Functional Neurosurgery

DBS delivers a high-frequency electrical current in the area called the STN (Subthalamic Nucleus). This current modulates misbehaving neuronal activity and decreases the symptoms of Parkinson’s disease. STN DBS help in the reduction of medication dosages. It is very important to understand that, only symptoms that are responsive to medications could improve with DBS except for tremor, which can be resistant to medications but still responds to DBS. In addition, some non-motor symptoms can also improve.

Tremor is also known as the shaking or vibration of a hand or other body parts. Most commonly it affects hands. There are different types of tremors. The most common is essential tremor which affects both upper limbs distally. If drug therapy fails then DBS is also an option for disabling tremor cases.

DBS delivers a high-frequency electrical current in the area called the Thalamus. This current modulates misbehaving neuronal activity which can cause tremors. DBS can help is the correction of this misbehaving neuronal activity and thereby improve the quality of life of patients suffering from drug-resistant refractory tremors.

Dystonia is a neurological condition characterized by abnormal posturing or twisting of body parts caused by involuntary muscle spasms. There are various types of dystonia based on body distribution. Dystonia can affect both adults and children. In most cases, DBS is done for generalized dystonia. However, it may help in drug and botulinum-resistant cervical or segmental dystonia interfering with Activities of daily living (ADLs) in selected cases.

Deep brain stimulation (DBS) is the placement of electrodes usually on both sides and rarely on one side of the brain. The electrodes are connected to a battery (IPG- implanted over the chest) via an extension cable, which is surgically tunnelled under the skin.

DBS is not a cure for dystonia, but it definitely helps in alleviating the symptoms of dystonia.

DBS delivers a high-frequency electrical current to an area in the brain called the Globus pallidus interna (GPi). This current modulates the misbehaving neuronal activities, which occur in dystonia, and reduces symptoms of dystonia. Following surgery, this could allow a reduction in medication dosages along with a reduction of dystonic symptoms. However, it is important to keep in mind that in dystonia the improvement following DBS surgery is gradual and the maximum result of DBS is usually seen after 1-2 yrs. In the following years also, patients continue to show improvement.

The initial part is a detailed pre-surgical clinical evaluation by the Functional Neuromodulation Team. Once a patient considers undergoing DBS surgery, he/she has to get admitted in the evening before the day of the planned “Levodopa Challenge Test”. We stop all medications on the previous night and then evaluate the patient in the “off” period in the morning and then slightly higher than the usual dose of morning medication is given to the patient. After this, we re-evaluate the patient after 30-45 minutes in the “on” period. The video recording of this testing is also done. Scores of “on” and “off” periods are compared. If the score improvement is acceptable according to protocol then the patient is evaluated by a Neuropsychologist for detailed cognitive and behaviour assessment. Following this, the patient is discharged and the appointment is booked for DBS Multidisciplinary team (MDT) meeting. In this meeting, the results of all tests done are discussed with the patient and his/her family. If the patient qualifies the candidacy criteria for surgery, all the possible pros & cons related to DBS surgery are discussed. All the possible doubts & queries of the patient and his/her family related to disease, DBS surgery and post-surgical course are also thoroughly addressed by a team of experts. Following this final decision regarding DBS surgery is made. In case if patient and family agree to the same then presurgical investigations along with fitness are planned accordingly.

You will be given a date of admission for surgery. The morning dose of the medications with or without previous night doses is skipped according to “off” symptoms. As it is required for evaluation during surgery. MRI of the brain is also done as part of this evaluation. If the patient has severe tremors or dyskinesia (uncontrolled movements), may be required to perform MRI under sedation or sometimes under anaesthesia.

IMPORTANT: It is essential that if the patient is taking medications like aspirin, clopidogrel, warfarin or non-steroidal anti-inflammatory drugs (NSAID): e.g. ibuprofen, naproxen, diclofenac etc. are stopped two weeks before and until two weeks after surgery. This is mandatory to maximally avoid the risk of bleeding in the brain during surgery. If pain relief is necessary, Paracetamol is safe to use as well as Tramadol. Please discuss with the DBS team if you take any of those medications and if you take contraceptives or homeopathic over-the-counter medications.

If you are taking blood-thinning medications or anticoagulation drugs for heart disease or bleeding problems, you will need to be referred to your responsible doctors to get advice on how to stop the blood-thinning medications and the risk involved in stopping medications temporarily.

The hospital stay is between 7-10 days. As soon as the patient feels well & stable and the DBS team feels so, he/she can be discharged home after testing the stimulation parameters to confirm the effectiveness of DBS. Next, the follow-up would be after 5-8 days for stitches removal. We usually start programming 2-6 weeks after the surgery. It may take several months to achieve the optimal balance of DBS settings and medication regimes to achieve the maximum possible benefit. Hence, patients are required to attend regular follow-ups at the hospital with the DBS team, whereby the DBS settings are fine-tuned.

• DBS treatment requires a lifetime commitment to regular follow-ups for review and assessment.
• Exercise and physical activity can be resumed a few weeks after surgery Sauna, steam room and sunbeds are not recommended.  Scuba diving (no greater than 33 feet) with vigilance can be done.
• Extreme/ contact sports can risk breaking or damaging the DBS hardware
• Resume work within 4-6 weeks after surgery.
• It is advisable not to drive a vehicle for 6 weeks following surgery.
• Travelling – always carry an identification card for the DBS. Do not go through airport metal detectors. If you need to travel in an aeroplane within 4 months after surgery, please get advice from the DBS team Do not stand near theft detectors and any object with a strong magnetic field.
• Patients will require regular battery checks and battery replacement (usually every 3-5 years for non-rechargeable DBS and 10-20 years for rechargeable DBS).
• Patients will be given a personal controller to enable them to carry out battery checks and limited adjustment of DBS settings.
• Patients should inform the DBS team if they require surgical, dental or investigative procedures to check hardware compatibility.
• Specific medical equipment that is contraindicated for use in patients with DBS include the following:

• Monopolar electrocautery .
• Diathermy
• Bone growth stimulator
• Lithotripsy
• Arc welding

Note: This list is not exhaustive. Please contact the device booklet and manual and contact the DBS team for further advice.

• X-rays, CT scans, and mammograms are safe to use, however, patients are advised to inform the doctor or technician.
• Ultrasound is safe however the ultrasound probe should be applied directly over the implanted battery or cables because this will damage the implanted DBS battery.
• The general rule is that MRI is contraindicated in DBS-implanted patients. However, depending on the model and make of the implanted DBS device, MRI can be performed under a strict protocol. Please contact the DBS team for advice.

DBS surgery has got two stages. Stage 1 involves the placement of electrodes in the brain and Stage 2 IPG (Implantable Pulse Generator) / battery is placed on the chest wall. Usually, both stages are done one after the other on the same day but on rare occasions, Stage 2 may be delayed for a few days.

Stage-1

The first thing in the morning on the day of surgery is the fixation of the Stereotactic frame on the head. A local anaesthetic will be injected at four sites on the head where pins of the frame are inserted to fix the frame. Sometimes if required sedation may be given to make you asleep to help with any sort of discomfort. Then a CT scan will be done to work out where the electrodes will need to be placed about the frame. Then the patient will be shifted to OR for electrode placement.

The electrode placement will be done with the frame on and the patient in an awake state most of the time. A local anaesthetic will be injected to numb the skin. Sometimes it may also be done under general anaesthesia if needed. First, the skin would be opened and a small hole would be drilled (about 14mm) into the skull. If done awake, the patient will be required to move limbs, speak or describe any unusual sensations felt. In this way, we will work with you to find the best position for electrodes. Usually, the first electrode is placed on the side opposite to the dominant hand (i.e. On the left side for the right-handed) followed by the same procedure on the opposite side. This procedure usually takes around 3-4 hours but may vary from patient to patient.

After electrode placement on both sides, another CT will be done to confirm the position of the electrodes. If the position is satisfactory, the frame will be removed and the procedure for battery (IPG) placement will be done under general anaesthesia.

Stage-2

The electrodes inserted in Stage 1 are connected to internal connecting leads. They are tunnelled under the skin of the neck behind the ears and connected to the battery which sits under the skin below the collarbone on the chest. The battery can be placed on either side. The final decision of the side of battery placement is of the patient according to his/her choice and comfort. This procedure takes around 1-2 hours.

Following surgery patient will be shifted to ICU typically for a day and then if the condition permits, will be shifted back to the ward. The battery/IPG may be turned on 2 days after surgery. This will begin by screening the electrodes for efficacy and side effects. This process will take around 30 minutes to 1 hour. Placement of the electrode itself often improves the symptoms for a short while, in that case, the battery may not be turned on before discharge. Although final programming will start on follow-up visits.

DBS surgery, as mentioned earlier, significantly improves the quality of life of people with Parkinson’s disease. It extends the “on” time and reduces the duration and severity of “off” symptoms in more than 90% of properly selected patients.

Around 80-90% improvement is seen in tremors in most patients. Although it is never possible to predict with absolute certainty how many benefits a patient will get, the “on” – “off” assessment can give some idea about the likely benefit.

Reduction in medication doses is possible and this in turn may improve side effects like dyskinesia.

It usually improves non-motor symptoms like pain, sadness and sleep disturbances.

DBS to the thalamus can significantly improve the quality of life for people with tremor. The aim of the stimulator is only to help to reduce the severity of your tremors. It is not a cure for the underlying disease. The degree of improvement people get varies from one person to another. The DBS will not improve any ataxia (uncoordinated movements) you have in addition to the tremor. It may be the case that we can improve your tremor so that the violence of the movement doesn’t interfere with activities, but your control of fine movement may not improve.

On average people have around an 80-90% improvement in their tremor, although some people will experience less than this. The tremor recording that we did before the operation can help us to predict how much improvement you will get, but it is never possible to be absolutely certain of this before the operation.

Some people may notice a change in how clear their speech is when the stimulation is set to provide best control of their tremor. In this case, we can provide limits of stimulation so that you can adjust the settings to suit you in particular situations.

Surgery on the pallidum (Gpi) can significantly improve the quality of life of patients with dystonia. The aim of the stimulator is to help to reduce the severity of symptoms, including the muscle spasms, posture and pain. The DBS surgery is not a cure for your dystonia; it can only improve your symptoms. The amount of improvement people get varies from one person to another.

On average people have around a 60%-70% improvement in

their symptoms, although some people will experience more than this and some will experience less. It is not possible to predict accurately how much improvement you will get. The improvement is usually gradual, taking anything from a few weeks to several months to happen.

All treatments and procedures have risks & possible complications and the DBS team will talk to you about the possible risks related to the DBS procedure in detail during MDT consultation before surgery.

Possible complications during the “Levodopa Challenge Test”

Due to the withdrawal of medications overnight, the patient may develop severe withdrawal symptoms. Which may include severe “off” symptoms, perspiration, orthostatic hypotension, nausea, vomiting, worsening of generalized pain, fatigue, altered sensorium to severe complications like NMS.

Possible risks and complications related to surgery

As with all types of surgery, DBS involves some degree of risk and chance of complications.

Complications from DBS surgery are very rare. Most complications are reversible, easy to treat, and do not cause lasting morbidity.

Common risks & complications (more than 5%):

• Headaches usually improve with time
• Minor pain, and bruising at the site of surgery

Uncommon risks & complications (1-5%)

• The most serious complication is surgical site and implants may become infected and need to be removed. This may require repeated surgery in the future when the infection has been cured.
• Psychological (e.g. suicidal ideation), confusion and/or memory disturbance, and weight gain can occur. This may be temporary (mostly) or permanent.
• Stimulation can cause slurred speech, tingling sensations, walking difficulty or poor balance. By programming, we aim to reduce these side effects but to get maximum improvement in Parkinson’s symptoms sometimes it may be difficult to achieve complete control of these symptoms.
• The operation may not be as successful as expected, only partially successful, or the stimulation effect may wear off with time. This may require further treatment and/or programming.

Rare risks and complications (Less than 1%)

• The Most serious complication (around 0.5%) is a risk of stroke from the procedure. It involves bleeding into the brain. Which may result in weakness on one side of the body, speech difficulty, and vision impairment. The severity is related to the location and size of the bleed. Very rarely it requires surgical intervention.
• The lead, wires or battery may move, get displaced or try to come through the skin. This may require further surgery.
• There is the possibility of device malposition, malfunction and lead fracture (the wire breaking). This would mean redoing the procedure, but may also mean replacing additional parts of the DBS system.
• Seizures may require medication. This condition may be temporary or permanent.
• Fluid leakage from around the brain may occur through the wound after the operation. This may require further surgery.
• Death as a result of this procedure is very rare (0.2%).

Wound care advice:

Before surgery, all patients are swabbed for bugs that are sensitive to

antibiotics, Methicillin-sensitive staphylococcus aureus (MSSA) and for bugs that are not sensitive to antibiotics, Methicillin-resistant staphylococcus aureus (MRSA). If the swab result is positive, or the patient cannot obtain an MSSA swab, patients are advised to strictly

follow a treatment regime for 5 days before surgery.

• After surgery, patients are advised to avoid touching the wound area.

• Regular hand washing is advised.

• Always keep the wound area clean and dry.

• The wound dressing will be checked daily and will be replaced as and when required.

• Patients are advised not to wash their hair until the stitches are taken out.

• Stitches are taken out 10-14 days after the surgery