The influence of prior percutaneous rhizotomy on outcomes following microvascular decompression for trigeminal neuralgia

OBJECTIVE Microvascular decompression (MVD) is an effective intervention in patients with trigeminal neuralgia (TN). How prior rhizotomy can impact long-term pain outcomes following MVD is not well understood. In this study, the authors sought to compare pain outcomes in patients who had undergone primary MVD versus those who had undergone secondary MVD after a single or multiple rhizotomies. METHODS The authors retrospectively reviewed the data on all patients who had undergone MVD at their institution from 2007 to 2020. Patients were included in the study if they had undergone primary MVD or if their surgical history was notable for past rhizotomy. Barrow Neurological Institute (BNI) pain scores were assigned at preoperative and final follow-up appointments. Perioperative complications were noted for each patient, and evidence of pain recurrence was recorded as well. A history of rhizotomy as well as other variables that might influence TN pain recurrence were evaluated using a Cox proportional hazards model. The impact of prior rhizotomy on TN pain recurrence following MVD was further assessed using Kaplan-Meier survival analysis. RESULTS Of 1044 patients reviewed, 947 met the study inclusion criteria. Of these, 796 patients had undergone primary MVD, 84 had a history of a single rhizotomy before MVD, and 67 had a history of ≥ 2 rhizotomies prior to MVD. Patients in the single rhizotomy and multiple rhizotomies cohorts exhibited a greater frequency of preoperative numbness (p < 0.001), higher preoperative BNI pain scores (p < 0.005), and higher rates of postoperative numbness (p = 0.04). However, final follow-up BNI pain scores were not significantly different between the primary MVD and prior rhizotomy groups (p = 0.34). Cox proportional hazards analysis revealed that younger age, multiple sclerosis, and female sex independently predicted an increased risk of pain recurrence following MVD. Neither a history of a single prior rhizotomy nor a history of multiple prior rhizotomies independently increased the risk of pain recurrence. Furthermore, Kaplan-Meier analysis of pain-free survival among the 3 groups revealed no relationship between a history of prior rhizotomy and pain recurrence following MVD (p = 0.57). CONCLUSIONS Percutaneous rhizotomy does not complicate outcomes following subsequent MVD for TN pain. However, patients undergoing rhizotomy before MVD may have an increased risk of postoperative facial numbness compared to that in patients undergoing primary MVD.