Occipital Nerve Stimulation in Chronic Migraine: The Relationship Between Perceived Sensory Quality, Perceived Sensory Location, and Clinical Efficacy-A Prospective, Observational, Non-Interventional Study.

INTRODUCTION: Occipital nerve stimulation (ONS) is used to treat therapy-resistant chronic migraine. Clinical use has resulted in a wide intraindividual and interindividual variation of clinical efficacy. The aim of this study was to analyze a potential relationship between sociodemographic variables, headache parameters, perceived sensory quality, perceived sensory location, as well as clinical efficacy. METHODS: Thirty-two subjects (21.9% male, mean age 45.77 years) suffering from chronic migraine refractory to other treatment and therefore treated with ONS were included in this study. We used a computer-based imaging method for mapping the ONS-induced perceived sensory location, the perceived spatial sensory field size, as well as the perceived sensory quality in a long-term course over 21 months in weekly time intervals. Additionally, the effect of ONS on the migraine headache was documented weekly by the participants using a verbal rating scale. Over the observation period, a total of 808 individual weekly data sets were recorded and a potential relationship between ONS-induced perceptions and headache parameters could be analyzed. RESULTS: We found that 48.9% of stimulation intervals were reported as effective by patients. Women displayed a significantly higher responder rate than men. The reported effectiveness did not differ depending on age, the average number of migraine days per month, the MIDAS score, or the duration of the migraine disorder prior to ONS treatment. Implantation with trial period led to significantly lower responder rates than without the trial period. The most frequently perceived sensory quality of "tingling" was found significantly more frequently in non-responders than in responders. Responders displayed significantly lower pleasantness scores for their reported perceptions than non-responders. Sensations that were spatially perceived above the line connecting the external acoustic meati with the external occipital protuberance (MOP line) led to patients reporting a positive clinical effect significantly more frequently than sensations spatially perceived below the MOP line. Spatially small fields of sensory perception were correlated with a higher responder rate than those covering broader areas. CONCLUSIONS: The ONS-induced sensory location, the size of the spatial sensory field, as well as the sensory quality are significantly correlated with the reported clinical effectiveness. The results suggest that besides surgical technique, the individual and continuous programming of the stimulation parameters is clinically relevant in increasing the therapeutic effectiveness.