Stroke Lesion Volume and Injury to Motor Cortex Output Determines Extent of Contralesional Motor Cortex Reorganization.
Cathrin M Buetefisch, Marc W Haut, Kate P Revill and 7 others
PMID 36786394WHAT IT FOUND
In 35 people with subacute stroke, no single corticospinal tract measure was related to contralesional motor cortex reorganization overall.
In participants with no measurable motor output, larger stroke volume was linked to more reorganization, and hand function was worse with more damage.
Key findings
01No single measure of corticospinal tract damage was related to contralesional motor cortex reorganization across the whole sample.
02In participants with no measurable motor output, greater stroke lesion volume was related to greater contralesional motor cortex reorganization; in participants with measurable output, it was not.
03Hand function was worse as stroke lesion volume and corticospinal tract lesion load increased, and participants with measurable motor output had better hand function than those without.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The analysis included 35 participants after 66 consented and enrolled, 30 excluded, 36 participated, and 1 further excluded, so the sample was small. The paper reports the subacute time point only, so it does not show how these relationships change over the 6 month follow up planned in the longitudinal study. The study was observational, so it cannot show that lesion volume, motor output, or contralesional reorganization caused hand function impairment. Corticospinal tract lesion load and motor evoked potential measures depend on excitability at several levels and are not perfectly specific for injury to the motor cortex output pathway. Only 3 participants had purely cortical lesions, so injury to the primary motor cortex itself was not separately quantified. Contralesional stimulus response area can reflect either greater excitability or more neurons being stimulated, so it does not identify one biological mechanism.
Declared interests
The publication types list non U.S. government and NIH extramural research support. The supplied text does not include an author conflicts of interest statement.
The easy way to misread this
Do not conclude that contralesional motor cortex reorganization causes impaired hand function. In the whole group it was not related to hand function, and a relationship appeared only in participants with no measurable motor output.