Increasing chronic subdural hematoma after endoscopic III ventriculostomy

Object:Endoscopic III ventriculostomy (ETV) is an effective and a rather sa fe treatment for noncommunicating hydrocephalus secondary to aqueductal ste nosis and other obstructive pathologies. Though not devoid of risk, ETV is increasingly replacing shunt operations: and it prevents related complicati ons; including overdrainage. Methods: We report a rare case of a large chro nic subdural hematoma (ChSDH) after ETV in a patient with aqueductal stenos is. Three weeks after he was shunted elsewhere, he presented to us with cli nical symptoms of intracranial hypotension and overdrainage. ETV was perfor med and the shunt removed uneventfully. On routine postoperative MRI a few weeks later, a large ChSDH was noted, the patient being totally asymptomati c. Since the ChSDH grew significantly, causing a mass effect on the follow- up MRI, it was finally drained. Large and increasing ChSDMs have previously been reported secondary to overdrainage after shunt placement, but not aft er ETV. Conclusions: We conclude that though rare, a ChSDH may evolve even after ETV, if there is a substantial decrease in previously elevated intrac ranial pressure.