Parkinson’s News Today recently published an article featuring a study in Italy showing the benefits of deep brain stimulation in patients with late-stage Parkinson’s disease.
The history of the subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson’s disease has been a model of success ever since it was first proposed in the 1980’s.
To date, over 120,000 Parkinson’s patients throughout the world have been implanted with DBS systems. Patients and their physicians have reported improvements in motor symptoms and involuntary movements.
However, there are no guidelines for physicians to follow when considering when, how, or if DBS should be interrupted or discontinued in treating late-stage Parkinson’s disease. This is the focus of a recent study conducted by researchers in Italy.
STN-DBS has shown efficacy in controlling Parkinson’s motor symptoms in patients whose disease is advanced and no longer see improvement in motor symptoms from their medication.
About Discontinuation
The benefits of STN-DBS in late-stage Parkinson’s are unclear. Specifically, physicians do not have guidelines to rely on when considering interruption or discontinuation of STN-DBS treatment for these patients.
The study in Italy evaluates STN-DBS’s usefulness for patients with late-stage Parkinson’s, especially patients who respond poorly.
The researchers stressed that the decision to recommend an elderly and possibly frail patient for STN-DBS should be based on benefits such as alleviating symptoms and improved quality of life.
These considerations prompted the researchers to create a guide for other physicians when deciding whether to interrupt or discontinue STN-DBS.
About The Study
Thirty-six late-stage Parkinson’s patients (median age of 71 years; average disease duration 27 years) were recruited at eight Italian DBS centers. The enrolled patients had received prior treatments with STN-DBS.
One other prerequisite was a requirement that their antiparkinson’s medication and stimulation parameters showed stability for three months prior to enrollment.
The researchers were looking for a minimum of ten percent improvement in patients, in which case the patients would be kept on STN-DBS, and the study would be ended.
Working With Poor Responders
Poor responders would have their stimulation turned off for a month while continuing to take their medication. After one month the patient’s motor function would be re-assessed.
If at that time no adverse events were reported and their motor function was stable, the patient and physician would most likely feel that it would appropriate to discontinue the stimulation.
However, if the patient’s condition began to deteriorate, the stimulation would be turned back on.
The Methodology
Patients who were being assessed were considered “off” their medication as they had received the last dose over twelve hours prior to taking the test.
The test was administered to some patients as “on” meaning the stimulation was activated for these patients but turned “off ” for others in the study. Each stimulation period lasted for over one hour prior to being assessed.
About the Implantation
The procedure involves the surgical implantation of an electrode in the patient’s brain. The electrode stimulates an area of the brain associated with a motor function called the subthalamic nucleus.
A neurostimulator that generates voltage-controlled pulses is also set under the skin. The neurostimulator was utilized in the development of a formula that guides doctors in their decision about whether to consider DBS discontinuation.
A formula was also created for physicians to use as a guide to treatment decisions for patients with late-stage Parkinson’s.
Results of the Study
After assessing the thirty-five enrolled patients, eighty percent were classified as being good responders. These numbers translate into a rating of a 17% improvement, which is statistically significant and clinically meaningful.
For patients who exhibited significant improvement, this was characterized as improvement in the patient’s:
- Resting tremor
- Postural stability
- Rigidity
- Movement
There were no improvements in posture, speech, or gait that were considered to be significant.
Only seven patients were assessed as poor responders, in which case the stimulation was switched off.
There were no specific features that the researchers could rely on to predict a poor response to the treatment.
Conclusion
After the study ended, only three of the thirty-five enrolled patients had discontinued the STN-DBS and were switched “off”. This suggests that 92% of patients in the study continued benefiting from STN-DBS.
The results of the study conducted by the researchers in Italy correspond to the general consensus that ninety-two percent of late-stage Parkinson’s patients have experienced improvement through STN-DBS.
