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Radio-Frequency Facet Nerve Blocks
Lumbar
  History  
  In the latter third of the 20th century the modern specialty of spine care first began to  evolve.  A number of innovative concepts and associated procedures were the result of this.  Some of these therapies have not successfully withstood the test of time but others have remained in the treatment armamentarium because of their well-demonstrated continuum of safety and efficacy.  The chronicle of how facet and medial branch injections and radio-frequency (RF) blocks came to be is a particularly intriguing tale known, but only to a few. 
 
  History   
The modern era of interest in the facet (zygoapophyseal) joints came about when clinicians began to recognize that these structures were important sources of low back pain and resulting disability.  It appears that Joel Goldthwait was the first to recognize this connection in 1911 (The Lumbosacral Articulation: an explanation of many cases of 'lumbago,' 'sciatica,' and 'paraplegia.'" Boston Medical Surgical Journal 1911) followed soon after by Ralph Ghormley  in 1933 (Low Back Pain with Special Reference to the Articular Facets, with Presentation of An Operative Procedure." Journal of American Medical Association 1933). 

The credit for the first anatomic studies performed on the innervation of the facet joints goes to Professor Guy Lazorthes and his associates in Toulouse France, beginning in the 1950s (Lazorthes G, Gaubert J: L'innervation des articulations interapophysaires vertebrales, Comp Rend Assoc Anat 43:488-494, 1956).  Because his works were published only in French journals a number of decades passed before his contributions were appreciated by the English speaking medical world.  The later work of Drs. Stanley Paris , Nikolai Bogduk, and others in the 1980s served to complement and confirm the original work of Lazorthes and to build a scientific basis for our present understanding and associated treatment of  the "facet syndrome" as an important contributor to the etiology of low back pain in the world's population.  
              
Dr. Paris is shown above studying the dorsal root complex of a cadaver.  In the drawing at right the green dot is on the dorsal ramus of the emerging dorsal nerve root ganglion.  The yellow dot shows the point at which this ramus the continues as extremely small A-delta and C-fiber branches which are actually thinner than a spider web strand which averages 4-5 µm (microns) .  These minute sensory nerves innervate the facet joints.  The medial branch of this complex is the typical target for  injections and permanent radio-frequency (RF) blocks; also referred to as "cauterizations", "ablations", and "neurolysis".
The task of attempting to make sense of all of this information fell to Professor William Kilkaldy-Willis at the University of Saskatoon, Saskatchewan, Canada who, on the basis of his personal research (Kirkaldy-Willis W et al. Pathology and Pathogenesis of Lumbar Spondylosis and Stenosis, Spine, Vol 3, No. 4, pp. 318-328, 1978) during the 1970s initiated the concept of  the "degenerative cascade".  Kirkaldy-Willis' anatomic studies were soon confirmed by radiologists and clinicians who could then begin to visualize these same entities on computed tomographic scans (CT) and then on magnetic resonant imaging (MRI) studies.
In the first of the illustrations above the arrows point to areas of the articular facet joint which have eroded and have  resulted in joint dysfunction as shown on this CT scan.  In the second image the arrow points to a similar area of erosion in a pathologic specimen provided by Professor Kirkaldy-Willis.  The third image also shows facet joints with more advanced degenerative change which has led to a degenerative spondylolisthesis (last illustration) due to progressive degeneration of these facet joints.  When more advanced facet degeneration occurred it could create lateral spinal stenosis, the most common reason for creation of the "failed back surgery syndrome".  It is important to point out that if the patient is a non-smoker the great majority of these patients, with non-surgical care self-heal.

In the late 1960s an Australian surgeon, W. E. Skyrmer Rees, first introduced the concept of treating facet related low back pain by surgically cutting the intertransverse ligament with a scalpel in order to section the dorsal ramus as a means of producing a sensory blockade and thus relieving back pain secondary to what has become called the "facet syndrome".  The illustration shown below was drawn by Rees, in 1971, to illustrate how a "Beaver Eye Knife" (scalpel) was utilized to surgically section this intertransverse ligament and the dorsal ramus of the postganglionic segment of the spinal nerve.
Rees referred to his procedure as "dorsal root rhizolysis" and usually performed it on both sides.  Following publication of his work in the 1975 Medical Journal of Australia American neurosurgeon C. Norman Shealy visited Rees in Australia.
Shealy observed Rees' procedures, and returned to the United States where he performed rhizolysis on a number of his own patients.  He concluded that while the procedure seemed to have merit in producing pain relief it was certainly not minimally invasive and often produced significant subcutaneous hematomas.  Shealy's previous experience with radio-frequency coagulating electrodes used to treat conditions such as trigeminal neuralgia led him to replace the Beaver scalpel with a radiofrequency electrode probe.  
It remained for some of Shealy's neurosurgical colleagues to further refine this clinically valuable technique . A significant improvement was achieved when neurosurgeon Charles Ray (seen below), designed a trocar type electrode.  At about this time, based on the anatomic studies of Paris and Bogduk, it became evident that a that a much more safe and selective procedure could be performed by simply cauterizing the medial branch of the dorsal nerve ramus at the base of the transverse process (providing a definitive [and safe] bony end-point) for the procedure.
This percutaneous approach replaced the need for of general anesthesia and replaced it with "monitored anesthetic control" using local anesthesia and parenteral supplementation (i.e. Fentanyl and  Versed).  At this point percutaneous radio-frequency facet blocks then became the "gold standard" for safety and efficacy.
Shown above is a radiofrequency procedure in progress.  The Ray electrode (or other RF electrodes) are inserted percutaneously under fluoroscopic control and directed to the base of each transverse process, where a monitored RF coagulation lesion is produced.
The illustration to the left demonstrates the standard target neurosurgical target areas which were recommended for the  placement of the radiofrequency probe in the 1970's.  The procedure was always performed bilaterally and at multiple levels.
The reason for lesion production bilaterally and at multiple sites has to do with the non-specifi sensory input system of the facet which is similar to a spider's web and the goal is not to destroy the system but to block some of the "strands" to simply cut down on the sensitivity of the system's sensitivity.  

Some clinicians initially issued dire predictions that RF lesioning would produce "Charcot" joints (total denervation of a joint sometimes seen with syphilis or diabetes initially described by Jean-Martin Charcot, 1825-1893, Professor of Neurology at the University of Paris) or denervation of the paravertebral muscles.  Fortunately, there has been no evidence, over time, that this occurs.  Other dire predictions regarding significant have also not been borne out. 

What has become evident is that the RF procedure, by decreasing the sensitivity of the A-Delta and C fiber facet "alarm system" has been most effective in relieving low back pain related to the facet "syndrome" and providing the opportunity of initiating a "window of opportunity" of better health habits (mainly cessation of smoking), appropriate exercise and daily health maintenance to allow for normal self-healing to occur..

  The Burton Experience  
The Burton Experience with percutaneous radio-frequency facet blocks began in the early 1972 when the Editor invited Norman Shealy to give a presentation on "Articular Nerve of Luschka, Rhizotomy for Back and Leg Pain" at Temple University Health Sciences Center in Philadelphia.  The term "Luschka" referred to German Anatomist Herbert von Luschka (1820-1875) who studied and described the uncovertebral (facet) joint. This usage became synonymous with the the term "zygoapophyseal joint." 

Following this symposium a Joint Study Group consisting of neurosurgeons Shealy, Prieto, Burton, and Long  initiated an interinstutional trial of this procedure.  These clinical results were presented at the annual meeting of the American Association of Neurological Surgeons in Los Angeles in 1973.  In the Burton series the overall long-term procedure efficacy(3 year follow-up) was 67% (Burton CV: Percutaneous Radiofrequency Facet Denervation, Applied Neurophysiology, 39:80-86, 1977) and it is interesting to note that even today this same efficacy determination has continued, unchanged,  in the Editor's clinical practice.  

Radiofrequency facet blocks are now, after over 30 years of clinical application, considered to be "well established" by the world spine specialist community.  They have, on the basis of a large population of clinical use, proven to be a valid and important, minimally invasive, low risk procedure for the well-selected patient with a "facet syndrome" when applied by experienced physicians using x-ray control. 

In a prime example of one of the great examples of perversity in our health care system many procedures such as lumbar radiofrequency facet blocks have been denied for third party payor coverage as being "experimental or investigational" based on the fact that double blinded and controlled studies weren't done over the two scores of time ending the 20th century (P.S. the same is true for appendectomy for acute appendicitis):
 

Remarkably,  Nath et al actually did a randomized controlled study to confirm efficacy which was published in the Journal Spine in 2008 (Nath et al, Percutaneous Lumbar Zygoapophyseal (Facet) Joint Neurotomy Using Radiofrequency Current, in the Management of Chronic Low Back Pain, Spine, Vol. 33, No. 12, pp. 1291-1297, 2008).

Initially RF facet blocks were always performed by neurosurgeons.  Once a high degree of safety and efficacy had been well demonstrated however "pain management" specialists entered upon the clinical scene and spine procedure oriented clinics specializing in percutaneous procedures began to pop up in most large communities in the U.S.  This has clearly now become "big business" particularly in regard to repeat epidural steroids and facet and medial branch injections and blocks for which there has become marked over utilization.  At the annual meeting of the North American Spine Society Venu Akuthota, M.D., and associates  reviewed a interventional spine procedure database of 12 million to 14 million privately insured adults in the U.S. and found that a minority of the procedurists accounted for the majority of the procedures  performed.  The range of procedures performed (individual patient over the course of one year) for epidural steroid injections was 1-51, for facet or medial branch blocks 1-135, and for radiofrequency medial branch ablations was 1-34.  In the Editor's clinical practice less than 5% of patients ever required more than one session of radiofrequency medial branch ablations.

While the neurosurgical experience demonstrated that it was not unusual for patients to experience continued pain relief for many years following percutaneous RF Facet blocks (good results for as long as 20 years are known by the Editor).  The representation to patients that this is something which needs to be repeated, on a regular basis, throughout a patient's life clearly reflects a point of view not substantiated by fact and inconsistent with the patient's best interests. 

For the right patient, and if performed by the right specialist for the right reasons, radiofrequency facet blocks, in the lumbar area, as well as in the thoracic and cervical areas,  have been a successful endeavor.  In a study performed at Johns Hopkins by Steven Cohen in 2010 it was pointed out that "if we just do the radiofrequency procedure first, we're going to help more people and we're going to save a lot of money." 

 

Dorsal Root Rhizolysis and Dorsal Root Rhizotomy-  When Australian surgeon, W. E. Skyrmer Rees, first introduced the treating of low back pain emanating from the facet joints he actually intended to completely sever the dorsal nerve root with a scalpel.  He was the one, in the 1960s to coin the term "dorsal root rhizolysis", which a correct description of what he was attempting to do.  The Latin "Rhiz" is translated "root", referring to nerve root (i.e. dorsal nerve root) and "lysis" means "to cut".  The term "otomy" is a bit more complex because it is used, in present medical lingo, to mean "to open".  However,  "otomy" derives from the Greek work "tome"  meaning "to cut" and we are therefor back to meaning surgical division of of some or all the fibers of a nerve; not a minimally invasive percutaneous coagulation of small nerve fibers. 

Articular Nerve of Luschka Rhizolysis- Term used by Shealy to describe his modification of the Rees procedure.  Rhizolysis is a misnomer and von Luschka never described a nerve associated with the uncovertebral joint.

Percutaneous Radiofrequency Facet Denervation-  Term used originally by Burton in the 1970s to describe partial denervation of the facet joints.

Percutaneous Radio-Frequency Facet Nerve Blocks (PRFFNB)- Term used by Burton.  Although unwieldy, this verbage is correct.  To be more specific the medial branch of the articular nerve should be identified.

Percutaneous Radiofrequency Medial Branch Nerve Ablation is the more specific term and is being used more at the present time..