In Reply: Pain Outcomes Following Microvascular Decompression for Drug-Resistant Trigeminal Neuralgia: A Systematic Review and Meta-Analysis

To the Editor:

We thank the authors¹ for reading our systematic review and meta-analysis on microvascular decompression (MVD) for drug-resistant trigeminal neuralgia (TN).² Their point is well made that MVD is a safe and effective treatment of TN for patients who have evidence of neurovascular compression on imaging and those who are good surgical candidates. On the other hand, less invasive ablative treatments such as radiofrequency lesioning (RFL), balloon compression, and glycerol injection remain treatment options for patients without evidence of neurovascular compression or who may not be able to tolerate an open surgery.

The rate of pain freedom is variable in the literature for percutaneous procedures. After RFL, pain freedom is reported to be as high as 98% to 99% immediately after surgery and 62% to 80% at 1-yr follow-up.^3,4 Long-term pain freedom was achieved in 58% to 73% of patients at approximately 5 yr after RFL.^3,4 The variability in pain freedom likely reflects the heterogeneity of the data with most datasets combining patients who underwent single or multiple procedures, and had different pain descriptions, ages, and medical management. The time until pain recurrence after RFL has been reported to be 17 to 28.7 mo.^5,6 Similar to the conclusions in our study, Burchiel Type I compared to Type II pain and initial compared to repeat procedure were significant independent predictors of 1-yr pain freedom for RFL in a recent meta-analysis.^7,8

Recently, multiple new meta-analyses and prospective studies examining the effectiveness of percutaneous procedures in producing pain freedom for TN have been conducted. For patients undergoing glycerol treatment, immediate pain relief was 54% to 98% and long-term pain freedom, approximately 5 yr post-op, was 28% to 51%.⁹ Time until pain recurrence was 14 to 24 mo.^5,6 Initial pain freedom after balloon compression is 82% to 94% with pain freedom at approximately 5 yr being 55%.^6,10 Balloon compression produced a significantly better initial pain relief rate than glycerol or RFL in one large retrospective review. A recent meta-analysis comparing the different percutaneous techniques, though, found that RFL was associated with higher odds of immediate pain relief than glycerol injection with largely similar long-term rates of pain recurrence. Balloon compression and glycerol injection were not statistically different in immediate and long-term pain freedom. RFL was associated with a higher risk of facial hypesthesia, whereas balloon compression had higher rates of mastication weakness and diplopia compared to other techniques.¹¹

There has been a shift from percutaneous treatment of TN to MVD. After examining the Centers for Medicare and Medicaid Services national database, the number of MVDs performed for cranial neuralgias increased by 167% in 2016 compared to 17 yr earlier. Concurrently, percutaneous treatments such as RFL and glycerol injection decreased over the same period by 42.9 cases per year.¹² MVD is associated with a greater rate of pain freedom than RFL and a reduced incidence of facial numbness. As with all neurosurgical procedures, appropriate patient selection is critical as MVD is associated with a greater risk of postoperative complications such as spinal fluid leak, wound infections, and hearing loss.³ Overall, we agree with the authors that if patients are good candidates for and are amenable to MVD, this procedure would be preferable to ablative lesions for long-term pain freedom.

Disclosures

Dr Englot is funded by the NIH/NINDS (1R00-NS097618). Dr Rolston is supported by the NIH/NCATS (1KL2TR002539-01). The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.