Browsing by Author "Crinion, Jennifer T."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Better long-term speech outcomes in stroke survivors who received early clinical speech and language therapy: What’s driving recovery?(2021) Roberts, Sophie; Bruce, Rachel M.; Lim, Louise; Woodgate, Hayley; Ledingham, Kate; Anderson, Storm; Lorca-Puls, Diego L.; Gajardo-Vidal, Andrea; Leff, Alexander P.; Hope, Thomas M.H.; Green, David W.; Crinion, Jennifer T.; Price, Cathy J.Establishing whether speech and language therapy after stroke has beneficial effects on speaking ability is challenging because of the need to control for multiple non-therapy factors known to influence recovery. We investigated how speaking ability at three time points post-stroke differed in patients who received varying amounts of clinical therapy in the first month post-stroke. In contrast to prior studies, we factored out variance from: initial severity of speaking impairment, amount of later therapy, and left and right hemisphere lesion size and site. We found that speaking ability at one month post-stroke was significantly better in patients who received early therapy (n = 79), versus those who did not (n = 64), and the number of hours of early therapy was positively related to recovery at one year post-stroke. We offer two non-mutually exclusive interpretations of these data: (1) patients may benefit from the early provision of self-management strategies; (2) therapy is more likely to be provided to patients who have a better chance of recovery (e.g., poor physical and/or mental health may impact suitability for therapy and chance of recovery). Both interpretations have implications for future studies aiming to predict individual patients’ speech outcomes after stroke, and their response to therapy.Item How right hemisphere damage after stroke can impair speech comprehension(2018) Gajardo-Vidal, Andrea; Lorca-Puls, Diego; Hope, Thomas M. H.; Parker Jones, Oiwi; Seghier, Mohamed L.; Prejawa, Susan; Crinion, Jennifer T.; Leff, Alex P.; Green, David W.; Price, Cathy J.Acquired language disorders after stroke are strongly associated with left hemisphere damage. When language difficulties are observed in the context of right hemisphere strokes, patients are usually considered to have atypical functional anatomy. By systematically integrating behavioural and lesion data from brain-damaged patients with fMRI data from neurologically-normal participants, we investigated when and why right hemisphere strokes cause language disorders. Experiment 1 studied right-handed patients with unilateral strokes that damaged the right (n = 109) or left (n = 369) hemispheres. The most frequently impaired language task was: auditory sentence-to-picture matching after right hemisphere strokes; and spoken picture description after left hemisphere strokes. For those with auditory sentence-to-picture matching impairments after right hemisphere strokes, the majority (n = 9) had normal performance on tests of perceptual (visual or auditory) and linguistic (semantic, phonological or syntactic) processing. Experiment 2 found that these nine patients, had significantly more damage to dorsal parts of the superior longitudinal fasciculus and the right inferior frontal sulcus compared to 75 other patients who also had right hemisphere strokes but were not impaired on the auditory sentence-to-picture matching task. Damage to these right hemisphere regions caused long-term speech comprehension difficulties in 67% of patients. Experiments 3 and 4, used fMRI in two groups of 25 neurologically-normal individuals to show that, within the regions identified by Experiment 2, the right inferior frontal sulcus was normally activated by (i) auditory sentence-to-picture matching and (ii) one-back matching when the demands on linguistic and non-linguistic working memory were high. Together, these experiments demonstrate that the right inferior frontal cortex contributes to linguistic and non-linguistic working memory capacity (executive function) that is needed for normal speech comprehension. Scientifically, our results link previously unrelated literatures on the role of the right inferior frontal cortex in executive processing and the role of executive processing in sentence comprehension; which in turn helps to explain why right inferior frontal activity has previously been reported to increase during recovery of language function after left hemisphere stroke. The clinical relevance of our findings is that the detrimental effect of right hemisphere strokes on language is (i) much greater than expected, (ii) frequently observed after damage to the right inferior frontal sulcus, (iii) task dependent, (iv) different to the type of impairments observed after left hemisphere strokes and (v) can result in long-lasting deficits that are (vi) not the consequence of atypical language lateralisation. IntroductionItem The impact of sample size on the reproducibility of voxel-based lesion-deficit mappings(2018) Lorca-Puls, Diego L.; Gajardo-Vidal, Andrea; White, Jitrachote; Seghier, Mohamed L.; Leff, Alexander P.; Green, David W.; Crinion, Jennifer T.; Ludersdorfer, Philipp; Hope, Thomas M. H.; Bowman, Howard; Price, Cathy J.This study investigated how sample size affects the reproducibility of findings from univariate voxel-based lesion-deficit analyses (e.g., voxel-based lesion-symptom mapping and voxel-based morphometry). Our effect of interest was the strength of the mapping between brain damage and speech articulation difficulties, as measured in terms of the proportion of variance explained. First, we identified a region of interest by searching on a voxel-by-voxel basis for brain areas where greater lesion load was associated with poorer speech articulation using a large sample of 360 right-handed English-speaking stroke survivors. We then randomly drew thousands of bootstrap samples from this data set that included either 30, 60, 90, 120, 180, or 360 patients. For each resample, we recorded effect size estimates and p values after conducting exactly the same lesion-deficit analysis within the previously identified region of interest and holding all procedures constant. The results show (1) how often small effect sizes in a heterogeneous population fail to be detected; (2) how effect size and its statistical significance varies with sample size; (3) how low-powered studies (due to small sample sizes) can greatly over-estimate as well as under-estimate effect sizes; and (4) how large sample sizes (N ≥ 90) can yield highly significant p values even when effect sizes are so small that they become trivial in practical terms. The implications of these findings for interpreting the results from univariate voxel-based lesion-deficit analyses are discussed.