1019 - Sunken Flap Syndrome in Acute Rehabilitation: A Case of Positional Neurological Decline Improved by Shunt Adjustment

Sunken Flap Syndrome is a rare complication following decompressive craniectomy, marked by visible scalp depression with new or worsening neurological symptoms. It usually develops weeks to months postoperatively when atmospheric pressure exceeds intracranial pressure, displacing skin and brain tissue. This can cause cognitive decline, altered mental status, or paradoxical herniation. Symptoms often improve after cranioplasty, which restores normal intracranial pressure. Early recognition is essential to prevent lasting deficits.

Case Description:

A 35-year-old male presented after assault with a ruptured A2 aneurysm, left frontal intraparenchymal and subarachnoid hemorrhages, and multiple subdural hematomas. He underwent right hemicraniectomy with external ventricular drain placement, later requiring left EVD replacement and ventriculoperitoneal (VP) shunt insertion with drainage setting at Certas 7. After stabilization, he was discharged to acute rehab. Throughout acute rehab, he presented with somnolence, disorientation, postural headaches, and fluctuating left upper extremity weakness (5/5 to 2/5). Symptoms drastically improved with Trendelenburg positioning and IV fluids, however interventions had temporary effects. CT Head later showed leftward midline shift, sunken scalp flap, uncal herniation, and decreased ventricular size. Adjustment of VP shunt to Certas 8 led to near-complete resolution, allowing patient to tolerate upright positioning and participate in therapies.

Discussions:

In rehabilitation, distinguishing hydrocephalus, post-traumatic headache, and sunken flap syndrome is critical. Hydrocephalus typically presents with ventriculomegaly and improves after CSF diversion. Migrainous headaches are usually non-positional and lack acute neurological decline. By contrast, sunken flap syndrome is characterized by positional neurological deterioration, improvement with Trendelenburg or IV fluids, and visible scalp concavity. CT imaging helps differentiate these conditions and guides shunt management.

Conclusions:

Risk factors for sunken flap syndrome include large craniectomy defects, delayed cranioplasty, CSF drainage, and severe TBI. Conservative measures such as fluids and postural adjustments may provide temporary stabilization, but definitive treatment requires cranioplasty, which restores intracranial pressure dynamics and improves functional recovery.