Clinical detection and movement recognition of neuro signals.

Neuro signal has many more advantages than myoelectricity in providing information for prosthesis control, and can be an ideal source for developing new prosthesis. In this work, by implanting intrafascicular electrode clinically in the amputee's upper extremity, collective signals from fascicules of three main nerves (radial nerve, ulnar nerve and medium nerve) were successfully detected with sufficient fidelity and without infection. Initial analysis of features under different actions was performed and movement recognition of detected samples was attempted. Singular value decomposition features (SVD) extracted from wavelet coefficients were used as inputs for neural network classifier to predict amputee's movement intentions. The whole training rate was up to 80.94% and the test rate was 56.87% without over-training. This result gives inspiring prospect that collective signals from fascicules of the three main nerves are feasible sources for controlling prosthesis. Ways for improving accuracy in developing prosthesis controlled by neuro signals are discussed in the end.

[Experimental study of biocompatibility of LIFEs in peripheral fascicles].

OBJECTIVE: To study the biocompatibility of longitudinally implanted intrafascicular electrodes (LIFEs) in a rabbit sciatic nerve model. And to discuss the possibility of peripheral fascicular signals as a new signal source to control an electronic prosthetic hand. METHODS: LIFEs were implanted chronically into sciatic peripheral fascicles of rabbits as recording and stimulating electrodes. Motor-evoked potentials (MEP) and cortical somatosensory-evoked potentials (CSEP) were recorded by using a transcranial stimulation system (TCS) over six-month period to observe the change of the signals recorded. At the end of the experiments, the fascicles at the electrodes implanted site were anatomized for histological examination under light microscope and transmission electron microscope. In human test, LIFEs were implanted into radial nerve, ulnar nerve and medial nerve of an amputee volunteer. Signals were detected when the volunteer was asked to do different movements of his missing hand, and the signals recorded by LIFEs were used to control an electronic prosthetic hand. RESULTS: The difference of onset latency (OL) of MEP and CSEP recorded at different time has remarkable statistical significance (one way ANOVA, P < 0.001). After multiple comparisons, onset latency (OL) of MEP and CSEP had no obvious change during 1 month, but significantly increased in the later time, and then became stable after 3 months after implantation. The difference of the interpeak amplitudes (IPAs) of MEP recorded at different time has remarkable statistical significance (one way ANOVA, P < 0.001). The interpeak amplitudes (IPAs) of MEP had no distinct change during 1 month, but significantly decreased over the next period, and then became stable after 3 months. Though the interpeak amplitudes (IPAs) of CSEP decreased slowly over six-month period of the study, the difference has no statistic significance (one way ANOVA, P > 0.05). At the end of experiment, histological examination indicated that a typical foreign body reaction developed and electrodes caused a mild damage to fascicles. But inflammatory cells and neuroma were not seen around the electrodes. Signals recorded by LIFEs planted in proximal radial, ulnar and median nerve of the amputated arm were different when the amputee volunteer was ordered to do some different movements with his mind. Some signals could be used to control the seven-freedom electronic prosthetic hand. CONCLUSIONS: Longitudinally implanted intrafascicular electrodes (LIFEs) have excellent biocompatibility with peripheral fascicles. They can be implanted chronically into fascicles and record signals. Furthermore, LIFEs can record physiological signals of peripheral fasciculi when hand moves, and these signals could be used to control an electronic prosthetic hand through further research.

A reconstructed digit by transplantation of a second toe for control of an electromechanical prosthetic hand.

The treatment options for the loss of an entire human hand and part of the forearm are currently limited to the transplantation of toe(s) to the amputation stump or a Krukenberg's bifurcation hand, and using a cosmetic or functional prosthesis. The functional prosthetic hand, such as the prevailing myoelectrically controlled prosthetic hand, has an action accuracy that is affected by many factors. The acceptance rate of the three planes freedom myoelectronic hand by the patients was 46-90% because of poor function caused by the weakness of signal and strong external interference. In this report, the left second toe was transplanted to the patient's forearm amputation stump. Mandates from the brain are relayed by the action of this reconstructed digit, to control a special designed multidimension freedom electronic prosthetic hand. After rehabilitation and adaptation training, the correct recognition rate of the electronic prosthetic hand controlled by this reconstructed digit is a remarkable 100%.