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Keywords:

  • Machado-Joseph disease;
  • muscle energy metabolism;
  • SARA;
  • cerebellar ataxia;
  • surrogate marker;
  • 31P-MRS

Abstract

The aim of this study was to determine if muscle energy metabolism, as measured by 31P-magnetic resonance spectroscopy (MRS), is a metabolic marker for the efficacy of treatment of Machado-Joseph disease (MJD). We obtained 31P-MRS in the calf muscle of 8 male patients with MJD and 11 healthy men before, during, and after a 4 minute plantar flexion exercise in a supine position. The data showed that there was a significant difference between the groups in terms of the PCr/(Pi + PCr) ratio at rest (P = 0.03) and the maximum rate of mitochondrial ATP production (Vmax) (P < 0.01). In addition, Vmax was inversely correlated with the scale for the assessment and rating of ataxia score (r = −0.34, P = 0.04). The MJD group also showed a reduction in Vmax over the course of 2 years (P < 0.05). These data suggest that this noninvasive measurement of muscle energy metabolism may represent a surrogate marker for MJD. © 2010 Movement Disorder Society