Relationship between loss of pedal sensibility, balance, and falls in patients with peripheral neuropathy

The purpose of this study was to describe the relationship between balance and foot sensibility in a population of patients with impaired lower extremity sensation. The hypothesis was that increasing impairment of sensation correlates with impaired balance. To date, no report has investigated the relationship between loss of balance with the degree of sensibility in the foot in a population with neuropathy. Ten control subjects and 35 patients with sensory abnormalities and balance problems related to a neuropathy were evaluated. The MatScan Measurement System was used to measure their ability to stand still, maintaining their balance with their eyes open and then with their eyes shut. The degree to which the person moves while attempting to stand still is defined as "sway," which was recorded for normal and neuropathy patients. Sensibility of the foot was measured with the Pressure-Specified Sensory Device, which is noninvasive and nonpainful. The 1- and 2-point static touch thresholds are measured for the pulp of the big toe, medial heel, and the dorsum of the foot. Loss of 2- or 1-point sensation was recorded as sensibility score and compared with controls. Statistical analysis of data and their comparisons for the 2 groups was completed. There were 55% females in control and 64% in neuropathy patients, whereas average age was 50 and 62 years, respectively. Neuropathy was the result of diabetes in 64.5%, hypothyroidism in 19.3%, their combination in 13%, and of unknown etiology in the remaining 19% of patients. Controls had significantly lower mean sway than neuropathy patients (22.9 +/- 9% vs. 189.5 +/- 180%, P = 0.006). Likewise, sensibility score for normal and neuropathy patients was also significantly different (31.4 +/- 9% vs. 232.8 +/- 59%, P <0.0001). When compared with the controls, 99% upper limit of confidence, sensibility in the neuropathy group at the hallux pulp was abnormal at a level consistent with axonal loss in 52% and was completely absent in the remaining 48%. Similarly, at the heel, sensibility was normal in 6.5%, abnormal at a level consistent with axonal loss in 71%, and absent in the remaining 22.5%. The correlation coefficient between sway and sensibility score was 0.36. The results of this investigation for the first time document the intuitive relationship between increasing loss of foot sensibility and increasing loss of balance. These measurements can now be used prospectively to evaluate whether restoration of sensation to patients with neuropathy, through peripheral nerve decompression, can improve balance and reduce falls/fractures in this patient population.