Sinking skin flap syndrome and paradoxical herniation after hemicraniectomy for malignant hemispheric infarction

"Sinking skin flap" (SSF) syndrome is a rare complication after large craniectomy that may progress to "paradoxical" herniation as a consequence of atmospheric pressure exceeding intracranial pressure. The prevalence and characteristics of SSF syndrome after hemicraniectomy for malignant infarction of the middle cerebral artery are not well known.

We analyzed a prospective cohort of 27 patients who underwent hemicraniectomy for malignant middle cerebral artery infarction. All had a clinical and brain imaging follow-up at 3 months and were followed until cranioplasty.

Three of 27 patients (11%) had, at 3 to 5 months posthemicraniectomy, SSF syndrome with severe orthostatic headache as the main symptom. In addition, 4 patients (15%) had radiological SSF syndrome but no clinical symptoms except partial seizures in one. Patients with SSF syndrome had a smaller surface of craniectomy (76.2 cm(2) versus 88.7 cm(2), P=0.05) and a tendency toward larger infarct volume, an older age, and a longer delay to cranioplasty than those without this syndrome.

SSF syndrome either clinically symptomatic or asymptomatic affects one fourth of patients 3 to 5 months after hemicraniectomy for malignant middle cerebral artery infarction. It should be diagnosed as early as possible to avoid progression to a paradoxical herniation.