Inhibitory Effects of Circumferential Pressure on Flexor Carpi Radialis H-Reflex in Adults with Neurological Deficits

The effects of circumferential air-splint pressure on the flexor carpi radialis H-reflex in 22 participants with cerebrovascular accident and 5 with spinal cord injury were examined. H-reflexes were assessed by measuring the peak-to-peak amplitude change before, during, and after circumferential pressure was applied to the forearm. 12 H-reflexes (H/M_max ratio: M = 25%; SD = 14) were recorded before pressure application to obtain a baseline value for comparison of data. A pneumatic 34-cm air splint inflated to 51–60 mmHg provided pressure around the forearm. H-reflex recordings were taken at 1, 3, and 5 min. during and 1 min. after application of pressure. A one-way analysis of variance with repeated measures was applied to compare pressure and postpressure measurements against the baseline value. Tukey multiple-comparison tests were used when significant F ratios were noted. Analysis indicated H-reflex amplitudes decreased significantly at 1, 3, and 5 min. during pressure and quickly returned to baseline when pressure was released. The study suggests air splints decreased the H-reflex in participants with neurological deficits and may be used in the upper extremity temporarily to reduce muscle activity associated with neurological dysfunction.