Syndrome of the trephined.

"Syndrome of the trephined" or "sinking skin flap syndrome" is an unusual syndrome in which neurological deterioration occurs following removal of a large skull bone flap. The neurological status of the patient can occasionally be strongly related to posture. A 77-year-old male patient with an acute subdural hematoma was treated using a hemicraniectomy and evacuation of the hematoma. On the 9th postoperative day there was deterioration in sensorium associated with a sunken scalp flap and worsening midline shift on CT. A significant improvement in sensorium and a filling up of the scalp flap occurred after maintaining the patient's head in a dependent position. The patient subsequently made an excellent recovery following replacement of the bone flap. The pathophysiology of "syndrome of the trephined" or "sinking skin flap syndrome" is reviewed.