Deep Brain Stimulation (DBS) Surgery – The Game Changer

1. What is Deep Brain Stimulation (DBS) surgery:
   1. DBS is a surgical technique that has two electrical leads placed in the Sub Thalamic Nucleus (STN) or Globus Pallidus Internus (GPi) region of the brain,  which are connected to a Pulse Generator.  The Pulse Generator constantly generates electricity and sends them to the electrical leads to cancel out the misfiring neurons.
   1. DBS is most effective to counter motor symptoms such as tremors, brady kinesia, dyskinesia, dystonia etc.  It is not an effective solution for other, non-motor symptoms.  In  any case, your neurologist is the right person to assess the need for and timing of the DBS surgery.
2. Eligibility for DBS surgery : The first step is for your neurologist (or Movement Disorder Specialist) to assess your readiness and eligibility for DBS.  As per current practice, you may be considered eligible for DBS if you satisfy the following criteria:
   1. You should generally be less than 70 years of age.  however, depending upon your condition, you may be evaluated for suitability for this surgery up to 75 years of age.
   1. You should have had DBS for at least four years from diagnosis
   1. Syndopa (Sinemet in the US) and other dopaminergic medications are generally effective in mitigating your motor symptoms
   1. However, the effectiveness of these dopaminergic medications is decreasing or you are having to increase the frequency and / or dosage continually to counter the symptoms
   1. Side effects (such as dyskinesia) are affecting the quality of life
   1. I checked all five boxes above and my neurologist agreed that my quality of life was impacted such that it made sense to do the DBS surgery now.
3. Choosing the DBS device:  With that decision made, we had to choose the brand and model of the DBS device.  Upon discussion with the neurologist, we agreed that we will go for Percept PC from Medtronic, the most recent offering from them which features the BrainSense technology designed to capture brain signals using the implanted DBS leads while delivering therapeutic stimulation.  While, currently, the clinical benefits for the brain signals have not yet been established, these could become useful in future when those benefits become available.

• Choosing the team

It is important to pick the right team for the surgery – the neurologist, the Movement Disorder Specialist (MDS), if different from the neurologist, the neuro surgeon and the support team.  Check for the number of surgeries that the neurosurgeon has performed.  If possible, you may speak with a patient who has had DBS performed by the neurosurgeon that you are planning to engage with.  Another source of information is the contact from the device manufacturer (Medtronic, Boston Scientific, etc.) – he / she will be able to share his / her perspective on the neurosurgeon’s skills and experience.  Others that contribute to the surgery are the anesthetist, neuro-psychiatrist, and neuro-psychologist.

• STN or GPi as the target for placement of the leads:

The critical success factor for the surgery is placement of the leads in the exact position in the Sub Thalamic Nucleus (STN) or Globus Pallidus Internus (GPi), the two preferred targets.  While STN is preferred in tremor-dominant PD, GPi is preferred in cases where dyskinesia is predominant. 

• Neuromodulation

This is the process by which the neurologist or the MDS changes the settings for the electrical stimulation of the brain in order to (eventually) arrive at the optimal setting.  Ideally, if iterated correctly, there should not be any “off-period” motor symptoms (tremors etc,).  Also, you should be able to achieve significant reduction in medication that you were taking prior to the surgery.  Please note that the iterative process will take several weeks as the body has to get used to the settings which are changed by the MDS.  You need to ensure that your MDS has the appropriate and relevant experience and expertise to arrive at the correct device settings.

• Cost of the surgery

Most of the well-known private hospitals as well as some public hospitals in the bigger cities in India today are equipped to do DBS Surgery.  The surgery could cost anywhere from Rs. 15 lakhs to Rs. 25 lakhs, depending upon the following factors:

1. Device Manufacturer – Medtronic, Boston Scientific
   1. Device Technology – the sub-brand (Percept PC , for example), the model etc.
   1. Whether the battery is rechargeable or non-rechargeable.  As you would expect, rechargeable batteries cost more.  The more recent models also cost more.  The Medtronic Activa RC is replaced once in every 15 years.  Currently, only the non-chargeable version of Percept PC is available in India.
   1. Another point to note is that the costs of the surgery are not currently insurable as the insurance company will deem PD to be a pre-existing condition and, hence, not eligible for reimbursement.  However, if the insurance is taken prior to the onset of PD, the costs would be reimbursable.                            
2. My DBS experience: Pre-surgery (Day minus 7 to Day minus 0):
   1. Preparing for the surgery:  There are certain tests that are to be performed prior to the surgery itelf:
      1. Dopa challenge: The objective here is to review your dependence on Syndopa in terms of tremor symptoms.  Your neurologist will advise you to come to his clinic without taking your regular Syndopa dosages.  He will check your symptoms prior to and after you have taken your Syndopa medication and will record these in the Uniform Parkinson’s Disease Rating Scale (UPDRS).
      1. Psychiatric tests: to evaluate whether you have any symptoms that may suggest pushing out the surgery date – vivid dreams, insomnia etc.
      1. Psychology tests: A two-hour test to check if there are any indications of impairment of cognition – short term memory, verbal reasoning ability etc.  These are in the same format as for IQ tests.  Please ensure you are carrying your regular dosages of Syndopa.
      1. MRI of the brain: to check if there are any reasons why the surgery date may have to be pushed out.
3. Surgery (Day 0):
   1. Getting admitted:  You are usually admitted a day prior to the surgery date to help prepare for the surgery.  On the morning of the surgery, your head will be shaved – this will make it easier for the surgeon during his surgery.
   1. Awake surgery:  Perhaps the most scary part of preparing for the surgery is the idea that you have to be awake during the surgery.  The Anesthetist and his team visits you to fix a stereotactic frame – this is intended to prevent the head from moving out-of-sync with the body.  He gives you local anesthesia all around the top of the head – 12 injections overall, 6 per side!  This is intended to keep you awake, although you wouldn’t feel any pain arising from the surgical procedures that will be carried out on the brain.  The biggest challenge for the neurosurgeon is to drill into the skull.  The surgeon will plan for a couple of burr-holes to be drilled – the feeling is as thought you are directly beneath four helicopters at the same time!
      1. Post-surgery:
         1. First couple of days:
         1. Removing the clips and the scans (MRI, CT and X-ray):
      1. First clinical visit (Day 20):
         1. Met with my neurologist.  He provided some broad guidelines in terms of what to expect over the next several weeks:
            1. You should not expect magic (no tremors, significantly reduced medication) to happen instantaneously!
            1. The process to get to the optimal settings will take several weeks
            1. During each clinical visit, the neuro will adjust your settings in the app such that there is incremental benefit each time and the body gets used to the pulse generator’ role
            1. There will usually be some “lesion effect” – During the surgical procedure of deep brain stimulation (DBS), insertion of an electrode in the subthalamic nucleus (STN) frequently causes a temporary improvement of motor symptoms, known as the microlesion effect (MLE).  This lesion effect can last anywhere from a couple of days to weeks.  Over time, the lesion effect wears off while the DBS device settings will be adjusted for countering the tremors or other motor symptoms.
            1. My neurologist set the device for the left side of my body at 0.5 volts.  As the symptoms were very mild on my right side, this was set at 0.  I experienced only mild benefit from this setting – my overall medication (Syndopa Plus + Pacitane) intake did not reduce at this stage.
         1. Second visit (25th Apr 2024):
            1. During this visit, the setting for the left side was doubled at 1 volt.
            1. This had a very noticeable benefit with the “off-time” almost non-noticeable! 
            1. My medication also came down – Syndopa Plus intake reduced from 750 mg daily to 500 mg and Pacitane from 3 g per day to 2 g per day
            1. However, to counteract the effect of lower medication, the lesion effect started playing up, which had to be corrected in the third session.  At some point (several weeks after surgery), the lesion effect will wear off.  A broad mental formula to think of the beneficial effect of surgery is as follows:
               1. Beneficial (or adverse) effect of lesions + the beneficial effect of the device = net effect that needs to be addressed through medication
         1. Third visit (2^nd May 2024):
            1. The voltage setting was again increased from 1 to 1.5 volts. 
            1. At this setting, I am almost rid of my tremors!  It seems magical!!
            1. My medication is down to: 375mg of Syndopa (3*125mg) and 2 mg of Pacitane a day
            1.  The doctor told me that I will need a certain maintenance dosage of  Syndopa to take care of any mood swings that may be there
         1. Fourth visit (7^th May 2024):
            1. The voltage was now set at 2 volts
            1. My medication was further reduced to ½ Syndopa Plus – one in the morning, one in the evening and 1 Syndopa CR in the night.  Nil Pacitane.  Thus, my medication is now down to a little less than a third of the dosage prior to the surgery.
         2. Fifth visit (16^th May 2024):
            1. My tremors are virtually gone
            2. Settings retained as above in my 4^th visit
4. Exercise and DBS:
   Whether or not you have had DBS surgery, exercise should form a part of your every day life.  It is the only known “medicine” that slows down the progression of the disease.  It is important to understand that DBS is not a cure, PD continues to progress – it is only that the symptoms are kept under check or cancelled out with the help of electrical pulses. 
   There is no constraint or restriction on the exercise you can do after the DBS surgery.  Ideally, allow up to a couple of months’ recovery prior to recommencing your exercises after the surgery.
   That being said, you should consult your neurologist or MDS before recommencing your exercise regimen.
   Your exercises should cover a mix of cardio, strength, flexibility, and stretching.  Strength training should cover all six muscle groups – Shoulders, Chest, Biceps, Triceps, Lat and Legs.  In addition, you should do breathing exercises through Pranayamam.
   PwPs have a higher probability of cognitive decline.  You should also do exercises that improve your neuroplasticity – please see my blog here.   
   This is the mix of exercises that I do – on average, 2 hours a day, six to seven days a week:
   Jogging / running – 3 to 4 days a week for a total of 15k to 20k.  This covers cardio.
   Gym – 3 days a week for one hour each day with a trainer – focus is on strength training (weights), stretching, and flexibility.
   Yoga – mostly Pranayamam (breathing) for up to 30 minutes a day.  30-minute Yoga Nidra sessions, twice a week.
5. There are another couple of exercises that you can do not covered above, which really count as cardio:
   Cycling – which is proven to be particularly beneficial for PD.  You may review this article here.
   Climbing stairs – this is a very heart-healthy exercise.  However, PD patients who may also have heart trouble should probably avoid this.
   One thumb rule you could use is:
   Use the bicycle for a distance of up to 3 sq km.
   If you live up to the fifth floor, you can use the stairs instead of the lift.
   These habits incorporate an additional amount of cardio exercising to help meet your weekly target.
   Additional resources:
   Here’s a great video from Michael Fox Foundation that answers the following questions on exercise for PD:
   What’s the best exercise for Parkinson’s?
   How can I exercise if I have limited mobility or other symptoms?
   How much should I exercise?
   How hard should I push myself?
   When’s the best time of day to exercise?
   Can exercise be harmful?
   How can I motivate myself to exercise?