A case of the syndrome of the sinking skin flap: case report

A case of "the syndrome of the sinking skin flap" was presented. A 40-year-old-man had suffered from severe SAH 9 months before. An aneurysm of the anterior communicating artery was successfully clipped and the bone flap was removed for the purpose of the external decompression. Cranioplasty and V-P shunt were performed 1 month after SAH, but both were removed because of postoperative wound infection, viz. epidural and subdural abscess 4 months after SAH. Following this, L-P shunt was performed, and the patient was discharged with mild dementia. A concave deformity of the skin flap developed about 4 months after the L-P shunt. Neurological examination showed progressive left hemiparesis and akinetic mutism. A low CSF pressure was demonstrated, but RI cisternography revealed normal CSF circulation. Intrathecal infusion of the artificial CSF was carried out via lumbar puncture and concavity of the skin flap gradually improved. This procedure resulted in improvement of the neurological deficits. Cranioplasty with artificial bone was performed under continuous intrathecal infusion of the artificial CSF. Postoperative course was satisfactory and neurological examination revealed only mild dementia. The pathological mechanism in our case was probably due to the compression of the brain by the atmospheric pressure following the external decompression. Moreover, L-P shunt exaggerated this pathology by the overdrainage of CSF.