Acute intraoperative brain herniation during elective neurosurgery: pathophysiology and management considerations.

OBJECTIVES

To describe operative procedures, pathophysiological events, management strategies, and clinical outcomes after acute intraoperative brain herniation during elective neurosurgery.

METHODS

Review of clinical diagnoses, operative events, postoperative CT findings, intracranial pressure, and arterial blood pressure changes and outcomes in a series of patients in whom elective neurosurgery had to be abandoned because of severe brain herniation.

RESULTS

Acute intraoperative brain herniation occurred in seven patients. In each patient subarachnoid or intraventricular haemorrhage preceded the brain herniation. The haemorrhage occurred after intraoperative aneurysm rupture either before arachnoidal dissection (three) or during clip placement (one); after resection of 70% of a recurrent hemispheric astroblastoma; after resection of a pineal tumour; and after a stereotactic biopsy of an AIDS lesion. In all patients the procedure was abandoned because of loss of access to the intracranial operating site, medical measures to control intracranial pressure undertaken (intravenous thiopentone), an intraventricular catheter or Camino intracranial pressure monitor inserted, and CT performed immediately after scalp closure. The patients were transferred to an intensive care unit for elective ventilation and multimodality physiological monitoring. Using this strategy all patients recovered from the acute ictus and no patient had intracranial pressure > 35 mm Hg. Although one patient with an aneurysm rebled and died three days later the other six patients did well considering the dramatic and apparently catastrophic nature of the open brain herniation.

CONCLUSIONS

There are fundamental differences in the pathophysiological mechanisms, neuroradiological findings, and outcomes between open brain herniation occurring in post-traumatic and elective neurosurgical patients. The surprisingly good outcomes in this series may have occurred because the intraoperative brain herniation was secondary to extra-axial subarachnoid or intraventricular haemorrhage rather than intraparenchymal haemorrhage or acute brain oedema. Expeditious abandonment of the procedure and closure of the cranium may also have contributed to the often very satisfactory clinical outcome.