title: Frequent atrophic groups with mixed-type myofibers is distinctive to motor neuron syndromes.
abstract: This study was performed to determine whether there are distinctive features to the pattern of muscle denervation in motor neuron disease. We first compared muscle biopsies from patients with amyotrophic lateral sclerosis (ALS) or Kennedy's disease with other causes of denervation. Groups of atrophic muscle fibers, with individual groups containing both fiber types I and II, occurred frequently in motor neuron disease but not other causes of denervation. We then identified 11 additional muscle biopsies with frequent atrophic groups containing mixed fiber types. Chart review revealed that 10 patients had a final diagnosis of motor neuron disease or ALS and one had multifocal motor neuropathy. We conclude that muscle biopsy may have diagnostic utility early in the course of motor neuron disease. The muscle biopsy pattern of frequent atrophic groups containing mixed fiber types should suggest a diagnosis of a motor neuron syndrome or motor neuropathy.
authors.affiliation: Department of Neurology, Washington University in St. Louis, Box 8111, 660 South Euclid Avenue, St. Louis, Missouri, USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Baloh
authors.forename: Wojtek
authors.initials: W
authors.lastname: Rakowicz
authors.forename: Robert
authors.initials: R
authors.lastname: Gardner
authors.forename: Alan
authors.initials: A
authors.lastname: Pestronk
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis; D001706:Biopsy / Q000379:methods; D003937:Diagnosis, Differential; D005500:Follow-Up Studies; D006801:Humans; D016472:Motor Neuron Disease / Q000175:diagnosis*; D018485:Muscle Fibers, Skeletal / Q000145:classification / Q000473:pathology*; D009134:Muscular Atrophy, Spinal / Q000175:diagnosis; D009218:Myosins / Q000378:metabolism; D011115:Polyneuropathies / Q000175:diagnosis
chemical_list: D009218:Myosins