Absence of Perilesional Neuroplastic Recruitment in Chronic Poststroke Aphasia

Useless. Nothing here gives us anything on how to recover from aphasia. But a lot of blathering going on.

Absence of Perilesional Neuroplastic Recruitment in Chronic Poststroke Aphasia

Andrew Tesla DeMarco, Candace van der Stelt, Sachi Paul, Elizabeth Dvorak, Elizabeth Lacey, Sarah Snider, Peter E. Turkeltaub

First published May 4, 2022, DOI: https://doi.org/10.1212/WNL.0000000000200382 

Abstract

Background and Objectives A prominent theory proposes that neuroplastic recruitment of perilesional tissue supports aphasia recovery, especially when language-capable cortex is spared by smaller lesions. This theory has rarely been tested directly, and findings have been inconclusive. Here, we test the perilesional plasticity hypothesis using two fMRI tasks in two groups of patients with prior aphasia diagnosis.

Methods Two cohorts totaling 82 chronic left-hemisphere stroke patients with prior aphasia diagnosis, and 82 control participants underwent fMRI using either a naming task or a reliable semantic decision task. Individualized perilesional tissue was defined by dilating anatomical lesions, and language regions were defined using meta-analyses. Mixed modeling examined differences in activity between groups. Relationships with lesion size and aphasia severity were examined.

Results Patients exhibited reduced activity in perilesional language tissue relative to controls in both tasks. Although a few cortical regions exhibited greater activity irrespective of distance from the lesion, or only when distant from the lesion, no regions exhibited increased activity only when near the lesion. Larger lesions were associated with reduced language activity irrespective of distance from the lesion. Using the reliable fMRI task, reduced language activity related to aphasia severity independent of lesion size.

Discussion We find no evidence for neuroplastic recruitment of perilesional tissue in aphasia beyond its typical role in language. Rather, our findings are consistent with alternative hypotheses that changes in left-hemisphere activation during recovery relate to normalization of language network dysfunction and possibly recruitment of alternate cortical processors. These findings clarify left-hemisphere neuroplastic mechanisms supporting language recovery after stroke.

• Received October 4, 2021.
• Accepted in final form February 25, 2022.

• Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

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