Immediate effects of positioning devices on the normal and spastic hand measured by electromyography

There is a continuing controversy in the literature and in clinical practice about whether positioning devices are effective in decreasing spasticity and, if so, which type is most effective. In this study, the immediate effects of a volar resting splint, a finger spreader, a firm cone, and no device were compared on eight normal and four hemiplegic subjects. Electromyography (EMG) was used to measure flexor muscle activity of the tested forearm while the subjects squeezed a grasp meter with the contralateral hand and during the following relaxation period. Results showed significantly greater EMG activity for the finger spreader compared to no device in the flexor carpi radialis of normal subjects during the grasping period. Hemiplegic subjects did not show significantly less EMG activity when using positioning devices compared to no device. In fact, the volar splint appeared to increase the EMG activity while the subjects were grasping.