Long-term outcomes of peripheral nerve field stimulation in patients with refractory trigeminal neuralgia: a cohort study

OBJECTIVE Peripheral nerve field stimulation (PNFS) is a neuromodulatory surgical treatment used to treat severe refractory trigeminal neuralgia. However, most studies have had comparatively short follow-up periods. Thus, the authors performed a long-term analysis of patients who had received PNFS for trigeminal neuralgia. METHODS An institutional database was searched for patients who had received PNFS from 2012 to 2017. Only patients with trigeminal neuralgia who received a permanent implant were included. The electronic medical records were reviewed, and patients were contacted for outpatient appointments or telephone interviews. Perceived treatment effectiveness was the primary outcome parameter. Additionally, revision surgeries, other invasive treatments after PNFS implantation, system explants, and the painDETECT questionnaire (PD-Q) score at the latest follow-up were assessed. RESULTS Fifteen patients (6 male and 9 female; median age 70 years, range 45–87 years) were included in the analysis, 7 with classic trigeminal neuralgia and 8 with secondary trigeminal neuralgia (7 due to multiple sclerosis, 1 due to an inoperable meningioma). The median symptom duration was 11.5 years (range 2.5–17 years) and the median follow-up duration was 93 months (range 30–126, IQR 66.5–107 months). Half the male patients still perceived treatment effectiveness at the latest follow-up assessment, but none of the female patients did. Kaplan-Meier analysis with the log-rank test revealed a median time to failure of 2 years, with a median of 5.1 years in males and 1.5 years in females (p = 0.003). The median PD-Q score was 16 (range 0–27). There were 7 revision surgeries in 4 patients, and 4 patients underwent additional procedures after implantation. CONCLUSIONS PNFS in trigeminal neuralgia is associated with a high rate of treatment failure in the long term, with females possibly experiencing worse results than males.