Differential diagnoses and investigations
- Mechanical back pain
- Degenerative changes of the spine
- Inflammatory spondyloarthropathy such as Ankylosing spondylitis
- Scheuermann’s disease
- Underlying sinister cause such as metastatic changes or infiltration of the vertebral bodies
The patient had been working in a very physical job as a landscape gardener since his late teenage years. Moreover, he reported suffering from back pain and stiffness since then. He had had no previous imaging of the spine. The most likely cause due to the very clear history of early morning stiffness improving with activity was that of an inflammatory spondyloarthropathy. However, Scheuermann’s disease was also a strong possibility. Mechanical back pain or degenerative changes of the spine was possible but less likely due to the fact that the pain affected all his spine. Metastatic infiltration was a consideration but appeared very unlikely as although it was evident that the patient was in pain, he looked otherwise very muscular and healthy and was clearly managing to do a physical job on a daily basis despite his pain.
The following plan was agreed on after discussing the above potential diagnosis with the patient:
- The patient was referred for blood tests and an MRI scan including STIR sequence of the whole spine. It was agreed that if the above tests pointed towards an inflammatory spondyloarthropathy, a referral would be made to a Rheumatology Service.
- If the MRI scan and blood tests ruled out an inflammatory spondyloarthropathy, he would be referred to see a specialist pain physiotherapist. He had never been seen by a physiotherapist in relation to his back, but had seen a physiotherapist when he had his hip surgery for a brief time post operatively.
- Medication was discussed in particular that Tramadol was not recommended for long term management of spinal pain and a plan was put in place to slowly wean off this mediation.
The blood results came through in the next 72 hours with:
- A positive HLA B27 test
- A CRP of 111ng/ml
- ESR of 48
- FBC showed normal white cell count and a Haemoglobin on 115gm/L
On the basis of the above and the concern that the unexpectedly significantly high CRP albeit with a normal white cell count, might point towards an unexpected discitis, the radiology department was contacted and asked to prioritise the MRI Scan request to urgent. A rheumatology opinion was also sought, and the plan at this point in time was for the patient to be seen urgently by a Consultant Rheumatologist.
MRI findings were as follows: Normal spinal alignment with no spondylolisthesis identified. There were anterior corner lesions at the T8, T9, T10 and L5 vertebral bodies suggestive of inflammatory lesions. There was bone marrow oedema in the left pedicle of the L5 vertebral body. The cervical, thoracic and lumbar discs were normal and the spinal cord was normal in signal intensity. There was no central or foraminal stenosis. There was sclerosis involving the sacral and iliac aspects of both sacroiliac joints with ankylosing consistent with burnt out bilateral sacroiliitis.
The diagnosis was therefore that of Ankylosing Spondylitis.
Ankylosing spondylitis is a chronic autoimmune inflammatory condition belonging to the spondyloarthropathy category of rheumatic diseases. It typically affects the axial skeleton but may also present with peripheral arthritis and extra-articular features such as iritis. Typically, symptoms start as in our patient in early adulthood and is most often diagnosed in patients under the age of 45 years. Ankylosing spondylitis is commoner in males, and can lead to disability and reduced quality of life if not adequately treated.
The initial site of inflammation tends to be in the sacro-iliac joints and then tends to spread upwards into the axial skeleton, with areas of inflammation burning out as seen in our patient. Although inflammatory markers including CRP and ESR are usually raised when the disease is active, it is unusual to see such an increase in the C reactive protein level, and this led to a suspicion that this patient may have had an underlying discitis which was not subsequently shown on MRI Scan.
A positive HLA-B27, a Class 1 surface antigen, is found in only 90% of patients, and females diagnosed with ankylosing spondylitis are more likely to be HLA B27 negative. However, 10% of North European people carry this gene but only around 5% of these will go on to develop Ankylosing Spondylitis.
If untreated, the inflammatory process in Ankylosing spondylitis can lead to significant damage of the spine with fusion into the typical bamboo spine. This can have a very significant impact on respiratory function and also increase risk of osteoporosis.
Management consists of a multidisciplinary team approach. Physiotherapy and self-management strategies are important. Pain control may be helped with non-steroidal anti-inflammatory drugs. Opioids such as Tramadol being taken by this patient are not recommended. Traditional disease modifying anti-rheumatic drugs such as methotrexate are not very effective, but biologic therapies aimed at inhibiting TNF-alpha which has been found to be elevated in the serum and synovial tissue of patients with AS have become very useful therapeutic agents.
Opportunities for self-directed learning
This would be a good opportunity to review:
- Blood tests in the diagnosis of rheumatological disorders
- Pharmacological management of rheumatological disorders