Objectives Syndrome of the Trephined (SoT) or sinking skin flap syndrome is characterised by neurological deterioration occurring after a delay post-craniectomy, with or without a significant postural component, that may improve with cranioplasty. The symptoms and signs seen are heterogeneous and can be readily missed. With increasing numbers of patients surviving after decompressive craniectomies, and often a long delay before cranioplasty, we think it important that awareness of this potentially lethal but reversible condition is raised.

Design Case Series.

Subjects Cases with suspected SoT were identified retrospectively from all admissions to a Level 1 Neurorehabilitation Unit over 2 years.

Methods Cases were identified by their treating clinicians. Their clinical features are described, and outcomes after cranioplasty are discussed.

Results From 36 patients admitted after craniectomy over 2 years, 4 patients with suspected SoT were identified, with a latency of 4–12 months post-injury. Late neurological deterioriation included reduced alertness and mobility, cognitive decline and headache. Two patients had a clear postural component to their symptoms. Coexisting hydrocephalus was sometimes seen, and complicated neurosurgical management. All cases improved after cranioplasty.

Conclusions SoT is an under-reported and under-recognised complication of craniectomy. It is a potentially reversible cause of significant late deterioration following craniectomy. Further research into the optimal timing for cranioplasty is needed.