Evaluation of neuromuscular function in inflammatory myopathy.

The assessment of neuromuscular function during the course of treatment in patients with inflammatory myopathy requires a combination of tests tailored to the clinical status of the patient. The use of timed functional tests, pulmonary function, functional grading, and manual muscle strength testing (coordinated with a physical therapist) provides the clinician and patient with reliable, easily performed measurements that are flexible enough for virtually all outpatient settings. Some patients may require assessment with only timed functional tests, such as the time to run 30 feet, climb four steps, and arise from supine to standing; other patients may need an assessment that uses function tests, functional grade scoring, and manual muscle strength testing. The 24-hour urinary excretion of creatinine is a simple method to measure changes in muscle mass, and determinations at 3- to 6-month intervals may provide a useful means to document the effects of treatment. Occasionally, more elaborate methods, such as MR imaging of muscle may be necessary to identify persistent inflammation in certain muscles or aid in the selection of a specific area of muscle to biopsy. The use of myometry, especially fixed myometry with QMT, is most suitable for clinical research. In the future, hand-held myometric equipment and, perhaps, even QMT, may become more adaptable to office practice, and their use will be more feasible for the routine care of patients with inflammatory myopathy.