Here is the second part of the discussion of Ankylosing spondylitis (AS), in which we are going to discuss the differential diagnosis (DD), investigations and treatment .
- Definition, causes, pathology and clinical picture of Ankylosing spondylitis is Here
- Definition, causes, pathology and clinical picture of Ankylosing spondylitis is Here
Differential diagnosis of Ankylosing spondylitis (AS)
• The inflammatory back pain of AS is usually distinguished by the following features.
- Age of onset < 40 years - Insidious onset
- Duration > 3 m - Improvement with exercise.
• AS must be differentiated from other causes of bachache (see later).
• Diffuse idiopathic skeletal hyperstosis (DISH) must be differentiated from AS .as it leads to marked calcification and ossification of paraspinous ligaments.
Investigations
1- X ray Sarco-iliac joint : erosion, sclerosis. It is often the first abnormality.
2- X ray Spine (The disc is preserved, unlike in spondylosis).
• Square shaped vertebrae.
• Calcification of longitudinal ligament.
• Bony bridging between vertebral bodies = syndesmophytes ==> bamboo spine.
3- Laboratory finding (there is no specific laboratory test).
• Normochromic anemia.
• ESR +++ ,+++ CRP during activity.
• Rheumatoid factor -ve.
• HLA Testing is rarely of value because of the high frequency of HLA-B27 in the population.
• Alkaline Phosphatase l' with activity .
Treatment of Ankylosing spondylitis
(The principles are to relieve pain and spinal stiffness).
• The key of treatment is early diagnosis to start preventive exercise program before syndesmophytes have formed. Excercises aim to maintain spinal mobility, posture and chest expansion (swimming is recommended).
• NSAIDs : relieve symptoms, but don't alter the course of the disease
• Local steroid : for enthesopathy and planter fasciitis.
• Genetic counselling.
• Systemic steroid sometimes required for treatment of uveitis.
• Sulfasalazine and methotrexate may be of value for peripheral arthropathy.
• TNF blockers are effective
• Surgery: plaster jackets to correct kyphosis, hip arthroplasty.
Prognosis
With exercise and pain relief, the prognosis is excellent and over 80% of patients are employed.