Peripheral neuropathy: a true risk factor for falls.

BACKGROUND

Several studies have recently linked peripheral nerve dysfunction in the elderly with postural instability and falls. Many causes of peripheral neuropathy (PN) have the potential for associated comorbidities, which could themselves be the true cause of these falls. This study tested the hypothesis that PN is not a cause of falls but just a marker for a comorbidity (e.g., central nervous system dysfunction) that is the true cause of falls in this elderly population.

METHODS

Twenty subjects with an electromyographically documented axonal peripheral neuropathy affecting the lower extremities were identified (PN group) and matched by age and sex with 20 subjects with normal lower extremity electrodiagnostic studies (C group). A focused history and physical examination designed to identify factors other than PN which might cause falls was performed, and a history of falls or postural instability over the previous year was obtained.

RESULTS

PN was found to be significantly associated with the self-report of falls (11/20, 55% vs 2/20, 10%; odds ratio 17.0, 95% CI = 2.5, > 100) and postural instability (7/9, 77% vs 0/0, 0%; odds ratio 13.0, 95% CI = 1.5, > 100) over the previous year. There was no significant difference between the two groups in total number of other risk factors known to be associated with falls, (23 PN group vs 18 C group). The PN group did take a significantly greater number of medications known to be associated with falls (10 PN group vs 1 C group, p < .01), but the usage pattern among fallers and nonfallers within the PN group suggests that medications were not the primary cause of the falls. The PN subjects who fell demonstrated significantly worse vibratory sense at the ankle and finger (p < .05), and significantly decreased unipedal stance time (3.1 sec vs 9.1 sec, p < .05) than the PN subjects who did not fall.

CONCLUSIONS

No associated factors or comorbidities explained the high rate of falls in elderly persons with PN, suggesting that PN is a true risk factor for falls in the elderly. Relatively greater impairment in vibratory sense and ability to maintain unipedal stance may identify those within the PN group who are at a higher risk for falls.