title: H-index is important for postural control for people with impaired foot sole sensation.
abstract: BACKGROUND
  People with Peripheral Neuropathy (PN), especially those with impaired sensory inputs through the small-afferent fiber (type II afferent fibers) reflex loop (SAF), might depend more on the large-afferent fiber (type I afferent fibers) reflex loop (LAF) for postural control.
  
  
  OBJECTIVE
  To examine whether the function of the LAF reflex loop, reflected by the H-reflex and ankle joint proprioception, influences postural control when the SAF reflex loop is impaired, as indicated by reduced foot sole cutaneous sensation.
  
  
  METHODS
  Thirteen participants (8 women, 5 men) diagnosed with PN and 12 age-matched controls (7 women, 5 men) completed the testing protocol. Measures of interest included the H-index, active (AAP) and passive (PAP) ankle proprioception, plantar pressure sensitivity (PPS), average sway velocity (VAVG) and area (A95) during 30 seconds eyes-closed standing, 6-minute walk distance (6MWD) and timed up-and-go duration (TUG).
  
  
  RESULTS
  Statistically significant group-dependent regression was observed between VAVG and H-index. Compared to the control group, the PN group demonstrated reduced PPS (2.0 ± 1.9 vs. 4.2 ± 1.2, P < .05) and H-index (63.6 ± 10.9 vs. 76.4 ± 16.0, P < .05), greater VAVG (3.5 ± 2.1 vs. 1.6 ± 0.6 cm/s, P < .05) and A95 (10.0 ± 10.1 vs. 2.5 ± 1.5 cm2, P < .05), shorter 6MWD (442.2 ± 93.0 vs. 525.3 ± 68.2 m, P < .05), and longer TUG (9.4 ± 1.6 vs. 6.5 ± 1.3 s, P < .05). Within the PN group, but not the control group, the H-index was correlated with VAVG (r = -.56, P < .05). Moreover, within the PN group only, PAP scores were correlated with 6MWD (r = -.68, P < .05) and TUG (r = -.59, P < .05) performance. No other statistically significant group difference, correlation or group-dependent regression was observed.
  
  
  CONCLUSIONS
  VAVG, 6MWD, and TUG correlated with LAF reflex loop function observed among those with impaired functioning of the SAF reflex loop. This observation suggests that the LAF reflex loop may be critical to the control of balance in those individuals suffering from small-fiber PN.
authors: Louisiana State University, Baton Rouge, LA, United States of America; Georgia Southern University, Statesboro, GA, United States of America.
authors: Shuqi
authors: S
authors: Zhang
authors: Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Harvard Medical School, Boston, MA, United States of America; Institute for Aging Research, Hebrew SeniorLife, Roslindale, MA, United States of America.
authors: Brad
authors: B
authors: Manor
authors: Georgia Southern University, Statesboro, GA, United States of America; Key Laboratory of Exercise and Health Sciences, Ministry of Education, Shanghai University of Sport, Shanghai, China.
authors: Li
authors: L
authors: Li
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle / Q000503:physiopathology; D005260:Female; D005528:Foot / Q000503:physiopathology; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D006987:Hypesthesia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*