Sinking Skin Flap Syndrome and Paradoxical Herniation Provoked by a Malfunction of External Lumbar Drainage and CSF Leak

The sinking skin flap syndrome represents a less-frequent complication in patients after a decompressive craniectomy. It is defined as a neurological deterioration accompanied by a flat or concave deformity of the craniectomy-related skin flap. The underlying brain parenchyma is distorted correspondingly with its blood flow and metabolism being impaired and cerebrospinal fluid hydrodynamics being disturbed, thus causing cerebral dysfunction and neurological symptomatology. The most important options for reversal of this syndrome include Trendelenburg position, maintaining of the cerebrospinal fluid balance, and cranioplasty as a definite solution. We present a patient who underwent a decompressive craniectomy complicated by a cerebrospinal fluid leak in the operative wound treated by means of an external lumbar drainage. Subsequently he developed the sinking skin flap syndrome and a paradoxical cerebral herniation after the drainage system malfunction with a massive cerebrospinal fluid leak at the site of the lumbar drain insertion parallel to the drain itself. His symptoms were, however, successfully alleviated by a positional change, rehydration, and interruption of the lumbar drainage. This illustrational case suggests that clinicians should be aware that patients after decompressive craniectomy may develop a sinking skin flap syndrome as it may either represent an acute risk of a paradoxical brain herniation or complicate the further postoperative care if developed in a chronic way.