Although treating a disease by implanting an electrode into a patient’s brain and flicking a switch may seem like the stuff of science fiction, subthalamic neurostimulation is already an established treatment for advanced Parkinson’s disease. In patients with severe motor complications, neurostimulation can help manage motor fluctuations and dyskinesias, restore function, and improve quality of life. But do patients have to wait until symptoms are severe before they can flip a switch and turn science fiction into medical reality?
In this week’s NEJM, Dr W.M. Michael Schuepbach (Université Pierre et Marie Curie, Paris) and colleagues report on a study examining the use of neurostimulation in patients with early motor complications from Parkinson’s disease. The EARLYSTIM trial asked 251 patients about baseline quality of life using a 100-point questionnaire specific to Parkinson’s disease (the PDQ-39), then randomized them to subthalamic neurostimulation plus optimal medical treatment or optimal medical treatment alone. Adjustments to neurostimulation and medication were made according to pre-defined standards, while an independent expert panel assessed whether medication therapy was optimized.
At the end of the study, self-reported quality of life improved by about 8 points in the neurostimulation group but remained unchanged for the medication-only group. The neurostimulation group also had superior outcomes on a number of secondary endpoints, yet were also more likely to suffer a serious adverse event (55% versus 44%of patients, respectively).
In an accompanying editorial, Dr Caroline M. Tanner (Sanford University, Palo Alto) praises the EARLYSTIM trial as “one of the most rigorously conducted trials of neurostimulation” and suggests that aspects of the trial design may be used as a template for future studies. However, unlike the patients recruited to EARLYSTIM, patients in the real world tend to be older and are more likely to have dementia. It isn’t certain that these patients would reap similar benefits from this procedure. Moreover, neurostimulation has been associated with an increased risk of suicide, and the results of EARLYSTIM do little to quell those concerns. Other downsides include unknown long-term efficacy and cost.
While it’s not an electrical cure-all, neurostimulation may provide additional years of good function in carefully chosen patients. For these individuals and their families, this is one piece of science fiction future that they’ll be happy to have the option to consider now.