Since antiquity, the phenomenon of magnetism has been known, and it has been tried for therapeutic purposes. Through history, people have made use of both natural sources of magnetic fields (magnetic iron ore) and artificial ones (magnets, electromagnets). It was as late as the 1901 century that we started to produce time-varying magnetic fields, making numerous observations about its impact on humans, the nervous system included. A majority of these observations were cognitive in nature. There are, however, studies aimed at assessing the therapeutic results of the influence of magnetic fields, particularly of low frequencies. In terms of magnetotherapy with the use of a low-induction magnetic field, there are serious doubts concerning its effectiveness in general, including therapy for mental disorders. The year 1985 witnessed the introduction of transcranial magnetic stimulation (TMS) into medical practice as a diagnostic tool in neurology as well as in basic neurophysiologic and neuropsychological investigations. The 1990s began the epoch of investigations into possible applications of TMS in therapy of mental disorders, particularly depression. This work presents critical remarks and limitations of TMS, such as findings that its effectiveness is not particularly high. The traditional fixed stimulation of a definite area of the patient's head may lead to irritation of structures that, in a specific patient, may not be responsible for the symptoms of depression. The effectiveness could be improved only with the use of neuronavigation and prestimulation via functional neuroimaging diagnostics of the brain, which, however, would make TMS expensive and less practical. Application of higher magnetic field induction or higher stimulation frequency carries a risk of triggering convulsive activity on EEG or even a clinical seizure, although initially the greatest advantage of TMS was seen as the safety of the technique and its non-convulsive character. The advantages of evoking seizures with a magnetic method (MST/MCT - Magnetic Seizure/ Convulsive Therapy) instead of an electric one seem dubious. Introduction Research into application of magnetic fields in medicine has a long history (Chokroverty, 1990). On the one hand, these studies were of a cognitive character and could be described as involving magnetic stimulation. On the other hand, there were also attempts to apply it in therapy, thus corresponding with the concept of magnetotherapy (Bernhardt, Hdfeli, 2007). Static magnetic fields (both of natural and artificial origin) as well as time-varying ones of different induction values were applied, although the application range of the time-varying field was much wider. In the case of the time-varying magnetic fields, the ones used are those generated with low frequencies, i.e., up to 300 Hz (Fig. 11.1). The studies from the University of Sheffield proved to be a turning point. In 1982, Polson et al. proved that it is possible to stimulate the peripheral nerve with a magnetic field (achieving depolarization of the nerve cell membrane with subsequent discharging of an action potential). Three years later, Barker et al. (1985) managed to execute effective magnetic stimulation of brain, kicking off the age of transcranial magnetic stimulation (TMS). In the earlier period, the parameters of the magnetic field used in the experiments were inappropriate and insufficient (amplitude of the field to small = induction B and/or the rise time of the magnetic field too short, i.e., the derivative dB/dt).
magnetotherapy; transcranial magnetic stimulation; magnetoconvulsive; therapy; transcranial magnetic stimulation; randomized controlled-trial; seizure; therapy mst; human motor cortex; major depression; double-blind; electroconvulsive-therapy; resistant depression; brain-stimulation; electromagnetic-fields