Improving respiration in patients with tetraplegia by functional electrical stimulation: an anatomical perspective.

Patients with tetraplegia often have respiratory complications because of paralysis of the abdominal and intercostal muscles. Functional electrical stimulation (FES) has been used to improve breathing in these patients by applying surface stimulation to the abdominal muscles. We aimed to find the best nerves to stimulate directly to increase tidal volume and make cough more effective. Surface electrodes were placed on a patient's abdominal wall to find the optimum points for surface stimulation. These positions were plotted on a transparent sheet. The abdomino-intercostal nerves were dissected in five male dissecting room cadavers matched for size with the patient. The plastic sheet was then superimposed over each of the dissections to clarify the relationship between optimum surface stimulation points and the underlying nerves. Results show that the optimum surface stimulation points overlie the course of abdomino-intercostal nerves T9, 10, and 11. The success with selecting stimulation points associated with T9, 10, and 11 is probably because of the large mass of abdominal muscle supplied by these nerves. The constant position of the nerves below the ribs makes the intercostal space a possible site for direct stimulation of the abdomino-intercostal nerves.