Volume maximised glycerol rhizolysis for trigeminal neuralgia: a single centre analysis of outcomes

Abstract

Objectives Glycerol rhizotomy is an established treatment for medically refractory trigeminal neuralgia in select cases where microvascular decompression is contraindicated or not preferred. The standard approach is to inject a fixed volume of glycerol using Hartel’s technique into Meckel’s cave. We discuss a ‘volume-maximised’ technique of measuring the volume of Meckel’s cave using intra-operative fluoroscopy and injecting an equivalent volume of glycerol such that every patient receives a tailored quantity of glycerol dependent on the volume of Meckel’s cave. The safety and efficacy of this approach is analysed. Methods A retrospective analysis of 53 procedures where volume-maximised glycerol rhizolysis was utilised over a 7-year period (2012 –2018) at a single centre by the senior author was carried out. The incidence and duration of pain freedom and complications incurred over a median follow-up period of 8 years were analysed Results 37 procedures were carried out for typical trigeminal neuralgia, 13 for secondary trigeminal neuralgia, and 3 for atypical trigeminal neuralgia. Overall, pain freedom was achieved in 85% cases, and 92% in patients with typical trigeminal neuralgia. Median duration of pain freedom in patients with typical trigeminal neuralgia was 63 months, versus 6 months in those with secondary trigeminal neuralgia (p < 0.00001). 14 procedures (26.4%) resulted in mild and temporary complications. 54.7% of cases experienced hypoaesthesia in a distribution similar to or less extensive than the distribution of trigeminal neuralgia. The presence of hypoaesthesia post-procedure was highly predictive of longer pain freedom (95 months versus 8 months median pain freedom (p = 0.00003)). Conclusions Volume-maximised glycerol injection is safe and effective when compared to literature-reported outcomes post-standard volume glycerol injections. The duration of pain freedom achieved exceeds most literature-reported studies, with hypoaesthesia outcomes being comparable with previous studies. Pain freedom outcomes are more favourable in those with post-procedure hypoaesthesia.