High-Resolution Ultrasound for Diagnosing Severity of Traumatic Peripheral Nerve Injuries-in-Continuity: A Systematic Review, Meta-Analysis of Individual Participants' Data, and Illustrative Patient Series.

INTRODUCTION/AIMS: High-resolution ultrasound (HRUS) may help evaluate traumatic peripheral nerve injuries (PNIs), but the sonographic features that distinguish low- from high-grade injury remain poorly defined. This study evaluated the utility of HRUS for differentiating injury severity by synthesizing data from the literature and applying these findings to an illustrative institutional patient series.

METHODS

We queried for studies reporting HRUS findings in iatrogenic/traumatic PNI resulting in neurapraxia or axonotmesis. Individual participant data (IPD) were extracted and synthesized. Meta-analysis was performed via a 1-stage IPD approach to estimate associations between HRUS findings and injury grade. Findings from the review were then applied to an illustrative institutional series of five patients who underwent HRUS during initial clinical evaluation.

RESULTS

The systematic review included 74 patients from 24 studies. Focal nerve enlargement, hypoechoic nerve perimeter, and disruption of fascicular echotexture were observed in 82.4%, 63.5%, and 45.9% of patients, respectively. Fascicular echotexture disruption was present in 73.8% of high-grade injuries compared to 9.4% of low-grade injuries. Meta-analysis revealed fascicular echotexture disruption was independently associated with high-grade injury (aOR = 21.6; 95% CI [4.02-116], p = 0.002). Patient series findings were similar; one patient had preserved fascicular architecture and recovered under conservative management (low-grade PNI), while four patients had disrupted fascicular echotexture and were confirmed intraoperatively to have high-grade axonotmesis.

DISCUSSION: Traumatic PNIs demonstrated categorizable HRUS findings that may serve as a useful adjunct in multimodal assessment of injury severity. Disruption of fascicular echotexture appeared most associated with high-grade lesions-in-continuity, although prospective validation with standardized imaging protocols is needed.