Impact of Cranioplasty Timing and Status on Long-Term Survival and Functional Outcomes After Decompressive Craniectomy for Severe Traumatic Brain Injury.

Background: Decompressive craniectomy (DC) is a life-saving procedure for severe traumatic brain injury (TBI); however, its long-term outcomes remain controversial. Cranioplasty traditionally performed to restore cranial integrity, has been increasingly recognized for its potential role in neurological recovery. This study aimed to investigate the impact of cranioplasty timing and status on long-term mortality and functional outcomes after DC for severe TBI. Methods: We retrospectively reviewed 151 patients who underwent DC between 2014 and 2018. Patients were categorized into three groups according to cranioplasty timing: early (<3 months), late (≥3 months), and no cranioplasty. Clinical and radiologic data, including the Rotterdam CT scores, were analyzed. The primary endpoints were 5-year mortality and 12-month functional outcome assessed by the Glasgow Outcome Scale (GOS). Univariate and multivariate logistic regression analyses identified independent predictors and receiver operating characteristic (ROC) curves with are under the curve (AUC) values evaluated model performance. Results: Of 151 eligible patients (mean age = 53.9 ± 17.4 years; 82.1% male), overall 5-year mortality was 76.8% (116/151). Mortality differed substantially by cranioplasty group: 64.5% in early cranioplasty, 70.8% in late cranioplasty, and 82.3% in patients who did not undergo cranioplasty. Unfavorable 12-month functional outcomes occurred in 45.2%, 79.2%, and 91.7% of these groups, respectively. In multivariate analysis, no cranioplasty independently predicted both higher 5-year mortality (OR = 2.78, 95% CI = 1.06-7.25, p = 0.038) and unfavorable functional outcome (OR = 3.09, 95% CI = 1.18-8.09, p = 0.022). Older age was also associated with increased mortality (p = 0.019). ROC analysis showed moderate discriminative performance for 5-year mortality (AUC = 0.71) and good discrimination for unfavorable functional outcome (AUC = 0.80). Conclusions: Absence of cranioplasty was associated with higher long-term mortality and poorer functional recovery following DC for severe TBI. Early cranioplasty may enhance cerebral restoration and rehabilitation potential, improving both survival and neurological outcomes.