SIGNS AND SYMPTOMS

A facet cyst can develop without any associated symptoms. Very often the cyst is discovered incidentally on advanced imaging studies such as CT or MRI, ordered for the investigation of spinal pain or neurological symptoms. The mere presence of a facet cyst does not confirm that it is the sole cause of pain or symptoms that the patient is reporting. There may be a coexistent problem at the same spinal segment. A good example would be a herniated disc and synovial cyst found at the same level in the spine. The source of pain in this example may be attributable to herniated disc rather than the synovial cyst. The most common symptom associated with a facet joint synovial cyst is recurrent or persistent low back pain. The low back pain is often magnified in certain positions or with movement. A large facet synovial cyst can cause compression of adjacent neurological structure producing neurological signs and symptoms.

Neurological signs and symptoms include:

• Radiating extremity pain
• Extremity numbness or tingling
• Extremity weakness sin a spinal nerve distribution
• Neurogenic claudication
• Spinal cord compromise (myelopathy) if present in the cervical (neck) or thoracic (mid back) regions
• Cauda equina syndrome

CAUSES

The synovium is a thin film of tissue that produces fluid (synovial fluid) which, helps lubricate the joints. Degeneration of spinal facet joints can lead to a build up of synovial fluid pressure within the joint. The increased pressure can lead to escape of some of the fluid from the joint capsule, creating a sac-like protrusion, referred to as a synovial cyst.

Any condition which places the facet joint under enough strain or stress to injure supporting elements may contribute to the development of degenerative changes over time. This may lead to the development of a cyst. Potential causes include:

• Excessive stress on the lumbar spine
• Facet osteoarthritis (osteoarthropathy)
• Joint fluid accumulation
• Abnormal spinal segment movement

RISK FACTORS

The presence of two or more risk factors increases the likelihood of developing a degenerative spinal facet joint cyst. Risk factors for the development of a facet joint cyst include:

• Degenerative spondylolithesis
• Rheumatoid arthritis
• Spinal instability
• Osteoarthrits
• Calcium pyrophosphate deposition disease
• Spine trauma