The Evaluation prior to DBS Surgery
A team of experts, including a movement disorder specialist (a neurologist with extra training in Parkinson’s) and a neurosurgeon (a doctor who performs DBS procedures), conduct an extensive assessment when considering DBS for someone. The evaluation consists of medication and symptom review, examination both on and off Parkinson’s drugs, brain imaging, and oftentimes also detailed memory/thinking testing (to detect any problems that could worsen after DBS). If DBS is offered, it’s important to discuss the expected benefits (e.g., decreased tremor, fewer medications, etc.) as each person’s experience is unique. It’s also critical to discuss the potential surgical risks, including bleeding, stroke and infection.
The DBS Procedure and Device Programming
In DBS surgery, thin wires called electrodes are placed into one or both sides of the brain in specific areas (either the subthalamic nucleus or the globus pallidus interna) that control movement. Usually a person remains awake during surgery so that he or she can answer questions and perform certain tasks to make sure that the electrodes are positioned correctly. However, some medical centers now are using brain imaging to guide the electrodes to the right spot while a person is asleep. Each method has its pros and cons and may not be suitable for everyone or available everywhere.
Once the electrodes are situated, they are connected to a battery-operated device (similar to a cardiac pacemaker) that is typically placed under the skin below the collarbone. This device, called a neurostimulator, delivers continuous electrical pulses through the electrodes to decrease Parkinson’s symptoms.
A few weeks after surgery, a movement disorder specialist uses a handheld programmer to set parameters, tailored to each individual’s unique symptoms, into the neurostimulator. The DBS settings are gradually tweaked over time and medications are simultaneously adjusted. Most people are able to decrease (but not completely discontinue) Parkinson’s drugs after DBS. Determining the optimal combination of drugs and DBS settings — that which gives the most benefit and the least side effects — can take several months and even up to a year.