Radiofrequency Neuroablation in Chronic Low Back Pain
Clinicians and health care administrators are all acutely familiar with the impact that low back (LBP) has on quality of life, worker productivity and the workers’ compensation system. Numerous studies report the economic impact of LBP to be in the excess of $100 billion dollars. Additional studies suggest that LBP will effect nearly 80% of the population at some point in life.
Pain that persists despite routine medical management poses a difficult problem for patients and their treating physicians. When pain continues despite medical care, there is an increasing probability of physical disability, psychosocial dysfunction, drug dependence, and development of chronic pain.
Recent advances in technology, along with new understanding of the anatomy and Physiology of pain, make it possible to accurately diagnose and effectively treat pain previously thought untreatable. In the area of spinal pain for instance, spinal patho-physiology has allowed for a variety of new diagnostic and therapeutic interventions into low back pain, radiculopathy, neck pain and cervicogenic headache.
Etiology of Low Back Pain
Typically back pain may be precipitated by any of the following seven pain generators:
- Skin (e.g., shingles)
- Pathology of muscle and soft tissue with the possibility of myofacial pains, muscle ligament pains with strains
- Posterior complex pain emanating from the facet joint arthropatheis or spondylolisthesis with pars defects
- Medial complex or neuro origin pain from radiculopathy caused by either foraminal narrowing or neural encroachment from the herniated disc with radiculitis or a chemical radiculitis caused by a leakage of the nucleus pulposous
- Annulus tear and anterior complex pain emanating from possible degenerative or internally deranged disc disease
- Sacroiliac joint disease
- Back pain not specifically involving the spine may be related to some retro peritoneal masses or aortic aneurysm or sometimes renal mass or renal problems, thus intra-abdominal pathology needs to be ruled out
Radiofrequency neuroablation, or lesioning, has recently been used successfully as a treatment for chronic, refractory neck pain from whiplash injury, a condition in which recent scientific research has identified spinal facet joints as commonly responsible for persistent pain. Facet joints may also be the source for pain in certain types of cervicogenic headache and in non-radicular low back pain. Facet pain can be identified by its characteristic pattern of radiation, and the diagnosis is confirmed when pain is relieved transiently with precise fluoroscopic nerve block of the facet joint nerves. Radiofrequency denervation is gaining acceptance as an effective treatment option with minimal risk and low morbidity when more conservative approaches fail to relieve symptomatic relief. It is also successfully used for neuro-ablation of the ganglia in sympathetically maintained pain syndromes.
This article reports on the outcomes of a group of patients with chronic low back pain who have undergone radiofrequency neuroblation in an urban hospital setting. One male patient underwent the procedure for chronic neck pain he experienced for at least one year.
Of the 77% of patients who reported pain relief following their radiofrequency procedure; 69% indicated that they were somewhat satisfied to very satisfied with the procedure, while 23% had no relief, and 31% were not satisfied. Following the procedure, 13% of patients reported that there were able to sit pain free for 10 minutes or less; 18% were able to sit up to 30 minutes; 67% were able to sit for one hour or more (one participant did not answer this portion of the questionnaire).
Gross evaluation in functional status following the radiofrequency procedure showed improvement in 59% of patients in terms of sitting, 62% in terms of standing, and 67% in terms of walking.
Lumbar spine pathology is certainly a common and sometimes difficult problem to treat. Low back disorders are the most common site of problems along the entire spinal axis. In understanding the proper use of radiofrequency lesions and the treatment of chronic pain emanating from the lumbar spine, it is important to understand the correct anatomy and pathoanatomy of the lumbar spine itself.2
From an anatomical viewpoint, the lumbar spine has several sources that are potential generators. There are specific areas that have been identified thru neuroanatomical dissections as containing pain fibers. The areas in the lumbar spine that can generate pain include the annulus of the disc, the posterior longitudinal ligament, portions of the dural lining, the facet joints and capsules, the spinal nerve roots and ganglion, and the associated paravertebral musculature.3-5 Specific radiofrequency techniques have been devised for the treatment of pain emanating from the facet joints, nerve roots, and annulus fibrosis. No specific techniques have yet been devised for the treatment of pain emanating from the dura or posterior longitudinal ligament and the use of radiofrequency techniques for the treatment of muscular (myofascial) pain is certainly not appropriate.
The lumbar facet joints receive innervation from multiple levels of the lumbar spine.3,4,6 However, there is no clear-cut, one-to-one innervation pattern of joint to nerve root level.
Hence, to properly deinnervate a lumbar facet joint (even in a partial fashion) multiple levels need to be lesioned. The lumbar facet joints derive their innervation from the medial branches of the posterior primary ramus.4 From the levels of L1 through L4 the medial branches of dorsal rami run across the top of the transverse process at their own level and go through the intertransverse ligament at the base of the transverse process. Each medial branch then runs across the periosteum at the junction of the base of the transverse process. The nerve then wraps around the medial aspect of the base of the superior articular process and at that point is covered by a relatively dense connective tissue called the mamilloaccessory ligament.4 Finally, the nerves cross the lamina and divide into several branches that supply the paraverebral musculature, interspinas muscles and ligaments, and two separate facet joints. For all practical purposes, each medial branch actually innervates the facet joint above and below its anatomical course.