title: Muscle fiber atrophy in leg muscles after botulinum toxin type A treatment of cervical dystonia.
abstract: Previous electrophysiologic studies on the effects of local injections of botulinum toxin type A (BTX-A) have indicated impaired neuromuscular transmission in distant muscles. To further study possible distant effects of repeated BTX-A injections, we obtained percutaneous muscle biopsies of the vastus lateralis muscle from 11 patients with cervical dystonia. We examined the biopsies with histopathology and morphometry, and compared them with age-matched healthy controls. There was an increased frequency of angular atrophic type IIB fibers in the patient group, and the mean size of IIB fibers was significantly smaller (p < 0.05). In addition, there was a negative correlation between accumulated dose of botulinum toxin and relative size of type IIA fibers (p < 0.05). We postulate that the observed atrophy is due to distant effects of botulinum toxin causing progressive denervation-like changes in non-treated muscle. This observation calls for further, prospective studies of the long-term effects of the treatment.
authors.affiliation: Department of Neurology, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Ansved
authors.forename: T
authors.initials: T
authors.lastname: Odergren
authors.forename: K
authors.initials: K
authors.lastname: Borg
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004421:Dystonia / Q000188:drug therapy*; D006801:Humans; D007273:Injections, Intramuscular; D007866:Leg; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology*; D009334:Neck Muscles; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A