Should deep-brain stimulation treatment be considered earlier in Parkinson’s disease?

This study investigated the benefits of subthalamic neurostimulation for treatment of Parkinson’s disease that has recently stopped responding well to medication. The study concluded that subthalamic neurostimulation is an appropriate and effective treatment option for early fluctuating Parkinson's.

Patients with Parkinson's disease are initially prescribed medication, such as levodopa, to help improve motor symptoms. Levodopa acts as a substitute for the chemical dopamine, which is lost in Parkinson's disease.

Over time, the effectiveness of levodopa wears off and patients can experience periods of motor fluctuations and abnormal movements (dyskinesias). Subthalamic neurostimulation (STN), or deep brain stimulation (DBS), is an alternative, surgical treatment for PD. It is recommended for patients with advanced Parkinson's who are unresponsive to medication. It is highly invasive and requires lifelong specialized care following surgery. 

STN is not a cure for Parkinson's disease, and is generally used only in the later stages of the disease. There is some evidence to suggest that it should be considered as a treatment option for patients in early fluctuating stages of the disease.

Six clinical reports have investigated the effectiveness of STN compared to other treatment options. STN was more effective than medication at reducing symptoms in the ‘off state’ by 35% to 50%. This is the period when medication is not having any affect and symptoms are noticed. STN improved mobility in Parkinson's patients in early fluctuating and advanced stages.

Eleven studies investigated the length of time over which STN is effective. Improvements in motor symptoms including tremor, rigidity and abnormal movements were maintained over time (5-10 years later). There was no evidence that STN can delay late stage Parkinson's symptoms including dementia, speech problems and poorer gait.

Studies investigating quality of life following STN consistently reported improvements. The improvements are similar in patients with early fluctuating and advanced disease stage.

Side effects are common due to the invasive nature of the surgical procedure. Post-operative care is crucial and requires a specialized team. The risk of brain hemorrhage ranged from 1.6% to 5%.

A recent clinical trial (EARLYSTIM) reported improvements in motor function following STN in patients with early fluctuating Parkinson's disease. Adverse effects including depression and injuries were reported, however there was a lower incidence of surgical complications. A number of patients attempted suicide in this study (evenly split between control and surgical groups).

The authors concluded that subthalamic neurostimulation may be an appropriate and effective treatment option for selected patients with early fluctuating Parkinson's disease.

This study reviewed only 1 study investigating STN in early fluctuating Parkinson's (EARLYSTIM). More studies are needed to determine if it is an appropriate and effective treatment option.