A 64 y.o. male presented with a temporal bone fracture and subdural requiring craniectomy for increasing pressure.

His initial CT is shown below

the temporal bone fracture

The subdural requiring craniectomy for increasing pressure. The pt recovered and was discharged after surgery

He returned six months later with a shift of the midline and altered mental status. What needs to be done?

Our patient has post trephination syndrome or sunken flap syndrome.  This is an unusual complication of the removal of a large bone flap.  The patient often has  altered mental status, dizziness, speech problems and hemiparesis. Parkinsonian tremors and sixth nerve palsy have also been reported.

A significant improvement in the sensorium can occur after maintaining the patient’s head in a dependent position like putting the patient in Trendelenburg position. The bone flap must be replaced. 

There are multiple theories about why this phenomenon happens.    It is thought that atmospheric pressure can act directly on the underlying cerebral tissue in the absence of a bone flap.  In the upright position the ICP is normally negative in a closed skull.  It there is a cranial defect the ICP will equalize with atmospheric pressure  and the ICP will increase if the patient  is sitting. Evidence for this theory comes from studies showing the ICP normalizes after the bone flap is replaced.

This Neolithic skull  is rounded off by a growth of new bone indicating the patient survived the operation. The Inca were particularly skilled at the procedure with a survival rate of 75%. Less skilled were Civil War physicians who performed the procedure routinely on head wounds with a survival of 46%.

Trephination is a surgical procedure which involves drilling a hole in the skull of a living person.  It is one of the oldest surgical procedures in the world and can be found as early as the Neolithic period.   The word Trephination comes from the Greek word trypanon which is  an auger used by a carpenter.  It was the tool used to drill a hole in the skull.

French trephination tool

In our patient the bone flap was replaced but was deteriorating leading to erosion of the bone and skin.  The plan was for replacement by neurosurgery.

Vivek J, Reilly P.  Syndrome of the trephined Case Reports J Neurosurg. 2009 Oct ;111(4):650-2.

Mokri B.  Orthostatic headaches in the syndrome of the trephined: resolution following cranioplaswty. Case Reports Headache. 2010 Jul;50(7): 1206-11.

Fodstad H, Love A, Ekstedt J, et al. Effect of cranioplasty on cerebrospinal fluid hydrodynamics in patients with syndrome of the trephined. Acta Neurochir(Wien) 1984; 70(1-2):21-30.