Ricerc@Sapienza

Chronic migraine (CM) affects up to 4% of the global population, causing a mean annual cost (in euro) of 2400 €/patient/year. Greater Occipital Nerve (GON) block is a minimally invasive technique known to be effective as prophylaxis in chronic migraine. Although side effects are sparse, they may be cumbersome, so GON block should be used carefully. However, to date, no efficacy predictor factors are available for this technique. We will investigate habituation deficit and intensity dependence of auditory evoked potentials (IDAP) as potential predictor of clinical response to GON block. Habituation deficit is the hallmark of migraine and it changes according to the status of disease, changing from CM to EM; IDAP is a measure of central serotonergic transmition, found to be altered in migraine, being steeper (low serotonin) interictally and higher (high serotonin) ictally. We will recruit consecutive patients with chronic migraine (CM) with/without medication overuse headache (MOH), according to ICHD3 beta criteria and tenderness in GON emergence point, with a fulfilled headache diary for a month before and a month after the GON block. Healthy volunteers (HVs) without history of headache will be recruited as gender- and age-matched control. CM/MOH and HVs presenting other neurological or psychiatric conditions will be excluded. Visual (habituation) and auditory (IDAP) evoked potentials will be recorded before (T0) and after 1 week (T1) from the GON block. GON blocking will be performed with 4mg betamethasone and 2% lidocaine, unilaterally or bilaterally according to tenderness. Clinical data (headache frequency, day, etc) will be recorded at baseline (T0) and after 1 month (T2). Wilcoxon's test for paired samples and Whitney-Mann test for independent samples will be used to compare groups (CM before and after; and CM and HV). We speculate that a baseline milder habituation deficit and a higher IDAP slope may be related to a higher response rate to GON block.