Intraoperative findings of pain recurrence after microvascular decompression for trigeminal neuralgia: experience with revision surgery

Abstract

Recurrence or persistence of pain after microvascular decompression (MVD) for trigeminal neuralgia (TN) remains a challenging clinical problem. Revision procedures may reveal intraoperative findings  underlying recurrent or persistent pain, including residual/unrecognized primary or newly developed neurovascular compression (NVC), scar-related adhesive changes, and “Teflon-associated” pathology. Objective: To identify intraoperative findings  underlying pain recurrence/persistence after MVD for TN and to evaluate the outcomes of revision procedures. Materials and methods: Between 2023 and 2026, 36 patients with recurrent pain after primary MVD for TN were evaluated at the Romodanov Neurosurgery Institute of the National Academy of Medical Sciences of Ukraine. The mean interval to pain recurrence was 18.2±6.4 months. Two cases of early recurrence (≤6 months) were documented. All patients underwent clinical pain phenotyping and magnetic resonance imaging (MRI) assessment for the presence of NVC, deformation, or displacement of the trigeminal nerve root. The decision to perform revision surgery was made on an individualized basis according to clinical–instrumental concordance. Revision surgery was performed in 9 (25.0%) patients: MVD alone (re-MVD) was performed in 6 (16.7%) patients with confirmed evidence of NVC, whereas re-MVD combined with selective proximal microtomy was performed in 3 (8.3%) patients with equivocal intraoperative evidence of NVC and severe pain. The primary endpoint was pain intensity assessed using the Barrow Neurological Institute Pain Intensity Score (BNI-PS) at 6 months. A clinically meaningful outcome was defined as BNI-PS I–IIIa. Sensory disturbances were assessed using the Barrow Neurological Institute Facial Numbness Score (BNI-NS). Results: In the revision surgery subgroup (n=9), intraoperative findings  related to Teflon, adhesive changes, and a clinically relevant venous component predominated. Teflon granuloma was identified in 2 (22.2%) cases, and migration/displacement of the Teflon pledget in 1 (11.1%) case. A clinically relevant venous component of NVC requiring revision was identified in 2 (22.2%) patients. In 1 (11.1%) case, microfascicles of the trigeminal nerve root were involved in dense scar tissue corresponding topographically to the pain distribution. Selective proximal microtomy was performed in 3 (33.3%) patients because convincing intraoperative evidence of NVC was lacking despite severe pain. In some patients with extensive adhesive changes in the cerebellopontine angle, whitish inclusions of the arachnoid membrane were observed microscopically. In patients without convincing indications for re-MVD, medical therapy was optimized and additional diagnostic evaluation was performed as clinically indicated. At 6 months after revision surgery, all 9 patients demonstrated improvement to BNI-PS I–IIIa; BNI-NS II was documented in 2 (22.2%) patients. A new mild sensory deficit developed in 1 (11.1%) patient. Conclusions: Standardized assessment of the clinical pain phenotype corresponding to BNI-PS >IIIb, combined with MRI verification of NVC and/or deformation or displacement of the trigeminal nerve root, may be useful for establishing indications for repeat surgery. Revision procedures after MVD for TN revealed “Teflon-associated” pathology and/or a clinically significant venous component of NVC in the setting of pronounced scar-related adhesive changes, occasionally involving microfascicles of the trigeminal nerve root corresponding to the topographic localization of pain. In this small revision-surgery series, all patients achieved a clinically meaningful outcome according to BNI-PS at 6 months; however, these findings are preliminary and require confirmation in larger cohorts with longer follow-up. Analysis of intraoperative findings  supports the practical value of comprehensive clinical and imaging-based assessment when determining indications for re-MVD and highlights the need to develop standardized selection criteria and treatment algorithms for this challenging population of patients with recurrent pain after primary surgical treatment.