Computer added locomotion by implanted electrical stimulation in paraplegic patients (SUAW)

Paraplegia means a live long sentence of sensory loss, paralysis and dependence with approximately 1000 new victims in every European country every year and 11.500 new traumatic SCI cases in the US. respectively. Sixty percent are injured before age 30. More than 90% of SCI victims may survive with nearly normal experience of live. Most patients will recover somewhat from SCI over time but no patient who remained plegic for one year regains voluntary motor function after that time period. Despite remarkable efforts and recent achievements in rehabilitation no treatment can be recommended so far to enhance functional recovery and restoring locomotion in paraplegic humans. FES as a technical compensation has become therefore a challenging treatment to restore muscle function and to prevent atrophy and to improve mobility and quality of life at the same time. In paraplegics FES could be the basis to restore locomotion. One of the advantages of an implanted FES version (neuroprosthesis) is that the FES system, electrodes, and cables remain permanently implanted within the body, so that the patient can stay without cables, the programmer attached to the crutches. The SUAW project, supported under BIOMED II Programme by the European Community was aimed to finalize and to put into practice the results of previous research and development. The novel implant with an ASCI-Chip has 16 channels, 8 on each side, 20 mA for monopolar and 2 mA for bipolar stimulation, only one electrode can be stimulated at a given time. Stimulation of 6 muscle groups of both legs are known to be sufficient for locomotion: M. ileopsoas (erector of the body, hip flexor), M. gluteus maximus (hip extensor), M. gluteus medius (lateral hip stabilisator, knee abductor), Mm. hamstrings (knee flexor) stimulated by epimysial electrodes, Mm. sartorius and rectus femoris (knee extensor) stimulated by neural, bipolar electrodes. Patient's selection criteria were: stable spinal cord lesion between T7 and T11, minimum 1 year after the accident without deformity of the spine, the muscle groups for locomotion responding to external FES with the EXOSTIM programmer with the same programme used later for the neuroprosthesis. Two paraplegic male patients, T8, 38 and 31 years old respectively, were operated on by an international group of surgeons according to the protocol in 09/1999, respectively 7/2000. The postop. course was uneventful. Because the threshold of the primary implant was too low regarding scare tissue around the electrodes, this implant was changed in 01/2000 and worked perfectly. Both patients are happy with the success of the novel treatment modalities.