title: Prospective study of the incidence of transient radicular irritation in patients undergoing spinal anesthesia.
abstract: BACKGROUND
  There is considerable controversy regarding the role of subarachnoid 5% hyperbaric lidocaine in the syndrome transient radicular irritation (TRI). This randomized, double-blinded, prospective study was designed to determine the incidence of TRI and identify factors possibly contributing to its development.
  
  
  METHODS
  One hundred fifty-nine ASA physical status 1 or 2 patients undergoing outpatient knee arthroscopy or unilateral inguinal hernia repair were prospectively randomized to receive spinal anesthesia with 5% hyperbaric lidocaine with epinephrine (60 mg with 0.2 mg epinephrine for arthroscopy or 75 mg with 0.2 mg epinephrine for hernia repair), 2% isobaric lidocaine without epinephrine (60 mg for arthroscopy or 75 mg for hernia repair), or 0.75% hyperbaric bupivacaine without epinephrine (7.5 mg for arthroscopy or 9.0 mg for hernia repair) in a double-blinded fashion. On the 3rd postoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications including TRI, defined as back pain with radiation down one or both buttocks or legs occurring within 24 h after surgery. Postoperatively, time from injection to block resolution, ambulation, voiding, and ready for discharge were recorded by a postanesthesia care unit nurse blinded to the group assignment.
  
  
  RESULTS
  The incidence of TRI was greater in patients receiving lidocaine than in those receiving bupivacaine (16% vs. 0%; P = 0.003). There was no difference in the incidence of TRI between the patients receiving 5% hyperbaric lidocaine with epinephrine and those receiving 2% isobaric lidocaine without epinephrine (16% vs. 16%; P = 0.98). The incidence of TRI was greater in patients undergoing arthroscopy than in those undergoing hernia repair (13% vs. 5%; P = 0.04). There was no difference in discharge times in patients receiving bupivacaine versus those receiving hyperbaric lidocaine with epinephrine (292 vs. 322 min; P = 0.61).
  
  
  CONCLUSIONS
  The incidence of TRI is greater with lidocaine than bupivacaine, decreasing the lidocaine concentration to 2% does not prevent TRI, and surgical position may be an important contributing factor. Discharge times at our institution are not different when equipotent doses of 0.75% hyperbaric bupivacaine or 5% hyperbaric lidocaine with 0.2 mg epinephrine are used in ambulatory patients undergoing spinal anesthesia.
authors.affiliation: Department of Anesthesiology, Virginia Mason Medical Center, Seattle, Washington 98111, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Pollock
authors.forename: J M
authors.initials: JM
authors.lastname: Neal
authors.forename: C A
authors.initials: CA
authors.lastname: Stephenson
authors.forename: C E
authors.initials: CE
authors.lastname: Wiley
mesh_terms: D000328:Adult; D000368:Aged; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D000779:Anesthetics, Local / Q000009:adverse effects*; D001416:Back Pain / Q000209:etiology*; D002045:Bupivacaine / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007866:Leg; D008012:Lidocaine / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine; D002045:Bupivacaine