The paradox of relief: how decompression sets the stage for hydrocephalus—a retrospective inquiry into its clinical determinants

Background Post-traumatic hydrocephalus (PTH) is a common complication following decompressive craniectomy for traumatic brain injury (TBI), occurring in 7–36% of patients. Despite its significant impact on recovery and long-term outcomes, the relative contribution of pre-operative, intra-operative, and post-operative factors to PTH development remains incompletely understood. Objective To identify and quantify independent risk factors for PTH following decompressive craniectomy and develop a clinically applicable risk stratification framework. Methods A retrospective cohort analysis of 142 consecutive patients who underwent decompressive craniectomy for TBI was conducted. The primary outcome was radiologically defined hydrocephalus. Pre-operative, intra-operative, and post-operative clinical and radiological variables were analysed using univariable and multivariable logistic regression. Model performance was assessed using area under the receiver operating characteristic curve (AUC), Hosmer–Lemeshow goodness-of-fit testing, and pseudo-R 2 values. Results Hydrocephalus developed in 43 patients (30.3%). Univariable analysis identified lower Glasgow Coma Scale (GCS) on arrival, post-operative interhemispheric hygroma, subdural hygroma, herniation, intraventricular haemorrhage, and pseudomeningocele as significant predictors (all P < 0.01). Intraoperative surgical parameters showed no association with PTH. The final multivariable model identified two independent predictors: lower GCS on arrival (OR 0.88, 95% CI 0.79–0.99; P = 0.032) and post-operative interhemispheric hygroma (OR 4.89, 95% CI 1.95–12.28; P = 0.0007). The model demonstrated strong discrimination (AUC = 0.807) and excellent calibration (Hosmer–Lemeshow P = 0.69), with overall classification accuracy of 81.0%. GCS score of ≤ 8 on arrival was significantly associated with increased hydrocephalus risk in binary analysis ( P = 0.007), whereas the same threshold at intubation was not significant. Conclusions Post-operative complications, particularly interhemispheric hygroma, are the strongest predictors of PTH following decompressive craniectomy, while surgical technique parameters show no significant association. These findings support the implementation of structured post-operative surveillance protocols to enable early detection and intervention in high-risk patients. A clinical risk assessment checklist incorporating these factors may improve prognostic accuracy and guide individualised management strategies.