Diaphragmatic EMG Uncovers Left-Right Diaphragmatic Imbalance After Ischemic Stroke with Implications for Motor Recovery

BackgroundStroke-associated respiratory dysfunction has been increasingly recognized, yet whether diaphragmatic impairment after stroke involves lateralized neuromuscular imbalance remains unclear. MethodsIn 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. ResultsIschemic 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. ConclusionsThese 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. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=190 SRC="FIGDIR/small/737872v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@10001a4org.highwire.dtl.DTLVardef@16bc3d5org.highwire.dtl.DTLVardef@5e40aorg.highwire.dtl.DTLVardef@be53b7_HPS_FORMAT_FIGEXP M_FIG C_FIG