title: Electrophysiological stimulation (Tsui test) is feasible for epidural catheter positioning in adults with chronic back pain: a cohort study.
abstract: OBJECTIVE
  Determining epidural catheter placement and accurately depositing corticosteroids at the site of the pathology in adults with chronic back pain can be challenging. Fluoroscopy is considered the standard of care for guiding epidural catheter positioning and subsequent injection in patients receiving epidural corticosteroids, but the technique has some limitations. We hypothesized that electrophysiological stimulation using the Tsui test is feasible for determining the appropriate epidural catheter position in adults with chronic back pain receiving epidural corticosteroids.
  
  
  METHODS
  We conducted a prospective cohort study of 12 patients receiving epidural corticosteroid injections for chronic back pain. Anatomical landmarks and epidural needle positions were initially confirmed by fluoroscopy. Epidural catheter position was assessed according to sensory and motor responses, as described by Tsui et al. (Can J Anaesth 45: 640-644, 1998). The current was increased slowly from zero until muscle activity was visible or the current reached 10 mA. The catheter was then advanced until muscle responses occurred in the desired myotome. The test was deemed positive or negative according to the Tsui criteria. The anatomical level was confirmed by fluoroscopy prior to injection.
  
  
  RESULTS
  Electrophysiological stimulation effectively established the appropriate epidural catheter position in 11 patients (92%). Epidural stimulation occurred at a mean (SD) threshold of 3.95 (3.35) mA. The kappa statistic between interventions was 0.65, indicating a substantial level of agreement.
  
  
  CONCLUSIONS
  This study demonstrated that electrophysiological stimulation using the Tsui technique is feasible for epidural catheter positioning in adults with chronic back pain. It may optimize epidural steroid injection in this population.
authors.affiliation: Department of Anesthesia and Pain Medicine, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada, mcauliffeniamh@gmail.com.
authors.forename: Niamh A
authors.initials: NA
authors.lastname: McAuliffe
authors.forename: Sharon
authors.initials: S
authors.lastname: Pickworth
authors.forename: Tania
authors.initials: T
authors.lastname: Direnna
authors.forename: Aaron
authors.initials: A
authors.lastname: Hong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001416:Back Pain / Q000188:drug therapy*; D002404:Catheterization / Q000379:methods*; D002908:Chronic Disease; D015331:Cohort Studies; D004558:Electric Stimulation / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005471:Fluoroscopy / Q000379:methods; D005938:Glucocorticoids / Q000008:administration & dosage* / Q000627:therapeutic use; D006801:Humans; D007268:Injections, Epidural; D008297:Male; D008875:Middle Aged; D009339:Needles; D011446:Prospective Studies
chemical_list: D005938:Glucocorticoids