Intracranial Hypotension-associated Cerebral Swelling following Cranioplasty: Report of Two Cases.

Cranioplasty is a comparatively simple neurosurgical procedure, and fatal complications are rare. This report describes two cases of critical brain swelling after otherwise uneventful cranioplasty. Both cases had subarachnoid hemorrhage and extremely similar clinical courses. They underwent decompressive craniotomy and clipping in the acute phase and had cranioplasty in the chronic phase, resulting in serious cerebral swelling and death. Deep venous sinus thrombosis was revealed in the autopsy for one case. Although no venous occlusion was identified in the other case, radiological findings suggested venous congestion. In both cases, intraoperative cerebrospinal fluid leakage was massive and was prolonged by a drain; therefore, we hypothesized that intracranial hypotension (IH) caused stagnation of venous flow. Neurosurgeons should be aware that fatal venous congestion induced by IH may occur after cranioplasty. To avoid this, tight dural closure should be obtained, and avoidance of the use of subcutaneous drains should be considered.