Effects of acute intermittent hypoxia on hand use after spinal cord trauma: A preliminary study

Abstract

Objective: To test the hypothesis that daily acute intermittent hypoxia (AIH) combined with hand opening practice improves hand dexterity, function, and maximum hand opening in persons with chronic, motor-incomplete, cervical spinal cord injury.

Methods: Six participants completed the double-blind, crossover study. Participants received daily (5 consecutive days) AIH (15 episodes per day: 1.5 minutes of fraction of inspired oxygen [FIo2] = 0.09, 1-minute normoxic intervals) followed by 20 repetitions of hand opening practice and normoxia (sham, FIo2 = 0.21) + hand opening practice. Hand dexterity and function were quantified with Box and Block and Jebsen-Taylor hand function tests. We also recorded maximum hand opening using motion analyses and coactivity of extensor digitorum and flexor digitorum superficialis muscles using surface EMG.

Results: Daily AIH + hand opening practice improved hand dexterity, function, and maximum hand opening in all participants. AIH + hand opening practice improved Box and Block Test scores vs baseline in 5 participants (p = 0.057) and vs sham + hand opening practice in all 6 participants (p = 0.016). All participants reduced Jebsen-Taylor Hand Function Test (JTHF) time after daily AIH + hand opening practice (-7.2 ± 1.4 seconds) vs baseline; 4 of 6 reduced JTHF time vs sham + hand opening practice (p = 0.078). AIH + hand opening practice improved maximum hand aperture in 5 of 6 participants (8.1 ± 2.7 mm) vs baseline (p = 0.018) and sham + hand opening practice (p = 0.030). In 5 participants, daily AIH-induced changes in hand opening were accompanied by improved EMG coactivity (p = 0.029).

Conclusions: This report suggests the need for further study of AIH as a plasticity "primer" for task-specific training in spinal cord injury rehabilitation. Important clinical questions remain concerning optimal AIH dosage, patient screening, safety, and effect persistence.

Clinicaltrialsgov identifier: NCT01272336.

© 2017 American Academy of Neurology.

Figures

Figure. Effects of daily AIH on hand function after cSCI

(A, B, D, and F) Box-whisker plots represent 95% confidence intervals relative to mean (horizontal black line). Vertical error bars indicate SD. Asterisks correspond to statistical significance after post hoc Holm-Bonferroni correction. Color dots represent results from individual participants. (A and B) Effects of daily (5 consecutive days) AIH + HOP (white) vs sham + HOP (gray) on clinical measures of hand dexterity (BBT) and speed (JTHF) tests relative to BL. (C) During hand opening, maximum hand aperture (Amax) quantified by recording distance between LEDs of finger and thumb (black circles) with 3-dimensional motion capture system and corresponding activity of ED and FDS muscles recorded with EMG via standard dual surface electrodes (white circles). (E) Mean (black trace) ± SD (gray traces) of representative participant (S01) during hand opening (top) with corresponding EMG recordings (bottom). (F) Change in ED and FDS coactivity at Amax after AIH + HOP. AIH = acute intermittent hypoxia; BBT = Box and Block Test; BL = baseline; cSCI = cervical spinal cord injury; ED = extensor digitorum; FDS = flexor digitorum superficialis; HOP = hand opening practice; JTHF = Jebsen-Taylor Hand Function Test; LED = light-emitting diodes; MVC = maximum voluntary contraction.