findings in our case and confirm that the signal seen on diffusion-weighted images in the EC is related to a T2 effect.

Reversible metronidazole-induced encephalopathy.

We report the neuroimaging findings of a case of reversible metronidazole-induced encephalopathy. Magnetic resonance imaging (MRI) demonstrated lesions in highly suggestive locations. Follow-up imaging performed 1 month after cessation of metronidazole therapy demonstrated resolution of imaging findings.

Intrasphenoidal rathke cleft cyst.

Symptomatic Rathke cleft cysts (RCC) are reported in the sellar and suprasellar regions, but no case of sphenoidal RCC has been reported. We report a case of sphenoidal RCC in a 41-year-old man. The lesion was revealed by headaches and diplopia. Symptoms disappeared transiently after a spontaneous rhinorrhea but relapsed 4 months later. MR imaging showed a cystic sphenoidal lesion, isointense on T1-weighted images (WI) with peripheral gadolinium enhancement and hyperintense on T2 WI. The patient underwent surgery through a transrhinoseptal approach. The wall of the sphenoid sinus was paper-thin. The cyst contained a motor-oil-like fluid and communicated widely with the nasal fossa. Its wall was partially extracted. Symptoms and signs ceased after surgery. MR imaging performed 1 year later showed the disappearance of the sphenoidal cyst. Embryological origin of RCCs is discussed. The hypothesis of a continuum between the different epithelial cystic lesions of the sellar and parasellar region is discussed. Imaging has an important impact on the diagnosis; nevertheless, the specific characterization remains difficult.

[Deep cerebral venous system thrombosis: report of two cases]. / Thrombose veineuse cerebrale profonde: à propos de deux observations.

We report two cases of cerebral deep venous thrombosis in female adults. The first patient presented with headaches and confusion 20 days postpartum. Deep cerebral internal venous thrombosis was suspected based on the CT scan showing bilateral hypodensity in the thalamus and internal capsules. The diagnosis was confirmed on cerebral angiography. The patient was treated but died within 3 weeks of the onset of symptoms. The second patient had no obvious predisposing factors. She presented with confusion and fever. The diagnosis was strongly suggested by the CT scan, which showed spontaneous high density in the deep venous system associated with bilateral hypodensities in the thalamus and internal capsules. Venous MR angiography revealed obliteration of internal cerebral veins and the great vein of Galen. Ten days after appropriate therapy, the patient recovered completely.

[Central neurocytoma]. / Le neurocytome central.

Central neurocytoma is a rare intraventricular tumors occuring in young adults. The computerized tomography and the MR imaging permit to suspect the diagnosis that remains however difficult. Imunohistochemestry allows the diagnosis. We report hereby 8 new cases of central neurocytoma collected in the Institute of Neuroradiology of Tunis, four men and four women. The ages of the patients ranged from 17 to 34 years at the time of the diagnosis. The clinical and neuroradiological features of this tumour will be presented and discussed.

[Gliomatosis cerebri]. / La gliomatose cerebrale.

The Gliomatosis Cerebri (GC) is an infiltrating and rare primitive tumour of the brain. It is characterized by diffuse neoplastic proliferation of glial cells involving of at least two lobes of the brain, without a distinct tumor mass and with the preservation of the anatomical and neuronal architecture. According to the WHO classification, GC is categorized as a high-grade neuroepithelial tumor of uncertain origin (GradelV). Now the diagnosis is facilitated via stereotactic biopsies of the representative lesion identified in magnetic resonance. Our objective is to present 4 new cases, and recall the clinical and radiological features and the prognosis.

[Balò's concentric sclerosis in a North-African patient]. / Sclérose concentrique de Balò chez un patient nord-africain.

INTRODUCTION: Balo's concentric sclerosis is a rare variant of multiple sclerosis described by Balo in 1928. It is characterized by alternating rings of demyelination and spared myelin. CASE REPORT: We report a case of Balo's concentric sclerosis diagnosed by the typical MRI findings of concentric rings of demyelination. Medullar and brain localisation were found and clinical course was good under intravenous corticosteroids. CONCLUSION: MRI provides the best diagnostic information for Balo's concentric sclerosis, allowing early diagnosis and treatment.

[Plasmocytoma of the skull base revealing multiple myeloma]. / Plasmocytome de la base du crâne révélant un myélome multiple.

We report a case of sphenoidal plasmocytoma in a 57-year-old male revealing multiple myeloma. MRI showed a tumor located in the sphenoid sinus with local extension. Diagnosis was made by histology after transsphenoidal resection. We discuss the imaging features of plasmocytomas and review the principal differential diagnoses.

[Spontaneously hyperdense intracranial epidermoid cyst]. / Kyste épidermoïde intracrânien spontanément hyperdense.

Intracranial epidermoid cysts are relatively rare tumors. These cysts are generally nearly isodense to CSF at CT and nearly isointense to CSF on T1W and T2W MR imaging. Spontaneously hyperdense epidermoid cysts are exceptional. We report the case of a 12-year-old girl with a spontaneously hyperdense epidermoid cyst of the posterior fossa presenting with focal neurological symptoms. The diagnosis was confirmed at histological examination.