Deep brain stimulation & other surgical treatments
As Parkinson’s progresses you may find that medication does not adequately control your symptoms. If this happens, your doctor may recommend deep brain stimulation.
Deep brain stimulation (DBS)
Brief intro + link to detailed Med info page [separate doc/sections for Medtronic + Boston + St Jude] [copy being supplied by pharma]]
Deep brain stimulation (DBS) uses one or two surgically implanted medical devices called neurostimulators, similar to cardiac pacemakers, to deliver electrical stimulation to precisely targeted areas on each side of the brain. DBS is used mainly to treat people with advanced Parkinson’s as well as other movement disorders such as essential tremor and dystonia.
A stereotactic head frame is used to keep the patient's head still during surgery and the neurosurgeon uses special imaging techniques, such as magnetic resonance imaging (MRI) or computerised tomography (CT), to map the brain and locate the site to be stimulated: either the subthalamic nucleus (STN) or the internal globus pallidus (GPi). The patient remains awake through out as it is important that they can give feedback regarding the sensations they experience as the surgeon establishes the exact site for the implant. As the brain itself has no pain receptors this is not painful, although the lengthy surgery can be demanding and tiring.
Stimulation appears to block the signals that cause disabling Motor symptoms and so helps provide greater control over movement. Once the leads are implanted in the brain, extensions are fitted down through the neck to an Implantable Pulse Generator (IPG) which controls the delivery of neuro-stimulation, and is placed under the skin in the chest. A hand held device is used to programme and to switch the IPG on and off so stimulation can readily be adjusted.
Unlike lesioning, DBS does not cause permanent damage to the brain and the stimulation it provides can be adjusted as frequently as necessary, allowing for some change in symptoms over time.
Other surgical treatments
Over time, medication may no longer effectively control Parkinson’s symptoms. In some carefully selected cases, surgery may help. Neurosurgery (surgery of the brain) focuses on three target areas to treat Parkinson’s:
- the subthalamic nucleus (STN) – this seems to be the site that helps most symptoms so is more favoured
- the thalamus - for treating drug-resistant tremor
- the globus pallidum internus (GPi), a part of the globus pallidus - for treating stiffness, dyskinesia and akinesia, dystonia and pain
The choice of treatment and the target selected is based on a careful evaluation of each patient and his or her needs.
Neurosurgery is usually only considered for people with Parkinson’s whose symptoms are no longer adequately controlled by medication. It is generally not recommended for anyone with psychiatric problems, dementia, cerebrovascular disease, uncontrolled high blood pressure or for people over 75.
The first step when considering surgery is to discuss it with your doctor. He or she will then refer you to both a neurologist and a neurosurgeon who specialise in treating Parkinson’s. Each form of surgery carries its own risks and you should discuss these, and the likely benefits, with the experts.
Your neurosurgeon will answer your questions and explain what the surgery involves and what happens afterwards. You may also want to ask how many operations the surgeon has performed and the results that have been achieved.
This involves very carefully damaging a particular part of the brain. The damage is called a lesion. Computer imaging is used to locate the target site precisely. The lesion is made by inserting an electrode with its tip at the site and then passing an electric current through the tip.
There are currently three target areas for lesioning:
- Pallidotomy – This is the most common lesioning technique, in which a lesion is made in the GPi area of the brain. This is usually only carried out on one side of the brain; more rarely both sides are lesioned to control severe symptoms, but the risks are greater.
- Thalamotomy – A lesion is made in the thalamus, usually only on one side, as treating both sides is thought to be too risky.
- Subthalamotomy – A lesion is made in the STN area of the brain. This is less commonly used because it carries higher risks and the long-term effects are unclear.
Because lesioning is irreversible and cannot be modified without further surgery, it is not ideal and is unlikely to be a long-term treatment option.
Gamma knife surgery
This is a type of radiotherapy which involves directing gamma radiation through the skull at damaged brain tissue. The risks of this surgery are relatively high compared to other techniques and it is therefore not currently considered practical.
Other surgical techniques under research
For information on other techniques currently under research see Current research.
Last updated: Dec 2014