The therapy by ischemic stress induces a durable EEG synchronization in alpha frequency band

The effect of forearm or calf ischemia on computerized EEG was studied in five patients with peripheral nervous system affections and five patients with cerebral infarction. Spatial analysis of power spectra in various frequency bands was performed in two 8-sec epochs, the former before ischemia and the latter after 5-min from the cessation of circulatory arrest which lasted 15 min. Transient peripheral ischemia resulted in consistent augmentation of alpha activity involving both the anterior and the posterior hemispheric areas, bilaterally. On the other hand, the slower frequency bands (theta, delta) underwent minor, nonsignificant alterations after ischemic stress. The rise of alpha amplitude induced by ischemic stress was ascribed to the activation of nonspecific thalamic system. The activation of this system might also be involved in the favourable effects exerted by ischemic stress on motor recovery of paretic limbs.