title: Driving reaction time before and after primary fusion of the lumbar spine.
abstract: METHODS
  Controlled prospective study.
  
  
  OBJECTIVE
  To determine whether driving reaction time (DRT) is influenced by primary lumbar fusion.
  
  
  BACKGROUND
  The effects of radiculopathy and nerve root blocks on DRT have been reported recently. To our knowledge, the relationship between lumbar fusion and DRT has not been previously studied although it is important for driving safety. The aim of the present study was to test the hypotheses that DRT after lumbar fusion is (1) altered after the operation, (2) influenced by pain, (3) influenced by the patient's driving skill, and (4) differs from the DRT of healthy controls.
  
  
  METHODS
  Twenty-one consecutive patients (mean age, 53.5 years; SD 10.8) receiving primary lumbar fusion were tested for their DRT 1 day before surgery (preoperative), the day before discharge (postoperative) and 3 months after surgery (follow-up; FU). DRT was assessed using a custom-made driving simulator. The severity of back pain was determined on visual analogue scales separately for usual pain (VAS-U) and pain during testing (VAS-T). We also determined the patients' subjective driving frequency. Normative DRT data from 31 age-matched healthy controls were used for comparison.
  
  
  RESULTS
  The preoperative DRT was 685 milliseconds (Md; IQR 246) and the postoperative DRT 728 milliseconds (Md; IQR 264), which was further reduced to 671 milliseconds (Md; IQR 202) after the FU period. Statistical significance was registered between postoperative and FU DRT (P = 0.007). Moderate to high correlations (0.537 < r < 0.680) were found between the VAS rating of back pain and DRT. Control subjects had a DRT of 487 milliseconds (Md; IQR 116), which differed significantly from the DRT of patients at all 3 time points of testing (P < 0.001).
  
  
  CONCLUSIONS
  It appears safe to continue driving after discharge from the hospital following lumbar fusion. DRT improved significantly during FU, indicating a positive effect of the intervention on driving skills. DRT correlates with the severity of back pain.
authors.affiliation: Department of Orthopedic Surgery, Innsbruck Medical University, Innsbruck, Austria. michael.liebensteiner@i-med.ac.at
authors.forename: Michael C
authors.initials: MC
authors.lastname: Liebensteiner
authors.forename: Franz
authors.initials: F
authors.lastname: Birkfellner
authors.forename: Martin
authors.initials: M
authors.lastname: Thaler
authors.forename: Christian
authors.initials: C
authors.lastname: Haid
authors.forename: Christian
authors.initials: C
authors.lastname: Bach
authors.forename: Martin
authors.initials: M
authors.lastname: Krismer
mesh_terms: D000328:Adult; D000368:Aged; D001334:Automobile Driving / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000150:complications / Q000523:psychology; D011446:Prospective Studies; D011930:Reaction Time / Q000502:physiology*; D013123:Spinal Fusion / Q000009:adverse effects; D013997:Time Factors