An update on spinal cord stimulation

Spinal Cord Stimulation (SCS) has been used successfully for over 40 years to treat chronic pain disorders. This article will highlight a recent review of the literature by Falowski et al (2008), which tracks the evolution of the technology, its current applications and challenges for the future.

Spinal Cord Stimulation (SCS) is a procedure which delivers electrical currents to the spinal cord to reduce the sensation of neuropathic pain. In 1965, the ‘gate control’ theory of pain paved the way for SCS. Two years later, dorsal column stimulation was performed for the first time on a patient suffering from terminal cancer. Since then, there have been significant technological advancements, and now a renewed interest in special electrode arrays to deliver stimulation to the spinal cord. Over the past 40 years, SCS has become a widely used procedure, and has the support of many neurosurgeons and anaesthesiologists who specialise in pain management. The popularity of SCS is largely due to its superior success rates. It has been reported that SCS reduces the experience of chronic pain by 50%.

Despite numerous studies, the exact casual mechanisms of SCS are uncertain. Imaging studies have shown that stimulation creates complex electrical fields that could affect several local structures. Animal studies have shown that SCS causes serotonin, substance P and GABA to be released in the dorsal horn. Further research is needed to see if these results can be extrapolated to humans.  

As SCS has become more developed, it has been used to treat a wider variety of pain disorders. Traditionally, the use of SCS was confined to treating neuropathic pain, including postlaminectomy syndrome (failed back surgery syndrome), complex regional pain syndrome, phantom limb pain and spinal cord injury pain. More recently, SCS has been a successful therapy for intractable angina pain, abdominal or visceral pain and chronic critical limb ischaemia and pain.

Promising studies show that SCS may offer pain relief for sufferers of refractory angina pectoris. SCS may even offer other benefits such as an improved exercise capacity and recovery time. This is likely to be the result of increased myocardial blood perfusion, and hence reduced ischaemia. In 1973, SCS was shown to improve blood flow in the lower limbs. This led to the use of SCS to treat chronic critical limb ischaemia and pain. In subjects with peripheral vascular disease, it is thought that inhibition to the sympathic system results in increased blood flow.

Originally, scientists believed that nociceptive pain could not be ameliorated by SCS. Several studies have since shown that SCS can provide relief for people suffering from abdominal or visceral pain. In particular, patients with malignancies in the abdominal region may benefit from SCS.

There are now many different devices available for SCS. These include trial percutaneous electrodes, permanent plate electrodes, totally implantable rechargeable and non-rechargeable pulse generators (IPG) and RF driven pulse generators. With such a wide range of choice, patients are sure to find a device that suits them best. Patients should be aware that severe complications of SCS such as paralysis are extremely rare. SCS is a very safe procedure, but does pose the small risk of infection or pain at the implant site. 

Over a period of 40 years, SCS has become an advanced and sophisticated technology used to reduce patients’ pain symptoms. SCS has been continually improved and is now safer and more reliable. In addition, its potential uses have been extended to include conditions such as abdominal and visceral pain, angina pain and chronic critical limb ischaemia. SCS is now widely accepted as a superior therapy for the management of chronic pain, and continues to gain popularity.

(Source: Falowski S et al. Spinal cord stimulation: an update. Neurotherapeutics 2008; 5: 86-99)