Cerebral Blood Flow–Derived Myogenic Dynamics Reveal Impaired Postischemic Cerebrovascular Recovery in Experimental Stroke

BACKGROUND: Restoration of cerebral blood flow (CBF) after ischemic stroke does not necessarily indicate recovery of cerebrovascular regulation. We tested whether myogenic-band dynamics derived directly from CBF signals provide information beyond mean perfusion during cerebral ischemia and after acute stroke. METHODS: Transient focal cerebral ischemia was induced in 29 Sprague-Dawley rats using middle cerebral artery occlusion/reperfusion. Bilateral laser-Doppler flowmetry (LDF)-derived CBF signals were decomposed using empirical mode decomposition and Hilbert transform, and myogenic-band activity (0.15-0.4 Hz) was quantified by absolute and relative power. Cross-validated logistic regression models were used to evaluate whether myogenic-band power provided discriminative information beyond mean CBF alone. RESULTS: Ipsilateral mean CBF fell from 73.5±51.8 p.u. at baseline to 52.2±38.0 p.u. during late ischemia (P=0.0088), then increased to 126.6±91.5 p.u. after 3 hours of reperfusion (P=0.0050 versus baseline). Relative myogenic-band power decreased from 37.43±14.65% to 13.35±7.51% during ischemia (P<0.0001) and remained below baseline after reperfusion (20.74±12.02%, P=0.00033 versus baseline); contralateral relative power was comparatively preserved. Combining mean CBF and myogenic-band power improved discrimination of baseline from late ischemia (AUC, 0.99 versus 0.70 for mean CBF alone) and late reperfusion (AUC, 0.88 versus 0.70). CONCLUSIONS: Frequency-specific analysis of LDF-derived CBF reveals persistent, lateralized abnormalities in myogenic-band dynamics that are not captured by mean perfusion alone. The persistence of depressed myogenic activity despite restored or elevated mean CBF demonstrates incomplete recovery of frequency-specific oscillatory dynamics after reperfusion. These findings support myogenic-band power as a potential functional measure of persistent postischemic cerebrovascular dysfunction.