Sequential isokinetic and manual muscle testing in patients with neuromuscular disease. A pilot study

The purposes of this study were to compare the value of isokinetic testing and manual muscle testing (MMT) in longitudinal measurements of muscle strength in patients with neuromuscular disease and to identify any consistent pattern demonstrated by the isokinetic testing of patients with specific diagnoses. We measured knee extensor muscle strength at periodic intervals in patients, using MMT and isokinetic testing at angular limb velocities of 30 and 180 degrees/sec. An isokinetic fatigability test also was conducted. The results indicated that in patients who were graded 9 to 10 (ie, within normal limits) by MMT methods, sequential isokinetic strength tests revealed improvement not indicated by MMT. In patients, however, having weakness detectable by MMT and whose course was deteriorating, isokinetic testing did not seem to add clinically significant information for long-term management. Some patients with myotonia demonstrated an increase in peak torque during the fatigability test; this response was unique among the diagnoses we tested. Isokinetic testing may provide, in some patients with neuromuscular disease, valuable information when used in conjunction with MMT for sequential monitoring of strength. Continued research is needed to investigate the value of isokinetic testing in the diagnosis and management of patients with neuromuscular disease.