What is Deep Brain Stimulation?
You have probably had many treatments for your pain, most of which will have been of little or no help. This surgical procedure works by targeting two areas of the brain that are part of the pain pathway. We introduce a small amount of electrical current to these areas, which helps to mask the pain that you are feeling. Hopefully this will reduce the burning sensation of your pain and at the same time reduce your level of pain.

Who might be suitable for DBS?
A number of painful conditions can be treated using DBS. This is, however, a last-resort treatment only to be used when all other therapies have been exhausted. The conditions which respond best to DBS include:

• Facial pain
• Cluster headaches
• Phantom limb pain
• Post-stroke pain
• Failed back surgery pain
• Complex regional pain syndromes

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

What are the alternatives to surgery?
A number of medications may be useful for pain. These include the standard opioid and non-opioid analgesic agents, membrane stabilising agents and anticonvulsants, as well as the most recent agent to be released- Pregabalin. Special medical treatments such as Ketamine infusions, local nerve and joint blocks, as well as other surgical options such as spinal cord stimulation and peripheral nerve stimulation should also be considered. It is critical that you have been assessed by a pain specialist before contemplating DBS.

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
  

What happens before surgery?
We will send you pain charts to fill in. The first is a body map. You should shade in the areas of your body that are affected with pain.

The second chart is a pain diary. Fill this in over a period of a week or so. If your pain varies over the day, do a few scores per day, but if your pain tends to stay the same over the day a daily score will be enough.

The third chart is called McGill Questionnaire. This chart does not rely on numbers but helps you to describe your pain to us. As it states on the form, not every group of words may apply to you. Pick the words that best describe your pain.
As an outpatient, before surgery you will have:

• An MRI scan. This scan 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 is done to ensure that associated conditions such as depression and anxiety are clearly evaluated.

How is deep brain stimulation performed?
This is usually done in 2 stages, several days apart. Your admission will be for approximately 7-10 days.

Stage 1 (Placement of Electrodes)
The first operation (Stage 1) involves placement of special wires (electrodes) in specific regions of the brain. We target one or two several areas in the brain, namely the periventricular grey region (PVG) or sensory thalamus. 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 pain and eye movements, to guide the final position of the electrode. 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 your pain 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.

After Stage 1
One or two electrode wires (depending which areas of the brain have been targeted at operation) may be coming through the skin. We will attach these wires to a small external stimulator and test the stimulation for several days. This gives you and your surgeon time to find the best settings for you.

Throughout your admission you will frequently be asked to score and describe your pain. This will allow us to know if the treatment is working or not. It also gives time for you to decide whether or not you are happy with the amount of pain relief you are getting.
If the results are fairly convincing with stimulation during the first procedure, the wires may not be brought out through the skin (as this may slightly increase the risk of infection); in that case, the second operation will be performed at a convenient time.

Stage 2
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 next?
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.

How successful is DBS for pain?
Deep Brain stimulation helps up to 70% of the patients selected for treatment. The rate of reduction in pain varies from patient to patient. On average, pain scores are reduced by 50%. For example if a patient had a pain score of 10/10 we would be able to reduce it to 5/10, on average. We are particularly successful with getting rid of the burning sensation aspect of the pain in the majority of patients.

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%)

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 follow-up is required?
We will keep in close contact with you after your discharge from hospital and can alter your stimulation if necessary to maintain good pain relief. The battery life will vary depending on your stimulation settings (on average the battery will last between 3-5 years). We will need to see you at least once a year to check the battery and ensure you have continued pain relief.

How long will the benefits last?
This will vary from patient to patient. Typically, patients obtain a benefit for several years or longer. The benefit may gradually decreases with time and so the stimulator settings may be increased to compensate for this. 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.