The effect of diabetic neuropathy on lower leg muscle spindle function and postural control strategies

The first aim of this study was to demonstrate that diabetic neuropathy not only affected plantar cutaneous sensation but that muscle spindle function of the lower legs was also affected. The second aim was to demonstrate that adaptations in postural strategies occurred when loss of peripheral sensation was severe enough.;Four groups were selected: a non-diabetic control, a diabetic, non-neuropathic control, a diabetic, mildly neuropathic and a diabetic, severely neuropathic group. Before subjects were entered into the study, they had to meet a large number of exclusion criteria. The groups were successfully matched on marginal distributions for gender, age, height and weight. There were no significant differences between the groups on other possible confounding factors.;Three tests were used to demonstrate loss of muscle spindle function in diabetic neuropathy. Vibration was used to stimulate muscle spindles to bias feedback from those receptors. All three tests appear to confirm a loss of muscle spindle function due to diabetic neuropathy. Furthermore, the changes in muscle spindle function described for neuropathic subjects were most pronounced in the group of subjects with severe diabetic neuropathy.;Subjects with significant loss of sensation in the lower legs were expected to adapt their strategy of postural control by controlling lower limb movement at the hip joint (hip strategy). Although there were no significant changes in postural control strategies for the neuropathic subjects compared to the control subjects, there were significant differences for the group of subjects with severe diabetic neuropathy. The severe neuropathic subjects tended to move less at the ankle joint during the voluntary sway test. More importantly, there was a significant difference with respect to the relative contribution of hip movement in the voluntary sway test for the severe neuropathic group. Severe loss of muscle spindle function in combination with loss of cutaneous sensation resulted in adaptations in the postural control strategy in the group of subjects with severe diabetic neuropathy. Therefore, the reduced stability in diabetic neuropathy appears to be the result of a more general loss of peripheral sensory receptor function in the lower legs then has previously been realized.