IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society
-
IEEE Trans Neural Syst Rehabil Eng · Sep 2004
Acute peripheral nerve recording characteristics of polymer-based longitudinal intrafascicular electrodes.
We examined the recording characteristics of two different types of polymer-based longitudinal intrafascicular electrodes (LIFEs) in peripheral nerve: single-stranded (s-polyLIFEs) and multistranded (m-polyLIFEs). Recordings were also made from Pt-Ir wire-based electrodes (PtIrLIFEs) as a control. The electrodes were implanted in either tibial or medial gastrocnemius branches of the rabbit sciatic nerve, and in the sciatic nerve of rats. Recorded neural activity induced by manually elicited afferent neural activity showed that both polyLIFE versions performed comparably to PtIrLIFEs.
-
IEEE Trans Neural Syst Rehabil Eng · Jun 2004
Clinical TrialThe effects of trunk stimulation on bimanual seated workspace.
This study explores the effects of functional electrical stimulation (FES) of the lumbar trunk extensors on the seated posture and bimanual workspace of subjects with spinal cord injury (SCI). Four subjects with motor complete SCI with implanted intramuscular stimulating electrodes to activate the lumbar erector spinae were studied. The positions of markers on the pelvis, trunk, and hands were monitored by a motion capture system during bimanual reaching maneuvers. ⋯ With a backrest, the change in posture with FES allowed individuals with SCI to reach further in the sagittal plane and carry heavier masses by shifting the trunk, allowing increased elbow extension, or a combination of the two mechanisms. Reaching with FES was consistently preferred over reaching without FES. This preliminary study is encouraging for future research on trunk stability and reaching ability with FES.
-
IEEE Trans Neural Syst Rehabil Eng · Jun 2004
Clinical TrialPerformance of epimysial stimulating electrodes in the lower extremities of individuals with spinal cord injury.
This study describes the performance of surgically-implanted epimysial stimulating electrodes in the muscles of the lower extremities for use in functional neuromuscular stimulation (FNS) systems for standing after spinal cord injury. A total of 86 epimysial electrodes were implanted in 13 volunteers with low tetraplegia or paraplegia receiving the Case Western Reserve University/Veteran Affairs (CWRU/VA)-implanted standing/transfer neuroprosthesis. The neuroprosthesis consisted of bilateral epimysial electrodes in the knee and hip extensors (vastus lateralis, gluteus maximus, and adductor magnus or semimembranosus) and intramuscular electrodes at the T12/L1 or L1/L2 spinal roots for trunk extension. ⋯ Four mechanical failures were observed, all in the posterior muscles of the thigh, leaving 95% of all electrodes operational at all followup intervals. Probability of 24-month survival is estimated to be 93% plateauing to a steady state of 90% at four years. These results indicate that epimysial designs are appropriate for long-term clinical use in the large muscles of the lower extremities with implanted motor system neuroprostheses.
-
IEEE Trans Neural Syst Rehabil Eng · Jun 2004
Comparative StudySelective and independent activation of four motor fascicles using a four contact nerve-cuff electrode.
Any one of the four motor nerves in the cat sciatic nerve could be activated selectively and independently, from threshold to saturation, using a self-sizing spiral cuff electrode containing four radially placed monopolar contacts. These studies were carried out in nine adult cats with acute implants. Of the 36 possible fascicles, 23 fascicles could be activated selectively with current stimuli applied to a single contact and ten of the remaining fascicles could be activated selectively with current stimuli applied to two contacts, "field steering." In three experiments, time constraints precluded attempting selective activation through "field steering" techniques. ⋯ In seven experiments, carried out in two animals, selective activation was verified by collision block techniques. The results of these experiments support the hypothesis that selective and independent activation of any of four motor fascicles in the cat sciatic nerve is possible using a four contact self-sizing spiral cuff electrode. Furthermore, in a more general case, these results support the concept of a "tunable" electrode that is capable of "steering" the excitation from an undesirable location to a preferred location.
-
IEEE Trans Neural Syst Rehabil Eng · Jun 2004
Clinical TrialThe effect of joint angle on the timing of muscle contractions elicited by neuromuscular electrical stimulation.
Neuromuscular electrical stimulation was used to evoke isometric knee extension contractions in seven individuals with spinal cord injury (SCI) and the time for knee extension torque to rise and fall was measured across a range of knee angles. The stimulated muscles took more than twice as long to develop 50% of maximum torque at an angle of 15 degrees, compared to an angle of 90 degrees. ⋯ The difference in torque rise time with joint angle has implications for modeling functional activities that differ greatly in their joint angles. This study provides regression equations whereby activation times for the quadriceps muscles of individuals with SCI can be predicted for specific angles of knee flexion.