title: Chronic subdural hematoma: a systematic review and meta-analysis of surgical procedures.
abstract: OBJECTIVE
  In this paper the authors systematically evaluate the results of different surgical procedures for chronic subdural hematoma (CSDH).
  
  
  METHODS
  The MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and other databases were scrutinized according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) statement, after which only randomized controlled trials (RCTs) and quasi-RCTs were included. At least 2 different neurosurgical procedures in the management of chronic subdural hematoma (CSDH) had to be evaluated. Included studies were assessed for the risk of bias. Recurrence rates, complications, and outcome including mortality were taken as outcome measures. Statistical heterogeneity in each meta-analysis was assessed using the T(2) (tau-squared), I(2), and chi-square tests. The DerSimonian-Laird method was used to calculate the summary estimates using the fixed-effect model in meta-analysis.
  
  
  RESULTS
  Of the 297 studies identified, 19 RCTs were included. Of them, 7 studies evaluated the use of postoperative drainage, of which the meta-analysis showed a pooled OR of 0.36 (95% CI 0.21-0.60; p < 0.001) in favor of drainage. Four studies compared twist drill and bur hole procedures. No significant differences between the 2 methods were present, but heterogeneity was considered to be significant. Three studies directly compared the use of irrigation before drainage. A fixed-effects meta-analysis showed a pooled OR of 0.49 (95% CI 0.21-1.14; p = 0.10) in favor of irrigation. Two studies evaluated postoperative posture. The available data did not reveal a significant advantage in favor of the postoperative supine posture. Regarding positioning of the catheter used for drainage, it was shown that a frontal catheter led to a better outcome. One study compared duration of drainage, showing that 48 hours of drainage was as effective as 96 hours of drainage.
  
  
  CONCLUSIONS
  Postoperative drainage has the advantage of reducing recurrence without increasing complications. The use of a bur hole or twist drill does not seem to make any significant difference in recurrence rates or other outcome measures. It seems that irrigation may lead to a better outcome. These results may lead to more standardized procedures.
authors.affiliation: Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, China; and.
authors.forename: Weiming
authors.initials: W
authors.lastname: Liu
authors.forename: Nicolaas A
authors.initials: NA
authors.lastname: Bakker
authors.forename: Rob J M
authors.initials: RJ
authors.lastname: Groen
mesh_terms: D020200:Hematoma, Subdural, Chronic / Q000401:mortality / Q000601:surgery*; D006801:Humans; D015994:Incidence; D019635:Neurosurgical Procedures / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D011183:Postoperative Complications / Q000453:epidemiology; D012008:Recurrence; D015996:Survival Rate; D016896:Treatment Outcome
keywords: CSDH = chronic subdural hematoma; M-H = Mantel-Haenszel; RCT = randomized controlled trial; chronic subdural hematoma; meta-analysis; review; traumatic brain injury