Transposition versus interposition method in microvascular decompression for trigeminal neuralgia: midterm analysis of both techniques in a single-center study.

Objective: Operative interposition of material between the trigeminal nerve and offending artery for surgical treatment of drug-resistant trigeminal neuralgia (TGN), following the Jannetta method, has been proven to be the most successful invasive treatment. Reexplorations of patients with recurrence of TGN have revealed nerve root irritations and scarring due to interposed material. To prevent these complications, modifications of microvascular decompression (MVD) aim at transposing the vessel away from the trigeminal nerve, without attachment of additional material to the nerve root. Given that both techniques (interposition and transposition) have been performed in the authors' institution, they decided to analyze them for the short- and midterm outcomes.

Methods: All patients who had undergone MVD for drug-resistant TGN in the authors' institution between 2008 and 2022 were analyzed retrospectively. Outcome at discharge and follow-up was evaluated using the Barrow Neurological Institute pain intensity score. Additionally, complications and pain recurrence were assessed.

Results: A total of 114 patients were operated on using transposition and 110 patients were treated using interposition. For transposition 102 patients were followed up for a median of 31.5 months, and for interposition 100 patients were followed up for a median of 95 months. At discharge 92.1% versus 94.5% of patients in the transposition and interposition groups, respectively, experienced a good outcome (Barrow Neurological Institute pain intensity scores I-III). At follow-up, 83.3% versus 85% of patients in the transposition and interposition groups, respectively, continued to demonstrate a good outcome. In 4.9% of patients in the transposition group and in 6% of patients in the interposition group, recurrence of pain occurred. Complications occurred in 24.6% of patients in the transposition and in 27.3% of those in the interposition group. The most frequent complications were facial hypesthesia (10.5% vs 11.8%, transposition vs interposition), followed by CSF leaks (2.6% vs 8.2%).

Conclusions: Transposition for MVD is an elegant way of solving vessel-nerve conflicts at the cerebellopontine angle. Similar to interposition, transposition shows positive short- and midterm outcomes for patients experiencing drug-resistant TGN. However, the main objective of transposition, which is improved prevention of recurrence and reduction of complications at the trigeminal nerve, could not be confirmed in this study.