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A new study on deep brain stimulation involving six NBIA patients shows that it provided long-lasting improvement for dystonia, a common feature of the disease that causes painful, prolonged muscle spasms.
Dr. Pierre Castelnau, the lead author from the Clocheville Children’s Hospital, Tours, France, presented at the Scientific Workshop a study performed with the group of Professor Philippe Coubes, Gui de Chauliac Hospital, Montpellier, France (www.urma-montpellier.org).
From this study involving 6 PKAN patients (4 typical, 2 atypical), Dr. Castelnau said they found that abnormal movements and spasms disappeared in all six while they were at rest. Three patients who had been in wheelchairs no longer needed them afterwards, and speech became intelligible in half of the patients. Writing became legible in five of the six, according to the study, published earlier this year in the Annals of Neurology by the American Neurological Association.
Dr. Castelnau stated, “Although DBS does not cure PKAN, it provides a great source of hope for the patients and their families for relief from disabling dystonia. There is a reasonable amount of experience accumulated over the past 10 years in PKAN and other diseases causing dystonia. However, collaborative studies should be promoted to better explore DBS benefit in these diseases and the role of NBIA families toward this goal could be very important.”
Although it is not known whether DBS would be as effective for the non-PKAN forms of NBIA where no PANK2 mutation has been identified, it seems that the so-called secondary dystonias show a good and comparable response to DBS benefit in primary dystonia, Castelnau said. He believes that longer periods of observation and specifically designed studies are needed to appreciate DBS’s impact on non-motor aspects of the disease, such as visual, cognitive and psychiatric symptoms.
Dr. Penny Hogarth, who discussed the study and various treatments available for NBIA at the Third International Family Conference, said she was encouraged by the results of the French study. However, she was not endorsing DBS surgery over a medical approach to treatment, making the point that the potential risks and benefits of each approach should be made on an individual basis. Although DBS results in other neurological disorders have been very encouraging, studies involving larger number of patients with PKAN and non-PKAN forms of NBIA are needed before widely recommending surgery, she said. Hogarth noted that any invasive brain surgery, including DBS, carries a risk of brain bleeding, stroke, seizures, and infections.
The surgical team in France reports a very low rate of such complications for over a hundred children operated on for a variety of neurological disorders. Their safety record, which is not duplicated by other surgical teams in North America or Europe, may come from their relatively rapid and straightforward surgical procedure based on magnetic resonance imaging (MRI) control rather than long lasting peri-operative electrophysiological recordings. Hogarth encourages any family considering DBS as a treatment option to inquire about the experience, surgical methods and complication rate of the surgical team contacted.
Baclofen is another option for dystonia. This drug can be given by mouth with good benefits but it may be more effective for some patients when delivered via an implanted pump device directly to the spinal cord, Hogarth said. Some patients report better results than others.
Botulinum toxin (Botox) injections are also used to relax individual muscles, but it’s only effective for about three months, so you must get new injections on a regular basis. A host of other medications are often prescribed for NBIA patients, and some can be helpful, including Valium; dopamine blockers, such as Tetrabenazine; and dopamine replacers, such as Sinemet. “We’re very unclear about the role of dopamine in this disorder,” Hogarth said. “It could vary depending on the disorder type.” The other confounding problem with NBIA is, despite the therapy, it continues to progress, she said.
The recent progress in dystonia therapy provides new avenues of hope for NBIA patients. While more research is needed to identify specific treatments which can cure the genetic deficits, these functional and reversible approaches provide a potential improvement of autonomy in daily living that were not accessible in the past.
Please see our Web site at www.NBIAdisorders.org for the power point presentation from Dr. Hogarth’s session on dystonia treatments.
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