Unipedal Stance Time Research Articles

Moderate peripheral neuropathy impairs weight transfer and unipedal balance in the elderly

Objective: To quantitatively assess the performance of elderly with and without moderate, electrodiagnostically confirmed peripheral neuropathy (PN) on tasks of weight shifting and maintenance of unipedal balance. Patients and Methods: A case control study with PN subjects selected from a computerized data bank of all patients who had undergone electrodiagnostic studies at a university-based referral center. Control subjects of similar age and same gender were selected from the same source. Clinical examination included neurological and gross motor components. Quantitative evaluation included testing while the subjects stood with a force plate under each foot. Center of reaction (CR) excursions and ground reaction forces were quantified in: (1) six trials as subjects transferred their weight from bipedal stance to unipedal stance, on command, and attempted to maintain it for at least 3 seconds; and (2) in two additional trials in which subjects held unipedal stance for as long as possible. Results: No subjects in either group had difficulty with level gait, a 180-degree turn, or required examiner assistance during an eyes-closed Romberg test. Biomechanical testing revealed that although the PN group used the same time to transfer their weight onto one foot as the C group, they achieved a significantly (1) lower rate of success in reliably maintaining 3 seconds of unipedal stance (.12 vs .58, p = .021), and (2) shorter mean maximum unipedal stance time (3.8 vs 32.3sec, p < .001). Furthermore, the PN group experienced greater difficulty in maintaining unipedal stance, as evidenced by significantly greater fluctuations in their ground reaction forces. Conclusions: The demonstrated impairment in reliability of unipedal stance in elderly with PN likely contributes to their known high rate of falls. Furthermore, unipedal stance testing serves to sharpen the physical examination by verifying the functional significance of impaired distal sensation—a common finding in the elderly.

Peripheral neuropathy: a true risk factor for falls.

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. 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. 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. 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.