Right hemisphere structures predict poststroke speech fluency

Pani, Ethan; Zheng, Alex; Wang, Jasmine; Norton, Andrea; Schlaug, Gottfried

doi:10.1212/wnl.0000000000002613

Cited by 58 publications

(72 citation statements)

References 39 publications

(52 reference statements)

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“…Supporting our findings, in patients in the chronic state of recovery from left hemisphere ischemic stroke, FA values in specific regions of interest in the contralateral hemisphere (middle temporal gyrus, precentral gyrus, and pars opercularis) were predictive of speech fluency. 38 Similarly, in a cohort of patients with right hemispheric ischemic stroke, with the use of Tract Based Spatial Statistics, FA values in the specific regions of the contralateral hemisphere correlated with performance on neuropsychological testing. 33 Our data now offer new evidence to demonstrate the utility of global measures of WM integrity in this population.…”

Section: Resultsmentioning

confidence: 98%

Integrity of normal-appearing white matter and functional outcomes after acute ischemic stroke

Etherton

Cougo

et al. 2017

Neurology

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Objective: To characterize the effect of white matter microstructural integrity on cerebral tissue and long-term functional outcomes after acute ischemic stroke (AIS).Methods: Consecutive AIS patients with brain MRI acquired within 48 hours of symptom onset and 90-day modified Rankin Scale (mRS) score were included. Acute infarct volume on diffusion-weighted imaging (DWIv) and white matter hyperintensity volume (WMHv) on T2 fluidattenuated inversion recovery MRI were measured. Median fractional anisotropy (FA), mean diffusivity, radial diffusivity, and axial diffusivity values were calculated within normal-appearing white matter (NAWM) in the hemisphere contralateral to the acute lesion. Regression models were used to assess the association between diffusivity metrics and acute cerebral tissue and longterm functional outcomes in AIS. Level of significance was set at p , 0.05 for all analyses.Results: Among 305 AIS patients with DWIv and mRS score, mean age was 64.4 6 15.9 years, and 183 participants (60%) were male. Median NIH Stroke Scale (NIHSS) score was 3 (interquartile range [IQR] 1-8), and median normalized WMHv was 6.19 cm 3 (IQR 3.0-12.6 cm 3 ). Admission stroke severity (b 5 0.16, p , 0.0001) and small vessel stroke subtype (b 5 21.53, p , 0.0001), but not diffusivity metrics, were independently associated with DWIv. However, median FA in contralesional NAWM was independently associated with mRS score (b 5 29.74, p 5 0.02), along with age, female sex, NIHSS score, and DWIv.Conclusions: FA decrease in NAWM contralateral to the acute infarct is associated with worse mRS category at 90 days after stroke. These data suggest that white matter integrity may contribute to functional recovery after stroke. Neurology ® 2017;88:1701-1708 GLOSSARY AD 5 axial diffusivity; AIS 5 acute ischemic stroke; DTI 5 diffusion tensor imaging; DWIv 5 diffusion-weighted imaging volume; FA 5 fractional anisotropy; FLAIR 5 fluid-attenuated inversion recovery; IQR 5 interquartile range; MD 5 mean diffusivity; MNI 5 Montreal Neurological Institute; mRS 5 modified Rankin Scale; nDWIv 5 normalized diffusion-weighted imaging volume; NAWM 5 normal-appearing white matter; NIHSS 5 NIH Stroke Scale; nWMHv 5 normalized white matter hyperintensity volume; RD 5 radial diffusivity; TOAST 5 Trial of Org 10172 in Acute Stroke Treatment; tPA 5 tissue plasminogen activator; WM 5 white matter; WMH 5 white matter hyperintensity; WMHv 5 white matter hyperintensity volume.The role of white matter hyperintensity (WMH), or leukoaraiosis, in outcomes after acute ischemic stroke (AIS) is increasingly recognized through its link to larger acute infarct lesions, 1 likelihood of infarct expansion, 2 and association with worse functional poststroke outcomes. [3][4][5] However, a growing body of evidence suggests that macrostructural white matter (WM) disease burden, quantified as WMH on T2-weighted fluid-attenuated inversion recovery (FLAIR) MRI, may not adequately reflect the total extent of WM injury and that microstructural injury to normal-appear...

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Section: Resultsmentioning

confidence: 98%

Integrity of normal-appearing white matter and functional outcomes after acute ischemic stroke

Etherton

Cougo

et al. 2017

Neurology

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“…Importantly, higher grey matter volume in these regions is associated with better residual language functions in chronic post-stroke aphasia patients [Xing et al, 2015]. Similarly, increased fractional anisotropy (FA) has been observed in the right IFG pars opercularis for chronic post-stroke aphasia patients relative to healthy controls, and higher FA in this region is associated with better speech production abilities for patients [Pani et al, 2016]. Our findings add to this literature by showing that functional activation in specific right frontal regions during language task performance is associated with better expressive language abilities in chronic post-stroke aphasia patients with extensive left hemispheric damage.…”

Section: Discussionmentioning

confidence: 99%

“…Importantly, higher grey matter volume in these regions is associated with better residual language functions in chronic post-stroke aphasia patients [Xing et al, 2016]. Similarly, increased fractional anisotropy (FA) has been observed in the right IFG pars opercularis for chronic post-stroke aphasia patients relative to healthy controls, and higher FA in this region is associated with better speech production abilities in patients [Pani et al, 2016].…”

Section: Right Hemispheric Compensation In Patients With Extensive Lementioning

confidence: 95%

The canonical semantic network supports residual language function in chronic post‐stroke aphasia

Griffis

Nenert

Allendorfer

et al. 2016

Human Brain Mapping

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Current theories of language recovery after stroke are limited by a reliance on small studies. Here, we aimed to test predictions of current theory and resolve inconsistencies regarding right hemispheric contributions to long-term recovery. We first defined the canonical semantic network in 43 healthy controls. Then, in a group of 43 patients with chronic post-stroke aphasia, we tested whether activity in this network predicted performance on measures of semantic comprehension, naming, and fluency while controlling for lesion volume effects. Canonical network activation accounted for 22–33% of the variance in language test scores. Whole-brain analyses corroborated these findings, and revealed a core set of regions showing positive relationships to all language measures. We next evaluated the relationship between activation magnitudes in left and right hemispheric portions of the network, and characterized how right hemispheric activation related to the extent of left hemispheric damage. Activation magnitudes in each hemispheric network were strongly correlated, but four right frontal regions showed heightened activity in patients with large lesions. Activity in two of these regions (inferior frontal gyrus pars opercularis and supplementary motor area) was associated with better language abilities in patients with larger lesions, but poorer language abilities in patients with smaller lesions. Our results indicate that bilateral language networks support language processing after stroke, and that right hemispheric activations related to extensive left hemisphere damage occur outside of the canonical semantic network and differentially relate to behavior depending on the extent of left hemispheric damage.

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“…2–6 One large cross-sectional study showed that aphasia severity was associated with stroke volume, time post-onset, and percentage of damage to 35 brain regions. 2 Three studies have shown a strong association between lesion load in the AF (along with the integrity of right hemisphere white matter tracts 5 ) and outcome of naming and speech fluency in post-stroke aphasia. 4–6 One longitudinal study of 21 aphasic individuals showed that age, initial severity, and the pattern of activation on functional imaging at baseline were associated with degree of impairment at six months.…”

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confidence: 99%