Acute symptomatic cerebellar tonsillar herniation following intraoperative lumbar drainage.

Complications of tonsillar herniation associated with lumbar drainage have been reported in the literature. However, acutely symptomatic tonsillar herniation after intraoperative lumbar drainage is rare. The following case illustrates the risk associated with cerebrospinal fluid (CSF) drainage in the setting of tonsillar herniation. The use of lumbar drainage during cranial surgery is a common practice for reducing intracranial pressure and enhancing exposure, but is not without complications. In addition to the complications of the insertion procedure itself, the change in pressure gradient between the intracranial and the suboccipital compartments is of key importance. The authors present the case of a patient who underwent a subtemporal craniotomy for resection of mesial temporal cavernous malformation with intraoperative lumbar drainage. The patient had a preexisting, asymptomatic 4-mm Chiari malformation and progressive neurological deficits resulting from further cerebellar tonsillar herniation in the early postoperative period developed, which required a lumbar blood patch, decompressive suboccipital craniectomy, and C-1 laminectomy with duroplasty. After placement of the lumbar drain and subsequent CSF drainage, the change in CSF pressure gradient above and below the foramen magnum probably led to the herniation. Unfortunately, the patient has lasting neuropathic pain and cervical cord signal changes on MR images.