So say European doctors including Jens Volkmann, MD, of the neurology department at Germany's Christian Albrechts University.
Dystonia includes "twisting, repetitive movements or abnormal postures caused by involuntary muscle contractions," write the researchers.
They studied 40 people who had had severe dystonia for at least five years.
The patients were about 40 years old, on average, and lived in Germany, Austria, or Norway. They had tried dystonia medications with "partial" success, the researchers write.
First, the patients were videotaped while walking and tapping their fingers. They also took psychological, quality of life, and mental skills tests.
A week later, the researchers programmed the devices in half of the patients to start working. They set the other patients' devices to not deliver any brain stimulation for three months.
The patients didn't know if their devices were programmed for brain stimulation. Three months later, they were videotaped and tested again.
Patients were more likely to show movement improvements, less disability, and better quality of life with the working implants.
Their movement scores (based on the videotapes) improved by 39%, their disability dropped 38%, and their quality of life rose 30%, the study shows.
In comparison, movement scores improved by 5%, disability scores by 8%, and quality of life by 11% in the patients who didn't get brain stimulation.
The researchers extended the study for three more months. This time, they set all the brain implant devices for deep brain stimulation.
The patients who continued deep brain stimulation for those three extra months maintained their improvements.
Those who previously hadn't gotten deep brain stimulation caught up with the other patients' gains.
The patients varied in their degree of improvement, and six didn't reach the researchers' minimum goal of a 25% drop in dystonia symptoms.
During the study, 19 patients reported 22 side effects, including infection after the implantation surgery and slurred but understandable speech.
The speech side effects were resolved or improved by adjusting the stimulation, the researchers write.
The study was partly funded by Medtronic, which makes the deep brain stimulation device. Medtronic is a WebMD sponsor.