title: The risk of persistent paresthesia is not increased with repeated axillary block.
abstract: Neurologic deficits are noted on physical examination in approximately 0.2%-19% of patients after regional anesthetic techniques. Laboratory and clinical studies suggest that a subclinical neuropathy occurs much more often. Performing a regional anesthetic technique during this period may result in additional nerve trauma. We evaluated the frequency of neurologic complications in patients undergoing repeated axillary block. A total of 1614 blocks were performed on 607 patients. The median number of blocks per patient was two (range 2-10 blocks). The median interval between blocks was 12.6 wk, including 188 (31%) patients who received multiple blocks within 1 wk. Sixty-two neurologic complications occurred in 51 patients for an overall frequency of 8.4%. Of the 62 nerve injuries, 7 (11.3%) were related to the anesthetic technique; the remaining 55 (88.7%) were a result of the surgical procedure. Patient age and gender, the presence of preexisting neurologic conditions, a surgical procedure to a nerve, and total number of blocks did not increase the risk of neurologic complications. No regional anesthetic technique risk factors, including elicitation of a paresthesia, selection of local anesthetic, or addition of epinephrine, were identified. The success rate was higher with the paresthesia technique than with nerve stimulator technique or transarterial injection, and with use of mepivacaine versus bupivacaine. We conclude that the frequency of neurologic complications in patients undergoing repeated axillary block is similar to that in patients receiving a single regional technique. These patients are not likely to be at increased risk of neurologic complications.
  
  
  CONCLUSIONS
  The risk of neurologic complications was not increased in patients who underwent multiple axillary blocks, even within a 1-wk interval. No risk factors for anesthetic-related complications were identified. However, block success rate was increased with the paresthesia technique and the injection of mepivacaine versus bupivacaine.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905, USA. horlocker.terese@mayo.edu
authors.forename: T T
authors.initials: TT
authors.lastname: Horlocker
authors.forename: R P
authors.initials: RP
authors.lastname: Kufner
authors.forename: A T
authors.initials: AT
authors.lastname: Bishop
authors.forename: P M
authors.initials: PM
authors.lastname: Maxson
authors.forename: D R
authors.initials: DR
authors.lastname: Schroeder
mesh_terms: D000322:Adrenergic Agonists / Q000009:adverse effects; D000328:Adult; D000367:Age Factors; D000779:Anesthetics, Local / Q000009:adverse effects; D001365:Axilla / Q000294:innervation*; D002045:Bupivacaine / Q000008:administration & dosage; D004558:Electric Stimulation; D004837:Epinephrine / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects* / Q000379:methods; D010292:Paresthesia / Q000209:etiology*; D011183:Postoperative Complications; D019233:Retreatment; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors; D016896:Treatment Outcome