The use of dynamic posturography to detect neurosensorial disorder in IDDM without clinical neuropathy

The main aim was to evaluate the relative importance of sensory interactions for postural stability in 45 patients with insulin-dependent diabetes mellitus (IDDM) with and without peripheral neuropathy. All subjects had normal electronystagmography. Dynamic posturography provides functional, selective testing of three sensory modalities in maintenance of balance, i.e., vestibular, visual, and somatosensory. The Sensory Organization Test (SOT) includes six test conditions during which the subject tries to maintain an upright stance with as little sway as possible. The subject stands on a movable platform facing a square visual surrounding, which can be rotated independently. The test is performed first with the eyes open, then with the eyes closed. The second component of posturography testing consists of the Motor Control Test (MCT) concerning motor responses routinely used in balance maintenance. Compared to control subjects, IDDM patients with peripheral neuropathy but not patients without neuropathy showed lower scores for test conditions SOT 1 (analysis of variance, ANOVA F = 8.3; Scheffe test: p = 0.0007), SOT 2 (F = 6.6; p = 0.004), SOT 3 (F = 3.4; p = 0.04), and SOT 6 (F = 3.4; p = 0.04). The muscle response latencies in MCT were prolonged for small forward perturbations (F = 4.6; p = 0.02) in neuropathic patients (148.3+/-14.2 ms) with respect to control subjects, but not in non-neuropathic patients with respect to control subjects (135.2+/-13.3 ms). Sural (r = 0.2; p = 0.002) and peroneal (r = 0.12; p = 0.02) nerve conduction velocities showed significant correlations with muscle response latencies of MCT for small forward perturbations. Our results suggest a subclinical dysequilibrium in IDDM patients with peripheral neuropathy. The results of dynamic posturography may reflect the impairment of the somatosensory system, rather than a specific lesion of vestibular and/or visual modalities.