Free fat can migrate to the subarachnoid cerebrospinal fluid (CSF) after craniotomy, even without fat graft.
Fat droplets migrating via the ventricular system obstructed a ventriculoperitoneal shunt catheter.
Free fat in the CSF led to aseptic “lipoid” meningitis and neurological sequelae.
Partial catheter fat obstruction may dissipate with conservative management.