LONDON -- Electrical stimulation of the occipital nerve could be another option for patients with drug-refractory chronic cluster headaches.
LONDON, March 9 -- Electrical stimulation of the occipital nerve could be a new option for people with drug-resistant chronic cluster headaches.
In two pilot studies -- one here and one in Belgium -- the minimally invasive procedure was effective in reducing the intensity and frequency of cluster headache attacks for most patients, Peter Goadsby, M.D., of University College London and the University of California San Francisco, and colleagues, reported online in The Lancet.
The stimulation, administered by implanted electrodes, had few side effects other than paraesthesia in the occipital region, both research groups reported, but the benefit took weeks or months to appear.
Deep-brain stimulation of the hypothalamus has been shown to help intractable chronic cluster headache, which is regarded as a devastating disorder, according to Dr. Goadsby.
But deep brain stimulation carries with it a risk of cerebral hemorrhage that in at last one case has been fatal, said Dr. Goadsby.
Unlike deep brain stimulation -- which has an almost immediate effect -- improvements were not noticed for weeks, the researcher said, although the paraesthesia in the occipital region was felt as long as the stimulators were turned on.
On the other hand, Dr. Goadsby and colleagues said, if the equipment failed for any reason -- such as a dead battery -- the cluster headaches returned to their baseline intensity and frequency within days.
The latter finding, the researchers said, appears to rule out a placebo effect.
The British researchers enrolled eight patients in an open-label, uncontrolled trial, in which electrodes and a pulse generator made by Medtronic of Minneapolis were implanted.
At a median follow-up of 20 months, six of the eight patients were sufficiently satisfied with the experiment that they would recommend it to others, Dr. Goadsby and colleagues reported.
Two patients reported improvement of 90% to 95% in frequency and intensity of attacks, the researchers said, while four others reported more moderate improvements. Only one patient said the stimulation had no effect.
The Belgian group, led by Jean Schoenen, M.D., of Lige University, also enrolled eight patients with drug-resistant chronic cluster headaches and implanted similar equipment from Medtronic. Again, there was no control group, and because of the associated paraesthesia, it may be impossible to conduct a placebo-controlled trial, the researchers noted online in The Lancet Neurology.
Results were slightly better than in the British group - two patients were free of pain after a follow-up of 16 and 22 months, respectively; three patients had around a 90% reduction in the frequency of attack, and two patients had improvement of around 40%. One patient reported no effect.
Over the study period, the frequency of attacks fell by about 50% on average, the researchers said.
But that includes the early months of the study, in which the effect had not yet appeared. When the researchers compared baseline values to the last month of treatment, the average reduction in attack frequency was 79.9%.
To verify that the stimulators were causing the effect, the researchers switched them off from time to time and found that severe attacks recurred within one to four days.
To establish the clinical value of the procedure, more patients need to be studied, Anna Ambrosini, M.D., Ph.D., of the Mediterranean Neurology Institute in Pozzilli, Italy, wrote in accompanying commentary in The Lancet.
But there are enough data to suggest that patients with intractable chronic cluster headaches could be offered a trial of occipital nerve stimulation before going on - if necessary - to deep brain stimulation, she wrote.