Reverse brain herniation during posterior fossa surgery.

Posterior fossa tumors are commonly associated with obstructive hydrocephalus. Relieving the raised intracranial pressure by draining the cerebrospinal fluid presents the possibility of reverse herniation of the brain. A 5-year-old male child with a diagnosis of posterior fossa space-occupying lesion and hydrocephalus was scheduled for craniectomy in the prone position. After craniectomy, the surgeons placed an intraventricular shunt catheter to drain out cerebrospinal fluid in an attempt to reduce the tense brain so as to facilitate easy dissection of the tumor. The patient had sudden and severe bradycardia followed by asystole. A diagnosis of reverse coning was made. Immediately, the surgeon injected 10-15 mL normal saline into the ventricles. There was a spontaneous return of the sinus rhythm and the rest of the course of surgery was uneventful. We present this case showing a rare phenomenon and its successful management.