Synovial Facet Cyst
Synovial Facet Cyst
ANATOMY OF THE SPINE
The human spine is formed by individual vertebrae and connective tissue discs in between. The vertebrae form the spinal canal. There are seven cervical, twelve thoracic, and five lumbar vertebrae. The intervertebral discs are the link between the individual vertebral bodies.
Normal anatomy of the spine. Longitudinal section and cross sections through the cervical, thoracic and lumbar spine.
The little joints that link the vertebrae together are known as facet joints. They help to stabilize the spine and, together with the intervertebral discs, allow a certain degree of mobility of the spinal cord. The spinal canal should be wide enough to allow nerve roots to float freely in cerebrospinal fluid.
The front border of the spinal canal is built by the vertebral bodies and intervertebral discs, the side by the intervertebral joints (facets) and back by the ligamentum flavum (yellow band) and vertebral arches. Discs consist of an outer fibrous ring (annulus fibrosus), which surrounds an inner gel-like center (nucleus pulposus).
The spinal cord and nerve roots lie within the spinal canal. The spinal cord extends downwards approx. to the 1st lumbar vertebra. Below, only nerve roots are present in the spinal canal. At the level of the intervertebral disc the nerve roots pass through the neural root foramina to exit the spinal canal. The spinal cord and nerve roots conduct electric-like signals from the skin and joints to the brain, and process of movement is initiated from the brain to the muscles.
Synovial cyst is a benign cyst (a fluid-filled sac) arising from the facet joints of the lumbar spine due to degeneration. They usually cause chronic presure on the nerve roots. Rarely, intracystic hemorrhage in the cyst may cause acute compression of one or more nerve roots.
Synovial cyst in the lumbar spine
CAUSE OF SYMPTOMS
Gradually progressing compression of one or more lumbar nerve roots in the recessus/root canal
SYMPTOMS AND SIGNS
Tingling, shooting pain or muscle weakness (paresis) of one or both legs
THE DIAGNOSIS IS BASED ON Medical history Clinical exam
and at least one of the following tests: Magnetic resonance imaging (MRI) Computer tomography Myelography
additionally you may have to do: Radiographs Functional (dynamic) radiographs
Diagnostic nerve root block
Facet joints block Electromyography
A MRI image showing a transverse T2 section of a lumbar synovial cyst
The treatment may be non-surgical or surgical. Minimally invasive methods like percutaneous steroid injection and percutaneous cyst rupture improve the symptoms in about half the patients (PMID: 27683703
). The rest of the patients usually require surgery to achieve long-term relief of symptoms.
Non-surgical treatment may include Physiotherapy Physical exercise Treatment with heat (Fango) Nonsteroidal anti-inflammatory drugs
Epidural corticosteroid infiltrations
CT-guided rupture of the synovial cyst
WHEN SHOULD AN OPERATION BE PERFORMED?
Elective surgery should be considered when a significant muscle weakness (>72 hours) is present or the symptoms (e.g. pain) impair the patient’s quality of life and conservative treatment fails to achieve significant improvement within 6-8 weeks.
WHAT IS THE GOAL OF SURGERY?
To release the compressed nerve roots
To improve symptoms (e.g. pain reduction)
To stop the worsening of the symptoms
To preserve the protective function of the spine
HOW IS SURGERY PERFORMED?
Posterior decompression of the spinal canal without fusion
WHICH OTHER DISEASES SHOULD BE EXCLUDED (DIFFERENTIAL DIAGNOSIS)? Peripheral arterial occlusive disease (PAOD) A disease of peripheral nerves (e.g. polyneuropathy) Lower back pain / Lumbar facet joint pain Radiculitis Tumor of the spine Peripheral nerve compression syndromes Vertebral fractures
Diseases of the hip or knee Sacroiliac joint pain Disc herniation