Die Rolle der Magnetstimulation in der Diagnostik des peripheren Nervensystems

Summary

Magnetic stimulation has recently been introduced as a new method for stimulation of neuronal tissues. Up to now most investigators were emphasized the advantages of this method for the investigation of the central nervous system. With this paper we want to show that magnetic stimulation may also be useful for the examination of the peripheral nervous system.

Both, magnetic and electrical stimulation, seem to employ the same stimulation mechanisms in the nervous tissue. The results obtained with both methods should therefore be comparable. By measuring EMG-latencies after electrical and magnetic stimulation (Fig. 1) the exact site of magnetic stimulation can be determined. Magnetic stimulation offers major advantages over electrical stimulation: 1) Magnetic stimulation is a painless method even when high stimulus intensities are used. 2) Magnetic stimulation can reach deep neuronal structures that are not easily accessible using electrical stimulation (Fig. 2, Fig. 3). 3) Using a wide range of stimulus intensities (Fig. 4, Fig. 5) magnetic stimulation provides a much better descrimination of different components of the compound muscle action potential than electrical stimulation. Magnetic stimulation seems to be a promising new method for the electrodiagnostic examination of pain- sensitive patients, especially when deep-lying peripheral nerves have to be investigated.

Zusammenfassung

In der vorliegenden Arbeit soll untersucht werden, welche Rolle der Magnetstimulation in der Diagnostik des peripheren Nervensystems zukommt. Es wird gezeigt, daß elektrische und magnetische Stimulationen peripherer Nerven prinzipiell zu gleichen Ergebnissen führen, da offensichtlich ähnliche neuronale Erregungsmechanismen ablaufen. Die Vorteile der magnetischen Stimulation im Vergleich zur elektrischen Reizung liegen jedoch in der größeren Eindringtiefe, der wesentlich höheren Diskrimination einzelner Komponenten der Summenaktionspotentiale im schwellennahen Reizstärkenbereich und besonders im nahezu schmerzfreien Reizvorgang. Die magnetische Stimulation bietet sich daher besonders für die Untersuchung bisher unzugänglicher tiefliegender Nerven bei schmerzempfindlichen Patienten an.

Key words:

Time-varying magnetic fields - Magnetic stimulation - Nerve stimulation - Recruitment of compound action potentials