Early-Onset Sunken Brain Syndrome: An Exploratory Review of Risk Determinants and Surgical Implications

Sunken brain syndrome (SBS) is a severe but preventable complication of decompressive craniectomy (DC), characterized by paradoxical herniation, cortical compression, and neurological decline. Despite rising incidence, early-onset SBS (≤3 months post-DC) remains poorly understood. This study integrates a case-informed review and literature-based analysis to explore possible contributors to SBS development. Motivated by a clinical observation of a 50-year-old woman with aneurysmal subarachnoid hemorrhage, who developed SBS 7 weeks post-DC, we reviewed 65 early-onset SBS cases to identify risk patterns. Her clinical course raised concerns about underrecognized risk factors and limited preventive strategies incorporating vigilant postoperative monitoring. Patients were categorized by clinical and pathophysiological characteristics. Cardiovascular (42%) and neurological (38%) comorbidities were most common. Those with intracranial hemodynamic or hydrodynamic instability, particularly sustained hypoperfusion or prolonged cerebrospinal fluid disturbance, developed SBS more rapidly. We used a weighted risk-scoring model to classify patients into low-, medium-, and high-risk groups. Cumulative incidence analysis showed that high-risk patients developed SBS earlier (median: 30 days, interquartile range: 21-55) than low-risk ones (median: 89 days, interquartile range: 60-89), suggesting a link between risk burden and SBS acceleration. Cranioplasty within 90 days post-DC demonstrated better functional outcomes than delayed or no cranioplasty. Conservative measures were also effective when applied rapidly, underlining the value of multimodal neuromonitoring in catching early symptoms. While this study offers a hypothesis-generating framework for future research to develop structured models for early-onset SBS prevention, its exploratory nature and small sample size make larger cohorts necessary for validation.