Winter 2008

Insights into Neurotoxins Provide Relief From Dystonia

Since the 1980s, physicians have been using neurotoxins, particularly botulinum toxin, to minimize dystonia symptoms. A first-line, FDA-approved therapy for cervical dystonia, hemifacial spasm and blepharospasm — and used off-label for other focal dystonias — neurotoxin injections can be quite effective in the right situations.

But, says Jill Ostrem, M.D., "The procedure can be challenging in the absence of experience and expertise in identifying the overactive muscles to target for injection — particularly those in the neck — and in deciding how much toxin should be injected into each muscle."

Choosing the Right Approach

Ostrem and her colleagues at the Movement Disorders Clinic at UCSF Medical Center evaluate dystonia patients and consider the use of neurotoxins in the context of other treatment options. Neurotoxin injections are often considered before medication for patients with cervical dystonia, blepharospasm and hemifacial spasm because they are usually more effective and result in fewer side effects.

"In cases where dystonia affects the whole body, if medications like trihexyphenidyl, baclofen and benzodiazepine fail, then for certain problematic body regions — not the whole body — neurotoxins are a localized treatment option that can provide relief," Ostrem says. "For example, we can use neurotoxins to help relax the muscles of the hand to improve function and reduce pain."

Once they've decided to use neurotoxin injections, Ostrem and her colleagues usually begin with a low dose based on published guidelines. "This is because we don't often know how each individual patient might respond," she says. "If the patient does not show an adequate response to the low dose — not enough effect or not enough duration of effect — and does not have side effects, then we might consider increasing the dose at the next injection session."

Side effects can range from mild, flu-like symptoms or local bleeding to excessive weakening of the muscle. "The main worry in cervical dystonias is that there will be some spread of the toxin to nearby muscles that involve swallowing," says Ostrem. "If this occurs, the side effect is usually mild and transient. In the right hands, neurotoxin injection is a safe and effective treatment that lasts for about three months until the nerve regenerates, at which time the treatment can be given again."

Patient Needs Drive New Research Paths

While dystonia is not usually life-threatening, the pain and embarrassment that it can cause patients drive some of the research efforts at the UCSF Movement Disorders Clinic. Ostrem's colleague, Graham Glass, M.D., is the principal investigator in a study of patients with refractory cervical dystonia. The study tests the usefulness of information gained from a multichannel EMG machine that simultaneously records all cervical muscle activity. This will potentially help the injector have a better sense of the specific dystonic muscles involved.

"This technique is not routinely used in clinical practice today," Ostrem says. "It is our hypothesis that the information will enable the injector to deliver the toxin more accurately to the affected muscles, which may result in greater improvement of symptoms."

For more information, contact Dr. Ostrem at (415) 353-2437.

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