ISSN:
1432-0932
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The interpretation of normal and pathological findings of motor evoked potentials obtained by the use of transcranial magnetic stimulation depends on adequate examination technique, including the appropriate positioning of the recording electrodes over the muscle. On the basis of knowing the location of the motor end plate zones in muscles, magnetic stimulation of the motor cortex of 30 healthy adults was performed in order to explore the influence of the position of the surface recording electrodes on potential parameters and to establish the standard location of the recording electrodes over the biceps brachii, medial vastus, anterior tibial and abductor hallucis muscles for diagnostic use in spine disorders. The cortical latencies and peak-to-peak amplitudes of the evoked potentials were analysed by varying the location of the recording electrodes and the stimulus intensities. The latencies were significantly shorter when the different electrode lay more proximally over the muscle belly. Reproducible potentials with sharp negative onset and maximum amplitude were recorded with a separation of 5–7.5 cm between the different electrode, located over the motor end plate area, and the indifferent electrode, located over the distal myotendinous junction. This implies that the parameters of evoked potentials depend on the position and separation distance of the recording electrodes over the muscles and that it is possible to record the potentials using a lower stimulus intensity and, above all, on relaxed muscles, which may prove to be applicable for intraoperative monitoring of the spinal cord using magnetic stimulation. Therefore it is recommended to use the verified motor end plate zone location as a standard marker for the recording of motor evoked potentials for diagnosis of lesions of descending motor pathways.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00298243
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