SA3 - Does Postoperative Magnetic Resonance Neurography Influence Reoperation Rate?

Abstract: Background: Magnetic resonance neurography (MRN) is a noninvasive imaging modality with a validated role in the diagnosis of peripheral trigeminal neuropathies (PTNs) (1,2).

Purpose: The purpose of this study was to compare reoperation rates after trigeminal nerve repair between subjects who received postoperative MRN (P-MRN) and those who did not (NP-MRN). Additional aims were to assess reoperation rate among a subgroup of subjects who underwent trigeminal nerve repair with processed nerve allograft and to determine the functional sensory recovery (FSR) rate in the allograft subgroup who received reoperation with allograft.

Study Design: This retrospective cohort study consisted of consecutive subjects who underwent trigeminal nerve repair between 2014 and 2025 the University of Texas Southwestern Medical Center.

Predictor Variable: The primary predictor variable was postoperative MRN.

Outcome Variable: The primary outcome variable was reoperation.

Covariates: Demographic covariates included age and sex. Preoperative covariates included the nerve injured (LN, IAN), laterality of the injured nerve, and etiology of injury. Operative covariates included repair type, Sunderland classification, and injury-to-surgery time in days.

Analyses: The primary predictor variable groups and the primary outcome variable groups had large unequal sample sizes for analysis so homogeneity of variance could not be assumed. For the effect of the covariates on the primary predictor variable and the effect of the covariates on the primary outcome variable, independent Welch's t-tests were used. The effect of the primary predictor variable on the primary outcome was evaluated using chi-squared analysis. A P value of < .05 was considered statistically significant.

Results: There were 35 nerve repairs in the P-MRN group and 145 in the NP-MRN group. The reoperation rate was 20% in the P-MRN group and 0% in the NP-MRN group. A statistically significant difference was observed between groups (P < .001). The reoperation rate of all allograft repairs in the study period was 4%. The FSR rate was 67% among subjects treated with allograft repair at both the initial operation and reoperation.

Conclusions: Postoperative MRN following trigeminal nerve repair was associated with a significantly higher reoperation rate. The reoperation rate was 4% among subjects who received allograft nerve repair, and the reason for reoperation in all cases was neuroma at the allograft repair site. The FSR rate was 67% among subjects treated with allograft repair at both the initial operation and reoperation. Given these findings, we suggest that MRN be performed by at least 3 months postoperatively on all trigeminal nerve repairs that show no improvement from baseline clinical NST.



References

1. Xia S, Thornton T, Ravi V, Hammad Y, Zuniga JR, Chhabra A. Efficacy of MR Neurography of Peripheral Trigeminal Nerves: Correlation of Sunderland Grade versus Neurosensory Testing. AJNR Am J Neuroradiol. 2024;45(3):335-341. doi: 10.3174/ajnr.A8120

2. Chhabra A, Ahlawat S, Belzberg A, Andreseik G. Peripheral nerve injury grading simplified on MR neurography: As referenced to Seddon and Sunderland classifications. Indian J Radiol Imaging. 2014;24(3):217-24. doi: 10.4103/0971-3026.137025.