Inhibitory casting decreases a vibratory inhibition index of the H-reflex in the spastic upper limb.

Abstract

To test the hypothesis that application of an inhibitory cast to the spastic upper limb will decrease a vibratory inhibition index (VII) of the H-reflex in the spastic upper limb. Prospective, nonrandomized, open-label trial. University tertiary care center. Eight adults with upper limb spasticity. Fiberglass cast application spanning the wrist to the upper arm. The amplitude of the H-reflex with and without continuous 60Hz vibration to the tendon of the flexor carpi radialis was measured, and the VII was calculated using the formula: [H-reflex amplitude (vibrated)/H-reflex amplitude (control)] x 100%. Mean VII decreased from baseline (70.7) on day 1 (67.6, p = .699), day 2 (55.9, p =.066), and day 3 (43.5, p = .033) of casting, and increased on day 4 (89.9, p = .146) after removal of the cast. Findings lend support to the idea that during application of an inhibitory cast motor neuron excitability is decreased in the spastic upper limb.