title: Intraneural catheterization of the sciatic nerve in humans: a pilot study.
abstract: OBJECTIVE
  Imaging studies in humans have shown that intraneural injection of local anesthetic may be relatively frequent. The incidence of intraneural catheterization is unknown. We speculated that early neural blockade after the injection of a small dose of local anesthetic might be a common finding produced by unintended intraneural catheterization. We investigated the clinical effect of a small dose of local anesthetic injected through a stimulating sciatic catheter, and also the placement of the tip of the catheters by computed tomography (CT) scan.
  
  
  METHODS
  In this descriptive study, a dose of 3 to 5 mL of 1.5% mepivacaine was injected through a stimulating sciatic catheter in 45 patients undergoing hallux valgus repair. Patients with early neural blockade at the foot, within 5 minutes after injection, were suspected to have an intraneural placement of the catheter. A CT scan of the thighs was performed in 10 additional patients to assess catheter tip placement.
  
  
  RESULTS
  Nine of 45 patients had early neural blockade with the small dose of local anesthetic. Seven patients underwent surgery without further supplementation. There was a statistically significant lower intensity of stimulating current through the catheter in the group of patients with early neural blockade. Of 10 CT scans, 3 showed clear intraneural placement of the catheter. No postoperative sequelae were observed.
  
  
  CONCLUSIONS
  Intraneural catheterization of the sciatic nerve may be a frequent finding and was not followed by nerve injury under the conditions of our small pilot study.
authors.affiliation: Department of Anesthesiology, Complexo Hospitalario Universitario de Santiago, Santiago de Compostela, Spain. jaime_rodriguez_garcia@yahoo.es
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodríguez
authors.forename: Manuel
authors.initials: M
authors.lastname: Taboada
authors.forename: Miguel
authors.initials: M
authors.lastname: Blanco
authors.forename: Juan
authors.initials: J
authors.lastname: Oliveira
authors.forename: María
authors.initials: M
authors.lastname: Bárcena
authors.forename: Julián
authors.initials: J
authors.lastname: Alvarez
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002404:Catheterization; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010865:Pilot Projects; D012584:Sciatic Nerve / Q000187:drug effects*; D014057:Tomography, X-Ray Computed
chemical_list: D000779:Anesthetics, Local