High frequency stimulation
About chronic pain
Pain messages are sent along special pain pathways and up the spinal cord, to the brain. Although we may feel the pain in a particular place, such as a joint, nerve or muscle, we only recognise the sensation as pain once it reaches the brain. Acute pain occurs during and after harm or damage to part of the body. It is shortlived and fades away once healing has taken place. However, pain occasionally continues beyond the natural time of healing despite efforts to relieve it. If it has been present for six months or more, it is classed as chronic. Chronic pain is different from acute as it is felt in the absence of harm or damage, and therefore has no useful purpose. In the case of an acute pain it is helpful to rest the area to let it heal, but this natural response can be detrimental in the chronic pain situation, leading to a vicious circle of pain and disability. Chronic pain can also result in problems like tiredness, boredom, depression or anxiety, which can make the pain harder to cope with. Some people with certain types of chronic pain, that has proved resistant to conventional treatments, may be helped by spinal cord stimulation alongside rehabilitation.
About spinal cord stimulation (SCS)
Electricity has been used to treat pain for thousands of years. Over the past forty years, spinal cord stimulation has been used to deliver low voltage electrical currents to the spinal cord to interfere with the sensation of pain. The mechanism of action is thought to be similar to rubbing a banged elbow, but may also be a result of the body responding by releasing its own natural painkillers called endorphins. Despite the fact that spinal cord stimulation does not cure or abolish pain, it can enable you to become more active, enjoy better sleep and reduce your pain medication.
Instructions for patients undergoing neuromodulation trial
- Record your pain scores on diaries provided, throughout the day and as often as is practical - especially before and after activity.
- Go about your daily activities as normal, but also test those activities which you normally find challenging and record your performance (e.g. in minutes).
- Take reasonable precautions to reduce the risk of a flare-up.
- Please do not shower or allow the dressing on your back, or device, to get wet.
- Reapply tape supplied if the dressing comes loose at the edges.
- Be careful not to allow the cables to snag on door handles etc.
- Occasionally turn your device off for comparison.
- Please do not operate machinery, including vehicles, whilst the device is on.
The reason for assessment prior to trial
Prior to the trial, the pain team will carry out a comprehensive assessment of your pain and its effect on your day-to-day life. They will also be able to answer any questions you may have, or reassure you about any concerns.
The reason for a spinal cord stimulation trial
A trial of stimulation is carried out before considering a permanent implant because despite careful assessment and pain treatment selection, not every person feels the same degree of pain relief. A permanent implant involves surgery which carries potential risks, so it is important to be sure it is going to be beneficial.
When you come into hospital you will not need pyjamas / nightdress, but it may be useful to bring a dressing gown and slippers. You can have a light breakfast (for example tea and toast) before 8am and then clear fluids only. You will be required to return to the Jefferson day surgery ward for a number of days during the seven to nine days of your trial. Hotel accommodation can be provided for patients who do not live locally.
What you will experience in theatre
The procedure is carried out under a local anaesthetic while you are awake. It is done in theatre to reduce the risk of infection. You will be assisted to lie on the theatre table, face down if possible, with a cushion under your stomach. An X-ray machine will be positioned over you so the doctor can accurately see the bones in your spine. Following this, local anaesthetic will be injected to numb the skin where the trial stimulator lead will be passed through a hollow needle, into the space around the spinal cord. The stimulator lead is then adjusted with the help of X-ray monitoring until it is in the right place; this can take up to an hour of operating time. On completion, the needle is then taken out leaving the stimulator lead in place. A stitch is sometimes applied to secure the stimulator lead and a clear waterproof dressing is applied.
On return to the ward
When you return to the ward, the Pain team will visit you to inspect your dressing, ensure you feel okay and answer any of your questions. A battery box will be connected to the end of the stimulator leads and programmed wirelessly by a computer. You will be given a hand-held controller device to trial various therapy options yourself during the course of the trial. If you are getting any pain from the wound you may need to take simple painkillers such as Paracetamol.
Possible complications of the trial
The trial stimulator leads can move, occasionally leading to loss of pain relief if corrective programming is unsuccessful. Wound infection, damage to the spinal cord, meningitis and bleeding or infection around the spinal cord are rare complications but could be serious or even life threatening. Rarely a small leakage of spinal fluid from around your spinal cord can occur during the procedure in theatre resulting in headache and abandoning of the procedure – the trial will be rescheduled. In rare cases this headache may become persistent.
Over the remaining days of your trial
You must not allow water to enter the dressing, so please do not take shower or bath during the trial period and 48 hours after stopping the trial and removal of trial stimulator leads. You will be reviewed regularly by the members of the pain team. They will check whether the stimulation has improved your pain, activity levels, sleep and use of painkillers. In addition, each day a member of the team will check the site where the stimulator lead has been inserted.
Towards the end of a successful trial your physical capabilities will be formally measured after a period with the stimulator switched off. This is so we can measure
the physical benefits over time if you go on to have a permanent implant. Throughout the course of the trial, you will have an x-ray of the trial stimulator leads to record their position and along with previous images these will be shared with the stimulator company’s technical consultants for the sole purpose of achieving optimal stimulation settings. The team will also provide you with information and education about the permanent implant.
The final day of your trial
If the trial is considered successful by you, the implanting neurosurgeon and the pain team, the neurosurgeon will meet with you at their earliest convenience and explain the operation and answer your questions before adding you to the implant waiting list. Finally, before you leave hospital, one of the team will remove the trial stimulator leads on the ward, check the insertion site and apply a small dressing. We can show you the demonstration models of the implant if you wish to see them. You will be asked to check that your dressing and wound is dry and contact us immediately if any signs of infection develop (redness, swelling, pus discharge) at the wound site. Upon wound healing you can resume normal activities.
The permanent implant
To provide more time for preparation, it is usual to come to hospital the day before surgery. Your hospital stay for this procedure is normally one to two days. The operation takes about two hours and is usually done under local anaesthetic with sedation. The operation involves the placement of electrodes into the space around the spinal cord at the level where your trial stimulator leads were positioned. The connecting lead is passed under the skin, and connected to the pulse generator, which is usually positioned on your upper buttock under the skin. All the parts are completely enclosed inside your body. However, it is common to be able to see and feel the outline of the pulse generator.
After the operation
Later that day, or the next day, your stimulator will be switched on and programmed. The specialist pain team will do this using a hand-held computer that can communicate with your implant through the skin. You will also be shown how to use your own hand-held programmer. It is usual to have significant spinal pain during the first few days after surgery, and the wound on your buttock may also be sore. However, you will be given painkillers to help reduce this and it usually settles after a few days. It is important to perform gentle and regular movement to reduce your post operative pain. Once you are well enough, had a check X-ray and are confident in using your programmer you will be ready to go home. The ward will arrange for your staples to be removed 10 days after your surgery.
Once you have had the surgery we expect you will be able to perform daily activities with ease, however please be sensible and avoid activities that could put undue stress on the implanted system, because this could cause damage and/or displace the system. Whilst normal movement is necessary post-operatively for
healing and recovery try and avoid sudden, excessive or repetitive bending, stretching, twisting or bouncing.
After you leave hospital
It is important to keep your wounds dry and clean, until they have healed and the stitches or staples have been removed. If you spot any signs of infection such as redness, swelling or leakage from your wound sites, contact us immediately (rather than your GP) using the telephone numbers at the end of this leaflet. We will send you an appointment to attend the outpatient department three to six weeks after your operation. During this visit, we will check that your wounds have healed well and alter your stimulator settings if necessary. Following this, you will be reviewed at six months from the date of surgery, and then at regular intervals depending on the need for readjustment, monitoring of battery life and the need to formally re-assess your physical progress.
Failure or breakage of part of the system, and movement of the electrode out of the correct position, which will require corrective surgery. Headache due to a small leakage of fluid from around your spinal cord, which can last a few days. In rare cases, this may become persistent. Wound infection, damage to the spinal cord, meningitis and bleeding or infection around the spinal cord are rare complications but could be life threatening.
Is high frequency stimulation safe?
We think so from initial studies. The HF Spinal cord stimulation System has European approval (CE marking), indicating that this system is safe. However the procedure is very novel in the way the stimulation frequency is used. The complication rate in routine use, in large numbers of patients is unknown. The main complication is infection, treated by antibiotics but often requiring removal of the stimulator system. What about the evidence for long term efficacy of HF-SCS? There is limited data regarding its long term efficacy as the treatment has not been around for long. If at any time you would like to have the system removed, the leads and stimulator can be taken out by the doctor here.
Frequently asked questions
How long will it take me to get back to normal activities?
- Occasional light lifting…………………… Three weeks after surgery
- Work and driving…………………………. Four to six weeks after surgery
- Heavy lifting……………..………………... 12 weeks after surgery
These timescales are only a guide and may vary for different people.
How long do the stimulator batteries last?
The rechargeable stimulator battery can last up to 8-10 years on typical settings. The pulse generator (battery) can usually be replaced as a day-case procedure using local anaesthetic.
Can I drive with stimulator on?
Yes, but only as long as you are not feeling any tingling sensations from the stimulation.
Can magnetic fields and electrical equipment affect the stimulator?
Yes. It is best to keep away from the following:
- Small magnets (including magnetic strips in freezers and fridges) – keep at least
- 25cm (10 inches) away from the stimulator
- Computer disk drives
- Household power tools – keep at arms length
- Radios, phones (cordless, mobile and conventional) – keep at least 10 cm (4 inches
- away from the stimulator
- Large industrial equipment – may reset stimulator to factory settings
- Electric substations – keep at least 8 metres (25 feet) away
- Arc welders – may cause a shock or a jolt, even when the stimulator is off
- Most household electrical equipment that works properly and is properly grounded will not interfere with your stimulator.
Will security devices interfere with the stimulator?
Certain theft or security devices may cause inappropriate or additional stimulation. Approach these devices slowly and if your stimulator is affected switch it off whilst you pass through the device. The stimulator may cause certain security devices to alarm, for example those found in airports, shops etc. You will be issued an ID card to carry with you in case this occurs.
Will any medical treatments or investigations interfere with the stimulator?
It is important to let your health care professional know that you have a stimulator before you attend for any treatment or investigations.
The following treatments/investigations can potentially interfere with your stimulator: Cardioversion / defibrillation / pacemakers (to treat irregular heart rhythms)
Consult us before having:
- MRI scans (used in X-ray departments)
- Ultrasound (used in X-ray and physiotherapy departments)
- Short wave diathermy (used in physiotherapy departments)
- Electrocautery (used during operations)
- Radiotherapy (used in X-ray departments for cancer treatment)
- Lithotripsy (used to break up bladder, kidney and gallstones)
- Bone growth stimulators (internal or external)
The following treatments / investigations should not interfere with your stimulator, if the precautions below are followed:
- TENS machines - the electrodes should be at least 10 cm away from the implanted system (including the leads)
- Mammograms - it is advisable to turn your stimulator off
- Laser treatment - avoid directing over the implanted system (including the leads)
- Dental drills, mixers and ultrasonic de-scalers that are properly maintained - keep at least 15 cm away from the implanted system (including the leads), but it is advisable to turn your stimulator off
Standard X-rays will not interfere with your stimulator
Can I go on board a plane?
- Commercial flights will not affect your stimulator.
When can I return to sport?
- Avoid contact sports as they could lead to electrode damage. You can return to activities like swimming when your wounds have healed. You should gradually build back up to other sports over the following six to eight weeks.
This leaflet is only a guide. For clarification and current information, please consult your Nevro User Manual issued to you with your hand-held programmer.
Contact the team immediately in the case of suspected infection/wound problems (fever, swelling, unexpected wound pain)
- Office hours (8.30am - 4.30pm Mon –Fri): Specialist Nurses/ Specialist Physiotherapist 0151 529-5644
- Out-of-office hours: Ring The Walton Centre switchboard on 0151 525 3611 and ask for the Senior Nurse Bleep Holder explaining that you are having a trial of spinal cord stimulation and explain the problem. They will then contact the neurosurgical registrar to advise you what to do.
Contact us during office house if you experience any of the following:
- Problems with the patient programmer
- Sudden loss of or change in stimulation coverage
- Last Updated:02 April 2018
- Review Date:04 April 2022
- Author:Pain/ Neuromodulation Team
Pain messages are sent along special pain pathways and up the spinal cord, to the brain. Although we may feel the pain in a particular place, such as a joint, nerve or muscle, we only recognise the sensation as pain once it reaches the brain.