title: Plantar flexion seems more reliable than dorsiflexion with Labat's sciatic nerve block: a prospective, randomized comparison.
abstract: Labat's classic approach to the sciatic nerve has not been able to show which motor response of the foot provides a more frequent rate of complete sensory and motor block. In this prospective, randomized, double-blind study, we compared plantar flexion with dorsiflexion with regard to onset time and efficacy of sciatic nerve block using the classic posterior approach. A total of 80 patients undergoing hallux valgus repair were randomly allocated to receive sciatic nerve block after evoked plantar flexion (n=40) or dorsiflexion (n=40). Twenty milliliters of 0.75% ropivacaine was injected after the motor response was elicited at <0.5 mA. Success rate was defined as complete sensory and motor block in all sciatic nerve distributions associated with a pain-free surgery. Time required for onset of sensory and motor block of the foot was recorded. Success was more frequent after elicited plantar flexion (87.5%) than dorsiflexion (55%; P <0.05). Onset of complete sensory and motor block of the foot was faster after elicited plantar flexion (10 +/- 10 min and 13 +/- 10 min, respectively) compared with dorsiflexion (20 +/- 11 min and 24 +/- 12 min; P <0.05). We conclude that plantar flexion of the foot predicts a shorter onset time and a more frequent success rate than dorsiflexion with Labat's classic posterior sciatic nerve block.
authors.affiliation: *University of Santiago de Compostela, Department of Anesthesiology, Hospital Clínico Universitario de Santiago, Spain; and †Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Manuel
authors.initials: M
authors.lastname: Taboada
authors.forename: Peter G
authors.initials: PG
authors.lastname: Atanassoff
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodríguez
authors.forename: Joaquín
authors.initials: J
authors.lastname: Cortés
authors.forename: Sabela
authors.initials: S
authors.lastname: Del Rio
authors.forename: Juan
authors.initials: J
authors.lastname: Lagunilla
authors.forename: Francisco
authors.initials: F
authors.lastname: Gude
authors.forename: Julián
authors.initials: J
authors.lastname: Álvarez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000758:Anesthesia; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D004562:Electrocardiography / Q000187:drug effects; D019054:Evoked Potentials, Motor / Q000187:drug effects; D005260:Female; D005528:Foot; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects*; D009407:Nerve Block; D010092:Oximetry; D011446:Prospective Studies; D012584:Sciatic Nerve