Spinal Cord Stimulation

Subcutaneous Electrical Nerve Stimulation (Neuromodulation)

Information for Patients

Spinal cord stimulation/ subcutaneous electrical nerve stimulation is a procedure designed to reduce pain by passing an electrical current over the nerves that supply a particular part of the body. It is a two stage procedure requiring a trial of an electrode insertion followed up by a full implantation of the electrical leads and battery (implantable pulse generator).

How does it work?

Neuromodulation is primarily used for neuropathic (nerve) pain. It is thought to work by confusing the pain signals that enter the spinal cord and brain. The exact mechanism of pain control is yet to be fully understood. It may also act by altering the chemical messengers in the brain and spinal cord and changing nerve pathways. 

What conditions is it used for?

These procedures are used for a range of painful disorders.   The most common disorders that benefit from neuromodulation are radicular pain (sciatica or nerve root pain), peripheral neuropathy ( a painful disease of the nerves of the hands and feet), peripheral vascular disease (arterial disease) and angina. There is excellent scientific evidence that neuromodulation reduces pain and improves quality of life for the above conditions.

In practice any illness that causes chronic pain may benefit from a trial of neuromodulation.   Some other conditions that are commonly treated include chronic headache, pain following surgery, spinal cord injury and phantom limb pain.

What preparation do I need to make before surgery

Ideally you want to be in the best medical shape before the surgery. As such the management of your other diseases should be at its optimum. This includes seeing your doctors to optimize the control of any chronic illness (eg diabetes, asthma) and seeing your dentist to ensure that your teeth are in the best state they can be in.

You should ring my office if you are unwell prior to the procedure, this includes flu like illnesses, dental infections, new medical issues and any skin problems over the area of the surgery such as boils, sores or pimples.

You will need to fast (solids and fluids) for six hours prior to the procedure, this usually means if your operation is planned for the afternoon you fast from six am that morning. If your surgery is in the morning you will have to fast from midnight the night before the procedure.

Anticipate that you will require approximately two to three weeks off work following the full implant and about three days off following the trial procedure.

How is the procedure performed?

The first stage procedure or trial is a relatively simple procedure and may be performed  as a day patient or inpatient. You will be admitted to hospital and transported to operating theatre. You will be given a sedative anaesthetic  which means you won’t be totally asleep but comfortable. Under sterile conditions a small incision (5mm) will be made and the introducer needle inserted either into the subcutaneous region around the area of the pain or the epidural space. The epidural space is a layer of fat and blood vessels that surrounds the spinal cord. The electrical lead is then maneuvered into position.  The lead is sutured down to the skin and the area is dressed. The lead will is connected to an external battery. An electrical current is passed through the lead. Ideally paraesthesia (pins and needles) is produced around the area of your pain.  The lead may have to be repositioned until the stimulation is satisfactory.   A technician will visit you while you are in hospital and adjust the settings for maximum pain relief. You can expect to stay in hospital for two to three days for the trial.    

The second stage is the full implantation. A small incision 5 – 10 cm is made to insert and tie down the lead and the lead is inserted as above.  A second incision is made for the stimulator battery, most often this is made around the buttock area (usually on the side of your dominant hand).  Occassionally an alternative area for the pocket may have to used.  A small pocket is created and the battery inserted. The lead is connected to the battery. The deep tissues are sutured (tied together) and staples are applied to the skin. You will be in hospital for one to two days after this procedure. Your local doctor can remove the staples one week after the operation.

What are the risks of the procedure?

Unfortunately, no procedure is without risk. There is a potential risk of the following complications:

  • No or partial response to the procedure
  • Patients can initially find the paraesthesia produced by the system unsettling but this usually settles
  • Infection
  • Movement or migration of the electrodes requiring revision or replacement  
  • Nerve and spinal injury
  • Risk of haemorrhage / bleeding
  • Exacerbation of pain
  • Collapsed lung if the procedure is being carried out over the chest wall

The battery also has a limited life span. Depending on which type of battery you choose to use (rechargeable or non rechargeable) and how much you use the system the battery may need to be replaced every four to ten years.

Are there any situations where it cannot be used? 

There are some situations in which it can be hazardous to have a nerve stimulator implanted. If a patient has any active infection then a stimulator can never be put in.

Other conditions that pose a risk include:

  • Bleeding disorder (usually if a patient is on warfarin or clopidigrel)
  • An existing implanted device such as a pace maker or muscle stimulator

Additionally, if a patient needs regular magnetic resonance scans (MRI) for any reason (eg spinal or brain tumor or disease) then this may be a reason not to insert a stimulator.  

Once you have the implant

For the first six weeks of the implant you can expect to have post operative pain around of the surgery. You may also find the sensation of the stimulator uncomfortable at first. You will need to have the settings of the device changed and assessed by the technician on a regular basis until it achieves maximal pain relief.

If you have a spinal cord stimulator then during the first six weeks it is recommened that you:

  • Not bend at the waist, leaning a little is acceptable
  • Not lift anything greater than five kilograms
  • Not be involved in any impact sports or high intensity activity eg tennis, golf, running, weightlifting

Long term it is sensible to purchase a wrist band / medical alert bracelet to notify health workers that you have an implant.
Whenever you see a doctor, dentist of health professional inform them that you have a nerve stimulator.

You are not able to have an MRI