Prospective study of peripheral neuropathy in Machado–Joseph disease

Authors

  • Marcondes C. França Jr. MD,

    1. Department of Neurology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
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  • Anelyssa D'abreu MD,

    1. Department of Neurology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
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  • Anamarli Nucci MD, PhD,

    1. Department of Neurology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
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  • Fernando Cendes MD, PhD,

    1. Department of Neurology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
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  • Iscia Lopes-Cendes MD, PhD

    Corresponding author
    1. Department of Medical Genetics, University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126 Cidade Universitaria “Zeferino Vaz,” Campinas, São Paulo 13084-971, Brazil
    • Department of Medical Genetics, University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126 Cidade Universitaria “Zeferino Vaz,” Campinas, São Paulo 13084-971, Brazil
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Abstract

Peripheral neuropathy (PN) has long been recognized in Machado–Joseph disease (MJD), but its natural history is an unsettled issue. Therefore, we prospectively assessed 40 with MJD for 13 months with nerve conduction (NC) studies and the revised total neuropathy score (TNSr) to study the progression of PN. There was no significant change in the TNSr score over the follow-up period. In contrast, the average sural sensory nerve action potential (SNAP) amplitude decreased significantly over the same interval from a mean of 13.2 μV to 9.8 μV (P < 0.001). There was an inverse correlation between the change in the sural SNAP amplitude and the length of the CAG triplet repeat expansion (r = 0.574, P < 0.001). The reduction in the mean sural SNAP amplitude also correlated with progression of ataxia. This indicates that PN progresses faster in individuals with larger (CAG)n expansions, and nerve conduction studies may be useful to study disease progression in MJD. Muscle Nerve, 2009

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