Arachnoid cysts

From WikiCNS

1. A developmental abnormality
2. Most occur in the Sylvian fissure (50%) and all associated with an arachnoid cistern such as the sylvian fissure, cerebellopontine angle, ambient cistern, cisterna magna, prepontine and interpeduncular cisterns, chiasmatic cisterns
   1. underlying cortex is normal
   2. Sylvian fissure arachnoid cysts are associated with seizures
3. Cysts are dark on MRI
   1. differential of low-attenuation lesions on CT include ependymal cysts, dermoid or epidermoid cysts, cystic astrocytomas, and lipomas, cysts associated with tumors
4. Treatment either with cyst fenestration or cystoperitoneal shunt