Spinal Cord Stimulation

The system has three parts. One or two leads, each carrying a row of small electrodes, lie in the epidural space at the back of the spinal canal, positioned at the level that corresponds to the painful region. A pulse generator, about the size of a small matchbox and containing a battery, is implanted under the skin, usually in the upper buttock or the flank. A handheld or smartphone controller lets the user turn the system on and off and choose between programmes. Different stimulation patterns are available: traditional stimulation replaces pain with a light tingling called paraesthesia, while high-frequency and burst patterns work without any sensation at all. Generators may be rechargeable, lasting many years, or non-rechargeable and replaced in a short procedure when the battery runs down.

The clearest indication is persistent nerve pain in the legs, with or without back pain, that continues after spinal surgery, sometimes called failed back surgery syndrome or persistent spinal pain syndrome. Other established indications are complex regional pain syndrome, painful diabetic neuropathy of the feet, nerve pain after injury or surgery to a peripheral nerve, and angina that cannot be relieved by stents, bypass or medicine. It is considered when pain has lasted more than six months, when it limits daily function, and when medicines, injections, physiotherapy and psychological pain management have been tried and are insufficient. There must be no further surgical option that would address the cause, no active infection, no untreated significant psychological condition, and the individual must be able to manage a rechargeable device or attend for battery replacement.

Treatment has two stages. In the trial, the patient lies face down under local anaesthesia with light sedation, and a needle is used to enter the epidural space under fluoroscopic guidance. One or two temporary leads are threaded up to the target level, often with the patient awake enough to confirm that the stimulation covers the painful area. The leads are anchored at the skin, connected to an external generator and left in place for several days while the patient carries on with normal daily activity and records pain scores and function. If the trial succeeds, the leads are removed and, at a second procedure, permanent leads are placed by the same route or, when a wider paddle-shaped lead is needed, through a small opening in the bone of the vertebral arch. A pocket is made under the skin, the generator is placed and connected, and the wounds are closed. The permanent implant is usually done under sedation or general anaesthesia and takes about 1 to 2 hours.

Assessment is multidisciplinary. It includes a pain specialist's review of the diagnosis and previous treatments, imaging of the spine, a psychological assessment of expectations, mood and coping, and a check for infection risk factors including diabetes control, skin condition and dental health. Blood-thinning medicine is stopped on medical advice, since bleeding in the epidural space is the most serious risk. Anticoagulation, immunosuppression and current infection all delay the procedure. Patients are counselled that the aim is a meaningful reduction in pain and improvement in function, not the abolition of pain, and that opioid reduction is usually part of the plan. For international patients, imaging, the treatment history and the medication list can be reviewed in advance, and the trial and implant are scheduled together so that both fit into one visit.

The trial period is spent out of hospital, moving normally, so that the effect on real daily activity can be judged. After the permanent implant, the wounds are sore for a week or so, and there is a firm limit on bending, lifting and twisting for about six weeks so the leads do not move before scar tissue anchors them. The device is switched on and programmed within days, and programming is refined at several visits over the first one to three months to find the settings that give the best relief. Driving is resumed once comfortable and with the stimulation adjusted for it. Physiotherapy and graded activity begin as soon as the wounds allow, and medicine is reduced gradually under supervision. For treatment abroad, the practical plan is a stay of about 2 to 3 weeks so that the trial, the implant and the first programming visits are all covered, with later programming carried out remotely or by a local centre.

The most common problems are technical rather than medical: a lead can move, so the stimulation no longer covers the painful area and needs repositioning, and a connection or lead can fracture. Infection of the implant occurs in a small percentage and may require removal of the system. Bleeding in the epidural space is rare but is the reason for careful management of blood thinners, since it can compress the spinal cord. Other risks include pain over the generator pocket, seroma, unwanted stimulation of the chest wall or abdomen, and loss of effect over time, which affects a proportion of users. Magnetic resonance imaging is possible with modern systems under specified conditions, and diathermy is not permitted. Where selection is careful and a trial has been positive, most implanted patients report a substantial reduction in pain, better sleep and better function, and many reduce their pain medicine. The device does not treat the underlying spinal condition, and results are checked and reprogrammed over the years.