A small, implanted electrostimulator helped about 25% of patients with frequent cluster headaches obtain virtually immediate and complete relief from acute attacks, researchers said here.
Additionally, in the sham-controlled trial involving 43 patients, some two-thirds showed some type of response to the patient-controlled therapy, including reductions in attack severity, frequency, or both, according to Rigmor Jensen, MD, PhD, of Glostrup Hospital in Glostrup, Denmark, speaking at the International Headache Congress.
The treatment involved an almond-size device placed behind the maxilla with a short lead projecting into the sphenopalatine ganglion (SPG), a nerve bundle that controls autonomic, sensory, and motor neural functions in the cranium. Patients can turn the stimulation on by holding a cellphone-sized controller to their cheek. Removing the controller turns the stimulation off. The specific stimulation parameters, including frequency and voltage, are programmed into the controller by the physician or a technician.
About Cluster Headache
Distinct from migraines, cluster headaches are marked by unilateral pain felt around and behind the eye with a severity that can be extremely disabling. It is often accompanied by neurological effects including tearing and nasal discharge. The attacks are relatively infrequent in most patients – occurring a few times annually – but about 15% experience them daily. Patients in the current study reported attack frequencies ranging from four to 70 per week.
Jensen noted that the SPG has been considered the locus for cluster headache since 1908, and a number of treatments have been attempted. These included injections of various drugs and surgical procedures, with many of these showing good short-term results. But these approaches are still invasive and have to be repeated with each attack, while those aiming for a permanent solution have often had irreversible adverse effects.
Animal and early clinical studies had suggested that high-frequency electrostimulation delivered to the SPG would be both effective and reversible, Jensen said. A U.S.-based company called Autonomic Technologies developed the device used in the current study and provided the funding.
Further confirmation of the SPG’s role in cluster headache was provided in another study reported here. Henrik Schytz, PhD, MD, reported results of a clinical study using the same Autonomic Technologies device showing that, with different settings than those used in the therapeutic trial, electrical stimulation can also induce cluster headaches.
Types of cluster headache
There are two types of cluster headache, episodic or chronic (long-term).
episodic – headache clusters are separated by headache-free periods of one month or more
chronic – headache clusters are separated by headache-free periods of less than one month, or are not separated at all
About 10% of cluster headache cases are chronic.
Who is affected
Cluster headaches are rare and affect around 1 in 1,000 people. Anyone can be affected, but approximately 8 out of 10 people who have them are men and most are smokers.
It’s not known what causes cluster headaches, but they’re more common in autumn and spring. In some people, an attack can be triggered by drinking alcohol or an extreme increase in temperature (such as from exercising in hot weather).
Instead of the 80-120 Hz frequency used in the other study, Schytz’s group set the device to rates of 5-60 Hz. In six patients who had received the device for therapeutic purposes, using this low-frequency setting produced immediate severe headache in three of them. Reverting to the normal high-frequency setting stopped the pain, Schytz said.
Short-Term Therapeutic Outcomes
The therapeutic results reported by Jensen and colleagues were not unexpected, as short-term outcomes in the first 32 patients treated in their study were published earlier this year in the journal Cephalalgia. But Jensen’s oral presentation, as well as two related posters presented ,here included results from the entire cohort and extended to 1 year after implantation.
What are the risk factors for cluster headaches?
In medicine, a risk factor is a condition, illness, situation or environment which raises the risk of developing a disease or condition. For example, obese people are more likely to develop diabetes type 2 compared to people of normal weight. Therefore, obesity is a risk factor for diabetes type 2.
For cluster headaches, the risk factors include:
Being male – approximately 8 in every 10 sufferers are male.
Being an adult – nearly all suffers say their cluster headaches started after they were 20 years old.
Ethnic ancestry – people of African ancestry are twice as likely to suffer from cluster headaches, compared to Caucasian people.
Smoking – the majority of male sufferers are smokers.
Alcohol consumption – a significant proportion of sufferers claim that alcohol is a key trigger during a cluster period (not during remission periods).
Genetics – if you have a close relative (parent or sibling) who has (had) cluster headaches, your risk of having them yourself is greater.
In the study, called CH-1, 43 patients were recruited, although five did not complete the initial treatment period. One became pregnant and was excluded, three had the device removed prematurely because of lead migration or improper positioning, and implantation failed in one. Jensen and colleagues reported data on the 38 who completed 3 to 8 weeks of active stimulator use, and on 28 who completed 1 year of follow-up.
The controller was set to randomly deliver full stimulation, imperceptible stimulation, or no stimulation at all for any given attack. Although patients were not told about the settings, they were not fully blinded because full stimulation is normally perceptible to patients.