Biomedical engineering specifications for epidural spinal cord stimulation to augment motor performance.

Stimulating electrodes were placed in the posterior portion of the epidural space in the upper thoracic spinal region in 28 patients with upper motor neuron disorders. Parameters of stimulation commonly used for chronic stimulation were a 200 microsecond pulse width, 22 Hz repetition rate, and 5 ma amplitude. Using a 16 gauge Touhy needle, platinum electrodes were passed between the posterior vertebral processes into and up the spinal epidural space to upper thoracic locations. Passive implanted receivers, powered and controlled by external RF transmitter/pulse-generator devices, were employed to provide the stimulus current to the electrodes. A description of available systems, problems and diagnosis of problems, and future directions is presented. This is based on studies in patients with stimulation systems implanted for more than six months.