ST. PAUL, MN -- October 21, 1999 -- A new medication offers patients relief
from a painful and often debilitating muscle disorder of the neck and shoulders
called cervical dystonia.
This new type of botulinum toxin-a medication frequently used to relieve muscle disorders-is safe and effective in most cervical dystonia patients, including those who have become resistant to other medications, according to two studies published in the October 22 issue of Neurology, the American Academy of Neurology’s scientific journal.
Cervical dystonia, also known as spasmodic torticollis, is characterized by abnormal, involuntary, muscle contractions of the neck or shoulder muscles. This results in abnormal head postures or repetitive, rhythmic, jerky movements and, frequently, tremor and pain. The disease usually occurs later in life. Disability from cervical dystonia may significantly interfere with the ability to lead a normal life.
Injection of botulinum toxin type A into affected muscles has been the primary therapy for cervical dystonia.
Botulinum toxin blocks the release of the neurotransmitter acetylcholine, temporarily weakening the muscle and releasing the painful contraction. Similar to botulinum toxin type A, type B toxin works by inhibiting the release of acetylcholine, but uses a different mechanism than type A toxin.
"About five percent of all patients treated with botulinum toxin type A develop resistance," said neurologist Mitchell Brin, MD, author of one of the studies and director of the Movement Disorders Division at Mount Sinai School of Medicine, New York. "The resistance is probably mediated through the formation of antibodies that result from the repeated injections. These patients have limited options for effective symptom relief."
Researchers do not know yet whether patients will develop an antibody to type B toxin.
"Dystonia is a terribly disabling condition. The development of another type of toxin is an important step in understanding the clinical use of these therapies in the management of inappropriate muscle contractions," Brin said. "My ultimate hope as a researcher is that we can use these toxins to also further our understanding of the disease, and ultimately find a cure for dystonia."
Researchers in the first study injected 109 cervical dystonia patients with placebo or botulinum toxin type B in two to four affected muscles in one session. Using a rating scale for improvement in pain, disability and disease severity, total score average improvement at week four for the group receiving placebo was 4.3 compared to 11.7 for patients receiving the full dose of botulinum toxin type B. The treatment’s beneficial effects lasted for 12 to 16 weeks.
The second study evaluated 77 patients who, after repeated use, had become resistant to therapy with botulinum toxin type A. Patients received toxin type B or placebo injections in two to four muscles and were evaluated for improvement for 16 weeks. At week four, those receiving placebo had rating scale average improvements of 2.0, while patients receiving botulinum toxin type B demonstrated significant improvements in pain, disability and severity with a total score average improvement of 11.1. Patients receiving toxin type B maintained improvements for 12 to 16 weeks.
No serious adverse side effects were reported, although more patients receiving botulinum toxin type B experienced dry mouth than those who had previously received type A.
Both studies were supported by grants from Athena Neurosciences, Inc., which markets botulinum toxin type B under the trade name NeuroBloc. The American Academy of Neurology, an association of more than 16,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research.
It is reported to provoke greater antibody formation, hence neds to be repeated at more frequent intervals.
Related Link: Athena Neurosciences, Inc.
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