Dynamic changes in upper limb short latency somatosensory-evoked potentials following stroke in the dominant hemisphere

Repeated upper limb short latency somatosensory-evoked potential (USSEP) studies were performed in 19 post-stroke patients and correlated with the clinical evaluation. Examinations were performed on admission to the rehabilitation centre, and again about 10 weeks later. Data analysis focused on the temporal changes occurring in each patient, and the relationship of these changes to the patient's clinical condition. In seven of the 19 patients, no cortical potentials could be detected on admission or follow-up. These patients had the worst clinical outcome. Whenever a cortical potential was found in the first examination, it was also detected in the second. Dynamic changes between examinations were mainly seen in the central conduction time (CCT) and showed an opposite trend in each hemisphere. In the second examination, the average CCT lengthened over the damaged hemisphere (p 0.03) but shortened (insignificantly) over the nonaffected hemisphere, relative to the CCT in the first test. A positive correlation (p 0.03) was found between the increase in NI/PI amplitude - measured peak-to-peak between the major negative component (NI) of the cortical response and the subsequent positive wave (PI)-and improvement in communication ability, especially comprehension. The USSEP can serve as an auxiliary tool in monitoring the recovery process of stroke patients. Changes in USSEP components occur over both hemispheres and may serve as markers of brain plasticity.