Surgery – Truss – Pad
Patent
1992-08-04
1994-05-24
Hindenburg, Max
Surgery
Truss
Pad
128732, A61B 505
Patent
active
053139569
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an apparatus for measuring the transport time of nerve signals.
BACKGROUND OF THE INVENTION
Apparatus are known and used for diagnosing certain types of nerve damage. For example, it is usual to apply electrical stimulating pulses to a heel of a patient with the patient lying flat on his stomach, and to measure the arrival time at the brain cortex, by attaching two electrodes to the skin of the crown of the patient's head, wherewith in the case of a normal person a signal of the order of 0.5-3 .mu.V will occur between the electrodes after a time lapse of 39.5.+-.3.3 ms from the time of administering the stimulating pulses. Although this signal contains a fair amount of noise, it is possible to obtain a summation signal from which the transport time can be determined with the aid of graphic methods or the like, by adding together a large number of signals.
Endeavours have also been made to obtain a more complete picture of the transport of the nerve signals, by positioning detectors along the spine, for instance so as to ascertain whether or not the function is influenced by defects in the spinal column. In this case, however, the disturbances which emanate from the muscles and the heart are much more troublesome. In order to eliminate these disturbances, incisive methods have been attempted, in which electrodes are inserted into the vertebral canal. Endeavours to measure the transport time of nerve signals have also been made with a combination of long measuring periods and patient relax periods, in which the patient is put to sleep or medicated. These investigations, however, cannot be carried out in polyclinics and are expensive, time consuming and somewhat unpleasant for the patient.
SUMMARY OF THE INVENTION
The object of the invention is to provide apparatus which will enable measurements of this kind to be carried out and which will also enable the transport time of nerve impulses from an extremity of the patient to the cortex to be mapped within a short period of time with the patient normally awake, so as to enable the investigation to be carried out in polyclinic facilities. There is a great need for investigations such as these, particularly in the case of patients suffering from back trouble and back pains, where it is known at present that if the patient is put on the sick list and does not return to normal or rehabilitates within three months, the patient will become permanently unfit for work, in up to 90% of the cases involved. A quick diagnosis carried out in a polyclinic within a short space of time is able to save the majority of these people and to return them to a normal life, by treating the patients adequately in time.
The most important problem solved by means of the present invention pertains to the signal to noise ratio in its widest meaning. Firstly, the signals are very small and are therefore subjected to normal noise. Secondly, artifacts exist, i.e. disturbances in the form of muscle impulses for instance, EMG, which can reach up to .+-.500 .mu.V, and impulses deriving from cardiac activity, ECG, which can reach up to .+-.2000 .mu.V, which shall be compared with the useful signals having an order of magnitude of only some .mu.V.
These problems are far less troublesome when the signals are detected with the aid of electrodes placed on the crown of the patient's head, since only smaller artifacts are caused by the spontaneous activity of the cerebral cortex, EG, and to some extent by eye movements.
According to the present invention, in addition to the electrodes placed on the patient's crown, electrodes can also be placed along the patient's spine so as to record simultaneously response curves at different locations, e.g. from 4 to 9 or more spinal locations.
The aforesaid problem is solved in accordance with the invention through a combination of two different features, namely by reducing the "muscle signals" as a result of making such signals audible to the patient through a loudspeaker (or through earphones or by v
REFERENCES:
patent: 3650264 (1972-03-01), Janssen
patent: 4064870 (1977-12-01), Dumitrescu et al.
patent: 4170225 (1979-10-01), Criglar et al.
patent: 4570640 (1986-02-01), Barsa
patent: 4794934 (1989-01-01), Motoyama et al.
patent: 4807643 (1989-02-01), Rosier
Gransberg Lennart
Knutsson Evert
Dorsograf AB
Hindenburg Max
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