P 242. Changes of mental activity and acoustic evoked potentials (AEP) under the influence of repetitive transcranial magnetic stimulation of premotor cortex on normal subjects and patients after severe head injury

Abstract

Introduction Repetitive transcranial magnetic stimulation (rTMS) is among perspective medical influences of activating character at patients with long posttraumatic unconscious state. Our previous researches of such patients revealed distinct positive changes of their state and increase of consciousness level after rTMS. Objective This study is aimed at analysing the changes of mental and bioelectric activity on low-frequency repetitive rTMS on normal subjects and on patients with post-traumatic unconsciousness after severe head injury for specification of separate functional characteristics “sensitivity” to this influence. Method Functional effects sub-threshold (60–80% of a motor threshold) low frequency rTMS 1–2 Hz of premotor cortex in three series of researches were estimated. (1) At 5 healthy volunteers analyzed influence of placebo and single rTMS on memory and attention indicators in psychologic tests, and also on the N100, N200, P300 AEP components to and in 1 h after influence. (2) At 7 patients with post-traumatic unconsciousness (the vegetative condition or an akinetic mutizm) estimated dynamics of state and separate clinical symptoms, and also AEP. (3) At 4 if 7 of these patients in the same way estimated effects of 7-day rTMS course. Dynamics of patients state estimated on stages of consciousness [Dobrokhotova et al. (1996)] and also on our ball scale of the functional activity, based on Glasgow, NIHSS, and UPDRS scales-with emphasis on the attention and movement sphere. AEP were recorded on 18 cannels by two-stimulus oddball paradigm, in the in tasks of listening sounds and accounts of the target. The latency and amplitude of N100, N200, P300 AEP were analyzed, and also spatial syncronization of each component according integrated coefficient of wavlet-synchronism. Results At healthy people after single rTMS strengthening of any attention according to neuropsychological tests was observed. It was accompanied by increase of power of P300 AEP in frontal and central departments of the left hemisphere along with strengthening intra-and interhemispheric functional weyvlet-communications of the left frontal area. At injury distinct positive changes of state are revealed at 5 of 7 patients both after single, and course rTMS. They concerned increase of consciousness level-along with increase of any movements, decrease in raised initially muscular tone. Increase of any attention was expressed more distinctly after course rTMS. Clinical dynamics was accompanied by normalization of amplitude and latency of all AEP components, as well as indicators of their spatial synchronism, especially for P300, connected in literature with any attention. Conclusion The most distinct changes under the influence of the rTMS this mode concern function of any attention: its activization in norm, and also emergence or improvements in pathology. Dynamics of clinical symptoms at patients with brain injury reflects, in our opinion, positive shifts both dofaminergic, and holinergic brain systems. Supported by RHGR 1 11-06-01-060.