A treatment called occipital nerve stimulation (ONS) has been found to reduce both the frequency and severity of headaches in patients suffering from chronic cluster headaches. The new trial results, published in The Lancet Neurology, suggest low doses of electrical stimulation are just as effective as higher doses.
The idea of electrically stimulating certain nerves to treat chronic pain has been around for more than half a century. Over time the technique was refined as scientists discovered implanting electrodes to stimulate the occipital nerve could treat migraine. In 2011 the treatment was approved for use in Europe but only for those suffering chronic migraine that was unresponsive to at least three drugs.
This new research focused specifically on patients with a condition labeled medically intractable chronic cluster headache (MICCH). This disabling condition covers about 15 percent of patients suffering chronic cluster headaches, who experience severe chronic attacks but do not respond to any current treatment.
The clinical trial was blinded and randomized, however, it was not placebo controlled. Instead, the researchers designed a dose responsive protocol because ONS causes paresthesia, a tingling sensation making it easy for subjects to tell real stimulation from sham.
“We, therefore, compared the effects of 100 percent versus 30 percent of the individually accepted electrical dose of ONS in a randomized, double-blind study,” the researchers write in the study. “Both intensities were hypothesized to cause similar paresthesia, mitigating the risk of unblinding, but differential efficacy.”
For six months 130 patients used the ONS device and, interestingly, the researchers saw improvements in both low- and high-dose cohorts. In fact, both dose groups reported similar levels of improvement, suggesting lower doses could be just as helpful as the higher accepted dose.
At the three-year follow-up point at least half of the entire cohort reported a consistent 50 percent drop in headache attack frequency. The researchers explain in the study it is impossible to completely exclude the placebo effect in these findings but note it's unlikely the improvements seen can be entirely considered placebo response.
“… it seems unlikely that such an abrupt and long-lasting dramatic clinical improvement in such a seriously and longterm chronically affected patient population, can be ascribed primarily to placebo,” the researchers write in the study. “All participants were highly disabled and had a long and unremitting chronic history of frequent and intensely painful attacks of cluster headache, not responding to ≥3 conventional preventive medications.”
Rolf Fronczek, a neurologist working with ONS in The Netherlands, says these new findings offer some hope to MICCH patients with no other treatment options. He does note patients need to be closely monitored as the treatment is still relatively experimental.
"Patients who could not previously be treated can now take advantage of a new and promising treatment,” says Fronczek. “However, scrupulous evaluation and monitoring are still necessary to keep their treatment at the optimum level."
The new study was published in the journal The Lancet Neurology.
Source: Leiden University
