Many years ago, I remember seeing a middle-aged and pleasant lady at my clinic. Having suffered from PD for at least eight years, she could hardly walk on her own.
She told me that had recently undergone brain surgery at a foreign country. Looking very contented, she related to me the improvement of her mobility following the surgery on both sides of her brain (bilateral pallidotomy). Unfortunately, the surgery was not that straight-forward – it was complicated by severe difficulty in speaking and swallowing food.
I was very concerned by the very fact that she did not consult any Neurologist (brain specialist) before going for the surgery.
This middle-aged lady had been diagnosed to have PD for hardly five years. Surprisingly, she had gone overseas to undergo brain surgery twice.
Prior to the first surgery, her physical disability was quite mild. With a small dose of medications, she was independent in her daily activities. She could walk on her own and even do some household work. However, she was still not happy with her treatment and as such opted to go overseas for the first surgery on right side of her brain (unilateral pallidotomy). She did have some improvement in her symptoms but remained unsatisfied.
Two years after the first surgery, she went overseas again for the second surgery on the other side of the brain (Deep Brain Stimulation / DBS). This time, she reported some improvement again but remained convinced that her treatment (brain surgery) had not been successful.
This was simply a case of ignorance. She was not aware that bilateral pallidotomy was associated with a high risk of complications (difficulty swallowing and speaking). If she had consulted her Neurologist prior to the brain surgery, she would have been warned about the possible complications of this procedure. She would have been advised to go for another relatively safer type of brain surgery, which is DBS.
Her first mistake was that she had undergone brain surgery “prematurely”, i.e. at an early stage of illness when she had only mild physical disability.
Generally, brain surgery is considered when patients’ quality of life is significantly impaired despite taking maximal doses of medications. In other words, brain surgery is indicated when patients cannot carry out daily activities (e.g. walking, eating, bathing, etc) on their own, despite taking very high dose of medications. This usually happens when patients’ illness has progressed for at least ten years (advanced PD). At this stage when patients are generally incapacitated and desperate for improvement, the risk of complications of brain surgery is justified.
Her second mistake was that she had unrealistic expectation in the treatment of PD – she thought she could be as physically active as she was before the illness started. She expected the brain surgery to completely “cure” all the symptoms of PD (which was an impossible task).
I have to emphasize that even the best medical (medications) and surgical (brain surgery) treatments for PD can just help patients to recover by 50-90%, and not 100%. The ultimate aim of treatment for PD is to enable PD patients to significantly improve so that they can have almost normal quality of life.
What are the types of brain surgery for PD?
There are three types of brain surgery:
This is a process whereby nerve tissue from either aborted fetus (unborn human baby) or pigs is transferred to the brain of PD patients. The “new” brain tissue can grow and compensate for the loss of the patient’s original brain tissue. It is hoped that this process will restore the function of the patient’s brain and consequently relieves the slowness of patient’s body movement.
Recently, there have been reports of “cloning”, a process whereby human brain tissue is developed from living brain cells in the laboratory. The brain tissue produced by “cloning” can be used as a source of brain transplant.
There are several limitations of transplantation in PD. Firstly, the relief of the physical disability following transplantation is not consistently seen. Secondly, the use of aborted human fetus is controversial, as anti-abortion groups do not agree with such practice. Thirdly, this process is very expensive and available in a few centers in the whole world.
Thus, transplantation is still at an experimental stage and not an established treatment for PD.
b) Lesioning procedures
In this type of brain surgery, a specific area in the brain is destroyed using precise targeting. These procedures are called thalamotomy, pallidotomy (Figure 1) and subthalamotomy according to the area of the brain that is operated upon. Lesioning procedures are usually carried out on only one side of the brain. They have been shown to improve the physical disability mainly on the opposite side of the body of PD patients. Lesioning procedures are associated with 1% risk of dying during surgery and 5% risk of permanent weakness of limbs or blindness.
However, one of the limitations of lesioning procedures is that PD eventually affects both sides of the body. Thus, most patients will eventually need surgery on both sides of the brain (bilateral lesioning procedures). Unfortunately, lesioning procedures on both sides is associated with high risk of complications such as difficulty in speaking (slurring of speech) and swallowing, as well as loss of voice. As a result, bilateral lesioning procedures are no longer routinely recommended nowadays.
Figure 1. Pallidotomy on right side of brain – brain scan showing a “hole” at the right side of the brain (red arrow) where a small part of the brain tissue has been destroyed.
c) Deep brain stimulation (DBS)
DBS (refer to the video section) is a procedure (Figure 2) whereby an electrode (a thin wire) is inserted into the target area in the brain, commonly STN or GPi. The electrode is connected to a pacemaker, which is a pulse generator that is embedded under the skin of the chest. The pacemaker contains a battery that generates electrical current which is delivered to the brain. The moment the pacemaker is turned “on” by remote control, the patient’s symptoms such as slowness of movement and tremor instantaneously disappear.
The main advantage of DBS over the lesioning procedures is that it can be carried out on both sides of the brain simultaneously with minimal complications. This is very useful because, as mentioned earlier, patients eventually have symptoms of PD on both sides of the body. Other advantages are its reversibility and the lack of tissue destruction. There are early indications that long term electrical stimulation of the brain targets may effect neuro-modulation and thereby modify the long term outcome of PD.
The complications of DBS are related to the surgery itself and to problems with equipment. Firstly, the insertion of electrode may lead to bleeding in the brain and infection (1%). Secondly, the electrical stimulation may cause symptoms such as muscle cramp, seeing flashes of light and numbness of body (3-5%). This type of complication is however easily reversible when the strength (voltage) of the electrical current is reduced. Rarely, the electrode may break or get displaced (1%). Overall, the risks of complications are very low when patients are in the hands of experienced surgeons. Generally, DBS is safer than lesioning procedures.
The battery in the pacemaker usually can last up to five years. When the battery runs out, all the surgeon needs to do is remove it and insert a replacement. This operation is performed on the chest; there is no need to go for a second brain operation.
Figure 2. DBS – an illustrative picture showing the lead electrode in the brain, that is connected with a long wire to the pacemaker (pulse generator) which is embedded in the chest wall.
At what stage of illness do patients need to consider brain surgery?
At present, most PD specialists believe that surgery should be delayed “as long as possible”.
It is generally recommended at a later stage of PD (at least ten years of illness). The two main indications (reasons) for brain surgery are: a) severe physical disability that affects the activities of daily living (working, walking, driving, doing household work, etc.) despite taking the maximal number and dosage of drugs, and b) disabling and severe motor complications, especially dyskinesia.
Timing of surgery is a complex matter. It is not well defined how long surgical treatment should be delayed. While it is not advisable to do surgery too early, on the other hand, restoring a patient’s function after he has lost his job or independence may be too late. This can result in serious psychosocial and financial problems.
Which patients have better chances to benefit from brain surgery?
It is very important to know that not all PD patients can improve after surgery.
The patients who are most likely to benefit from surgery are : a) those who have significant improvement of physical disability after taking medications (Madopar / Sinemet), and b) those who develop dyskinesia, which is an abnormal and excessive movement of body (swaying of head or arms or legs resembling “dancing”) that usually occurs after taking a dose of Madopar / Sinemet.
Thus, the proper selection of candidates is crucial and should be made only by Neurologists / Neurosurgeons (brain surgeon) in order to ensure the success of brain surgery.
What is the benefit of brain surgery?
Brain surgery certainly improves the symptoms (trembling of hands, body stiffness, slowness of movement) and physical disability due to PD. The dyskinesia is significantly improved. Usually the total daily dose of medications can be reduced after the surgery. In addition, the quality of life of patients is also improved.
It is important to realize that although brain surgery dramatically improves the symptoms of PD, it certainly does not cure PD nor does it slow down the progressive loss of brain cells. All the previous symptoms and physical disability of PD will eventually recur. Nevertheless, brain surgery gives new hope for PD patients, especially those who are significantly disabled despite receiving maximal drug treatment. They can have reasonably good quality of life for up to another seven years, and probably longer.
Which type of brain surgery should a patient go for?
Nowadays, among all the various types of brain surgery, DBS is generally considered the surgery of choice for PD. This is because it is relatively safe and can be carried out on both sides of the brain simultaneously with minimal complications.
The main limitation of DBS is the high cost of the procedure which is a consequence of expensive electronic equipment. In Malaysia, the cost of DBS is RM 80 000 for the initial surgery and RM 60 000 for the replacement of the battery (needs to be changed every 3-5 years). As such, for those who have financial problem, pallidotomy is preferred as it is much cheaper (the estimated cost of pallidotomy in Malaysia is projected at just about RM 3 000 – 5 000 if performed at a government institution).
Making the final decision to go for brain surgery
The final decision on undergoing brain surgery and the type of brain surgery should be made only after consulting the Neurologist. It is a decision made by both patient and Neurologist when the benefit of surgery outweighs the risk of complications of surgery: when it is really worth going for the surgery despite facing the risk of complications.
In which countries is the brain surgery carried out?
In Malaysia, DBS is available at Sunway Medical Center (Kuala Lumpur) and University Sains Malaysia (Kubang Kerian, Kelantan). The other countries where brain surgery is available are Singapore, Japan, Australia, India, Japan, China, United States and Europe (United Kingdom, France).
It is very important for patients to understand the benefit and complications before they consider undergoing brain surgery. Patients should know the various types of brain surgery for PD, the associated complications, improvement of symptoms after surgery and the proper procedures for seeking surgical treatment. Brain surgery has dramatically improved the long-term outlook in the management of PD, and given new hope to PD patients.
Pic 1. The DBS surgery is carried out by the Neurosurgeon with the help of the Neurologist. Through a small hole on the skull, a pair of electrodes are inserted into the brain. Unlike other brain surgeries, the patients are conscious during the DBS surgery.
Pic 2. The electrode (bottom) which is inserted into the brain.
Pic 3. The battery, which is implanted under the skin of the chest, sends electrical signals into the brain via the electrodes.
Pic 4. The lump on the chest wall is the place where the battery is implanted.