CHICAGO — The efficacy of deep brain stimulation can be maintained for up to 10 years in DYT1 dystonia, according to data from a prospective study in 26 consecutive patients.
DYT1 dystonia is a form of primary dystonia that typically presents in early childhood, starting in the foot or hand, and is caused by a specific mutation in the DYT1 gene.
Significant decreases in Burke-Fahn-Marsden dystonia rating scale motor and disability scores were observed 1 year after DBS surgery. No significant difference was found when the 1-year scores were compared with the scores at 3, 5, and 6 years for the whole population, Dr. Laura Cif reported in a poster at the 12th International Congress of Parkinson's Disease and Movement Disorders.
Efficacy of DBS therapy was maintained in the two patients who were followed as long as 10 years.
“The homogeneity of the population we studied minimized any variations in the interindividual response, which could be due to genetic background or surgical procedure,” she wrote.
Long-term disease progression is even more important in DYTI dystonia than in other disorders treated with DBS because patients are much younger at the time of surgery and therefore require significantly longer-term follow-up, according to Dr. Cif of the University of Montpellier (France). The age at onset ranged from 6 to 20 years in the study. Moreover, DYT1 dystonia can develop into a life-threatening condition.
Eighteen patients were implanted with a single pair of electrodes in the internal globus pallidus (GPi) and eight patients had a second pair of GPi electrodes implanted because of incomplete initial response or subsequent worsening. In spite of there being no significant difference one year after surgery, a significant difference was observed at 5 years between patients with a single lead vs. those with double leads in motor (8.95 vs. 31.5, P = .01) and disability (3.61 vs. 7.85, P = .021) scores. After implantation of additional pairs of leads, only four of eight patients showed improvement.
During the follow-up, no patient died, Dr. Cif said in an interview.