Pseudohypoxia brain swelling following lumbar spine surgery: a report of two cases

Pseudohypoxic brain swelling, or postoperative intracranial hypotension with associated venous congestion is a rare phenomenon described after neurologic and lumbar surgery that can be associated with or without a concomitant subdural hematoma (SDH).

We aim to describe a report of two cases of patients without a history of bleeding disorders or head trauma, but with a history of severe chronic lumbar spinal stenosis who developed intracranial hypotension with SDH following spine surgery without evidence of cerebrospinal fluid (CSF) leak/dural trauma both intraoperatively and on immediate postoperative laboratory studies and drain outputs. Both patients developed significant neurologic symptoms (generalized tonic-clonic seizures, coma) in the immediate postoperative setting with head computed tomography (CT) showing findings mimicking hypoxic brain injury. Both patients were treated with prompt medical management. One patient required surgical intervention in the form of craniotomy to evacuate a large SDH. In both cases the high-volume shift in CSF appeared to have been into an intact, but expanded dural tube as a result of generous lumbar decompression. While observed/confirmed high-volume CSF leak can complicate spine surgery and lead to intracranial hypotension, the possibility that clinically significant CSF diversion from the ventricles could occur in the setting of an intact dural tube has not been reported following multi-segment lumbar decompression surgery.

Pseudohypoxic brain swelling is a rare but serious potential complication of lumbar spine surgery. Imaging may be misinterpreted as hypoxia, but it is critical to differentiate these as the treatment is opposite. While both patients in this series demonstrated early and significant recovery of neurologic function postoperatively, demonstrating favorable outcomes for this rare phenomenon, these cases highlight the importance of early identification and multidisciplinary management of these patients, which often will require antiseizure medications and flat head position. These cases well exemplify this rare but serious complication of common lumbar spinal decompression surgery.