Diffusion MRI as a potential biomarker for monitoring recovery after surgical repair of traumatic peripheral nerve injuries: a preliminary feasibility longitudinal case series

After transection, peripheral nerve regeneration requires repair surgery in a timely manner. Unfortunately, up to 40% of peripheral nerve repairs fail to achieve functional recovery. Patients with failed peripheral nerve repairs require additional surgical interventions, but current methods detecting clinical failure offer limited information, resulting in delayed management and suboptimal outcomes. Diffusion tensor imaging may serve as a biomarker of nerve regeneration; however, the complex spatial and temporal changes along the distal segment of the nerve remains challenging to interpret. To address this, we applied the Gompertz function to mathematically characterize these changes and capture the nonlinear dynamics of recovery following nerve trauma. Severe peripheral nerve injuries of the ulnar or median nerve were analyzed in this study. Medical Research Council sensory grades representing absent to normal sensation, motor grades representing visible muscle contraction to normal strength and diffusion tensor imaging scans were performed longitudinally over twelve months postoperatively. Values of fractional anisotropy closely matched clinical evaluations and levels of nerve recovery. We provided a quantitative, noninvasive approach for characterizing recovery and reducing user-dependent variability in interpretation. These results suggest that Fractional Anisotropy may serve as a potential biomarker to monitor nerve recovery following surgical repair, potentially guiding clinical decisions for additional interventions.