A treatment for “untreatable” back pain
Martin Baggenstos, M.D.
Neurosurgeon, Providence Brain and Spine Institute
The Oregon Clinic Microneurosurgical Division
Chronic spinal pain and failed back surgery syndrome are common problems in the United States, and managing this persistent pain is challenging. A variety of treatment modalities have been designed, including physical therapy, steroid injections, chiropractic manipulations, acupuncture and a variety of pain medications.
Despite all of these measures, many patients are still left with intractable chronic pain. In the 1960s, spinal cord stimulation, or SCS, was explored to treat chronic pain through an idea known as the “gate theory of pain.” It was believed that by stimulating the dorsal portion of the spinal cord, we would inhibit pain signals to the brain. In 1967, the first electrode for spinal cord stimulation was placed. The field has advanced exponentially since then.
Common indications for SCS include failed back surgery syndrome, complex regional pain syndrome, diabetic neuropathy, phantom limb pain, angina pectoris and peripheral vascular disease. The indications are rapidly expanding to include spinal lumbar stenosis in patients who are not surgical candidates; occipital neuralgia; Raynaud’s syndrome and chronic intractable pain located in the head, face, jaw and neck; and post-thoracotomy syndrome.
Radicular pain tends to respond better to SCS than does low-back pain. Randomized controlled trials have shown that some patients with SCS have less pain and better health-related quality of life and functional capacity than those receiving just medical management or reoperation.
Because only the neuropathic component of pain is diminished with SCS, potential candidates must first undergo a detailed pain analysis. Likewise, MRI or CT imaging is performed to exclude any surgically curable causes of pain, such as spinal cord or nerve root compression.
Proper candidates for SCS must present with a well-defined, nonmalignant, organic cause of pain that cannot be treated with surgery. The patient also should have failed at least six months of conservative medical management.
Once a patient is an SCS candidate, a psychological evaluation is performed to determine the appropriateness of stimulator placement. Each patient then undergoes an SCS trial with a temporary electrode, typically lasting around a week, to assess the treatment’s efficacy. During this trial, patients typically note paresthesias over the area being treated. If various pain scales show at least 50 percent pain relief, the patient may be considered for permanent implantation.
A surgically implanted paddle sits over T7 and T8.
The permanent implant can be placed percutaneously or through open surgery. Hardware involves either percutaneous leads or a surgically implanted paddle in the epidural space. The leads are connected to an implanted pulse generator that is controlled by a handheld programmer. The patient has basic control of the stimulation parameters and turning the device on and off. Regular batteries have a life of three to five years, while rechargeable batteries can last up to 10 years.
Technological advances in SCS, a better knowledge of the mechanism of action, and careful patient selection have helped spinal cord stimulation become an effective tool to reduce pain. These advances have led this technique to become more accepted among pain physicians. Appropriate use of SCS can improve patients’ quality of life in cases where they have medically intractable pain or are not surgical candidates.