Background and Purpose This study was designed to assess the value of quantified electroencephalography (EEG) in the follow-up of stroke and its possible correlation with other measures of recovery.Methods EEGs were recorded over a period of 6 months in 34 patients with ischemic stroke in the middle cerebral artery territory who underwent spectral analysis. Two groups were formed: (1) 28 patients with a Barthel Index score of less than 60 at admission and (2) 6 patients with a Barthel score of over 60 and therefore with a much better prognosis. Ten recordings were made in each patient in the first group and at least three in the second group. Motor functions and activities of daily living (ADL) were assessed three times, on admission to the study and after 3 and 6 months.Results Quantified EEG was significantly abnormal in the affected hemisphere of the first group. Side and site were not relevant. Longitudinal recordings showed a significant improvement of the power spectrum in the first 3 months. Alpha mean weighted frequency of the injured hemisphere was always slower than that of the contralateral side. All patients improved in motor performance and ADL, with the greatest

Seventeen right-handed patients suffering from global aphasia caused by a recent stroke in the left-hemisphere were studied. Passive P300 auditory event related potential paradigm was applied every months for 6 months. Aachen subtests were used for evaluating comprehension. Only a minority of the patients displayed the P300 at the baseline. Those patients had the best outcome at the Aachen comprehension subtest. Latency and amplitude changed over time in an unpredictable way. The number of patients presenting with the P300 also fluctuated, since some patients could regain the potential, whereas some other patients could lose that from month to month. Passive P300 is a monitor of recovery following global aphasia. A single passive P300 recording is useful for prognostic purposes. Repairing mechanisms in the first 6 months have a non-linear trend.

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The study is aimed at identifying hemispheric language dominance in both the right-handed and left-handed participants. Eighteen right-handed and 18 left-handed young volunteers were invited to listen for 80 times to a 720 ms duration Italian word. Signals from 16 electrodes were averaged and displayed both as traces and maps. When the word was delivered to the participant, a positive component at 340 ms was recorded, following the N100-P200 complex. The potential was significantly lateralized to the left hemisphere in 50% of the right-handers. The left-handed group was less homogeneous. Six out of 18 participants (33%) had a right lateralization, six participants (33%) had the positive potential shifted to the left hemisphere. Finally, the remaining participants had a bilateral representation. The maps show that there are no two participants alike, independently of either sex or handedness. A 300 Hz tone of the same duration failed to evoke the P340. Results indicate the utility of event-related potentials in studying the language processing. The possibility to identify cortical localization permits a better prognosis of acquired aphasia. The method is relatively cheap and noninvasive. Application is suggested in those participants who are at risk of stroke or in patients to be submitted to a neurosurgical intervention nearby possible language areas.

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