Stimulating nerves in the brain may help ease pain for people who have not been able to find relief from cluster headaches, two teams say.

Cluster headaches usually occur in bouts or clusters that last from a week to a year, with severe headaches reoccurring on one side of the head. The attacks may last from 15 minutes to three hours.

Both studies were small, and involved implanting electrodes to stimulate a certain area of the brain called the occipital nerve.

"Occipital nerve stimulation in cluster headache seems to offer a safe, effective treatment option," said Peter Goadsby of University College London in Britain, who led the study published in Thursday's issue of The Lancet.

People with chronic cluster headaches usually take preventive drugs, but a small number of patients do not respond to the treatment.

Doctors have tried stimulation of the brain's hypothalamus as an alternative treatment for these patients, but there is a risk of developing a fatal brain hemorrhage.

Goadsby's team implanted electrodes to stimulate the occipital nerve in eight patients with cluster headaches who did not respond to medication. After an average of 18 months, six of them showed improvements in headache frequency and severity, and seven said they would recommend it to others.

When the battery in the device ran out, symptoms returned, the researchers said.

Worth further study

In a second study appearing in Lancet Neurology, researchers tested the electrode on another eight patients.

Jean Schoenen and colleagues from the Headache Research Unit of Belgium's Liege University said one patient went pain-free for 16 months, and another patient for 22 months. 

Three others said they had 90 per cent reduction in the frequency of attacks. Another person switched off the stimulator after four months, saying it did not work.

Overall, the studies suggest occipital nerve stimulation is slightly inferior and slower than deep-brain stimulation, but seems safer and has fewer side-effects, Anna Ambrosini of the Headache Clinic at Neuromed in Pozzilli, Italy, said in a Lancet commentary.

It is worth testing the electrode approach on a larger group of patients, she concluded, recommending patients try the approach before turning to deep-brain stimulation.