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

Objective: 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. Design: Prospective, nonrandomized, open-label trial. Setting: University tertiary care center. Participants: Fight adults with upper limb spasticity. Intervention: Fiberglass cast application spanning the wrist to the upper arm. Main Outcome Measure: 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: CH-reflex amplitude (vibrated)/H-reflex amplitude (control)] X 100%. Results: 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. Conclusion: Findings lend support to the idea that during application of an inhibitory cast motor neuron excitability is decreased in the spastic upper Limb. (C) 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.