Rheumatoid Arthritis & the Spine

Condition

Rheumatism is an inflammatory disease, which can involve the spine but can also involve joints and blood vessels. It is more common in women. Rheumatoid arthritis often involves the small joints of the hands destroying the joint surface. It can also be associated with osteoporosis and cyst formation in the bones, which weakens these. In the spine, the neck is involved in the majority of cases. This can lead to instability causing pain or pressure on nerves or the spinal cord (myelopathy). Within the cervical spine, the first two vertebrae are most commonly involved. It can lead to instability, which is called atlanto-axial subluxation. The thoracic and lumbar spine is rarely involved. Most patients with involvement of the spine have suffered from rheumatoid arthritis for many years (average 10-15 years). Early treatment of rheumatoid arthritis can reduce the risk of later complication not only in the spine. Therefore, it is important that patients with suspected rheumatoid arthritis are assessed and treated by a specialist as soon as possible.

The risk of instability of the spine is compression of the spinal cord (myelopathy). This often leads to clumsiness of the hands and in combination with the arthritis of the hands can be very disabling. Overall, the mobility of patients can reduce significantly and some may become bed bound. A particular complication of atlanto-occipital instability is occipital neuralgia. This is caused by pressure on a nerve which leaves the spine between the first two vertebrae. It causes pain in the upper neck – usually only on one side – which also radiates to the back of the head. It can be sharp and shooting in nature but also feel like a burning pain. Pannus is a term used for a soft tissue mass caused by the rheumatoid arthritis around the odontoid peg. This can lead to pressure on the spinal cord.

Clinical assessment

An accurate history of the patient’s symptoms is essential. This includes duration and severity of the symptoms, duration and other complications of the underlying rheumatoid arthritis, medication the patient has taken in the past and is currently taking and other medical conditions in particular diabetes and heart conditions which can cause complications during or following surgery.

A thorough clinical examination is necessary to establish the extend of neurological involvement but also of the musculo-skeletal system. It is especially important to detect even subtle signs of myelopathy as this has an impact on the management strategy.

Investigations

The question whether a patient suffers from rheumatoid arthritis should be well established and where there is any doubt patients will need tests to make a clear diagnosis. In my opinion, all patients with suspected rheumatoid arthritis should be seen by a specialist /rheumatologist) in particular before any surgical intervention is planned! These tests usually include blood test (rheumatoid factors and may include x-rays).

For the spine flexion and extension x-rays and MRI-scan of the relevant part of the spine are important. These will show any abnormal movement in particular in the cervical spine. It will also show compression of the spinal cord although it is important to remember that the MRI might be normal because it is taken with the patient lying with the neck straight. As the instability usually occurs in flexion, i.e. the head bend forward it might not show, hence the flexion and extension views.

Treatment

Medical treatment forms the basis for patients with rheumatoid arthritis. This varies significantly depending on the severity and progression of the disease. Many patients require steroid medication and other powerful drugs which can significantly improve the outlook for patients with this potentially very disabling disease. Surgery is nowadays only necessary in a small number of patients thanks to the early detection and effective treatment of most patients.

Surgery

There are three indications for surgery: Pain, instability and spinal cord compression:

Pain It is important to understand what kind of pain can respond to surgery. Many patients suffer from musculo-skeletal neck pain with or without rheumatoid arthritis and this pain does not respond to any surgical intervention. However, pain due to instability or pressure on nerves (radiculopathy and occipital neuralgia) can significantly improve with decompression and fusion. A careful assessment of the pain and ideally review by a pain specialist is important before any surgery to make sure that all conservative(i.e. non-surgical) treatment options have been tried before. In many cases surgery can be avoided with a combination of painkillers, injections and physiotherapy.
Instability In most cases, instability occurs between the first and second vertebra (atlanto-axial subluxation). Clinicians measure the distance between the dens of the axis and the anterior arch of the atlas in flexion and extension (so-called Atlanto Dental Interval – ADI, images above) . A difference of less than 3mm is normal. In cases of less than 6mm one can often safely watch and wait with repeat x-rays at regular intervals (6-12 months) if the patient has no clinical signs of cervical cord compression. If the subluxation is more than 7mm, surgery should be considered. However, even in a number of these cases surgery is not necessary if there is no progression of the subluxation or clinical evidence of cervical cord compression. Subluxation of more than 10mm usually requires surgery. All patients with instability causing cervical cord compression should be operated regardless the degree of instability. In rare cases, the odontoid peg can migrate upwards and cause pressure on the brainstem (basilar invagination). This usually requires more extensive surgery from the front and back. Other rare cases of instability include subaxial subluxation (slippage of the 3rd – 7th vertebra in the neck. Few patients require surgery for this and surgical options are not different than for degenerative arthritis (see anterior cervical discetomy and cervical laminectomy).
Cervical cord compression All patients with signs of cervical cord compression (myelopathy) should be referred for a surgical opinion by a spinal surgeon. The aim of surgery is to prevent progression of the neurological problems rather than hoping for a full recovery. Therefore, treatment at an early stage is important before a patient has developed significant disabilities. If a conservative approach is chosen, patients should be carefully observed.

Non-surgical treatment options

Collars play little role in the treatment of instability. Even hard collars often do not provide adequate stability in the upper cervical spine. In the long term they may cause wasting of the muscles which can make matters worse. However, many patients with rheumatoid arthritis and involvement of the cervical spine wear a soft collar when travelling which may avoid some pain due to sudden movements. As long as it is a well fitting collar which is only worn at intervals, it is a sensible option.

Surgical options

Decompression and fixation are often both required because of the co-existence of compression of the spinal cord or nerve roots and instability. The choice of the procedure depends on the extend of the compression and/ or instability, surgeon’s preference and other factors such as bone quality. Common procedures are C1-C2 fixation and occipito-cervical fusion. Transoral surgery (decompression through the mouth) is rarely needed.

Outlook and prognosis

Surgery does not alter the progression of the underlying rheumatoid arthritis and only deals with its complications. Decompression and fixation for spinal cord compression stops or significantly slows down the deterioration. Some patients improve which usually means a better function of the hands because the hands feel less stiff. Walking may also improve but it is important to understand that the main aim of surgery is to prevent deterioration. Unfortunately, some patients continue to deteriorate despite successful surgery. This is because the spinal cord has been damaged too severely (see cervical myelopathy). Failure of the fusion is an uncommon but well described complication because of poor bone quality. Many patients will have been on steroid medication for many years, which can have a negative effect on wound healing.