Diagnostic yield of muscle fibre conduction velocity in myopathies.

We prospectively assessed diagnostic yield of muscle fiber conduction velocity (MFCV) studies in patients with signs and symptoms suggestive of a myopathy. Results were analysed with respect to the final diagnosis, and compared to the reference standard, which was qualitative electromyography (EMG), turns-amplitude analysis (TAA), and muscle biopsy. We included 125 patients, in whom a myopathy was diagnosed in 71, and a neuromuscular disorder was excluded in 54. Sensitivity of MFCV for the presence of a myopathy was 84%, and specificity 83%. Diagnostic yield of MFCV was superior to EMG, TAA, and muscle biopsy in patients with metabolic myopathies, non-dystrophic myopathies, and channelopathies. We concluded that measurement of MFCV is a quantitative EMG technique with a high diagnostic yield. In certain myopathies, MFCV may be more informative than conventional EMG examination.