title: Nerve localization techniques for interscalene brachial plexus blockade: a prospective, randomized comparison of mechanical paresthesia versus electrical stimulation.
abstract: Postoperative neurologic symptoms (PONS) are relatively common after upper extremity orthopedic surgery performed under peripheral neural blockade. In this study, we prospectively compared the incidence of PONS after shoulder surgery under interscalene (IS) block using the electrical stimulation (ES) or mechanical paresthesia (MP) techniques of nerve localization. For patients randomized to the MP group, a 1-in, 23-g long-beveled needle was placed into the IS groove to elicit a paresthesia to the shoulder, arm, elbow, wrist, or hand. For patients randomized to the ES group, a 5-cm, 22-g short-beveled insulated needle was placed into the IS groove to elicit a motor response including flexion or extension of the elbow, wrist, or fingers or deltoid muscle stimulation at a current between 0.2 and 0.5 mA. Each IS block was performed with 50-60 mL of 1.5% mepivacaine containing 1:300,000 epinephrine and 0.1meq/L sodium bicarbonate. Two-hundred-eighteen patients were randomized between the two groups. One patient was lost to follow-up. Twenty-five patients (23%) in the ES group experienced paresthesia during needle insertion. The incidence of PONS using the ES technique was 10.1% (11/109), whereas the incidence with the MP technique was 9.3% (10/108) (not significant). The PONS lasted a median duration of 2 mo, and symptoms in all patients resolved within 12 mo. The success rate, onset time, and patient satisfaction were also comparable between groups. We conclude that the choice of nerve localization technique can be made based on the patient's and anesthesiologist's comfort and preferences and not on concern for the development of PONS.
authors.affiliation: Hospital for Special Surgery, Department of Anesthesiology, Weill Medical College of Cornell University, New York, New York 10021, USA. liguorig@hss.edu
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Liguori
authors.forename: Victor M
authors.initials: VM
authors.lastname: Zayas
authors.forename: Jacques T
authors.initials: JT
authors.lastname: YaDeau
authors.forename: Richard L
authors.initials: RL
authors.lastname: Kahn
authors.forename: Leonardo
authors.initials: L
authors.lastname: Paroli
authors.forename: Valeria
authors.initials: V
authors.lastname: Buschiazzo
authors.forename: Anita
authors.initials: A
authors.lastname: Wu
mesh_terms: D000328:Adult; D001917:Brachial Plexus / Q000473:pathology*; D004558:Electric Stimulation / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects* / Q000379:methods*; D009417:Nerve Tissue / Q000187:drug effects*; D010292:Paresthesia; D017933:Peripheral Nervous System / Q000473:pathology; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires; D016896:Treatment Outcome