Isokinetic muscle strength assessment of lower limbs in diabetic neuropathy

ABSTRACT

Motor dysfunction is a late and rare feature in diabetic distal sensory polyneuropathy. Early impairment of motor function in diabetic sensory neuropathy is largely unknown. We studied sixty patients with diabetic distal polyneuropathy, 30 patients with subclinical and 30 with clinical overt diabetic neuropathies. Thirty age and sex matched healthy subjects were used as a control group. Quantitative assessment of maximal muscle strength of extensors and flexors at knee and ankle was measured by isokinetic dynamometry in all patients and control subjects. The degree of neuropathy was determined by clinical and electrophysiological studies. Maximal isokinetic muscle strength in all patients was reduced by 14% for the ankle extensors [p<0.03] and by 17% for the ankle flexors [p<0.02]. At the knee, strength of extensors and flexors was reduced by 7% [NS] and 14% [p<0.05], respectively when compared with the control group. Muscle strength was significantly reduced in clinical diabetic neuropathy when compared with the control [p<0.05]. Impaired muscle strength was closely related to the severity of neuropathy. Amplitude of the compound muscle action potential was related to the strength at the ankle [r = -0.45, p< 0.01] and knee [r = -0.42, p< 0.02]. Diabetic patients may have early muscle weakness at the ankle and knee related to the presence and severity of diabetic neuropathy. Isokinetic dynamometry is a useful tool for evaluating muscle strength in early diabetic sensory neuropathy