Klinische Neurophysiologie 2009; 40 - P350
DOI: 10.1055/s-0029-1216209

Event-related desynchronization of sensorimotor EEG rhythms in hemiparetic patients with acute hemispheric stroke

M Stepien 1, V Nikulin 1, J Conradi 1, FU Hohlefeld 1, V Kunzmann 1, G Waterstraat 1, G Curio 1
  • 1Berlin

Objective: To investigate the dynamics of EEG oscillations in patients with acute cortical or subcortical stroke during the performance of a sensorimotor task.

Methods: A group of 17 patients with acute (2–13 days) hemiparesis caused by subcortical (n=10) or cortical strokes (n=7) as well as age-matched control subjects (n=10) were studied. Subjects pressed a mouse button either with their left or right index finger as required by a visual cue. Scalp EEG was recorded with 65 channels. Event-related desynchronization (ERD) was analyzed in four frequency bands covering the major spontaneous sensorimotor EEG rhythms: alpha1 (8–10Hz), alpha2 (10–12Hz), beta1 (15–20Hz) and beta2 (20–25Hz). The electrode with the strongest ERD, regularly found close to the motor cortex, was analysed with ANOVA; all results reported are significant at p<0.05.

Results:

  • Compared to the control group, in patients with cortical strokes the amplitude of alpha ERD was decreased for both, lesioned and, marginally significant, also for the non-lesioned hemispheres.

  • Within the cortical stroke group, the lesioned hemisphere showed a smaller alpha ERD compared to the non-lesioned hemisphere when each was contralateral to the acting hand.

  • When cortical stroke patients moved their paretic hand, the ipsilateral (i.e., contralesional) alpha ERD was stronger than the contralateral (ipsilesional) ERD.

  • In hemispheres with a cortical stroke, the alpha1 ERD was stronger for ipsilateral (healthy) than for contralateral (paretic) hand movements.

  • Patients with subcortical strokes exhibited an alpha ERD in the lesioned hemisphere which did not differ from the control group but was significantly stronger than in patients with cortical strokes.

Conclusions: Acute stroke causes early reorganization of the neuronal network leading to changes in the dynamics of neuronal oscillations both in lesioned and non-lesioned hemisphere. Such changes were found significant only in patients with cortical stroke and only for alpha oscillations, which are known to reflect cortical excitability. Most interestingly, the relatively well preserved amplitude of alpha ERD in a hemisphere with a cortical stroke for movements of the healthy hand (cf. result 4) might be indicative for a rehabilitative potential through training of the remaining cortical network with enforced use of the paretic hand.