Deep brain stimulation (DBS) improves overall quality of life and social functioning in patients in earlier stages of Parkinson’s disease, according to results of a two-year clinical trial.

The study, led by Günther Deuschl, a professor at Christian-Albrechts-University in Kiel, Germany, and Yves Agid, a professor in neurology and experimental medicine at the Hôpital de la Salpêtrière in Paris, France, is reported online in the New England Journal of Medicine on 14 February.

The researchers conclude that DBS was more effective than medical treatment in patients with Parkinson’s disease and early motor complications.

DBS is already established as a treatment for patients with advanced Parkinson’s disease.

It is not a cure, and it does not stop the disease from progressing, but in the right patients, it can significantly improve symptoms, especially tremors, and it can also relieve muscle rigidity.

To perform DBS, the neurosurgeon drills a hole in the skull and inserts an electrode about 10 cm into the brain. The electrode delivers mild electrical signals that disrupt and block the brain impulses that cause Parkinson’s symptoms.

A wire under the skin connects the electrode to a battery implanted near the collarbone.

DBS can be done on one or both sides of the brain. The target areas are usually the thalamus, subthalamic nucleus, and globus pallidus. In this study, the target area was the thalamus.

The purpose of the 2-year clinical trial, called EARLYSTIM, was to assess the use of DBS in earlier stages of Parkinson’s disease, when “motor complications have just developed and before patients are significantly affected in their social and occupational functioning”.

The study recruited 251 patients with early motor complications and randomly assigned them to receive either DBS or best medical treatment.

The patients were of average age 52 and had had the condition for an average of 7.5 years.

To measure effectiveness of the treatment, the researchers assessed quality of life measures from a questionnaire known as PDQ-39, and social functioning from a short psychosocial questionnaire known as SCOPA-PS.

They assessed changes in key areas of motor disability and activities of daily living using the scale UPDRS II. They also assessed any improvements in complications resulting from use of Levodopa, one of the main drugs used to treat Parkinson’s.

The results showed that patients who received DBS had a 26% improvement in quality of life scores compared with no improvement in the medical treatment group. There was a similar result for social functioning.

The results also showed that compared to medical therapy, DBS was significantly superior to medical treatment with respect to motor disability, activities of daily living, levodopa-induced motor complications, and time with good mobility and no dyskinesia.

Among adverse side effects, suicide or attempts at suicide were not very different in the two groups, suggesting the cause lies with the patients rather than the type of treatment, something that is important to take into account in patient counseling, note the authors.

Deuschl says in a statement:

“The study showed surprisingly homogeneous results in favor of DBS compared with medical treatment.”

“The most important result is that quality of life of these patients and their social functioning was significantly improved. It is also meaningful that the operation has fewer side effects in this younger population than in advanced disease,” he adds.

Deuschl suggests that the study has the “potential to change the international guidelines for the treatment of Parkinson’s disease and will put DBS as a treatment option at a much earlier stage of disease severity.”

In an accompanying editorial, Caroline Tanner, an epidemiologist who lectures in health research and policy at Stanford University, describes the study as “one of the most rigorously conducted trials of neurostimulation”.

However, she warns that the patients in the trial were not typical Parkinson’s patients: they were all under 60 years old when they underwent the surgery, they didn’t have dementia, and on the whole they responded well to the medication.

Matthew Stern, Parker Family Professor of Neurology at the University of Pennsylvania, says:

“While it is premature to recommend DBS to all patients with motor complications, particularly earlier in the course of PD, it can now be considered a treatment option in this group of individuals.”

He says these results “will surely fuel the debate on the impact of DBS on disease progression further and underscores the need for long term follow up of the EARLYSTIM patients”.

A study published in Neurology in 2012, suggests that DBS remains an effective treatment for Parkinson’s disease for at least three years.

Written by Catharine Paddock PhD