What is Deep Brain Stimulation?
Deep brain stimulation (DBS) works by targeting one of several areas in the brain that are part of the movement disorder pathway. By placing a fine wire (electrode) very precisely within the desired area, we are able to introduce a small amount of electrical current to these areas, which causes deactivation of the nerve cells. This electrode is connected to a battery which is implanted under the skin, allowing a small pulse of electricity to be delivered 24 hours a day. The most commonly targeted regions are the subthalamic nucleus (STN), thalamus (Vim), pallidum (GPi), and pedunculopontine nucleus (PPN) in Parkinson's disease, the thalamus (Vim) for essential tremor and multiple sclerosis tremor, and the pallidum (GPi) in dystonia.

What are the goals of DBS surgery?
The aims of DBS are as follows:

• Reduction of abnormal involuntary movements
• Improvement in function
• Reduction of medications (or medication side effects)
• Improvement in quality of life

Which conditions is it used to treat?
DBS is used to treat several types of movement disorders:

• Parkinson’s disease
• Essential tremor
• Dystonia (including spasmodic torticollis or “wry neck”)
• Post-traumatic dystonia and tremor
• Multiple sclerosis tremor
• Tourette’s syndrome

What are the advantages of deep brain stimulation?
DBS is an important and useful neuromodulation technique. It is generally:

1. Highly effective
2. Minimally invasive
3. Associated with few and infrequent side effects
4. Non-destructive (unlike most other forms of surgery)
5. Reversible

What are the reasons for surgery?
When medications are no longer working well, or their side effects are to severe, surgery may be of value.

Clinical studies and experience suggest that surgery should be considered early rather than late, due to the high likelihood of developing severe medication side-effects with long-term treatment, better outcomes with earlier surgery, and a higher chance of avoiding, delaying or minimising the economic and social side-effects associated with advanced movement disorders.

What are the alternatives to surgery?
At present, the only alternatives to surgery are medications. You should check with a movement disorder neurologist to ensure that you have tried all of the appropriate medications before seriously considering surgery.

Before your admission to hospital
Before you are selected for DBS surgery, you will undergo an extensive series of assessments and investigations. Most of these are performed as an outpatient (no hospital admission required). You will be reviewed by a neurologist with specific training and expertise in this area, and also by a neurosurgeon, Dr. Richard Bittar.
As an outpatient, before surgery you will also have:

• An MRI scan. This helps us to map your brain for the surgery so we can clearly see the areas to target during the operation.
• A Neuropsychology assessment. This will include an assessment of your suitability for this operation.
• A Clinical Psychology assessment. This will include an assessment of any potential depression or anxiety (both of which also may require treatment), as well as your suitability for this operation.
• Other investigations and consultations will be arranged as necessary.

What do you need to tell the doctor before surgery?
It is important that you tell your surgeon if you:

• Have blood clotting or bleeding problems
• Have ever had blood clots in your legs (DVT or deep venous thrombosis) or lungs (pulmonary emboli)
• Are taking aspirin, warfarin, or anything else (even some herbal supplements) that might thin your blood
• Have high blood pressure
• Have any allergies
• Have any other health problems

Special precautions
It is important that you stop certain drugs before surgery, especially ones that thin your blood. If you are taking aspirin, warfarin, or other blood-thinning agents (including herbal products) it is very important that you contact us two weeks before your admission so that we can discuss stopping them with you. If you are taking warfarin we may need to admit you earlier but each case varies, so it is important that you phone and we can discuss the plan for you.

What are the specific risks of this type of surgery?
As with all types of surgery, there is a small chance of complications.

• There is a 2-3% chance of stroke or haemorrhage from this procedure
• There is a small risk of infection (3%)
• Seizures are very uncommon
• There could be movement of the electrode, and it may need to be replaced in a separate procedure
• Failure of the stimulator
• The risk of death is extremely small (less than 1 in 100)

What are the risks of anaesthesia and the general risks of surgery?

• Significant scarring (‘keloid’)
• Wound breakdown
• Drug allergies
• DVT (‘economy class syndrome’)
• Pulmonary embolism (blood clot in lungs)
• Chest and urinary tract infections
• Pressure injuries to nerves in arms and legs
• Eye or teeth injuries
• Myocardial infarction (‘heart attack’)
• Stroke
• Loss of life
• Other rare complications

What does the operation involve?
This is done in 1 or 2 stages, sometimes several days apart. Your admission will be for approximately 4-5 days.

Stage One (Electrode Placement)
The first operation (Stage 1) involves placement of special wires (electrodes) in specific regions of the brain. We target one of several areas in the brain, depending on your clinical condition. In Parkinson's disease and dystonia, an electrode is implanted on each side of the brain in the majority of cases. To target these small areas of the brain accurately we have to use a type of surgery called stereotaxy.

Before surgery you will have a special frame attached to your head. This is usually done with local anaesthetic and sedation, and is not too bothersome. The frame must stay on for the surgery, but will be removed as soon as it is over. You will usually be awake for the surgery so that we can use changes in your tremor, stiffness, and slowness of movement to guide the final position of the electrode. Some patients with dystonia will be given a general anaesthetic for the entire procedure (ie. will be asleep). Then you will have a CT scan (which will be fused with your preoperative MRI to help us to locate the specific areas in relation to the metal frame) before being taken to the operating theatre. Some more local anaesthetic and some light sedation will be given before one or two small holes are shaved in your skull. This does not hurt, and is usually much less uncomfortable than going to the dentist!

The electrode is then slowly inserted and the electrical activity will be monitored to guide its final placement. Once we are confident that we are in the correct position, we will stimulate through the tip of the electrode to see whether this helps and too look for side effects. We then secure the electrode in place (by a special plastic cap attached to your skull beneath the skin). A CT brain is performed immediately after surgery to confirm satisfactory electrode placement and to rule out significant bleeding or other problems. This procedure takes several hours.

In some cases, where the clinical improvement is perfect during the initial stage and there is enough time to do so, we will proceed directly to the second stage (battery implantation).

Occasionally, if the results of testing during the surgery are unclear, we will bring temporary extension leads out through the skin, and will conduct further testing after surgery to see whether the stimulation is producing a benefit. In such cases, Stage 2 will be performed once the benefits of surgery (and absence of significant side effects) are clear.

Stage Two (Battery Implantation)
Implantation of the battery (implantable pulse generator or ‘IPG’) is usually done several days or weeks after Stage 1. If the timing is only a few days, you will remain in hospital during this time; otherwise you will be discharged and readmitted.

This second operation (Stage 2) involves giving you a general anaesthetic (ie. you will be asleep for the procedure. A small incision is made over your scalp, and a slightly longer incision just below your collarbone. The ends of the electrodes which were inserted into you brain at the first operation are then connected to extension leads, which are tunneled under the skin from your head to your chest. They are, in turn, plugged into a the battery which is then placed under the skin just below your collarbone (sometimes this is placed in your abdomen or flank). The end result is that the electrodes, extension wires, and battery will all be underneath your skin. If you are a fairly thin person, a modest ‘bump’ will be visible over your chest where the battery sits (this is rarely noticeable when wearing clothes).

Your battery will be programmed over the next couple of days so that the stimulation you receive will be best for your movement disorder. Your neurologist will adjust your stimulation settings and medications progressively over a number of months.

What happens after I am discharged from hospital?
You should be ready for discharge from hospital 1-2 days after the second operation. Your GP should check your wounds 4 days after discharge. We will advise you when to have your stitches removed at your GP's surgery or by the Precision Neurosurgery Practice Nurse. You will need to take it easy for 6 weeks.

You should do an hour of gentle exercise, such as walking, every day. You should not sign or witness any legal documents until you have been seen by your GP. You will be reviewed after 6-8 weeks by your neurosurgeon. You should not drive a motor vehicle or operate heavy machinery your neurosurgeon gives you the go ahead.

There are some restrictions on the types of scans you can have once the stimulator has been inserted (ie. MRI scans). You will also be given detailed information about other things you must avoid, such as metal detectors at airports. It is critical that you read such information thoroughly. There may be some other restrictions on what you can and cannot do, and these will be discussed with you before surgery or during your hospital stay.

What follow-up is required?
Your neurosurgeon and neurologist will keep in close contact with you after your discharge from hospital and can alter your stimulation if necessary to maintain a good effect. The battery life will vary depending on your stimulation settings (on average the battery will last between 2-4 years). We will need to see you at least once a year to check the battery.

How successful is surgery?
Surgery for movement disorders frequently results in a reduction in symptoms and signs, an improvement in quality of life, and a reduction in medication intake. Some patients are able to return to their previous occupation following successful treatment. Surgery does not return you to "normal" however, and it is important that you understand this before going ahead. Overall, the majority of patients will significantly benefit from surgery, whilst a minority will not derive a significant improvement.

How long will the benefits last?
This will vary from patient to patient. Typically, patients obtain a benefit for 5 years or longer. The benefit gradually decreases with time (due to progression of the underlying disease). A small proportion of patients may benefit from repeat surgery if the benefits drop off.

What should you notify your doctor of after surgery?

• Increasing headache
• Fever
• Swelling or infection of the wounds
• Leakage of fluid from the wound
• Fitting (seizures)
• Abnormal sensations or movements in your face, arms or legs
• Weakness or numbness
• Drowsiness
• Any other concerns

What are the costs of surgery?
Private patients undergoing surgery will generally have some out-of-pocket expenses.

A quotation for surgery will be issued, however this is an estimate only. The final amount charged may vary with the eventual procedure undertaken, operative findings, technical issues etc. Patients are advised to consult with their Private Health Insurance provider and Medicare to determine the extent of out-of-pocket expenses.

Separate accounts will be rendered by the anaesthetist and sometimes the assistant, and hospital bed excess charges may apply. Medical expenses may be tax deductible (you should ask your accountant).

You should fully understand the costs involved with surgery before going ahead, and should discuss any queries with your surgeon.

What is the consent process?
You will be asked to sign a consent form before surgery. This form confirms that you understand all of the treatment options, as well as the risks and potential benefits of surgery. If you are unsure, you should ask for further information and only sign the form when you are completely satisfied.