What is Peripheral Nerve 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 one or more nerves which are transmitting most of the pain. We introduce a small amount of electrical current to these nerves, which helps to mask the pain that you are feeling. This procedure is ordinarily non-destructive and reversible.
Who might be suitable for peripheral nerve stimulation?
A number of painful conditions can be treated using peripheral nerve stimulation. Patients with the following conditions who have failed all standard medical therapies may benefit:
- Complex regional pain syndromes (‘neuropathic pain’)
- Nerve injuries (from trauma or previous surgery)
- Long-standing back pain
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, anti-inflammatory medications, 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 should also be considered. It is critical that you have been assessed by a pain specialist before contemplating peripheral nerve stimulation.
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. These are important in planning your surgery and monitoring your response.
The first chart 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.
Who will perform surgery? Who else will be involved?
Surgery will be carried out by your Precision Neurosurgery surgeon. A surgical assistant will be present and an experienced anaesthetist will be responsible for your anaesthetic or sedation.
What are the aims and potential benefits of surgery?
The goals and potential benefits of surgery include:
- Pain reduction
- Reduced medication requirements
The chance of obtaining a significant benefit from surgery depends upon a wide variety of factors. Your neurosurgeon will give you an indication of the likelihood of success in your specific case.
What are the possible outcomes if treatment is not undertaken?
Potential outcomes of not treating your condition include:
- Ongoing pain
- Reduced quality of life
How is peripheral nerve stimulation performed?
This is usually done in 2 stages, several days apart.
Stage 1 (Electrode Implantation)
You will be taken to the operating theatre and your skin cleaned with antiseptic. Local anaesthetic will be injected and you will be lightly sedated, or alternatively a light general anaesthetic may be administered. An incision will be made and the nerve will be identified and prepared. One or two electrodes (wires) will be placed alongside the relevant nerve or nerves. These will be brought out through the skin, and secured in place. You will then be transferred back to the ward after a brief period of time in the recovery room.
These electrodes will be attached to a small external stimulator, and the effects of stimulation on your pain will be tested for at least several days. 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.
Stage 2 (Battery Insertion)
If you are happy with the amount of pain relief that you obtained from the trial, we will carry out the full implantation several days or a week or two later. This procedure is performed under general anaesthetic (ie. you will be asleep).
The temporary external wire extensions are removed and the previously implanted electrodes are connected to extension wires which are, in turn, plugged into an implantable pulse generator (battery). This battery is normally implanted under the skin in your chest, back, or abdomen. Your battery will be programmed over the following days and weeks so that the stimulation you receive will be best for you.
What happens next (after implantation of the permanent system)?
You should be ready for discharge from hospital 1-2 days after the second stage of your 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 after your surgery. 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 can drive a motor vehicle after a few weeks if you do not have too much discomfort.
You will also be given some detailed information about 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 discharge from hospital.
How successful is peripheral nerve stimulation for pain?
Peripheral nerve 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 around 50%. For example if a patient had a pain score of 10/10 we would be able to reduce it to 5/10.
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 small risk of infection (3%)
- There could be movement of the electrode, and it may need to be replaced in a separate procedure
- Failure of the stimulator
- Small risk of bleeding
- The chance of making your pain worse, rather than better is less than 1%
- The risk of death is extremely small (less than 1 in 30,000)
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’)
- Loss of life
- Other rare complications
What happens down the track?
We will keep in close contact with you after your discharge from hospital. You will probably require repeated programming adjustments over the first few months to optimise your pain relief. Your pain medications can be reduced as tolerated.
The battery life will vary depending on your stimulation settings (on average the rechargeable batteries used will last at least 5 or 10 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?
- Swelling or infection of the wounds
- Weakness or numbness
- 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.