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Alex Teghipco

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3 papers

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YNICL Journal 2025 Journal Article

Hypoperfusion regions linked to National Institutes of Health Stroke Scale scores in acute stroke

Hana Kim
Alex Teghipco
Chris Rorden
Julius Fridriksson
Mathew Chaves
Argye E. Hillis

BACKGROUND: The National Institutes of Health Stroke Scale (NIHSS) is widely used to assess stroke severity. While prior studies have identified subcortical regions where infarcts correlate with NIHSS scores, stroke symptoms can also arise from hypoperfusion, not just infarcts. Understanding the potential for neurological recovery post-reperfusion is essential for guiding treatment decisions. The goal of this study was to identify brain regions where hypoperfusion correlates with NIHSS scores, using computed tomography perfusion (CTP) scans in cases of acute ischemic stroke. METHODS: In this prospective observational study, we analyzed CTP scans and NIHSS scores from 89 patients in the acute phase. We employed a unique support vector regression approach to overcome limitations of traditional mass univariate analyses. Additionally, we used stability selection to identify the most consistent features across subsets, reducing overfitting and ensuring robust predictive models. We verified the consistency of results through nested cross-validation. RESULTS: Both cortical and subcortical areas, including white matter tracts, showed associations with NIHSS scores. These regions aligned with functions such as language, spatial attention, sensory, and motor skills, all assessed by the NIHSS. CONCLUSIONS: Our findings reveal that hypoperfusion in specific brain regions, including previously underreported cortical areas, contributes to NIHSS scores in acute stroke. Moreover, this study introduces a novel brain mapping approach using CTP imaging and stability selection, offering a more comprehensive view of acute stroke impairments and the potential for recovery before structural reorganization occurs.

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YNICL Journal 2024 Journal Article

Progressive lesion necrosis is related to increasing aphasia severity in chronic stroke

Lisa Johnson
Roger Newman-Norlund
Alex Teghipco
Chris Rorden
Leonardo Bonilha
Julius Fridriksson

BACKGROUND: Volumetric investigations of cortical damage resulting from stroke indicate that lesion size and shape continue to change even in the chronic stage of recovery. However, the potential clinical relevance of continued lesion growth has yet to be examined. In the present study, we investigated the prevalence of lesion expansion and the relationship between expansion and changes in aphasia severity in a large sample of individuals in the chronic stage of aphasia recovery. METHODS: Retrospective structural MRI scans from 104 S survivors with at least 2 observations (k = 301 observations; mean time between scans = 31 months) were included. Lesion demarcation was performed using an automated lesion segmentation software and lesion volumes at each timepoint were subsequently calculated. A linear mixed effects model was conducted to investigate the effect of days between scan on lesion expansion. Finally, we investigated the association between lesion expansion and changes on the Western Aphasia Battery (WAB) in a group of participants assessed and scanned at 2 timepoints (N = 54) using a GLM. RESULTS: Most participants (81 %) showed evidence of lesion expansion. The mixed effects model revealed lesion volumes significantly increase, on average, by 0.02 cc each day (7.3 cc per year) following a scan (p < 0.0001). Change on language performance was significantly associated with change in lesion volume (p = 0.025) and age at stroke (p = 0.031). The results suggest that with every 10 cc increase in lesion size, language performance decreases by 0.9 points, and for every 10-year increase in age at stroke, language performance decreases by 1.9 points. CONCLUSIONS: The present study confirms and extends prior reports that lesion expansion occurs well into the chronic stage of stroke. For the first time, we present evidence that expansion is predictive of longitudinal changes in language performance in individuals with aphasia. Future research should focus on the potential mechanisms that may lead to necrosis in areas surrounding the chronic stroke lesion.

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YNICL Journal 2016 Journal Article

Disrupted functional connectivity affects resting state based language lateralization

Alex Teghipco
Ali Hussain
Madalina E. Tivarus

Pre-operative assessment of language localization and lateralization is critical to preserving brain function after lesion or epileptogenic tissue resection. Task fMRI (t-fMRI) has been extensively and reliably used to this end, but resting state fMRI (rs-fMRI) is emerging as an alternative pre-operative brain mapping method that is independent of a patient's ability to comply with a task. We sought to evaluate if language lateralization obtained from rs-fMRI can replace standard assessment using t-fMRI. In a group of 43 patients scheduled for pre-operative fMRI brain mapping and 17 healthy controls, we found that existing methods of determining rs-fMRI lateralization by considering interhemispheric and intrahemispheric functional connectivity are inadequate compared to t-fMRI when applied to the language network. We determined that this was attributable to widespread but nuanced disturbances in the functional connectivity of the language network in patients. We found changes in interhemispheric and intrahemispheric functional connectivity that were dependent on lesion location, and particularly impacted patients with lesions in the left temporal lobe. We then tested whether a simpler measure of functional connectivity to the language network has a better relation to t-fMRI based language lateralization. Remarkably, we found that functional connectivity between the language network and the frontal pole, and superior frontal gyrus, as well as the supramarginal gyrus, significantly correlated to task based language lateralization indices in both patients and healthy controls. These findings are consistent with prior work with epilepsy patients, and provide a framework for evaluating language lateralization at rest.

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