As discs degenerate the central bulk of the disc fragments and gradually leaves the disc thus reducing bulk and height and causes the disc wall (Annulus) to buckle and bulge. Weight bearing X-rays show that the normal rectangular disc becomes triangular with loss of height in the back of the disc. This causes abnormalities of posture and function and exaggerated loading of the back of the disc and the facet joints. The loss of height may result in a reduction in the volume (narrowing) of the doorway (Foramen). The increasing "sloppiness" ("Instability") of the disc segment causes abnormal movements in the facet joint with wear and tear of the surface and thickening of the bone margins and capsule. This compensatory increase in facet joint mass encroaches upon the spinal canal and foraminal volume. In patients with a congenitally small foraminal volume these changes may lead to the symptoms of Lateral Recess Stenosis. In some patients, the sloppiness in the disc allows the vertebrae to displace forwards (Spondylolisthesis) or backwards (Retrolisthesis) upon each other further aggravating nerve root irritation where the nerves are tethered to the disc, facet joint or margins of the foramen (Pedicles) or vertebral bodies.
The repeated displacement of the two surfaces of the facet joint causes stretching of the joint capsule and may causes an area of thinning and weakness through which the lining of the joint may extrude. This out-pouching may form fluid in its own right thus forming a sac of fluid which becomes surrounded by an isolating wall called a cyst.
In some patients the cysts may fill by fluid expressed from within the facet joint through a narrow neck which acts as a one way valve.
Facet Joint Cysts may remain symptomless for many years but may cause symptoms of Lateral Recess or Axial Stenosis. The classic presentation is one of activity related pain and weakness with wasting eased by bending the back or neck forwards (Flexion). The symptoms ease after a period of rest during which the cyst may empty and or engorgement of the veins compressed in the foramen or spinal canal subside and the blood supply to the nerve returns and with it the pain decreases and power is restored until the activity related engorgement recurs (neurogenic claudication).
Not only may the cyst cause symptoms by direct compression but also by tethering between the cyst and the nerve, adjacent structures, ligaments (Superior Foraminal Ligament), capsule or local bone spurs (osteophytosis) from the facet joint or the vertebral margins resulting in more constant back pain, buttock and leg pain or neck pain, shoulder and arm pain and loss of function
The pattern of symptoms depends on the nerves involved and individual variations in the distribution of the nerves within the spine and junctions ("Plexuses") outside the spine. These variations may lead to errors in conventional diagnosis overcome by aware state diagnosis.
To these symptoms may be added the symptoms of inflammation as seen in High Intensity Zones. The body's protective spasm may lead to additional symptoms from the neck in to the shoulder or "Sacro-Iliac" joint or buttock (Piriformis Muscle Syndrome) from the lumbar spine. These features may arise directly from the facet joint or from overriding (sliding) of the facet joint leading to compression of the nerve further aggravated by the presence of the cyst.
Once the cyst becomes symptomatic the symptoms and functional loss usually continue to worsen and degrade lifestyle to the point where definitive treatment is required by the patient.
The need for surgical intervention has to balance the risks of continued irritation and the induction of scarring and tethering around the nerves causing long term symptoms against the risks of surgery. The latter may be minimised by Endoscopic Minimally Invasive Spine Surgery.
Facet Joint Cysts are uncommon and may be symptom free (asymptomatic) for many years. Symptoms may improve with careful conservative management (Orthopaedic Therapy
with core spinal muscle and postural rehabilitation, pain killers, anti-inflammatory and anti-irritation drugs) and Intervertebral Differential Dynamics
(IDD) and Therapeutic injections
(facet joint injections, root blocks, therapeutic discograms) over a period of 3 months. Repeated episodes denotes a more chronic condition less likely to be resolved by these conservative measures which can be addressed with further Chronic Pain Management as above or Endoscopic Minimally Invasive Spine Surgery using discrete targeted solutions such as TELDF (Foraminoplasty
), Endoscopic Selective Discectomy
, Laser Disc Decompression
, Annuloplasty or Automated Percutaneous Lumbar Discectomy
, supplemented with modification of the internal disc structure and metabolism with Gelstix or ultimately stem cells. The transforaminal endoscopic approach allows the nerve to thoroughly explored and the cyst wall to be resected (cut away) and the facet joint source treated. The endoscopic posterior approach suffers the same limitations as posterior open decompreesion surgery namely inadequate ability to explore the nerve sufficiently through the foramen.