Defining the Complication Landscape of Internal Neurolysis for the Treatment of Trigeminal Neuralgia via a Systematic Review of the Literature

Introduction: Trigeminal neuralgia (TN) is considered one of the most debilitating facial neuropathic pain syndromes that can affect an individual. Medical treatment remains first line therapy, with microvascular decompression (MVD) being the primary surgical intervention for patients with underlying neurovascular compression (NVC) of the trigeminal nerve. Internal neurolysis (IN) has recently shown promising results for trigeminal neuralgia pain-relief in patients with absent or low-grade NVC. However, the complications profile of IN has not been well defined.

Methods: A literature search of PubMed was performed using the search terms “Trigeminal Neuralgia,” “Internal Neurolysis,” and “Microvascular Decompression,” as well as common permutations of free text terms along with appropriate indexation terms. This search resulted in 57 articles, which were then reviewed for duplicates, non-English articles, and articles with alternative treatment methods. Articles without results differentiating treatment with IN versus other modalities were also excluded. A total of nine articles were considered for analysis, and PRIMSA guidelines were followed throughout the systematic review.

Results: The systematic review resulted in nine studies including a total of 459 people, 323 (70.4%) of which underwent IN. The mean/median range of follow-up was 12–90 months. Primary complications relating to trigeminal nerve manipulation included facial hypoesthesia, corneal numbness, corneal ulcer and anesthesia dolorosa. Immediate postoperative rates of facial numbness in all patients receiving IN was 46%, with individual studies showing rates of immediate postoperative facial numbness between 20 and 96%. This decreased at last follow-up to anywhere from 3.75 to 67.6%. The overall rate of corneal numbness/ulcer or loss of corneal reflex was 1.2%, although one study specifically did not report corneal symptoms postoperatively. One instance of anesthesia dolorosa was reported (0.3%).

Conclusion: Compared with standard MVD, the rate of facial hypoesthesia is higher with internal neurolysis. However, the rate of severe complications remain low and is comparable to other interventions for trigeminal neuralgia. More studies are warranted to compare the efficacy of IN and analyze the cost–benefit of long-term facial numbness and robust pain outcomes.