What formalities need to be done before Deep Brain Stimulation (DBS) surgery?
There are a few formalities to complete before DBS surgery:
1) VERIFYING THE DIAGNOSIS:
First and foremost, the diagnosis of Parkinson’s disease needs to be confirmed. A careful history and examination are critical. But, in addition, a small therapeutic experiment is also done.
Levodopa Challenge Test: You will be asked to stop taking your Parkinson’s medications for at least 12 hours and come to the hospital in the early morning. There, the Neurologist will carefully examine you and give you a score for motor functioning. He/She will use a very lengthy scale called the UPDRS-scoring system.
Then, you will be given a significant dose of levodopa, for example, 3 tablets. This dose is usually slightly higher than the dose you are currently taking.
The Neurologist will again reexamine you 30 minutes, 1 hour and if needed 1.5 hours after taking the Levodopa tablets. If your UPDRS score improves by 30% or more, it indicates that you are likely to improve after Deep Brain Stimulation Surgery (DBS). The maximal improvement that you see after this large dose of levodopa is likely to be the maximal improvement you can expect after DBS.
2) RULING OUT SEVERE DEPRESSION & COGNITIVE PROBLEMS:
DBS can occasionally worsen Depression. It may sometimes worsen thinking and memory issues. The ideal person for DBS is a well-adjusted individual with no problems with thinking and memory.
That being said, mild depression and thinking problems are very common with Parkinson’s disease. Therefore, the Neurologist will ask you to visit a psychiatrist and a neuropsychologist to quantify these issues.
Provided you do not have severe problems in these areas (e.g. suicidal tendencies), you will proceed with the rest of the workup.
3) GENERAL CHECKUP:
DBS involves general anaesthesia. Therefore, a thorough workup by an anaesthetist – including clearances for surgery from cardiologists, chest physicians or other doctors as appropriate – is an essential part of the preparation.
4) SETTING REALISTIC EXPECTATIONS:
This is possibly the most important part. You are counselled regarding the limitations of DBS. Your counselling will include some of the following concepts:
DBS is not a magic bullet. It leads to increased ON-time (4-6 hours on average) and decreased severity of symptoms during the OFF time. On average, after surgery, the patient can hope to have 11-12 hours of excellent functioning during the day. However, even after DBS many patients will still experience fluctuations and OFF-times.
DBS may also cause improvements in some often neglected symptoms such as improving the quality of your sleep.
Deep Brain Stimulation does not improve all symptoms of Parkinson’s disease. Some symptoms, such as unsteadiness do not respond to DBS treatment. Other symptoms such as freezing while walking, may show variable improvement.
You will need to take some medications even after DBS. The doses of medications after GPi-DBS may remain the same, or may even increase. Medication doses can be reduced after STN-DBS, but this is done carefully and gradually over 3-6 months.
Programming (described later) can take many months to complete. During this time, the patient can expect a gradual recovery of motor function. However, finding the optimum parameters for maximal benefit can take up to 6 months. Periodic reprogramming is usually required.
Most patients improve after DBS surgery. Some patients do not show adequate improvement even if the electrode is properly positioned, and the programming is done correctly. This lack of response in some patients happens in all institutions throughout the world. Some, but not all, of these patients may show improvement after advanced programming techniques. The exact reason why some people do not respond adequately is not known but is being vigorously researched throughout the world.
What is the procedure of Deep Brain Stimulation (DBS) surgery?
You will be asked to stop your medications at least 12 hours before the surgery.
In the first part of the surgery, you will be awake.
After making sure adequate anaesthesia is given to make the skull numb, a thin wire (the electrode) is inserted into the brain – this process is almost painless. The end of the wire is placed in one of two targets: The Sub-thalamic Nucleus, or the Globus Pallidus Interna. The wire is then connected to an electrical stimulator. Then, that part of the brain is stimulated. This stimulation is painless.
You are then asked to move your hand with and without the electrical stimulation. Your hand shaking and stiffness will also be recorded. If you show dramatic improvement with electrical stimulation, that confirms that the electrode is in the right position. The wire is fixed in that position.
The same process is then repeated on the other side. The location of both leads is later further confirmed by doing a CT-scan, which is then compared to your MRI – all to make sure that the wires are in the right location.
At this point, the major part of the surgery is over.
Once this part of the process is completed, you will sleep because of the anaesthetic medications. During this time, the surgeon will connect the final battery to the wires, and keep the battery below the skin of your chest.
The total duration of the surgery is about 4-6 hours.
What are the risks of Deep Brain Stimulation (DBS) surgery?
Although this is surgery on the brain, as compared to other surgeries, it is relatively minor. Therefore the risks involved are low. But they are not non-existent.
- The risk of death is less than 1%
- Approximately 5% of patients can have serious complications such as stroke, seizure and infection. But most of the problems are cured with medications. Only 1% of these patients have permanent problems due to these complications, such as permanent weakness on one side of the body.
- A few patients have minor problems such as problems in wire connection, or a non-functioning battery. These are easily corrected.
In short, almost about 90-95% of patients do not have any complications during or after the surgery, and the risk of death or permanent problems is minimal (less than 2%).
How long is the hospital stay after Deep Brain Stimulation (DBS) surgery?
About 5 days. Some patients may be discharged home early, while some may be observed for a slightly longer time.
What should you expect after Deep Brain Stimulation (DBS) surgery?
Most doctors will not switch on stimulation immediately after the surgery. They will wait for any swelling, post-surgery tiredness or confusion to settle before doing so. Many neurologists will wait for about 4 weeks before switching on stimulation.
However, many people report an improvement in their symptoms even before stimulation is switched on. The physical process of electrode insertion causes this improvement, possibly by disrupting bad circuits temporarily (micro-lesioning). This effect (non-electrical) is transient and usually wears off after 4 weeks.
In the initial month, you will keep very regular follow-ups with your neurosurgeon who will check for side-effects such as infection. After 4 weeks / 1 month, you will report for the first programming session with the Neurologist.
What is programming for Deep Brain Stimulation (DBS)?
The battery that is placed below the skin in the chest is programmable. It can be programmed using a wireless programmer.
The doctor can use a handheld device to change various parameters of stimulation, including:
1. The exact location getting stimulation.
2. The strength of the stimulus.
3. The duration of each “pulse” of stimulation and the frequency of these pulses.
In some devices (namely, St. Jude device) it may be possible to set additional parameters so that the current can be “steered” into the area of most benefit, and away from areas whose stimulation can cause side-effects.
DBS programming is an art rather than a science – The most common adjustment is gradually increasing the amplitude of stimulation of the contact that is closest to the target area. However, if this causes side-effects, then a contact slightly away from the target area may be a better choice. Increasing the pulse width instead of the amplitude when more stimulation is needed may lead to the battery lasting for a longer duration. Low-frequency stimulation may help with freezing of gait… and so on…
Therefore, you need to be patient during this process. The more you contribute to this process, the more you will benefit from it. Finding the best set of parameters for you will involve a good working relationship between you and the doctor, and can take 3-6 months.
What are the side effects of Deep Brain Stimulation (DBS)?
As noted before, two problems can become worse after DBS:
1. Psychiatric problems, such as severe Depression.
2. Problems with thinking and memory.
Because of this reason, all patients who undergo DBS are screened for this issue. If these issues are not severe before the surgery, usually they are not a problem after the surgery.
How long does the improvement with Deep Brain Stimulation (DBS) last?
Recent research indicates that improvement with DBS lasts for an extremely long time. We know now that it can last for 10 years and probably much more than that.
As the patients who had DBS implanted grow older, we will have more data on whether it lasts even longer than that. At this point, there is no evidence that DBS “stops working” at any point.
Dr. Siddharth Kharkar
Dr. Kharkar is a Neurologist, Epilepsy specialist & Parkinson’s disease specialist in Mumbai, Maharashtra, India. He has trained in the best institutions in India, US and UK including KEM hospital in Mumbai, Johns Hopkins University in Baltimore, University of California at San Francisco (UCSF), USA & Kings College in London.