Sinking skin flap syndrome: a case of improved cerebral blood flow after cranioplasty.

Sinking skin flap syndrome is defined as a series of neurologic symptoms with the skin depression at the site of cranial defect, which develop several weeks to months after large external cerebral decompression.The case of a 28-year-old female with the sinking skin flap syndrome is reported together with the evaluation of cerebral blood flow using xenon computed tomography (CT). Although her general condition stabilized within 7 months after the injury, the skin of the bilateral temporal regions was markedly depressed due to large bone defects. She was confined to bed and showed reduced levels of consciousness. We decided to treat this case by performing cranioplasty with a hydroxyapatite ceramic implant. Not only were good cranial contour reconstructed after cranioplasty, but neurologic conditions were also improved after cranioplasty. Regarding the change in cerebral blood flow in the present case, as measured with xenon CT, the cerebral blood flow 3 days after the injury was 18.7 +/- 12.3 mL/100 mL/min and 26.5 +/- 11.6 mL/100 mL/min in the left and right hemispheres, respectively. After the bilateral cranioplasty, it had increased by approximately 2-fold to 36.4 +/- 23.2 mL/100 mL/min in the left hemisphere and approximately 1.5-fold to 43.8 +/- 23.3 mL/100 mL/min in the right hemisphere as compared with the levels obtained 3 days after the injury.Therefore, xenon CT appears to be useful in the monitoring of regional cerebral blood flow in patients with cranial bone defects that are directly affected by atmospheric pressure and in predicting functional prognosis. For the sinking skin flap syndrome cases, cranioplasty is not only useful for cerebral protection and improvement of appearance, but cranioplasty is also useful for improving neurologic symptoms.