Functional connectivity between homotopic perisylvian regions correlates with functional status after stroke.
Takamichi Tohyama, Masaki Fukunaga, Yohei Otaka
Greater connectivity between matching brain areas on both sides of the perisylvian region correlated with higher daily-living independence in 58 stroke patients.
Lesion size and location did not. This is a cross-sectional biomarker finding, not a treatment result.
Key findings
1Interhemispheric connectivity between bilateral insulae, superior temporal sulci, and temporoparietal junctions showed significant positive correlations with total FIM scores (ρ = 0.536, P = 0.010; ρ = 0.513, P = 0.027; ρ = 0.511, P = 0.030, all corrected).
2The first principal component extracted from FIM-associated connections discriminated functional independence (FIM ≥ 108) from dependence within the sample with an AUC of 0.867 (95% CI 0.764-0.952), significantly outperforming the second component (AUC 0.561, P = 0.008).
3Lesion-symptom mapping in 32 patients with overlapping lesions found no brain regions significantly correlated with FIM scores, and lesion volume showed no significant correlation with FIM (ρ = -0.211, P = 0.111).
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How it was doneWhat they foundWhat it means for PTs
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What it does not show
Cross-sectional design: connectivity and FIM were measured at one time point, so the relationship is associative, not causal. Sample of 58 patients with a mean of 55 days (SD 43) since stroke, so the recovery phase varied widely across participants. Preprocessing failures restricted the sample to patients with relatively small lesions, so the finding may not apply to patients with large strokes. ROC analysis was within-sample only; no out-of-sample or independent validation was performed. Connections were preselected based on their association with FIM before PCA, which the authors note may limit generalizability. Lesion location was biased toward particular vascular territories (middle cerebral artery and lenticulostriate territories), which may have influenced the connectivity mapping.
Declared interests
No conflicts of interest declared. Funded by the Japan Society for the Promotion of Science, the Ministry of Education, Culture, Sports, Science, and Technology, and the Japan Agency for Medical Research and Development.
The easy way to misread this
Do not read the 0.867 AUC as a validated clinical tool for predicting individual stroke recovery. The analysis was within-sample only with no out-of-sample validation, the sample was 58 patients with predominantly small lesions, and the cross-sectional design shows association, not that connectivity drives recovery.
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