Incidence of Subdural Hygroma on Routine Early Postoperative Imaging Following Foramen Magnum Decompression for Chiari Malformation Type 1 in 156 Patients.

Objective: To determine the incidence of subdural hygroma (SDH) on routine early postoperative imaging following foramen magnum decompression (FMD) with dural opening in patients with Chiari 1 malformation (CM1).

Methods: Clinical and radiological data of 156 consecutive patients with CM1 who underwent FMD (2006-2023) were retrospectively analyzed. Computed tomography scans done on the seventh postoperative day or earlier were reviewed for the presence of SDH (infra-and supratentorial) and ventriculomegaly.