Persistent spinal pain syndrome
Persistent spinal pain syndrome is a pain disorder characterized by chronic pain originating in the spine. PSPS is categorized into two primary types:
- Type 1 : Spinal pain in patients who have not undergone surgery.
- Type 2 : Spinal pain following one or more surgeries.
Signs and symptoms
Common symptoms of failed back surgery syndrome include diffuse, dull, and aching pain in the back or legs, often accompanied by abnormal sensations such as sharp, pricking, or stabbing pain in the extremities. Patients may also experience pain at a different level from the location originally treated, along with an inability to fully recuperate and restricted mobility. Sharp, stabbing pain in the back, numbness, muscle spasms, or pain radiating from the lower back into the legs are frequently reported. In addition to physical discomfort, FBSS can lead to psychological symptoms such as anxiety, depression, and insomnia.Cause
The number of spinal surgeries varies around the world. The United States and the Netherlands report the highest number of spinal surgeries, while the United Kingdom and Sweden report the fewest. Some health systems in Europe have recently reported a trend toward more frequent surgical management. Success rates of spinal surgery vary for many reasons.Patients who have undergone one or more operations on the lumbar spine and continue to experience pain afterwards can be divided into two groups.
- The first group comprise those in whom surgery was not actually indicated or the surgery performed was not likely to achieve the desired result, and those in whom surgery was indicated but which technically did not achieve the intended result. Patients whose pain complaints are of a sciatic, radicular nature have a better chance for a good outcome than those whose pain complaints are limited to pain in the back.
- The second group includes patients who had incomplete or inadequate operations. Lumbar spinal stenosis may be overlooked, especially when it is associated with disc protrusion or herniation. Removal of a disc, while not addressing the underlying presence of stenosis, can lead to disappointing results. Occasionally operating on the wrong level occurs, as does failure to recognize an extruded or sequestered disc fragment. Inadequate or inappropriate surgical exposure can lead to other problems in not getting to the underlying pathology. Hakelius reported a 3% incidence of serious nerve root damage.
In the past two decades there has been a dramatic increase in fusion surgery in the U.S.: in 2001 over 122,000 lumbar fusions were performed, a 22% increase from 1990 in fusions per 100,000 population, increasing to an estimate of 250,000 in 2003, and 500,000 in 2006. In 2003, the national bill for the hardware for fusion alone was estimated to have soared to $2.5 billion a year.
For patients with continued pain after surgery which is not due to the above complications or conditions, interventional pain physicians speak of the need to identify the "pain generator" i.e. the anatomical structure responsible for the patient's pain. To be effective, the surgeon must operate on the correct anatomic structure, but is often not possible to determine the source of the pain. The reason for this is that many patients with chronic pain often have disc bulges at multiple spinal levels and the physical examination and imaging studies are unable to pinpoint the source of pain. In addition, spinal fusion itself, particularly if more than one spinal level is operated on, may result in "adjacent segment degeneration". This is thought to occur because the fused segments may result in increased torsional and stress forces being transmitted to the intervertebral discs located above and below the fused vertebrae. This pathology is one reason behind the development of artificial discs as a possible alternative to fusion surgery. But fusion surgeons argue that spinal fusion is more time-tested, and artificial discs contain metal hardware that is unlikely to last as long as biological material without shattering and leaving metal fragments in the spinal canal. These represent different schools of thought.
Another highly relevant consideration is the increasing recognition of the importance of "chemical radiculitis" in the generation of back pain. A primary focus of surgery is to remove "pressure" or reduce mechanical compression on a neural element: either the spinal cord, or a nerve root. But it is increasingly recognized that back pain, rather than being solely due to compression, may instead entirely be due to chemical inflammation of the nerve root. It has been known for several decades that disc herniations result in a massive inflammation of the associated nerve root. In the past five years increasing evidence has pointed to a specific inflammatory mediator of this pain. This inflammatory molecule, called tumor necrosis factor-alpha, is released not only by the herniated or protruding disc, but also in cases of disc tear, by facet joints, and in spinal stenosis. In addition to causing pain and inflammation, TNF may also contribute to disc degeneration. If the cause of the pain is not compression, but rather is inflammation mediated by TNF, then this may well explain why surgery might not relieve the pain, and might even exacerbate it, resulting in FBS.
Role of [sacroiliac joint] (SIJ) in [lower back pain] (LBP)
A 2005 review by Cohen concluded, 'The SI joint is a real yet underappreciated pain generator in an estimated 15% to 25% of patients with axial LBP'. Studies by Ha, et al., show that the incidence of SI joint degeneration in post-lumbar fusion surgery is 75% at 5 years post-surgery, based on imaging. Studies by DePalma and Liliang, et al., demonstrate that 40–61% of post-lumbar fusion patients were symptomatic for SI joint dysfunction based on diagnostic blocks.Smoking
Recent studies have shown that cigarette smokers will routinely fail all spinal surgery, if the goal of that surgery is the decrease of pain and impairment. Many surgeons consider smoking to be an absolute contraindication to spinal surgery. Nicotine appears to interfere with bone metabolism through induced calcitonin resistance and decreased osteoblastic function. It may also restrict small blood vessel diameter leading to increased scar formation.There is an association between cigarette smoking, back pain and chronic pain syndromes of all types.
In a report of 426 spinal surgery patients in Denmark, smoking was shown to have a negative effect on fusion and overall patient satisfaction, but no measurable influence on the functional outcome.
There is a validation of the hypothetical assumption that postoperative smoking cessation helps to reverse the impact of cigarette smoking on outcome after spinal fusion. If patients cease cigarette smoking in the immediate post operative period, there is a positive impact on success.
Regular smoking in adolescence was associated with low back pain in young adults. Pack-years of smoking showed an exposure-response relationship among girls.
A recent study suggested that cigarette smoking adversely affects serum hydrocodone levels. Prescribing physicians should be aware that in some cigarette smokers, serum hydrocodone levels might not be detectable.
In a study from Denmark reviewing many reports in the literature, it was concluded that smoking should be considered a weak risk indicator and not a cause of low back pain. In a multitude of epidemiologic studies, an association between smoking and low back pain has been reported, but variations in approach and study results make this literature difficult to reconcile. In a study of 3482 patients undergoing lumbar spine surgery from the National Spine Network, co-morbidities of smoking, compensation, self reported poor overall health and pre-existing psychological factors were predictive in a high risk of failure. Followup was carried out at 3 months and one year after surgery. Pre-operative depressive disorders tended not to do well.
Smoking has been shown to increase the incidence of post operative infection as well as decrease fusion rates. One study showed 90% of post operative infections occurred in smokers, as well as myonecrosis around the wound.