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Updated: May 2, 2026
Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms
Published on: August 11, 2015
Sinking Flap Syndrome: Risk Factors, Outcomes, and the Role of Neuroradiology in Cranioplasty Timing
Kyril L Cole1, Robert C Rennert1, Samuel A Tenhoeve2
1From the Department of Neurosurgery (K.L.C., R.C.R., S.T.M., W.T.C.), Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah.
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:
Among 166 included patients, SFS was formally diagnosed in 55 (33.1%) patients, but 23 (13.9%) others met the radiographic criteria regardless of radiology reports, suggesting that 30% (23/78) of SFS cases went uncalled. Among patients with called SFS, trauma was the most common cause (67.3%), with larger flap diameters (16.0 versus 14.7 cm, P = .03), midline shift of ≥8 mm (P < .001), and neurologic symptoms (80% versus 60%) being more prevalent than in those without called SFS. Patients with called SFS had longer intensive care unit stays, more trips to the operating room, and higher postoperative stroke and hemorrhage rates. Independent predictors of actual SFS development included trauma-induced injury (adjusted OR [aOR, 3.75]), flap diameter, ≥16 cm (aOR, 2.38), and midline shift ≥8 mm (aOR, 7.81). Neuroradiologist-called SFS halved the time to cranioplasty (median 9 versus 18 days, P = .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.
