Drainage versus no drainage after burr-hole evacuation of chronic subdural hematoma: a systematic review and meta-analysis of 1961 patients

Chronic subdural hematoma (cSDH) is a common neurosurgical condition that can cause severe morbidity and mortality. cSDH recurs after surgical evacuation in 5-30% of patients, but drains may help reduce this risk. We aimed to investigate the effect of drainage versus no drainage on the rates of recurrence and mortality, as well as the clinical outcomes of cSDH. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched four electronic databases (PubMed, Cochrane Library, Scopus, and Web of Science) to identify eligible studies reported up to June 2022. Using Review Manager software, we reported four primary outcomes as odds ratios (ORs) and confidence intervals (CIs). The meta-analysis included a total of 10 studies with 1961 patients. The use of drainage was found to be significantly more effective than non-drainage in reducing the "mortality rate" (OR = 0.65, 95% CI 0.43 to 0.97; P = 0.04), the "recurrence rate" (OR = 0.39, 95% CI 0.28 to 0.55; P < 0.00001), and occurrence of "gross focal neurological deficit" (OR = 0.58, 95% CI 0.37 to 0.89; P = 0.01). No significant difference was found in the occurrence of a Glasgow Coma Scale score of 15 (OR = 1.21, 95% CI 0.84 to 1.76; P = 0.30). The use of drains after burr-hole irrigation reduces the recurrence, mortality, and gross focal neurological deficit rates of chronic subdural hematomas.