Ventriculoperitoneal shunt malfunction caused by proximal catheter fat obstruction

• 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.

Ventriculoperitoneal (VP) shunt placement is the mainstay of treatment for hydrocephalus, yet shunts remain vulnerable to a variety of complications. Although fat droplet migration into the subarachnoid space and cerebrospinal fluid pathways following craniotomy has been observed, a VP shunt obstruction with fat droplets has never been reported to our knowledge. We present the first reported case of VP shunt catheter obstruction by migratory fat droplets in a 55-year-old woman who underwent suboccipital craniotomy for removal of a metastatic tumor of the left medullocerebellar region, without fat harvesting. A VP shunt was inserted 1 month later due to communicating hydrocephalus. The patient presented with gait disturbance, intermittent confusion, and pseudomeningocele 21 days after shunt insertion. MRI revealed retrograde fat deposition in the ventricular system and VP shunt catheter, apparently following migration of fat droplets from the fatty soft tissue of the craniotomy site. Spinal tap revealed signs of aseptic meningitis. Steroid treatment for aseptic “lipoid” meningitis provided symptom relief. MRI 2 months later revealed partial fat resorption and resolution of the pseudomeningocele. VP shunt malfunction caused by fat obstruction of the ventricular catheter should be acknowledged as a possible complication in VP shunts after craniotomy, even in the absence of fat harvesting.