Earlier may be better for neurostimulation in Parkinson’s

By Eleanor McDermid, Senior medwireNews Reporter

Adding neurostimulation to best medical therapy boosts quality of life in patients with relatively early-stage Parkinson's disease (PD), shows a randomized trial.

The study included patients who had only recently begun to experience motor symptoms - for about 1-2 years. They had been diagnosed with PD about 7 years before study entry, on average, whereas patients are typically considered for neurostimulation after living with the condition for 11-13 years.

In an editorial accompanying the study in The New England Journal of Medicine, Caroline Tanner (Parkinson's Institute, Sunnyvale, California, USA) cautions that neurostimulation only improves specific motor symptoms, while the underlying disease progress continues, eventually resulting in disability via other mechanisms.

"Ideally, treatment of Parkinson's disease should improve not only motor, but all, features of the disease," she says. "Neurostimulation of the subthalamic nucleus does not ameliorate all symptoms of Parkinson's disease, but for carefully chosen, highly functioning patients, it may provide many additional years of good functioning."

All 251 patients in the trial received best medical therapy, which was provided in accordance with guidelines in almost all patients, as rated by independent experts. Yet quality of life on the Parkinson's Disease Questionnaire (PDQ-39) declined slightly over the 2-year study period in the 127 patients who received only medical therapy, by 0.2 points (1%).

By contrast, the average score in the 124 patients who also underwent neurostimulation improved by 7.8 points (26%), resulting in a significant difference between the two groups, report Günther Deuschl (University Hospital Schleswig-Holstein, Kiel, Germany) and team.

Neurostimulation improved outcomes in the PDQ-39 domains covering mobility, activities of daily living, emotional wellbeing, stigma, bodily discomfort, and cognition, but not in those assessing social support and communication.

Tanner comments that "patient-determined outcomes arguably provide the most important assessment of the clinical value of neurostimulation." But she cautions: "Whether these results would be obtained in older patients with Parkinson's disease or in less-experienced medical centers is not known."

The quality-of-life improvements were paralleled by a 53% improvement in off-medication motor symptoms on the Unified PD Rating Scale, with a smaller but still significant improvement seen for on-medication scores.

Neurostimulation also resulted in reduced levodopa-induced complications, explained by the fact that these patients reduced their levodopa-equivalent daily dose by 39% over the study period, whereas those on medical therapy alone required a 21% dose increase.

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