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  • 1
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Focal electromagnetic slow-wave activity is generated in the vicinity of brain lesions. The present study confirmed this for the EEG delta band (1–4 Hz): Activity in the waking state was pronounced over the hemisphere of the lesion in 11 stroke patients suffering from aphasia, but not in 10 healthy controls. Changes of abnormal slow waves patterns were tracked from 1–3 months to 2 years poststroke by recording the EEG five times at 4-month intervals. Across the first year poststroke, mean left-hemispheric delta amplitude and equivalent current dipole strength decreased in parallel with the spontaneous recovery of language function, whereas the regional distribution of delta activity sources was stabile across time. No changes were observed during the second year poststroke. Results suggest that abnormal slow waves in the vicinity of brain lesions may be related to impairment in brain function, and that their measurement may assist in depicting the course of functional recovery.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Slow event-related potentials (ERP) were examined in healthy and aphasic subjects in two-stimulus designs comprising a word comprehension and a rhyming task. Aphasics, though selected to perform above chance level, made significantly more errors and responded more slowly than controls, although canonical correlations did not indicate a statistical relationship between performance measures and ERP amplitudes. A discriminant analysis of ERP amplitudes distinguished the groups for the slow wave (SW; 0.5–1.0 s post-S1 onset) in the word comprehension, for the SW and the initial contingent negative variation (iCNV; 1.0–2.0 s post-S1 onset) in the rhyming task. Similarly for both tasks, ERP topography showed left-anterior predominance of the negative SW and iCNV in controls, whereas participants with aphasia showed smaller anterior and larger left-posterior amplitudes. The centroparietal terminal CNV (tCNV; 1 s pre-S2) was smaller in participants with aphasia than in controls, but similar in topography. Results suggest left-anterior activation for those language processes that were presumably provoked in the present tasks, like lexical access, or phonological encoding. The pattern of participants with aphasia may indicate effects of language impairment and recovery, but also consequences of the brain damage.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 10 (1998), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Unilateral lesions in the posterior parietal cortex can degrade motion perception in the contralesional visual hemifield. Our aim was to investigate whether deficits caused by cortical lesions may be different for first- and second-order motion perception, and to study the time scale of any potential recovery. In nine patients with circumscribed lesions mainly in the parietal and fronto-parietal cortex, thresholds for direction discrimination were measured for stimuli presented peripherally in their ipsi- and contralesional hemifield. Subjects had to identify the direction of a vertically moving object embedded in a background of dynamic random dot noise. The object consisted of various proportions of signal and noise dots. Signal dots were either (a) coherently moving in the same direction as the object (first-order), (b) stationary (second-order: drift-balanced), or (c) coherently moving in the opposite direction (second-order: theta). Noise dots were flickering. Two patients showed significant threshold elevations for all three types of motion stimuli presented in their contralesional hemifield, while thresholds for ipsilesional targets were unaffected. Neither showed any selective deficit of first- versus second-order motion perception, but second-order motion was more impaired. Their lesions probably included the motion area V5-MT, which was spared in the other seven patients. One of the patients, who was retested several times during a 27-month postlesional period, showed complete recovery for first- and second-order motion direction discrimination, as well as for the detection of speed differences.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1459
    Keywords: Key words Stroke ; Vertebral artery dissection ; Chiropractic ; manipulation ; Carotid artery ; dissection ; Cervical spine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We analyzed the clinical course and neuroradiological findings of ten patients aged 27–46 years, with ischemic stroke secondary to vertebral artery dissection (VAD; n = 8) or internal carotid artery dissection (CAD; n = 2), all following chiropractic manipulation of the cervical spine. The following observations were made: (a) All patients had uneventful medical histories, no or only mild vascular risk factors, and no predisposing vascular lesions. (b) VAD was unilateral in five patients and bilateral in three. VAD was located close to the atlantoaxial joint in all eight patients and showed additional involvement of lower sections in six, as well as temporary occlusion of one vertebral artery in three. (c) Nine of ten patients had brain infarction documented by magnetic resonance imaging or computed tomography. (d) Onset of symptoms was immediately after the manipulation (n = 5) or within 2 days (n = 5). (e) Progression of neurological deficits occurred within the following hours to a maximum of 3 weeks. (f) Maximum neurological deficits were severe in nine of ten patients. (g) Outcome after 4 weeks–3 years included no or mild neurological deficits in five patients, marked deficits in three, persistent locked-in syndrome in one, and persistent vegetative state in one. (h) Informed consent was obtained in only one of ten patients. Thus, patients at risk for stroke after chiropractic manipulation may not be identified a priori. Neurological deficits may be severely disabling and are potentially life threatening.
    Type of Medium: Electronic Resource
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