Muscle tone in diabetic polyneuropathy evaluated by the quantitative pendulum test.

Abstract

To quantify the muscle tone of upper limbs in patients with diabetic polyneuropathy (DPN). Case-control study. Quantitative upper-limb pendulum tests were conducted, and model analysis was performed. Outpatient clinic of a medical center. The experimental group consisted of patients with type 2 diabetes suffering from symptomatic but not disabling polyneuropathy. The diagnosis of polyneuropathy was based on symptoms, signs, and nerve conduction velocity (NCV) study. The control group consisted of age- and sex-matched normative subjects. In total, 181 subjects were recruited, including 128 controls and 53 DPN patients. Not applicable. Quantitative biomechanic parameters (number of swings, relaxation index, stiffness constant and damping coefficient) were formulated and the differences between groups were investigated. The number of swings and stiffness constant showed no difference between groups. Relaxation index increased and damping coefficient decreased significantly in the DPN group. Muscle tone, defined as passive resistance in the tested range, in DPN patients was shown to be decreased. The decrease was mainly due to a decrease in the velocity-dependent component. The decrease did not correlate with the decrease in NCV and could not be detected by the conventional manual pendulum test performed at the bedside.