[Features of thalamocortical relations in the phantom pain syndrome (electrophysiologic studies during stereotaxic surgery)].

Corticographic effects are analysed in 14 patients with severe phantom-pain syndrome from data obtained in electric stimulation of specific sensory and nonspecific nuclear structures of the thalamus. The findings of EEG, ECoG and VP analysis reflect reorganization of the thalamo-cortical relationships in the phantom-pain syndrome in the direction of disorganization of the regulating mechanisms. Evidence of this are an increased excitability level in the thalamic nuclei and the central cortex, disorder of the regional differences of the weakly modulated alpha-rhythm, and marked changes in the amplitude and configuration of VP of the parietal and central cortical areas. Various frequencies of stimulating current were used to differentiate the specific sensory and nonspecific thalamic nuclei. It was found that for the identification of the relay sensory nucleus, stimulation with a frequency range of 1-20 Hz is most effective, in which there is local synchronization of the cortical rhythm corresponding with the duration of the stimulation. Electric stimulation with a frequency of 50 Hz and more induces reactions characteristic of nonspecific nuclei: general desynchronization of the cortical rhythm during stimulation with the development of characteristic "spindles" in the after-action.