Bulk flow of brain interstitial fluid under normal and hyperosmolar conditions

Although bulk flow of brain interstitial fluid (ISF) occurs with changes in hydrostatic and osmotic pressures, under normal conditions only diffusion of molecules in the ISF has been reported. Extrachoroidal cerebrospinal fluid (CSF) production and intracerebral injection studies, however, provide indirect evidence for the bulk flow of ISF under normal conditions. We studied tissue penetration profiles of an extracellular molecule in gray and white matter after 1-, 2-, 3-, and 4-h ventriculocisternal perfusions. Gray matter apparent diffusion coefficients were similar at different times as expected with diffusion; however, white matter coefficients decreased significantly with time, suggesting bulk flow of ISF. White matter data was reanalyzed for both bulk flow and diffusion; we calculated a diffusion coefficient of 3.00 x 10(-6) cm2/s and a velocity for ISF of 10.5 micrometers/min toward the ventricle. Additional animals were given 20% mannitol (1.5--3 g/kg) intravenously prior to a /-h ventriculocisternal perfusion. Mannitol produced a significant bulk flow of ISF away from the ventricle in gray matter. We estimate that 30% of extrachoroidal CSF production is from flow of ISF in white matter.

Subcortical arteriosclerotic encephalopathy (Binswanger): computerized tomography

The subcortical arteriosclerotic encephalopathy of Binswanger is characterized clinically by hypertension, dementia, spasticity, syncope, and seizures. It is usually diagnosed pathologically by the finding in white matter of diffuse demyelination or foci of necrosis plus arteriosclerotic and hypertensive vasculopathy. We present a case in which the diagnosis was made on the basis of the clinical course and a computerized tomogram which demonstrated extensive white matter degeneration. Postmortem examination confirmed both the diagnosis and the extent of the degeneration as shown by CT scan.

Cerebellar hemorrhage: reliability of clinical evaluation

Surgery without confirmatory radiological contrast studies has been advocated in patients suspected of having a cerebellar hemorrhage. To determine the reliabiligy of the clinical evaluation, records were reviewed of 33 patients in whom the diagnosis of cerebellar hemorrhage was initially suspected or subsequently confirmed. In 13 patients the correct diagnosis had been made initially by clinical evaluation, but in ten patients the correct diagnosis was not suspected at the initial evaluation. The remaining ten patients had typical backgrounds, symptoms, and signs of a spontaneous cerebellar hemorrhage, but radiological contrast studies and clinical observation indicated that other neurological lesions were responsible. Thus, utilizing solely the clinical evaluation, the diagnosis of cerebellar hemorrhage may be made only with difficulty and not with the certainty required for emergency surgery.

Meckel's cave meningiomas with subarachnoid hemorrhage

Two patients with Meckel's Cave meningiomas were initially hospitalized as a result of subarachnoid hemorrhage. Four-vessel angiography was necessary to exclude other causes of bleeding while demonstrating these lesions. Apoplectic presentation in both cases led to early diagnosis and successful surgical therapy. A review of the literature reveals subarachnoid hemorrhage to be a rarity in association with meningiomas. The two patients currently reported are believed to be the only examples on record of hemorrhagic meningiomas arising from the region of Meckel's Cave.