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 intraoperat ive brain herniation during elective neurosurgery. Methods-Review of c linical diagnoses, operative events, postoperative CT findings, intrac ranial 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 o r intraventricular haemorrhage preceded the brain herniation. The haem orrhage occurred after intraoperative aneurysm rupture either before a rachnoidal dissection (three) or during clip placement (one); after re section of 70% of a recurrent hemispheric astroblastoma; after resecti on of a pineal tumour; and after a stereotactic biopsy of an AIDS lesi on. In all patients the procedure was abandoned because of loss of acc ess to the intracranial operating site, medical measures to control in tracranial pressure undertaken (intravenous thiopentone), an intravent ricular catheter or Camino intracranial pressure monitor inserted, and CT performed immediately after scalp closure. The patients were trans ferred to an intensive care unit for elective ventilation and multimod ality physiological monitoring. Using this strategy all patients recov ered from the acute ictus and no patient had intracranial pressure > 3 5 mm Hg. Although one patient with an aneurysm rebled and died three d ays later the other six patients did well considering the dramatic and apparently catastrophic nature of the open brain herniation. Conclusi ons-There are fundamental differences in the pathophysiological mechan isms, neuroradiological findings, and outcomes between open brain hern iation occurring in post-traumatic and elective neurosurgical patients . The surprisingly good outcomes in this series may have occurred beca use the intraoperative brain herniation was secondary to extra-axial s ubarachnoid or intraventricular haemorrhage rather than intraparenchym al haemorrhage or acute brain oedema. Expeditious abandonment of the p rocedure and closure of the cranium may also have contributed to the o ften very satisfactory clinical outcome.