Estimation of skeletal muscle energy metabolism in Machado‐Joseph disease using 31 P‐MR spectroscopy

The aim of this study was to determine if muscle energy metabolism, as measured by 31 P‐magnetic resonance spectroscopy (MRS), is a metabolic marker for the efficacy of treatment of Machado‐Joseph disease (MJD). We obtained 31 P‐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 (V max ) ( P < 0.01). In addition, V max 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 V max 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