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Title: Changes in the somatosensory evoked potentials during recovery from stroke
Author: Al-Shahry, Fayz Saad
ISNI:       0000 0001 3408 700X
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1997
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Different aspects of cortical somatosensory processing were studied using scalp recorded somatosensory evoked potentials (SEPs) after stimulation of the median nerve of both sides of 24 healthy controls and 30 stroke patients. Twenty patients had SEPs recorded twice and 17 patients were recorded three times. Results on patients showed nine patients (45%) improved in SEP which corresponded to clinical improvement. Three patients (15%) with pure motor stroke had normal SEPs throughout, they recovered completely at the final evaluation apart from aphasia. The remainder showed various results: no recovery clinically but SEPs improved in two patients (10%), other two patients (10%) showed clinical recovery but SEPs not improved. Four patients (20%) did not show improvement either in SEPs or in function. Mapping of potential distribution showed high dissimilarity between the two sides and unstable potentials throughout even in patients who made a considerable functional recovery. Equivalent dipoles showed a considerable location changes which may indicate vicariation of cortical function. The unaffected hemisphere showed changes which are possibly part of the general phenomenon of diaschisis. Amplitude tended to be low initially and enhanced at the 2nd visit then decrease again later. Another key event of the changes on the normal hemisphere is a marked degree of Divergence in the potential waves especially in the descending limb of N20 and the subsequent waves was found in most of the patient's normal hemisphere. The results indicate considerable changes in the somatosensory system during recovery from stroke. Multidisciplinary studies using functional MRI, co-registration and PET as well will be needed to show to what extent these changes reflect alteration of the ischaemic penumbra or plastic changes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Dipoles; Diaschisis; Plasticity