title: Twist Drill Procedure for Chronic Subdural Hematoma Evacuation: An Analysis of Predictors for Treatment Success.
abstract: BACKGROUND
  Twist drill craniostomy (TDC) is a minimally invasive and cost-effective technique to treat chronic subdural hematomas (CSDHs). Predictors for treatment success such as imaging characteristics, hematoma volume, and drainage volume are not established; thus, they are purpose of this analysis.
  
  
  METHODS
  We retrospectively evaluated all data of patients with CSDH undergoing TDC in our institution between January 2010 and December 2013. We analyzed imaging characteristics (extension and composition), volumetrically calculated pre- and postoperative hematoma volumes, measured drainage volume, and clinical course. Primary treatment success was defined as sufficient if definitive treatment was achieved via a single TDC (TDC-1) and insufficient if more than one TDC was needed. The need for open surgical evacuation was defined as treatment failure.
  
  
  RESULTS
  Data of 233 patients undergoing 387 TDCs were available for our study. A total of 67% of TDCs treated CSDHs effectively, whereas the remainder required further open surgical evacuation. Via use of the median-split-method, we found that sufficient treatment was achieved more frequently in smaller hematomas (P < 0.05). Treatment effectiveness was neither correlated with hematoma image characteristics (presence of membranes: P = 0.11, extent of chronification: P = 0.55) nor with the respective drainage volume (P = 0.95). Residual hematoma volume was consistently greater than expected by drainage calculation (P < 0.05).
  
  
  CONCLUSIONS
  TDC is an effective treatment option for CSDH. Sufficient treatment with single TDC was more common in smaller hematomas with an associated smaller residual hematoma. Failure of brain re-expansion after TDC may increase the treatment failure rates. In these cases, an open surgical evacuation might accelerate treatment and clinical recovery.
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany; Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany. Electronic address: fjablawi@ukaachen.de.
authors.forename: Fidaa
authors.initials: F
authors.lastname: Jablawi
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Huda
authors.initials: H
authors.lastname: Kweider
authors.affiliation: Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany; Department of Diagnostic and Interventional Radiology, RWTH Aachen University, Aachen, Germany.
authors.forename: Omid
authors.initials: O
authors.lastname: Nikoubashman
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Clusmann
authors.affiliation: Department of Neurosurgery, RWTH Aachen University, Aachen, Germany.
authors.forename: Gerrit Alexander
authors.initials: GA
authors.lastname: Schubert
mesh_terms: D000368:Aged; D003399:Craniotomy / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D005858:Germany / Q000453:epidemiology; D046648:Hematoma, Subdural, Intracranial / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D006801:Humans; D008297:Male; D015995:Prevalence; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: Chronic subdural hematoma; Hematoma composition; Hematoma volume; Twist drill craniostomy