title: A comparative study of the patients with bilateral or unilateral chronic subdural hematoma: precipitating factors and postoperative outcomes.
abstract: BACKGROUND
  : Chronic subdural hematoma (CSDH) is a relatively frequent problem in neurologic or neurosurgical practice. Although CSDH is a well-known disease, data on bilateral CSDH are scarce compared with data on unilateral CSDH. The purpose of this study was to compare the clinical presentations, precipitating factors, computed tomography (CT) scan findings, postoperative complications, and outcomes between patients with bilateral and unilateral CSDH.
  
  
  METHODS
  : A retrospective study was performed on 129 surgical patients with CSDH from January 2002 to January 2005. These patients were divided into two groups: bilateral CSDH (45 cases) and unilateral CSDH (84 cases). Clinical presentations, precipitating factors, CT scan findings, postoperative complications, and outcomes of patients were analyzed.
  
  
  RESULTS
  : The mean age was 75 years for patients with bilateral CSDH and was 68 years for patients with unilateral CSDH (p = 0.696). Males predominated in each group (p = 0.696). The frequency of presenting symptoms of nausea and vomiting, headache, or unsteady gait was significantly greater in bilateral CSDH than in unilateral CSDH (p < 0.05). The incidence of usage of anticoagulant and antiplatelet therapy was significantly higher in bilateral CSDH group than in unilateral CSDH group (p < 0.05). The frequency of marked midline shift on CT scans was significantly greater in unilateral CSDH than in bilateral CSDH (p < 0.05). Coexisting systemic diseases, postoperative complications, and outcomes had no significant differences between both groups.
  
  
  CONCLUSIONS
  : Bilateral CSDH tended to occur more in patients with anticoagulant or antiplatelet therapy. Compared with patients with unilateral CSDH, patients with bilateral CSDH had more symptoms of increased intracranial pressure and lower incidences of midline shift on CT scans. Most patients with either bilateral or unilateral CSDH had a good postoperative outcome.
authors.affiliation: Department of Neurosurgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Tai-Hsin
authors.initials: TH
authors.lastname: Tsai
authors.forename: Ann-Shung
authors.initials: AS
authors.lastname: Lieu
authors.forename: Shiuh-Lin
authors.initials: SL
authors.lastname: Hwang
authors.forename: Tzuu-Yuan
authors.initials: TY
authors.lastname: Huang
authors.forename: Yan-Fen
authors.initials: YF
authors.lastname: Hwang
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003399:Craniotomy; D004322:Drainage; D005260:Female; D020200:Hematoma, Subdural, Chronic / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D015985:Precipitating Factors; D012189:Retrospective Studies; D012737:Sex Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult