Decomposition-based quantitative electromyography in the evaluation of muscular dystrophy severity.

INTRODUCTION: Electromyography is useful in the diagnosis of myopathies, but its utility in determining disease severity requires further investigation. In this study we aimed to determine whether decomposition-based quantitative electromyography (DQEMG) could indicate the severity of involvement in a cohort of patients with muscular dystrophies (MDs). METHODS: Fifteen patients with facioscapulohumeral (FSHD), limb-girdle (LGMD), and Becker (BMD) muscular dystrophy, and 7 healthy controls, participated in this investigation. Knee extensor isometric strength differentiated the "more severe" and "less severe" MD groups. The vastus lateralis (VL), biceps brachii (BB), and tibialis anterior (TA) muscle groups were investigated using DQEMG. RESULTS: All muscles from the MD group showed changes in mean MUP (motor unit potential) AAR (area-to-amplitude ratio), and turns, compared with controls (P < 0.05). More severely affected muscles (VL and BB) also had shortened mean MUP durations compared with controls (P < 0.01). CONCLUSIONS: DQEMG was capable of indicating the severity of MD involvement, as changes in MUP morphology reflected the progressive nature of the disease.

Percutaneous muscle biopsies: review of 900 consecutive cases at London Health Sciences Centre.

OBJECTIVE: In the present study we review our experience with 900 consecutive percutaneous muscle biopsies over the period 1993 to 2007. We examined the advantages and limitations of the procedure, biopsy site preferences, diagnostic range, frequency of diagnoses and quality of histopathology. Demographics, referral patterns and patients' perceptions of the procedure were also assessed. METHODS: Cases were identified through the London Health Sciences Centre Department of Pathology database. Standard biopsy procedures were followed using a manual trocar style instrument. With a neuropathology technologist in attendance at all biopsies, biopsies were oriented in the fresh state and snap frozen. RESULTS: Most referrals for muscle biopsy were from neuromuscular neurologists. The procedure was found to be efficient, well-tolerated and produced high quality specimens in all diagnostic categories. No major complications occurred. Failure to obtain an adequate tissue sample, although uncommon (< 2%), was usually due to marked obesity, edema or muscle wasting. Bleeding at the site was rarely problematic and no wound infections were reported. CONCLUSIONS: Needle muscle biopsies represent an efficient alternative to open biopsies when peripheral nerve sampling is not required and when large tissue samples are not needed for extensive biochemical analyses.