Volume of Brain Herniation in Patients with Ischemic Stroke After Decompressive Craniectomy

Decompressive craniectomy procedures are performed in patients with malignant intracranial hypertension. A bone flap is removed to relieve pressure. Later, a second operation is performed to reconstruct the skull after brain swelling has resolved. This surgical treatment would be improved if it were possible to perform a single operation that decompressed the brain acutely and eliminated the need for a second operation. To design a device and procedure that achieve this objective, it is essential to understand how the brain swells after a craniectomy procedure. We identified 20 patients with ischemic stroke who underwent a decompressive hemicraniectomy operation. Skull defect morphology and postoperative brain swelling were measured using computed tomography scan data. Additional intracranial volume created by placing a hypothetical cranial plate implant offset from the skull surface by 5 mm was measured for each patient. The average craniectomy area and brain herniation volume was 9999 ± 1283 mm2 and 30.48 ± 23.56 mL, respectively. In all patients, the additional volume created by this hypothetical implant exceeded the volume of brain herniation observed. These findings show that a cranial plate with a 5-mm offset accommodates the brain swelling that occurs in this patient population.