Therapeutical approaches to paroxysmal hemicrania, hemicrania continua and short lasting unilateral neuralgiform headache attacks: a critical appraisal
BACKGROUND Hemicrania continua (HC) is a primary headache that comprises persistent unilateral pain, is associated with cranial autonomic features, and is responsive to indometacin. Some patients are unable to tolerate this treatment or it is contraindicated; for these patients, the medical options for therapy are restricted. Occipital nerve stimulation (ONS) is an effective treatment for medically intractable primary headache, but only three cases of HC treated with ONS have been reported. Here, we report long-term safety and efficacy data for ONS in six patients with HC. ONS was provided by a unilateral neurostimulation device, known as a bion, which might be described as a second-generation ONS device. METHODS Six patients aged 18 years or older who were diagnosed with HC had a suboccipital bion device implanted ipsilateral to their headache and received continuous unilateral ONS. A crossover study design was used: the bion was on for the first 3 months, off for the fourth month, and on again during long-term follow-up. Detailed prospective headache diaries were kept for 1 month before implantation and for 5 months afterwards. Long-term data were obtained from patients' estimates of their outcome. The outcome of this study was assessed by a comparison of headache pain severity before and after ONS. FINDINGS At a median follow-up of 13.5 months (range 6-21 months), five of six patients reported sufficient benefit to recommend the device to other patients with HC. At long-term follow-up, four of six patients reported a substantial improvement (80-95%), one patient reported a 30% improvement, and one patient reported that his pain was worse by 20%. The onset of the benefit of ONS was delayed by days to weeks, and headaches did not recur for a similar period when the device was switched off. Adverse events were mild and associated with transient overstimulation. INTERPRETATION ONS appears to be a safe and effective treatment for HC, particularly when indometacin is not tolerated or is contraindicated. The bion device was well tolerated, easily inserted without significant morbidity, and is one-twentieth of the volume of current devices. Such miniaturised devices are a potential new option for treatment of HC.