Invasive neurostimulation

Chronic migraine afflicts 1-5% of the global population and poses a substantial burden on subjects’ quality of life and on health services utilization [1]. Although most patients benefit from abortive and preventive drugs, a subgroup of patients remains refractory to treatment. Refractory chronic migraine is one of the greatest chal- lenges in headache medicine and, in these patients, inva- sive techniques should be considered. In the past 20 years neuromodulatory approaches, already proved effective in other chronic pain syndromes, have been increasingly used for refractory primary headaches. Neuromodulation, a reversible and adjustable manipula- tion of pain pathways is an evidence-based invasive treat- ment for chronic pain conditions and it may be applied to any neural structure: spinal cord, deep brain, and periph- eral nerves. Recently, three 12-week follow-up prospective, rando- mised trials have been conducted to validate occipital nerve stimulation in chronic migraine and intractable chronic migraine associated to occipital localization of pain. Considering the primary outcomes (50% reduction in pain intensity, 50% decrease of headache days) all the three trials have failed. In one of these studies [2], although the second follow-up at 52 weeks has shown important effects on pain severity, headache days, HIT-6 and MIDAS scores (60% of patients achieved 30% reduction in headache days and/or pain, 50% achieved 50% reduction in headache days and/or pain, 70% reported excellent or good headache relief and improved QoL, 70% would undergo the procedure again), it has also shown high incidence of adverse events related to the procedure (70% of patients experienced at least one * Correspondence: marco.mercieri@uniroma1.it 1Department of Medical-Surgical Sciences and Traslational Medicine, Sapienza University of Rome, Sant’Andrea Hospital, Rome, Italy Full list of author information is available at the end of the article AE, 41% of AEs required supplemental surgery, 8.6% of AEs required hospitalization). A more recent prospective, open-label, exploratory study [3] assessing the long-term (6-months) safety, tolerability and efficacy of cervical high frequency (10 kHz), paresthe- sia-free, spinal cord stimulation in a cohort of 14 refrac- tory chronic migraine patients (refractory also to Onabotulinumtoxin-A) has shown good results on reduc- tion of headache days, medication intake, HIT-6 and MIDAS scores. The patients were carefully selected, for refractory chronic migraine, not considering topographic criteria for localization of pain, and were assessed by two different psychologists before eligibility. A significant reduction in headache days was observed at 24 weeks (average 7.0 days). Seven (50%) subjects recorded a >30% decrease in headache days, while 5 (36%) subjects reported a reduction in headache days greater than 50%. Eight sub- jects (57%) reverted to an episodic pattern of headache (<15 days a month). Medication intake reduced signifi- cantly, and four subjects discontinued triptans. Few adverse events have been reported. HF10-SCS deserves further clinical investigations to evaluate its possible role in the management of rCM.