Timing of deep brain stimulation in Parkinson disease: a need for reappraisal?

Abstract

We review the current application of deep brain stimulation (DBS) in Parkinson disease (PD) and consider the evidence that earlier use of DBS confers long-term symptomatic benefit for patients compared to best medical therapy. Electronic searches were performed of PubMed, Web of Knowledge, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials to identify all article types relating to the timing of DBS in PD. Current evidence suggests that DBS is typically performed in late stage PD, a mean of 14 to 15 years after diagnosis. Current guidelines recommend that PD patients who are resistant to medical therapies, have significant medication side effects and lengthening off periods, but are otherwise cognitively intact and medically fit for surgery be considered for DBS. If these criteria are rigidly interpreted, it may be that, by the time medical treatment options have been exhausted, the disease has progressed to the point that the patient may no longer be fit for neurosurgical intervention. From the evidence available, we conclude that surgical management of PD alone or in combination with medical therapy results in greater improvement of motor symptoms and quality of life than medical treatment alone. There is evidence to support the use of DBS in less advanced PD and that it may be appropriate for earlier stages of the disease than for which it is currently used. The improving short and long-term safety profile of DBS makes early application a realistic possibility.

FIGURE 1

Treatment pathways in Parkinson disease (PD) and the potential role of deep brain stimulation (DBS). The optimal treatment of PD evolves as the disease progresses. The figure shows a generally accepted paradigm for management (brown boxes). The current role for DBS is most commonly accepted for those PD patients with significant motor complications that limit quality of life, but whose other features (eg, L-dopa responsiveness, intact cognition) render them suitable for consideration of this therapy. We propose that DBS be considered earlier in the therapeutic program of PD (green boxes), when patients might be able to derive greater long-term benefit. COMT = catechol-O-methyltransferase; MAO-B = monoamine oxidase B. [Color figure can be viewed in the online issue, which is available at http://www.annalsofneurology.org.]