Abnormal EEG Responses to TMS During the Cortical Silent Period Are Associated With Hand Function in Chronic Stroke.
Whitney A Gray, Jacqueline A Palmer, Steven L Wolf and 1 others
PMID 28604171WHAT IT FOUND
In chronic stroke, brain stimulation with brain-wave recording during active thumb contraction showed abnormal brain responses and a longer pause in muscle activity than controls.
Hand-function links were tentative and not confirmed.
Key findings
01During active thumb contraction, stroke participants had larger early brain response peaks and delayed later peaks than controls.
02The silent period, a pause in thumb muscle activity, was longer in stroke than controls and longest on the stroke-affected side.
03Some hand-function correlations were significant before correction, but none reached the study's stricter significance threshold.
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 study had only 13 stroke participants and 12 controls, and one stroke participant was excluded from all analyses, so the results are limited by small numbers. Several hand-function correlations were only significant before correction for multiple comparisons, so they may be chance findings. Some data were missing because of coil overheating, time constraints, an undetectable silent period, or EEG artifact. The stroke group was heterogeneous, and the researchers could not examine whether lesion location affected the brain responses. The analysis focused on a single EEG channel, Cz, so it may not capture the full pattern of cortical activity. The TMS click can create auditory brain responses that contaminate EEG, especially at N100 and P180, although earplugs and a sham comparison were used. The stroke group was older than the control group, which may have influenced brain responses. The study did not test a rehabilitation intervention, so it cannot show that these brain responses can be changed or that changing them improves function.
The easy way to misread this
Do not conclude that brain stimulation and brain-wave recording are a validated clinical biomarker of hand function after stroke. The hand-function associations did not pass the study's stricter significance threshold, and the study was small and exploratory.