Ventriculo-peritoneal shunt blockage due to ruptured intracerebral dermoid cyst

Introduction: Intracranial dermoid cysts are rare congenital lesions that can rupture and disseminate intracranially. We present a unique case of a ruptured dermoid cyst leading to blockage of ventriculo-peritoneal shunts. Case Report: A 19-year-old female presented with clumsiness, gait disturbance and occipital headache. Examination revealed an ataxic gait, positive Romberg’s sign, lateral gaze nystagmus and hyper-reflexia in all four limbs with bilateral positive Hoffman’s sign. A Magnetic resonance scan revealed a large, heterogeneous midline cerebellar mass which had evidently ruptured at some point causing diffuse subarachnoid dissemination of fat. The patient underwent an uneventful posterior fossa craniectomy for removal of the cyst and was discharged home. She presented ten weeks later with headaches, ataxia, vomiting and decreased Glasgow Coma Scale. A cranial computed tomography (CT) scan showed ventriculomegaly which was treated with insertion of an external ventricular drain. The patient improved but attempts to clamp the external ventricular drain led to recurrence of symptoms. The patient underwent serial operations for ventriculo-peritoneal shunt insertion, but each time symptoms and Glasgow Coma Scale improved only temporarily. This was postulated to be due to free-floating intraventricular fat repeatedly clogging the shunts. Following endoscopic aspiration of the intraventricular lipoid material from the frontal horn before the final shunt revision, there has been no further symptomatic hydrocephalus. Conclusion: Fat dissemination from ruptured intracranial dermoid cysts can lead to blockage of ventriculo-peritoneal shunts. We recommend the removal of intraventricular fat from the outset if cerebrospinal fluid diversion is required.