Conference Coverage

Levodopa Monotherapy May Be Adequate After DBS for Parkinson’s Disease

Failure to remain on levodopa monotherapy often results from incident mood disturbances.


 

LAS VEGAS—For pharmacotherapy following deep brain stimulation (DBS), many patients can be adequately treated with levodopa alone, but only a small group can be managed with dopamine agonists alone, according to a study presented at the 21st Annual Meeting of the North American Neuromodulation Society. The data address a question about which there has been little objective guidance.

Based on the findings, efforts to reduce anti-Parkinson’s disease medications following DBS should be directed toward dopamine agonists first, according to Alfonso Fasano, MD, PhD, Codirector of the Surgical Program at the Movement Disorder Center of Toronto Western Hospital in Ontario. The data nevertheless provide the option for individualized therapy, he added. For example, for patients with good outcome after DBS and no significant history of impulse-control disorders, it may be possible to taper levodopa therapy first, while maintaining dopamine agonists.

Alfonso Fasano, MD, PhD

In the randomized controlled trial, 36 patients were assigned to receive monotherapy with a dopamine agonist or levodopa following subthalamic nucleus (STN) DBS. All patients were on both medications before surgery. The investigators did not identify any between-group differences in variables predicted to affect symptom control. Yet the proportion of patients that were able to stay on monotherapy at three months was different between the study arms.

“Perhaps the main result of this study was that we found it difficult to keep patients on dopamine-agonist monotherapy, even after a successful DBS procedure,” said Dr. Fasano.

At three months after surgery, the proportion of patients remaining on monotherapy was 81% in the levodopa group and 32% in the dopamine-agonist group. At that point in the follow-up, all other patients in the two groups were on both treatments. At six months, fewer patients were taking their assigned drug as a monotherapy. The proportion in the levodopa arm had decreased to 63%, and the proportion in the dopamine-agonist arm had decreased to 13%.

More of the failures in the dopamine-agonist arm, relative to the levodopa arm, resulted from inadequate control of motor symptoms. Failure in the levodopa arm more commonly occurred following mood and sleep disturbances. But the investigators observed failures for both reasons in both study arms.

DBS permits a reduction in anti-Parkinson’s disease medications, but dose reductions should be undertaken slowly, because mood disturbances have been reported after abrupt discontinuation of dopamine agonists, according to Dr. Fasano. Specific strategies for reducing anti-Parkinson’s disease medications following DBS have not been based on evidence, however.

Overall, the results of the randomized study “are in keeping with a common-sense” approach, Dr. Fasano said. While the results emphasize the limited proportion of patients who can remain on dopamine agonists alone following DBS, they also suggest that most patients receiving levodopa will require low doses of both therapies.

With these results and observations, “maybe we are getting closer to a guideline of what to do with respect to medication after surgery,” Dr. Fasano said.

—Ted Bosworth

Suggested Reading

Fasano A, Appel-Cresswell S, Jog M, et al. Medical management of Parkinson’s disease after initiation of deep brain stimulation. Can J Neurol Sci. 2016;43(5):626-634.

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