Functional electrical stimulation in tetraplegic patients to restore hand function.

The purpose of this collective review is to describe a new form of functional electrical stimulation called neuroprosthesis. This unique technology has been devised to produce lateral pinch and palmar grasp in persons with C5 and C6 motor level spinal cord injuries. This neuroprosthesis includes external as well as implanted components. First, a receiver is surgically implanted into the patient's chest above a pectoralis major muscle. The receiver stimulator is then connected to 8 surgically implanted epimysial or intramuscular electrodes. Restoration of upper extremity function can greatly improve the lives of people affected with tetraplegia. When contralateral shoulder movements trigger an external transmitting coil, it sends a radio wave impulse to the stimulator inducing contraction of the muscles. Many tetraplegics are regaining hand function using implanted functional electrical stimulation. One major limitation is that the key muscles to be stimulated may have lower motor neuron damage, but this obstacle has been successfully overcome using surgical modifications of the biomechanics of the hand.