Reversible giant arachnoid granulations

A 16-year-old boy with recurrent transient visual loss had bilateral papilledema. MRI revealed giant arachnoid granulations (GAG) in both transverse sinuses and signs of intracranial hypertension (figure). CSF opening pressure was 420 mm H2O. After depletive lumbar puncture, the size of GAG decreased and sinus lumen stenosis resolved (figure). Arachnoid granulations (AG) are CSF herniations through dural defects into sinuses.1 Since CSF removal led to their regression, GAG might be a consequence of intracranial hypertension. Our case supports the Krisch theory, which considers AG as a buffer of CSF compartment rather than a site of CSF absorption.2