Multiple concurrent cerebral haemorrhages in the absence of trauma or a bleeding diathesis suggest venous sinus thrombosis, multiple haemorrhagic infarcts, and haemorrhagic metastases. Iatrogenic venous obstruction is another possible cause. Patient 1 was a 55 year old obese woman who underwent a left posterior fossa craniotomy (Jannetta procedure) for trigeminal neuralgia. Examination and a CT of the head were normal. At surgery she was positioned on her right side with her head held in slight lateral flexion to place the left occipital area uppermost. During the operation the anaesthetist reported that on two occasions the pulse rate slowed only to return to normal when the retractor was immediately removed. The patient’s head was repositioned to provide increased lateral flexion and because of her short neck and broad shoulders, slight Trendelenberg tilt was applied. A large artery was found indenting the left fifth nerve. On repositioning the retractor, swelling of the left hemisphere was noted which bulged though the craniectomy. A small cerebellar resection was performed and the head repositioned with upward tilt. The operation was then abandoned.

Postoperatively she failed to regain consciousness. Brain CT showed moderate swelling of the left cerebellar hemisphere and both occipital lobes appeared hypodense. There were also high density haemorrhagic lesions in the left temporal, right frontal and occipital lobes. She died the next day.

At postmortem the brain …