Open and closed trials of botulinum toxin type A (Botox) in the treatment of disabling, chronic migraine and coexisting cervical dystonia suggest the therapy can offer significant relief. The following studies were presented at the 11th Congress of the International Headache Society.
A three-year, open-label trial of more than 200 patients with disabling, chronic migraine found that Botox significantly reduced the number of headache days and acute medications consumed, as well as associated disability. Ninan T. Mathew, MD, Director of the Houston Headache Clinic, reported results of Botox treatment on 208 patients (ages 16 to 77) who reported chronic intractable and disabling migraine attacks. Some of the patients had up to 10 Botox treatments, each consisting of about 32 injections in the scalp and neck.
The treatments’ effects lasted about 12.5 weeks, Dr. Mathew said. Three months after the initial injection, mean Migraine Disability Assessment (MIDAS) scores decreased from 83 to 27, and continued to decrease after the second and third treatments, at which point MIDAS scores stabilized in the range of 10.2 to 15.7. The mean number of headache days decreased from about 67 to 29 during three months of treatment.
Also, in 88 patients taking triptans, the mean number of tablets consumed decreased from about 16 per month before treatment to 4.2 tablets after treatment. Use of nonsteroidal anti-inflammatory drugs, isometheptene, or ergotamine also decreased significantly after Botox therapy, Dr. Mathew reported.
About 65% to 70% of patients respond to this treatment, according to Dr. Mathew. "We’re trying to identify why some patients respond and some don’t", he said. However, "long-term, continued benefit speaks against placebo effect," he noted -- although he allowed that large-scale, placebo-controlled trials in patients with chronic headaches are needed to confirm this. Such a trial is underway, with results not due for another year.
Two placebo-controlled studies suggested Botox can lessen pain in patients with cervical dystonia and provide effective prophylaxis against coexisting migraine and chronic tension-type headache. One study, presented by Mitchell Brin, MD, Associate Professor of Neurology at Mount Sinai School of Medicine in New York City and Allison Brashear, MD of Indiana University Medical Center in Indianapolis, was a double-blind, placebo-controlled, randomized study of Botox for management of pain in 170 patients with cervical dystonia.
Results showed that after six weeks of treatment, 29.5% of patients receiving Botox achieved at least a one-grade decrease in pain, compared with 12.5% of placebo patients.
The second study, presented by Hartmut Gobel, MD, Director of the Clinical Pain Research Group and the Kiel Pain Clinic in Germany, included 40 patients with migraine and tension-type headache. The study found that the average number of days with migraine and tension-type headache decreased significantly in the Botox group compared with the placebo group.
In the first month after treatment, the investigators observed a 41.6% decrease in the number of migraine days, while for the placebo group, the number of migraine days increased by 5.6%. Botox reduced the number of tension-type headache days by 19.3% one month after treatment, compared to an increase of 2.4% with placebo, the investigators reported.
Botox injections are not just for relaxing muscles, according to Kei Roger Aoki, PhD, and Minglei Cui, both employees of Allergan Inc., Irvine, California, the manufacturer of Botox, who reported the results of animal experiments which found that "inhibition of nociceptive processing at the peripheral site and at the spinal cord level may underlie the mechanism of Botox effects in alleviating pain conditions."