Electroencephalographic Phase Synchrony Index as a Biomarker of Poststroke Motor Impairment and Recovery.
Teiji Kawano, Noriaki Hattori, Yutaka Uno and 8 others
PMID 32691673WHAT IT FOUND
In 40 patients with stroke-related one-sided weakness, EEG signal timing between motor areas was related to arm impairment, and timing in the opposite hemisphere was related to later arm recovery.
Key findings
01Phase synchrony between the C3 and C4 electrodes in the alpha band was positively correlated with the upper limb motor score at admission.
02Phase synchrony centered on the hemisphere opposite the lesion, in the theta band, was positively correlated with gain in the upper limb motor score after rehabilitation.
03A theta-band cutoff of 0.667 classified patients with a gain of 5 or more on the upper limb motor score with 90% sensitivity and 65% specificity.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study used only 19 EEG channels, so spatial resolution was limited. All patients had cortical ischemic stroke, so the results may not apply to hemorrhagic stroke or subcortical lesions. It was observational, and rehabilitation duration varied; longer rehabilitation did not necessarily lead to greater gain. Acute-stage impairment could not be assessed because patients were transferred from other acute care hospitals. The study included 40 patients and 22 controls, and the authors note many covariates were analysed relative to the number of patients. Causality of the synchrony measures on recovery was not clarified. EEG timing and rehabilitation duration reflect Japan's health care system, so findings may not apply outside these time windows. 3 patients with high gain scores of 49, 35, and 31 might have influenced the correlation, but it remained significant after their removal. Data from 5 patients overlapped with a previous report.
Declared interests
YU has a pending patent JPA2015-166281 to RIKEN. KK has an issued patent JP6142354 to RIKEN, a pending patent US14/770,047 to RIKEN, and a pending patent JPA2015-166281 to RIKEN. The other authors declared no conflicts. The work was supported by Toyota Motor Corporation, and NH was supported by JSPS KAKENHI Grant Number JP26350602.
The easy way to misread this
Do not use these EEG synchrony values to choose therapy intensity or predict a patient's recovery. The study was observational, and the authors state that causality was not clarified.