Types of surgery

Surgery in Parkinson’s disease (PD) may be necessary for practical reasons, e.g., if a person is prescribed Duodopa® gel, a minor surgical procedure is required to insert the tube for delivery of the medication into the digestive tract (duodenum).

Surgery can also be used to directly address symptoms by targeting specific areas of the brain. There are two main forms of brain surgery currently used for PD:

• deep brain stimulation (DBS) – the most commonly used procedure at present. It involves implanting wires into the specific areas of the brain that are overactive in PD and connecting these wires to a device that delivers electrical pulses. This device, called a pulse generator, is implanted under the skin on the chest wall or abdomen (see Figure, below). The electrical signals are sent to the corresponding overactive areas of the brain to reduce their activity. This technique does not destroy any brain tissue and is reversible, but is usually intended as a long-term measure (may be permanent). DBS can be referred to as thalamic, pallidal, or subthalamic, depending upon which brain area is targeted.
• lesioning – involves destroying part of the specific brain region that is causing PD symptoms. The operation is named after the part of the brain that is targeted i.e., thalamotomy, pallidotomy, or subthalamotomy. Because it is destructive, lesional surgery is rarely performed for PD nowadays and, indeed, in most centres, subthalamotomy is not offered at all. Thalamotomy can only be carried out on one side of the brain and is therefore not usually very helpful for people with PD, whose symptoms almost always affect both sides of the body. Pallidotomy may be considered for a few people with very severe dyskinesias who cannot have subthalamic nucleus DBS, but it is also, generally, only performed on one side of the brain.

Deep brain stimulation (DBS)

(Click on animation to enlarge.)

Case story Mrs P was becoming unable to continue to live t home on her own because she was experiencing severe gait freezing and tremor when in the OFF state and was therefore taking quite large doses of PD medication, including a dopamine agonist. As a result of this medication, she had also become increasingly confused and her family did not feel that it was safe for her to live at home on her own. Following subthalamic DBS, she was able to substantially reduce her PD medications because her gait freezing and tremor were controlled by the deep brain stimulator. Her confusion subsequently also resolved and she continued to live at home for several more years.