Neurostimulation therapies for primary headache disorders: present and future

Purpose of review
Most pharmacological treatments of primary headache disorders are partially effective and have
cumbersome side effects. Therapies with better efficacy and tolerance are needed. Neurostimulation techniques may have this potential. This is an attempt to summarize the latest clinical trial results published in the field.
Recent findings
Hypothalamic deep brain stimulation is effective in drug-resistant chronic cluster headache (drCCH) but not riskless. Recent anatomical MRI studies indicate that the effective stimulation sites are rather widespread. Occipital nerve stimulation (ONS) seems to be effective in up to 76% of drCCH patients and its benefit long-lasting. A minority of patients are able to abandon preventive drugs. Its mechanism of action appears nonspecific. In chronic migraine, randomized controlled trials of ONS showed recently encouraging results, but long-term studies are missing. An ongoing sham-controlled trial suggests sphenopalatine ganglion neurostimulation (SPGS) efficacy in drCCH acute treatment, but possibly also in preventive
therapy. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) modulate cortical excitability and connectivity. TMS could prevent headache when applied over the occipital cortex during the migraine aura. Repetitive TMS and tDCS have provided mixed results in a few small studies and warrant further trials.
Summary
Neurostimulation therapies inaugurate a new era in headache management and offer a promising alternative to medications. Future studies are necessary to provide evidence-based efficacy data, knowledge on their mode of action and information about their pharmaco-economic advantages.