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​Odontoid Pannus (​Rheumatoid Pannus Arthritis, Odontoid Synovial Cyst)

Pannus is a type of extra growth in your joints that can cause pain, swelling, and damage to your bones, cartilage, and other tissue.

Learn about the treatment options for Odontoid Pannus at the UPMC Pituitary Center of Excellence.

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What is Odontoid Pannus?

Odontoid pannus is abnormal tissue that grows in the region of the odontoid process, a toothlike projection at the back of the second cervical vertebra. The odontoid process serves as the pivot point for turning the head.

This membrane of granulated tissue forms most often as a result of rheumatoid arthritis, in which the condition is called a rheumatoid pannus.

Odontoid pannus can also develop as a result of severe trauma to the neck, at the second cervical vertebra.

A similar but rarely diagnosed condition is an odontoid synovial cyst, which has similar symptoms and treatment.

Rheumatoid arthritis and rheumatoid pannus

Rheumatoid arthritis (RA) is a progressive autoimmune disease that causes chronic inflammation of the joints. When rheumatoid arthritis attacks, it usually begins in the synovium, a type of tissue that lines the joint capsule.

Cells in the synovium begin to grow and divide abnormally (synovitis) causing a thickening in the synovium, which results in an inflamed and swollen joint.

As the rheumatoid arthritis progresses, the synovium may grow larger and form an inflamed, granulated sheet of tissue called rheumatoid pannus. This tissue will spread from the synovial membrane, causing considerable destruction as it invades the subchondral bone.

Symptoms of cervical–spinal abnormalities develop in approximately 60 to 80 percent of patients with rheumatoid arthritis. When RA invades the cervical spine, the resulting extension of pannus into the spinal canal can compress the brainstem, spinal cord, and the vertebral arteries, resulting in severe pain and disability.

Left untreated, rheumatoid pannus may even result in sudden death.

Treatment options

Progressive deformity is caused by instability of the joints. When there is no neurological compromise, the recommended treatment is cranio-cervical fusion to stabilize the joints.

However, if you suffer from spinal cord or brainstem compression, then we recommend surgery to decompress these vital neural elements.

At UPMC, the preferred surgical treatment for spinal cord or brainstem compression caused by odontoid pannus, rheumatoid pannus, or synovial cyst is the Endoscopic Endonasal Approach (EEA) to decompress the brainstem and spinal cord.

EEA is an innovative, minimally invasive technique that uses the nose and nasal cavities as natural corridors to access hard-to-reach or previously inoperable conditions such as odontoid pannus. Benefits of EEA include:

  • No incisions to heal
  • No disfigurement
  • Faster recovery time

Diagnosing Odontoid Pannus

Your physician may perform a physical exam and ask about symptoms.

Odontoid pannus and odontoid synovial cyst symptoms

Symptoms of odontoid pannus may include:

  • Pain, weakness, and difficulty in movement
  • Partial paralysis
  • Muscle wasting
  • Quadriplegia

Testing for odontoid pannus

Your doctor will want you to have imaging tests such as CT or MRI scans to confirm the diagnosis.

Odontoid Pannus Treatment

If you have cervical instability and deformity as the result of odontoid pannus, but are not having neurological compression, the recommended treatment is cranio-cervical fusion to stabilize the joints.


Surgical decompression is necessary if the spinal cord and brainstem are compressed. The Endoscopic Endonasal Approach (EEA) is a direct way to decompress the brainstem and upper spinal cord. This state-of-the-art, minimally invasive approach allows surgeons to access the tissue through the natural corridor of the nose, without making an open incision.

EEA offers the benefits of no incisions to heal, no disfigurement, and a faster recovery time.

After endonasal decompression of the neural structures, you will need a cranio-cervical fusion to prevent recurrence and promote stability of the joints to avoid further neurological deterioration. This fusion stabilizes the underlying problem that caused the compression.

Most of the time, the EEA procedure is extradural, meaning that the lining of the brain is not opened. Most people can go home immediately after EEA, depending on the healing of the fusion procedure.

UPMC's neurosurgical team carefully evaluates each patient — looking at your condition from every direction — to find a path that is the least disruptive to your brain, critical nerves, and ability to return to normal functioning.