Diaphragm quantitative electromyography in difficult-to-treat asthmatic patients

ABSTRACT Quantitative electromyography is an important tool to evaluate myopathies, and some difficult-to-treat asthmatic patients may have a subclinical corticosteroid myopathic process, using only inhaled corticosteroid, according to some studies. In this report, diaphragm quantitative electromyography was used to evaluate asthmatic difficult-to-treat patients, comparing them with a control group. Significant differences were obtained in amplitude, duration and size index of motor unit action potentials, with lower parameters in the asthmatic patients, which may indicate a myopathic process.

Quantitative electromyography

Several quantitative electromyography (QEMG) methods are used for diagnosing and monitoring in patients with neuromuscular disorders. At weak effort of the muscle, motor unit potential (MUP) analyses as individual MUP, multi-MUP, and macro-EMG are diagnostically sensitive and well tested. At higher effort of the muscle, interference pattern analyses such as the turns amplitude analysis are also diagnostically sensitive. Other potential diagnostic methods are power spectrum analysis, muscle fibre conduction velocity analysis, and some surface EMG methods. In patients with myopathy, QEMG has an important role in the diagnosis as a supplement to blood tests, muscle biopsy, and genetic testing. In patients with neurogenic disorders such as anterior horn cell disorders, peripheral nerve lesions, or polyneuropathy, QEMG has important roles in characterizing the lesion and differential diagnosis. Furthermore, QEMG may be useful in the examination of patients with neuromuscular transmission failure, critical illness disorders, and in treatment of dystonic muscle with botulinum toxin.