Association between MR neurography-based objective quantitative parameters in inferior alveolar nerve and lingual nerve injuries.

Abstract

The diagnosis of inferior alveolar nerve (IAN) and lingual nerve (LN) injuries currently relies on imaging and clinical examinations. Magnetic resonance neurography (MRN) demonstrates limited sensitivity in mild-to-moderate IAN and LN injuries, while quantifiable parameters correlating with symptomatology and prognostic outcomes remain undefined. This study retrospectively reviewed 24 patients with IAN or LN injuries. Their clinical and imaging data were collected. MRN-based parameters, including apparent signal-to-noise ratio (aSNR) and apparent nerve-muscle contrast-to-noise ratio (aNMCNR), were calculated. Among the 24 patients, there were 17 patients with IAN injuries and 7 with LN injuries. This investigation demonstrated significantly elevated aSNR and aNMCNR on the injured side of mild-to-moderate IAN/LN injuries compared to healthy nerves (all p < 0.05). The injury-to-healthy ratios (aSNRi/h, aNMCNRi/h) exhibited marked increases relative to the internal control group (all p < 0.05). aNMCNRi/h showed inverse correlations with visual analog scale (VAS) scores and 5 Hz current perception threshold (CPT) measurements (p = 0.041 and p = 0.048, respectively). Longitudinal analysis in the 1-year follow-up cohort (n = 15) revealed a positive linear relationship between aNMCNRi/h and subsequent prognostic improvement magnitude (p < 0.001). This investigation establishes, for the first time, the clinical validity of aNMCNRi/h as a quantitative imaging parameter correlating with symptom severity and prognostic trajectories in mild-to-moderate IAN/LN injuries. The proposed parameter demonstrates potential for guiding patient-specific clinical decision-making, with implications for standardizing diagnostic protocols and optimizing rehabilitation strategies. Question Objective quantitative parameters correlating with symptomatology and prognosis in mild-to-moderate Inferior alveolar nerve (IAN) and lingual nerve (LN) injuries remain unestablished. Findings The apparent nerve-muscle contrast-to-noise ratio injured-to-healthy ratio demonstrates correlation with both symptomatology and prognostic outcomes in mild-to-moderate IAN and LN injuries. Clinical relevance This study pioneers the proposal of magnetic resonance neurography-based quantitative parameters correlating with symptomatology and prognosis, thereby addressing critical limitations of conventional Sunderland grading in the diagnostic-therapeutic management of mild-to-moderate IAN and LN injuries.