Facioscapulohumeral muscular dystrophy. A quantitative electromyographic study.
BACKGROUND
Quantitative electromyography (EMG) using different needle techniques has not been performed or reported on a relatively large group of patients with facioscapulohumeral muscular dystrophy (FSHD).


OBJECTIVE
To establish statistically: (1) correlations between clinical features of patients (age, disease duration and degree of weakness) and quantitative needle EMG/SFEMG,; (2) correlations between different EMG parameters in the patient group, and (3) quantitative EMG differences comparing patients with a healthy control group.


METHODS
Nerve conduction studies, and needle EMG (motorunit analysis, MacroEMG, SFEMG) were performed on Mm. triceps brachii and Mm. tibialis anterior according to standard techniques on 20 patients with FSHD.


RESULTS
Nerve conduction studies were normal. In Mm. triceps brachii and, to a lesser extent, Mm. tibialis anterior motorunit analysis and MacroEMG showed myopathic changes, that correlated with patient clinical parameters. In Mm. triceps brachii (but not in Mm. tibialis anterior) EMG results were statistically different in patients compared to control group data. The most sensitive indicators of a myopathy were MUP duration (motorunit analysis) and MUP area (MacroEMG). In the Mm. triceps brachii SFEMG revealed correlations between worsening pooled MCD data and patient clinical parameters. Pooled MCD results did not correlate with other MUP parameters. SFEMG showed abnormal jitter only in 2 patients with the longest disease duration.


CONCLUSIONS
Quantitative EMG results are compatible with a mild, slowly progressive myopathy. The most sensitive indicators of early muscle disease were MUP duration (motorunit analysis) and MUP area (MacroEMG) that would not be detected on "routine" EMG SFEMG showed subtle, progressive worsening of neuromuscular junction physiology. However, quantitative EMG and SFEMG showed that muscle fiber degeneration and loss followed a course independent of muscle fiber regeneration and reinnervation.
Stübgen
J P
JP
Department of Neurology, University of Pretoria, South Africa.
D000328:Adult; D000367:Age Factors; D016022:Case-Control Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000503:physiopathology*; D009431:Neural Conduction / Q000502:physiology*; D012720:Severity of Illness Index