Dynamics of Electroencephalogram Spectral Characteristics during Use of Transcranial Magnetic Stimulation in Patients with Refractory Depression

Objective. To study the dynamics of EEG spectral characteristics during transcranial magnetic stimulation (TMS) in therapeutically refractory depression. Materials and methods. The study included 32 patients with depression in the framework of recurrent depressive and bipolar affective disorders. TMS was performed and EEG recordings made on the background of ineffective thymoanaleptic treatment at reduced doses. TMS was applied at the projection of the left prefrontal cortex. Treatment courses consisted of 15 sessions with 100% threshold intensity. In each session, patients received 20 cycles of stimuli at a frequency of 15 Hz, duration 6 sec, separated by intervals of 60 sec. EEG recordings were made using a Neiro-KM instrument (Russian-made) with a bandpass of 0.5–45 Hz and a time constant of 0.3 sec before and after courses of TMS. EEG spectral analysis was by fast Fourier transformation with averaging of at least 30 2-sec epochs followed by mapping using the Brainsys system (made in Russia). Results and conclusions. Post-TMS EEG changes were generalized in nature and involved rearrangement of all frequency ranges in brain electrical activity. However, the greatest changes were seen at the α rhythm frequencies: the index increased in all cortical zones, though the greatest increase in α activity was seen in the occipital areas of the cortex, forming an α rhythm focus in these zones.