SURGERY FOR PARKINSON'S DISEASE - a patient's guide
There has been a recent resurgence in surgery for Parkinson's
disease due to advanced diagnostic imaging techniques like CT
scanning and MRI scanning.
Surgery to destroy a tiny part of the brain responsible for
sending incorrect messages to the movement control centre of the
brain began in the 1950s, but the operations were extremely risky and
when the drug levodopa was discovered in the 1960s, interest in the
However, since the late 1980s, new diagnostic techniques have
brought fresh interest in brain surgery. New imaging techniques have
helped to reduce the risk of the operation, providing surgeons with
more precision. These operations are known as "stereotactic lesional
surgery", and are suitable for certain groups of patients.
Surgery is not a cure for Parkinson's disease and surgeons are
very selective on who they operate to ensure they get a good
It is still not known how the surgery works, but it is very
successful for some patients.
There are three different operations used to treat Parkinson's
disease: "Pallidotomy" and "Thalamotomy" which have been used in the
past, and recently a new technique known as "Deep Brain Stimulation"
has been developed.
This operation involves making a cut in the deep part of the
brain, known as the thalamus, which is responsible for the tremors in
This operation is effective for tremors, and drug-resistant
tremors. The ideal candidate is a young patient, with a shake as the
predominant feature on one side that has not responded to drugs.
Complications include weakness down the same side of the body
which is being treated, softer speech, and difficulty swallowing.
Sometimes these unwanted effects disappear but in some patients they
If the operation is performed on both sides the risk of
complications is greater and few surgeons will operate on both sides
at the same time or within a short timeframe. Normally they require a
space of some years.
The operation also involves destroying part of the brain
responsible for Parkinson's disease, but this time the region known
as the globus pallidis is damaged. This part of the brain is
responsible for the stiffness, slow movements and tremors seen in
This operation helps ease most symptoms of Parkinson's disease.
The most dramatic benefit is for patients with drug-induced
dyskinesia (involuntary movements), and can reduce these abnormal
movements by 90 percent or more. The operation also helps to reduce
tremors, slowness of movement and stiffness. Patients are often able
to reduce their dose of levodopa following the operation.
The best candidate for this operation would preferably be a young
patient who has been on levodopa for sometime but the effects are
wearing off and has significant involuntary movements on one side of
Complications include weakness down one side, problems with
vision, speech, and an exaggeration of psychiatric problems if the
patient has a mental illness.
In Auckland, so far 27 pallidotomy operations have been performed
since 1996, with success rates similar to overseas results.
A large metal frame is fitted firmly over the patient's head, and
a CT scan or MRI scan is used to determine the correct measurements
of the area to be destroyed. The measurements are checked twice, and
a probe that is fitted on the frame is placed in the correct
Then, with the patient still awake, a mild electric current is
passed down the probe to the part which will be destroyed to test the
patient's reactions to the current. If the patient gets tingling in
the arm or sees flashing lights, it means the measurements may be
Once the measurements are absolutely correct, the probe is then
placed through the skull and a larger electric current is passed down
the probe which heats the tip and destroys the target area.
Deep Brain Stimulation:
This operation is the most recent advance in brain surgery for
Parkinson's disease. It involves placing fine wires deep in the brain
to the same positions used for either pallidotomy or thalamotomy
operations, and attaching them to a small electrical stimulator,
similar to a pacemaker, which is inserted in the collar bone.
The stimulator can be turned on and off by the patient with the
use of a magnet rubbed over the device, and to alter the amount of
electrical current being used to stimulate the brain.
The operation can be carried out on both sides of the brain at the
same time, and is believed to work by causing a paralysis of the
brain cells involved in the tremor and symptoms of Parkinson's
Surgeons need to be careful to get the balance right in this
operation. However, the risks with deep brain stimulation are less
than with thalamotomy and pallidotomy, and it can be turned off if
The operation is expensive and is not yet widely available in New
Zealand. It is hoped it will become more accessible in future.
This article is based on a speech to the New Zealand Parkinson's
Disease conference by Auckland neurologist Dr David McAuley.
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