The Subgaleal Pocket Technique for a Safe and Effective Internal Drainage in Managing Symptomatic Subdural Effusion in a Postcystoperitoneal Shunt Patient with Arachnoid Cyst

A BSTRACT Subdural effusion (SE) is a challenging complication following cerebrospinal fluid (CSF) diversion, often presenting with symptoms of increased intracranial pressure. In shunted patients, differentiating SE from subdural hygroma is critical for determining surgical management. While external drainage is a common intervention, it carries significant risks of infection and overdrainage. This case report evaluates the efficacy of a single-hole burr hole drainage combined with a subgaleal resorptive pocket. A 23-year-old male with a history of arachnoid cyst underwent cystoperitoneal shunt procedures presented with a 1-month history of progressive, refractory headaches, and emesis. Neuroimaging revealed a significant 18-mm left frontal SE. Despite a functioning shunt system, the patient’s symptoms necessitated surgical intervention. We performed a single-hole burr hole drainage followed by the creation of an expansive subgaleal pocket via blunt dissection. This “internal drainage” technique utilized the vascularized subgaleal layer for physiologic fluid resorption, avoiding the need for externalized hardware. The patient experienced immediate postoperative symptomatic relief. There were no procedural complications, and the patient remained neurologically intact throughout the hospital stay. At the 3-month follow-up, the patient reported complete resolution of headaches and vomiting, with no clinical evidence of effusion recurrence. The use of a subgaleal resorptive pocket in conjunction with burr hole drainage provides a safe and effective alternative to traditional external drainage for symptomatic SEs. This technique minimizes the risk of retrograde infection and maintains intracranial pressure stability, making it an ideal approach for complex patients with indwelling CSF shunts.