Electrical stimulation and myoelectric control. A theoretical and applied study relevant to prosthesis sensory feedback.
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Biomedical subjects
Publications and source records attributed to L Körner.
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A rehabilitation program is described for unilateral below-elbow amputees resulting in prosthesis acceptance in 9 out of 16 patients 1-4 years after application. The features of the program were information and early training of stump muscles after amputation, application of prosthesis as early as possible, and extensive information and follow-up at regular intervals for about one year. Technical service was given special attention and each patient had access to a spare prosthesis. At a follow-up examination the results of two functional performance tests were compared with a subjective clinical rating and with a rating of acceptance. The functional tests yielded equally much information about function as the conventional clinical ratings. Technical skill in controlling the prosthesis was found not to be related to acceptance.
The necessity for a sensory feedback system that would enhance patient acceptability of motorized hand prostheses is now generally acknowledged. Afferent electrical stimulation of the nerves in the amputation stump can convey sensory feedback from prostheses with the advantage of eliciting sensations in the phantom image of the lost hand. Experiments with percutaneous nerve stimulation of the amputation stump in below-elbow amputees showed that with stable electrode conditions, amplitude modulated stimulation was better than frequency modulated stimulation in terms of accuracy, delay, and transinformation both with intermittent and uninterrupted stimulation. With unstable electrode conditions, different results were noticed, since amplitude modulated stimulation is very sensitive even to minor changes in electrode position. It is concluded that afferent electrical nerve stimulation with adequate training and stable electrodes had characteristics of accuracy, transinformation and delay which are good enough to make it a suitable method of conveying information in a prosthesis feedback system.
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Oral administration of killed Bordetella pertussis organisms to mice results in increased resistance to an intracerebral infection with virulent B. pertussis cells. The rate of survival is dependent on the dose of antigen. But besides specific systemic immunity, which is persistent over a long period, also transient non-specific resistance is increased. These effects are evidently induced without penetration of bacterial substances into the circulation.
The single i.p. injection of 2.5 times 10-8 killed B. pertussis cells protected 23 out of a group of 24 NMRI mice (95.8%) against the subsequent intracerebral infection, whilst 13 out of 24 mice (54.2%) survived the intracerebral challenge with virulent B. pertussis cells after prior oral administration of 2.5 times 10-11 killed B. pertussis cells, as demonstrated by the mouse protection test. Similar treatment with non-specific substances, such as egg white and saline, did not result in any increase of resistance. Systemic anaphylactic hypersensitivity to bovine serum albumin could also be achieved, when either both the protein antigen and the B. pertussis vaccine were given by the oral route or when the B. pertussis vaccine was injected intraperitoneally into mice which had received the soluble protein antigen by the oral route. Such effects were not produced at all in the reverse situation, when the B. pertussis vaccine was orally administered in mice, which were given the soluble protein antigen by the intraperitoneal route. After oral inoculation of 6 times 10-11 killed B. pertussis cells neither splenomegaly nor blood lymphocytosis became detectable. It is still unknown, in which manner the orally administered B. pertussis vaccine effects protection against the intracerebral infection with virulent bacteria as well as susceptibility for systemic anaphylaxis. The data presented do not favor the view that those effects are due to the phenomenon of persorption.
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