Abstract

Background: Stroke-associated respiratory dysfunction has been increasingly recognized, yet whether diaphragmatic impairment after stroke involves lateralized neuromuscular imbalance remains unclear. Methods: In this controlled experimental study, transient left middle cerebral artery occlusion and reperfusion (tMCAO) was performed in mice, followed by multimodal assessment of treadmill-based peak oxygen uptake testing, diaphragm ultrasonography, bilateral diaphragmatic electromyography (dEMG) with simultaneous respiratory flow monitoring, behavioral assessment, and whole-mount immunofluorescence imaging of the diaphragm. Results: Ischemic stroke reduced exercise capacity and diaphragmatic excursion without detectable diaphragm thinning, indicating functional impairment rather than overt atrophy. Bilateral dEMG revealed a subacute left-right asymmetry in inspiratory activation, with the ipsilesional hemidiaphragm exhibiting reduced amplitude, decreased area under the curve, and altered burst duration, consistent with a relative contralateral-dominant pattern rather than frank hyperactivation. Whole-mount imaging demonstrated asymmetric nerve remodeling, characterized by a nadir in ipsilesional nerve fiber density at 1 week and partial recovery by 2 weeks after stroke. These structural changes closely paralleled the dEMG alterations, suggesting a neural substrate for lateralized dysfunction. Exploratory analyses further linked dEMG parameters with motor recovery. Conclusions: These findings provide novel evidence that ischemic stroke induces a left-right diaphragmatic neuromuscular imbalance, with structural and functional correlates in diaphragmatic innervation. The study further supports the utility of bilateral dEMG as a functional marker for assessing diaphragmatic dysfunction and monitoring recovery after stroke.