Obstructive hydrocephalus (secondary aqueductal stenosis)
Symptoms of increased intracranial pressure as vomiting, headache, and seizures. History of previous attaches of meningitis.
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MRI demonstrates marked dilatation of the supratentorial ventricular system noted with associated enlarged sized 4th ventricle, associated with webs at the distal portion of the aqueduct, causing marked tight distal stenosis and with proximal funneling.
This is associated with decreased mamillopontine distance (3 mm) and peri-ventricular T2/FLAIR hyperintensity reflecting associated trans-ependymal permeation. Webs are also noted at the 4th ventricular outlet foramina, notably the median foramen of Magendie, with consequent supratentorial ventricular dilatation and prominent 4th ventricular.
Dynamic CSF flow study & ultra thin 3D T2 Sagittal sequences revealed: Multiple webs noted at the distal portion of the aqueduct with consequent tight aqueductal stenosis and at 4th ventricle outlet foramen. Very Poor/absent CSF flow signal across the aqueduct at cine phase sequences matching the markedly tight focal aqueductal stenosis.
Multiple webs noted at the distal portion of the aqueduct and 4th ventricle outlet foramina, with a consequent marked tight aqueductal stenosis ... likely represent post-meningitic sequels. Subsequent active obstructive tetra-ventricular hydrocephalic changes, with transependymal permeation.
The absence of a flow-void signal intensity on sagittal T2 images at the aqueductal level is suggestive sign of aqueductal stenosis. MRI CSF flow study is helpful to determine the level of obstructive hydrocephalus.