H-index Measurement Is Important In Persons With Peripheral Neuropathy

Peripheral neuropathy (PN) is a neurodegenerative disease that damages the peripheral nervous system. The presentation of PN is usually symmetrical sensory nerve damage to distal extremities but progresses proximally. Strength, sensitivity, and endurance measures are useful tools in understanding effectiveness of interventions. However, nerve function measures should be considered for this population. H-index is measure used in many neurological studies and can provide new insight to peripheral neuropathy.

PURPOSE : To better understand nerve function, as measured by H-index, and its relation to functional motor output in people with PN.

METHODS : H-index, standing balance, Timed up-and-go (TUG), 6-min walk test, peak knee flexion/extension torque were measured from 12 participants with PN. H-index was determined by eliciting electrical stimulation at the posterior tibial nerve and recording latency of M- and H-waves by EMG on the lateral gastrocnemius. H-index was calculated as (Height (cm) / (latency (ms))^2* 2. Participants were seated and asked to walk as quickly and safely as possible around a cone placed 3 m away then return to their seat, TUG was the average time of three trials. For the 6 min walk test, participants were encouraged to walk as far as possible in 6 min. Peak knee flexion/extension was performed on a Biodex. Pearson correlation was performed between H-index and other measures of interest.

RESULTS : 12 participants (8 women, 4 men) age (72.5 ± 9.2), height (163.0 ± 11.9), body mass (171.8 ± 46.2) diagnosed with PN were tested. Causes of PN included diabetes (n=2), trauma (n=1), and idiopathic (n=9). Duration of PN was 10.0 ± 1.7 (Mean ± SD) years. Mean and standard error of mean for our measures of interest were as follows: H-index (61.21 ± 4.52); TUG (9.22±0.41); 6 min walk (429.58 ± 26.37); 95% area (0.82 ± 0.13); peak flexion (37.15 ± 6.43); and peak extension (64.73 ± 6.52). H-index was correlated with 95% area (R=.26), TUG (R=.51), 6 min walk (R=.27), but not peak flexion (R=.04) or peak extension (R=.002).

CONCLUSIONS : H-index as a measure of nerve function in people with PN is related to functional outcomes but not strength measures. H-index could be useful in understanding functional impairments in gait and standing balance among people with PN.