Back Pain Due to Ankylosing Spondylitis
Ankylosing Spondylitis (AS) is occasionally encountered in clinical practice where the patients present with low back pain. The diagnosis is sometimes delayed as initial radiographic findings do not show much change and classical radiological changes take some time to develop.
This condition predominantly involves young males in their 20’s and 30’s and 90% of cases are associated with the HLA-B27 antigen. The primary site of pathology is in the enthesis, the site of ligamentous attachment to the bone where there is inflammation. Associated synovitis in the adjacent joints is also an additional feature. The brunt of the disease is in the axial spine mainly sacroiliac joints. However, peripheral joints may also be involved in the 10% of cases. The mechanism of the disease process is cytokine-mediated which makes anti-cytokine therapy and effective means of treatment.
Ankylosing Spondylitis Clinical features
- Predominantly in males in 20’s and 30’s.
- Low back pain
- Morning stiffness
- Asymmetric peripheral arthritis in 10% of cases.
- HLA-B27positive in more than 90
- Pulmonary upper lobe fibrosis
- Aortic Regurgitation.
- Cauda equina syndrome.
- Increased incidence of prostatitis.
- Increased incidence of amyloidosis.
differential diagnosis Ankylosing Spondylitis
- Lumbar spondylosis
- Lumbar disc disease
- Tuberculosis of spine and other infections
- Metastatic bone disease
Tuberculosis of lumbar vertebrae is not uncommon in the USA and may present with low-back pain. Radiological investigations with X-rays and MRI scan will clinch the diagnosis. Although uncommon in young the generation, I have come across few cases of the metastatic bone disease mainly arising from the lower gastrointestinal tract. DISH (Diffuse Idiopathic Skeletal Hyperostosis) is a degenerative bone disease of the elderly which may mimic AS radiologically by the way of extensive calcification of anterior longitudinal ligaments. However, in this condition, SI joints are clear.
Ankylosing Spondylitis Treatment
Physical exercise is a very important facet to the treatment of AS. Certain exercise like swimming is helpful.
- NSAIDs- These are helpful in symptomatic relief. Both COX1 & COX2 inhibitors may be used. One needs to be aware of cardiovascular side effects of long-term COX2 use. Nocturnal use of the retard preparation of indomethacin will help alleviate morning stiffness.
- Sulphasalazine- Sulphasalazine in the dose of 2-3 g/day may help stiffness and been but not spinal mobility. There is a suggestion that use of sulphasalazine might reduce the attack rates of anterior uveitis.
- Methotrexate- One cohort study and 3 case series found mixed results with methotrexate.
- Bisphosphonates- It may have possible role on disease activity and physical function but not on spinal mortality
- Thalidomide- Thalidomide may also have some beneficial effect in improving the symptoms.
- Steroids- Both pulsed methylprednisolone for 3 days and the short course of oral prednisolone may improve the symptoms of AS.
- Anti TNF-a blockade- These drugs have a dramatic effect on the symptoms and they also improve spinal mobility. Patients with the long-standing disease also have shown to respond symptomatically. However, it is yet to be known that whether these drugs can finally prevent ankylosis and bony ossification. Infliximab is more potent than etanercept. In the issue of concomitant inflammatory bowel disease (IBD), Infliximab has then referred agent as etanercept does not work will in IBD.