Prognostic significance of subdural hygroma for post-traumatic hydrocephalus after decompressive craniectomy in the traumatic brain injury setting: a systematic review and meta-analysis.

Post-traumatic hydrocephalus (PTH) is a potentially morbid sequela of decompressive craniectomy for traumatic brain injury (TBI). Subdural hygromas are commonly identified following decompressive craniectomy, but the clinical relevance and predictive relationship with PTH in this patient cohort is not completely understood. Survey of seven electronic databases from inception to June 2019 was conducted following PRISMA guidelines. Articles were screened against pre-specified criteria. Multivariate hazard ratios (HRs) for PTH by the presence of subdural hygroma were extracted and pooled by meta-analysis of proportions with random effects modeling. We systematically identified nine pertinent studies describing outcomes of 1010 TBI patients managed by decompressive craniectomy. Of the overall cohort, there were 211 (21%) females and median age was 37.5 years (range 33-53). On presentation, median Glasgow Coma Scale was 7 (range, 5-8). In sum, PTH was reported in 228/840 (27%) cases, and subdural hygroma was reported in 449/1010 (44%) cases across all studies. Pooling multivariate-derived HRs indicated that subdural hygroma was a significant, independent predictor of PTH (HR, 7.1; 95% CI, 3.3-15.1). The certainty of this association was deemed low due to heterogeneity concerns. The presence of subdural hygroma is associated with increased risk of PTH after decompressive craniectomy among TBI patients based on the current literature and may mandate closer clinical surveillance when detected. Prospective studies, including those of intracranial hydrodynamics following decompressive craniectomy in the setting of TBI, will better validate the certainty of these findings.