Contrast-Enhanced Ultrasound Demonstrates a Severity-Dependent Hemodynamic Response to Acute Dural Decompression in Contusive Rodent Spinal Cord Injury.

Traumatic spinal cord injury (tSCI) is characterized by early microvascular disruption and regional perfusion failure that contribute to secondary tissue loss. The physiological effects of early decompression on spinal cord perfusion across injury severities remain incompletely defined. This study examined the influence of injury severity on perfusion dynamics and the impact of durotomy using contrast-enhanced ultrasound (CEUS) in a rat model of tSCI. Female Long-Evans rats underwent contusive injuries of graded severity (100, 150, 200 kDyn) at the T8 level, followed by decompressive durotomy or no further intervention. CEUS was performed at baseline, immediately after injury, 1 and 24 h postinjury to derive spatially resolved perfusion metrics, including normalized area under the curve (AUC) and spinal perfusion index (SPI). Perfusion was analyzed across defined regions: injury center, perilesional transition zone, and distal spinal cord. Functional recovery was assessed longitudinally using Basso, Beattie, and Bresnahan locomotor scoring and ladder walk testing, and spared myelin was quantified histologically at 8 weeks postinjury (wpi). Contusive tSCI produced an immediate, severity-dependent reduction in spinal cord perfusion at the lesion epicenter, with progressive involvement of adjacent segments at higher injury severities. Decompressive durotomy selectively improved perilesional perfusion following moderate injury (150 kDyn), reflected by a higher SPI (0.49 vs. 0.30, p = 0.005) and a concordant increase in perilesional AUC at 1 h. These perfusion changes were spatially restricted and transient. In exploratory analyses of chronic outcomes, moderate-injury cohort showed focal, nonsignificant trends toward greater perilesional myelin preservation and improved motor performance; total spared white matter and locomotor scores did not differ significantly between groups. These findings demonstrate that the perfusion benefits of early decompression are severity-dependent, with maximal effects in perilesional tissue following moderate injury. Quantitative CEUS provides a physiologically grounded approach for assessing therapeutic responsiveness in acute tSCI and may help guide optimization of decompressive strategies.