Frequent atrophic groups with mixed-type myofibers is distinctive to motor neuron syndromes

Department of Neurology, Washington University in St. Louis, Box 8111, 660 South Euclid Avenue, St. Louis, Missouri, USA.
Muscle & Nerve (Impact Factor: 2.28). 07/2007; 36(1):107-10. DOI: 10.1002/mus.20755
Source: PubMed


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.

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    • "ated to occur when denervated myofibers are reinnervated by collateral sprouts from neighboring axons ( Andersen et al . , 1996 ; Fischer et al . , 2004 ; Schaefer et al . , 2005 ; Soraru et al . , 2008 ) . On the other hand , it has also been reported that muscle biopsies from ALS patients exhibit muscle fiber atrophy but no fiber type grouping ( Baloh et al . , 2007 ) . The reason for this seeming discrepancy is not apparent from the data available , but ALS actually encompasses a spectrum of disorders , and it is possible that fiber type grouping occurs in some forms of the disease and not others ( Soraru et al . , 2008 ) . Because no type grouping in intercostal muscle ( this study ) or in pelvic"
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    • "Further, in Sod1 À/À mice, measurements of steady state redox potential of glutathione (which is routinely used as indicator of the intracellular redox state) in tibial nerve and gastrocnemius muscle showed a selective involvement of the nerve at 4 months, again indicating the primary involvement of the axon (Fischer et al., 2012). Thus muscle changes in Sod1 À/À mice are secondary to denervation; they are non-specific and also present in muscle biopsies from patients with ALS (Baloh et al., 2007a). "
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