Sinking Flap Syndrome: Risk Factors, Outcomes, and the Role of Neuroradiology in Cranioplasty Timing

BACKGROUND AND PURPOSE: Sinking flap syndrome (SFS) is an underrecognized complication of decompressive craniectomy often associated with neurologic decline. We assessed the neuroradiologist's role in identifying SFS, the effect of SFS development on the timing to cranioplasty, and predictive factors for development. We also propose standardized criteria for diagnosis. MATERIALS AND METHODS: We conducted a retrospective analysis of adults who underwent cranioplasty of ≥5 cm between 2019 and 2024. Radiology reports were reviewed for formal documentation of SFS. Patients meeting imaging criteria but lacking a documented diagnosis were classified as having "uncalled" SFS. Demographics, imaging findings, outcomes, and timing were analyzed. RESULTS: = .04) without increasing postoperative complications compared with uncalled SFS. CONCLUSIONS: SFS may be under-recognized, with nearly one-half of patients meeting imaging criteria but only 70% formally diagnosed. A neuroradiologist's recognition of SFS significantly shortens the time to surgery without increasing postoperative complication risks. Early identification can reduce downstream complications common to SFS development. Standardized criteria, greater awareness, and targeted surveillance of high-risk patients can support earlier intervention and improved outcomes.