Rowan, Alison Fiona; (2004) Speech and language outcome after unilateral basal ganglia infarctions acquired during childhood: A combined neuropsychological and neuroimaging study. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The aims of these studies were to determine the long-term consequences of unilateral basal ganglia damage on speech and language after childhood stroke, and to relate functional deficits to structural and functional changes in the brain. Patients with either left or right hemisphere infarction of the basal ganglia and no obvious cortical involvement on conventional neuroradiological examination took part in these studies. Neuropsychological assessments were used to evaluate the incidence and types of speech and language deficits. These investigations revealed impairments in articulation, with particular difficulties in the execution of sequential articulatory procedures, and some evidence for deficits in the acquisition of novel articulatory plans. Most of these difficulties occurred regardless of side of injury. Evidence for some impairment on receptive and expressive language functions, reading and spelling was also apparent, again regardless of side of injury. The absence of predicted differences related to side of injury on language performance was attributed, at least in part, to the considerably greater variance in the performance of the patients with left hemisphere injuries. Resulting neuropsychologcal profiles were related to the precise site and extent of lesions, using a range of magnetic resonance imaging (MRI) techniques, including conventional clinical imaging, voxel based morphometric (VBM) analyses of 3D data sets and diffusion tensor images, and perfusion imaging. VBM analyses of MR scans highlighted regions of grey and white matter density beyond the core site of the infarction, including Broca's and Wernicke's areas, that correlated with language performance in patients with left hemisphere injuries and not in those with right hemisphere injuries or control subjects. Furthermore, the three patients with poorest language function had haemodynamic abnormalities involving left hemisphere cortical language areas that were not observed in the other patients. All patients were seen in long-term follow up, and so recovery and/or reorganisation might have taken place, thus complicating the structure-function relationships. Performance on previous neuropsychological assessments was therefore compared to performance on neuropsychological assessments carried out for these studies. Dichotic listening, functional magnetic resonance imaging (fMRI) and event related potential (ERP) techniques were also used to examine the status of language organisation. Results suggested that the variation in performance seen in the language studies could not be attributed to changes in performance over the course of recovery or reorganisation of function. It was therefore concluded that language deficits after basal ganglia infarctions acquired during childhood might have been related to additional changes in grey and white matter, as well as haemodynamic abnormalities, affecting cortical language regions.

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