Therapeutic neurostimulation in chronic headaches: problems of patient selection.

Chronic daily headache that does not respond or no longer responds to prophylaxis is commonly encountered at specialist headache centres. Animal and brain imaging studies indicate that peripheral neurostimulation affects brain areas involved in pain modulation, providing a rationale for its use in these conditions. We examine problems related to the selection of chronic daily headache patients for peripheral neurostimulation. These conditions are often associated with analgesic (including opioid) overuse, and psychiatric or other comorbidities, and the terms used to describe them (chronic migraine, transformed migraine, chronic daily headache and chronic tension-type headache) are insufficiently informative about these patients when proposed for neurostimulation. Longitudinal studies indicate that pre-existing subclinical depressive and anxious states play a key role in chronicisation and that the probability of responding to treatment is inversely related to headache frequency. These considerations suggest the need for extensive characterisation of patients proposed for neurostimulation. We propose that patients being considered for neurostimulation should be followed for at least a year, and that their headache over this time should consistently be frequent (all or most days) and drug refractory. We also propose that only completely drug-resistant (as opposed to partially drug-resistant) patients be considered for neurostimulation unless there are other indications.