title: Botulinum toxin effect on voluntary and stretch reflex-related torque produced by the quadriceps: an isokinetic pilot study.
abstract: BACKGROUND
  An understanding of the mechanical effects of botulinum toxin type A (BoNT A) on spastic and voluntary muscle contraction may help predict functional responders.
  
  
  OBJECTIVE
  To compare the effect of BoNT A on the voluntary and stretch reflex-related torques produced by activation of the rectus femoris (RF).
  
  
  METHODS
  This was a prospective open study where 15 incomplete spinal cord injury patients, impaired by a stiff-knee gait, with RF hyperactivity in mid-swing quantified by formal gait analysis (GA), were assessed before and after RF BoNT A injection (Botox, 200 UI).
  
  
  METHODS
  Included isokinetic peak torque (and angle at peak torque) at 0° (supine) and 90° (seated) during passive stretch (10 deg/s, 90 deg/s, and 150 deg/s), and voluntary contraction (60 deg/s) of the quadriceps. Secondary measures included impairment by Modified Tardieu Scale (MTS), peak knee flexion and spatial-temporal data by GA, activity (6-minute walking test, timed stair climbing), and discomfort (Verbal Rating Scale).
  
  
  RESULTS
  Voluntary torque decreased (-16%; P = .0004) but with only a trend toward a decrease in stretch reflex-related torque. The angle at spastic torque increased at 90 deg/s (+5°; P = .03), whereas MTS, peak knee flexion (+4°; P = .01), spatial-temporal data, timed stair climbing test (25%; P = .02), and discomfort were significantly improved.
  
  
  CONCLUSIONS
  BoNT A appeared to delay the stretch-reflex angle at peak torque, whereas the voluntary torque decreased. After strict patient selection, BoNT A injection into the RF muscle led to improvements in impairment, activity, and discomfort.
authors.affiliation: Versailles University, Garches, France. b.bernuz@leonberard.com
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bernuz
authors.forename: François
authors.initials: F
authors.lastname: Genet
authors.forename: Philippe
authors.initials: P
authors.lastname: Terrat
authors.forename: Didier
authors.initials: D
authors.lastname: Pradon
authors.forename: Frederic
authors.initials: F
authors.lastname: Barbot
authors.forename: Bernard
authors.initials: B
authors.lastname: Bussel
authors.forename: Djamel
authors.initials: D
authors.lastname: Bensmail
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000494:pharmacology / Q000627:therapeutic use*; D004576:Electromyography; D005260:Female; D020233:Gait Disorders, Neurologic / Q000188:drug therapy* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000187:drug effects*; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D010865:Pilot Projects; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000187:drug effects; D012026:Reflex, Stretch / Q000187:drug effects*; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000150:complications / Q000188:drug therapy*; D019415:Torque; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A