Occipital Nerve Stimulation for Refractory Chronic Migraine: Results of a Long-Term Prospective Study

Background: Refractory chronic migraine affects approximately 4% of the population worldwide andresults in severe pain, lifestyle limitations, and decreased quality of life. Occipital nerve stimulation (ONS)refers to the electric stimulation of the distal branches of greater and lesser occipital nerves; the surgicaltechnique has previously been described and has demonstrated efficacy in the treatment of a widevariety of headache disorders.Objectives: The aim of this study is to evaluate the long-term efficacy and tolerability of ONS formedically intractable chronic migraine.Study Design: Prospective, long-term, open-label, uncontrolled observational study.Setting: Single public university hospital.Methods: Patients who met the International Headache Society criteria for chronic migraine, all of themhaving been previously treated with other therapeutic alternatives, and who met all inclusion and exclusioncriteria for neurostimulation, received the implantation of an ONS system after a positive psychologicalevaluation and a positive response to a preliminary occipital nerve blockage. The implantation was performedin 2 phases: a 10 day trial with implanted occipital leads connected to an external stimulator and, if morethan 50% pain relief was obtained, permanent pulse generator implantation and connection to the previouslyimplanted leads. After the surgery, the patients were thoroughly evaluated annually using different scales:pain Visual Analogue Scale (VAS), number of migraine attacks per month, sleep quality, functionality in socialand labor activities, reduction in pain medication, patient satisfaction, tolerability, and reasons for termination.The average follow-up time was 9.4 ± 6.1 years, and 31 patients completed a 7-year follow-up period.Results: Thirty-seven patients were enrolled and classified according to the location and quality of their pain,accompanying symptoms, work status, and psychological effects. Substantial pain reduction was obtainedin most patients, and the VAS decreased by 4.9 ± 2.0 points. These results remained stable over the followup period. Five of the 35 permanently implanted patients with migraine attacks at baseline were free fromthese attacks at their last visits, whereas the pain severity decreased 3.8 ± 2.5 (according to the VAS) inthe remaining patients. Seven of the 35 permanent implanted devices were definitively removed: 2 devicesbecause of treatment inefficacy, and 5 devices because the patients were asymptomatic and considered to becured from their pain, even with the stimulation off. Systemic side effects were not observed.Limitations: Limitations of the current study include its uncontrolled and open-label design.Additionally, not all patients completed the 7-year follow-up period.Conclusions: We consider that the trigemino-cervical autonomous and cervical connection may explainwhy ONS might relieve chronic migraine pain, but this is just a theoretical explanation which should bedemonstrated in future studies. The results achieved in this study suggest that ONS may provide longterm benefits for patients with medically intractable chronic migraine. These outcomes are slightly betterthan previous reports and were maintained over the 7-year follow-up. We believe that an accurateselection of patients, realization of diagnostic occipital nerve blocks, psychological evaluations, rigoroussurgical technique, and appropriate parameter programming helped us achieve these outcomes.Key words: Refractory chronic migraine, headache, occipital nerve stimulatino, peripheral nervestimulation, occipital nerve block