Biomedical subjects

A Cobianchi

Publications and source records attributed to A Cobianchi.

4 recordsLinked to original sources

PubMed2006

The role of P300 in the recovery of post-stroke global aphasia.

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.

Aphasia↗

PubMed2000

Can we exploit event-related potentials for retraining language after stroke?

PURPOSE: To ascertain the utility of event-related potentials in studying language processing in patients suffering from aphasia. METHODS: Recent methods to evaluate event related potentials in response to spoken words were applied in two young patients suffering from a recent aphasia in whom expressive deficits were particularly marked. Recordings were made on three occasions for each patient at the same time of the day. The second recording session took place after six months and the final one after one year. Eighteen right-handed subjects in normal health (10 women, 8 men) were enrolled as controls. RESULTS: Three kinds of potential were obtained over time, P300, P340 and N400. P300 was useful to monitor attention and discrimination. It improved over time. Both of our patients lacked a defined P340 potential, but longitudinal recordings could show a very slow reappearance over time although with a frequently inverted polarity. Apparently, the expressive aphasia did not improve over a one year interval. In contrast to P340, N400 was relatively preserved. This potential is linked to semantic judgement. The patients with relatively preserved comprehension were able to exhibit a N400 soon after stroke. The bilateral representation indicated that the right hemisphere was involved in some kind of language processing. CONCLUSION: The results indicate that digitized spoken words appear to be an appropriate tool because they permit the study of EEG changes on a millisecond-to-millisecond basis. Apparently, ERPs enable us to study receptive processes in patients with expressive aphasia. Moreover, they appear to be particularly suitable for monitoring the recovery of neural mechanisms responsible for language.

Acoustic Stimulation↗

PubMed1997

Event-related potentials to Italian spoken words.

Forty-four right-handed volunteers were invited to listen to Italian 5-letter words of different kinds, including non-words, digitally recorded. Signals from 16 electrodes were averaged and displayed both as traces and maps. When the same word was monotonously delivered to the subject, a positive component at 340 ms was recorded following the N100-P200 complex. This potential was automatic, phonologically driven, independent of habituation, specific for verbal material and lateralized to the left side. By contrast semantic tasks evoked bilateral N400, by using the oddball paradigm with different kinds of target stimuli, including non-words. The N400 duration was related to the task complexity. The late positive component was locked-in-time with the end of the words. Therefore, N400 reached its peak before the word completion. At that time the probability of recognition was 60%, progressively reaching 100% at the time of the late positive component. Intra- and interindividual variance was low. The findings indicates two different language processings: one is confined to the perisylvian regions of the left hemisphere in right-handed subjects and appears earlier, reflecting phonological processing, whereas the other one is bilateral and takes places when semantic judgments are going on. Event-related potentials during language processing appear to be a very useful tool, especially when EEG maps are displayed, giving us the information on both temporal and spatial events.

Adult↗

PubMed1994

EEG recordings in the course of recovery from stroke.

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 gain in the first 3 months. However, no correlation between quantified EEG and clinical testing was found. By looking at individual profiles, a frequent and unpredictable instability was seen in the "unaffected" hemisphere. In those who made the best recovery, the EEG spectrum became more symmetrical over the left and right hemispheres, an aspect that continued beyond the point of a good motor and ADL recovery. CONCLUSIONS: Quantified EEG undergoes early and subtle changes in the follow-up of stroke that can outlast clinical recovery. Routine evaluation for prognosis is not recommended because motor and ADL scales provide earlier and more accurate indicators. In contrast, quantified EEG can be useful for individual patients undergoing rehabilitation to monitor mechanisms of local repair and also to detect changes in the so-called normal hemisphere. It may reveal focal abnormalities that are undetected by coarse clinical evaluation and that call for appropriate neuropsychological testing.

Activities of Daily Living↗