Inflammatory back pain is the back pain which occurs due to inflammation of spinal joints and affects 1-2 in every thousand people. Mechanical back pain is the most common cause of back pain. This is different from the back pain from the mechanical causes.
Commonly affected joints are the sacroiliac joints but other parts of the spine are affected as well. Large peripheral joints can as well be affected.
Inflammatory back pain is most commonly associated with ankylosing spondylitis and spondyloarthropathies like psoriasis, inflammatory bowel disease, Reiter syndrome, and undifferentiated spondyloarthropathies.
Over the time the inflammatory back pain may cause ankylosis.
One of the most difficult challenges associated with inflammatory back pain is diagnosis making in patients presenting with inflammatory back pain because of overlap of symptoms with other causes of back pain. There is a delay in the presentation of a patient with back pain and reaching a definitive diagnosis. It is because most of the investigations in the early period of presentation are normal.
Features of Inflammatory Back Pain
Inflammatory back pain is characterized by
- The pain is insidious in onset
- The back pain is more than 3 months duration
- There is early morning back pain and stiffness which continues for one hour. The pain and stiffness get better after that.
- The exercise improves pain.
- Pain improves with exercise
- Pain occurs in young persons. Typical age of onset is less than 45 years but symptoms can begin as early as 15 years of age.
- Tenderness over SI joint. One or both joints may be affected.
- Men much more often affected than women.
- Strong genetic association with the gene HLAB27.
Lab Investigations
Routine lab tests may show inflammation – ESR and CRP are elevated. HLA B27 is positive in the majority of the patients.
HLA B27 stands for Human Leukocyte Antigen B27 and is a surface antigen that presents antigenic peptides to T cells, the body’s natural defense cells. HLA-B27 is strongly associated with ankylosing spondylitis, and other associated inflammatory diseases referred to as spondyloarthropathies.
It is not entirely clear how HLA-B27 influences disease.
Imaging
X-rays are essentially normal in early phases of diseases causing inflammatory back pain. Arthritic changes of the involved joints [for example sacroiliac joints] can be noticed in the later course of the disease.
MRI of the spine is able to find the joint inflammation much earlier and is an investigation of choice in patients with symptoms suggestive of inflammatory back pain.
Treatment
The first objective in a patient with inflammatory back pain is to reach the definitive diagnosis. This may be delayed for various reasons.
The patient is put on medication to control inflammation such as NSAIDs. The patient should also be put on exercises to maintain spinal function, initially under the supervision of a physiotherapist and then independently.
When a definite diagnosis is reached at, the patient is treated accordingly.
