Ankylosing spondylitis
What is Ankylosing spondylitis?
Ankylosing spondylitis (AS) is a chronic, multi-system inflammatory disorder primarily involving the sacroiliac (SI) joints and the axial skeleton. Other clinical manifestations include peripheral arthritis, enthesitis, and extra-articular organ involvement. The disease involves erosion of bone and increased bone formation in the spine, leading to bone fusion. In advanced cases, this can lead to spinal deformity.
AS most commonly occurs in men than women. It starts in the teens up to 40 years old but it can affect anyone of any age. It tends to be milder when it does occur in women, making it harder to diagnose. It occurs in 0.1-1% of the general population with the highest prevalence in northern European countries and the lowest in sub-Saharan Africa. About 1-2% people who are positive for HLA-B27 gene develop AS. This percentage increases to 15-20% if they have a first-degree relative with HLA-B27 positive AS.
There is currently no cure for ankylosing spondylitis but there are drugs that can help manage the pain and inflammation. Physical therapy can also relieve the symptoms.
Ankylosing spondylitis (AS) is a chronic, multi-system inflammatory disorder primarily involving the sacroiliac (SI) joints and the axial skeleton. Other clinical manifestations include peripheral arthritis, enthesitis, and extra-articular organ involvement. The disease involves erosion of bone and increased bone formation in the spine, leading to bone fusion. In advanced cases, this can lead to spinal deformity.
AS most commonly occurs in men than women. It starts in the teens up to 40 years old but it can affect anyone of any age. It tends to be milder when it does occur in women, making it harder to diagnose. It occurs in 0.1-1% of the general population with the highest prevalence in northern European countries and the lowest in sub-Saharan Africa. About 1-2% people who are positive for HLA-B27 gene develop AS. This percentage increases to 15-20% if they have a first-degree relative with HLA-B27 positive AS.
There is currently no cure for ankylosing spondylitis but there are drugs that can help manage the pain and inflammation. Physical therapy can also relieve the symptoms.
What causes Ankylosing spondylitis ?
The exact etiology of AS is unknown, but a combination of genetic and environmental factors works in hand to produce clinical disease.
The strong association of AS with HLA-B27 is direct evidence of the importance of genetic predisposition. Most people who have ankylosing spondylitis have the HLA-B27 gene. But many who have this gene never develop ankylosing spondylitis. AS is more common in persons with a family history of AS or another seronegative spondyloarthropathy.
Another possible mechanism of AS is presentation of an arthritogenic peptide from gastrointestinal tract bacteria by specific HLA molecules. This leads to chronic inflammation and erosion of bone and increased fibrosis and bone formation (ossification) in the spine, leading to bone fusion.This inflammation and fibrosis can occur in ligamentous and capsular attachment of tendon and ligaments to bone and is called enthesitis. The outer fibers of the intervertebral discs eventually undergo ossification to form syndesmophytes. Then progresses to chracteristic bamboo spine appearance.
The exact etiology of AS is unknown, but a combination of genetic and environmental factors works in hand to produce clinical disease.
The strong association of AS with HLA-B27 is direct evidence of the importance of genetic predisposition. Most people who have ankylosing spondylitis have the HLA-B27 gene. But many who have this gene never develop ankylosing spondylitis. AS is more common in persons with a family history of AS or another seronegative spondyloarthropathy.
Another possible mechanism of AS is presentation of an arthritogenic peptide from gastrointestinal tract bacteria by specific HLA molecules. This leads to chronic inflammation and erosion of bone and increased fibrosis and bone formation (ossification) in the spine, leading to bone fusion.This inflammation and fibrosis can occur in ligamentous and capsular attachment of tendon and ligaments to bone and is called enthesitis. The outer fibers of the intervertebral discs eventually undergo ossification to form syndesmophytes. Then progresses to chracteristic bamboo spine appearance.
Symptoms of Ankylosing spondylitis
Key features of the patient history that suggest ankylosing spondylitis (AS) during medical history taking are:
General symptoms:
Complications of AS
Key features of the patient history that suggest ankylosing spondylitis (AS) during medical history taking are:
- Gradual progressive onset of low back pain
- Symptomatic before age 40 years
- Symptoms experienced for more than 3 months
- Symptoms are worse in the morning or with inactivity
- Improvement of symptoms with exercise/movement
General symptoms:
- Chronic pain and stiffness in 70 % patients - mainly at lower back and sacroiliac joints
- Fatigue in 65% patients
- Fever and weight loss may occur during periods of active disease
- Inflammation pain can also occur elsewhere - neck, archilles tendon, heel of foot, patella , chest wall
- Loss of mobility as AS cause bone fusion: restrict chest movement resulting in difficulty to breath and limited movement of spinal back
Complications of AS
- Bamboo Spine : The vertebrae fused together resulting in stiff and inflexible spine
- Restricting lung capacity and function due to inflammation of the costovertebral and costotransverse joints, which limits chest-wall range of motion
- Eye inflammation (uveitis). One of the most common complications, it can cause rapid-onset eye pain, lacrimination, sensitivity to light and blurred vision. It occurs in 25-30% of patients
- Compression fractures
- Neurological deficits: secondary to spinal fracture or cauda equina syndrome as a result of spinal sternosis
- Heart problems: aortic insufficiency and conduction defects is generally a late finding and is rare.
Diagnosis of Ankylosing Spondylitis
The doctor will take a thorough medical history looking for distinct features of AS and conduct a physical examination.
Blood tests
There is no confirmatory blood tests for Ankylosing spondylitis. Tests are done to rule put other conditions and to test any genetic predisposition. Blood tests that are ordered are inflammatory markers like ESR, CRP and full blood count and HLA B27 genetic testing .
Imaging tests
1. X-rays : to look for early and advanced changes to the spine and pelvis. Early radiographic signs include squaring of the vertebral bodies caused by erosions. The inflammatory lesions at vertebral entheses may result in sclerosis of the superior and inferior margins of the vertebral bodies, called shiny corners (Romanus lesion). Ossification of the anulus fibrosus leads to the radiographic appearance of syndesmophytes. Over time, the syndesmophytes bridge together to form the classical "bamboo spine". Radiographs of the pelvis may show ossification of various entheses, such as the iliac crest, ischial tuberosity, and femoral trochanter, which is termed whiskering.
2. MRI/CT scans: may reveal early sacroiliitis, erosions, and enthesitis that are not apparent on x-rays. Also for neurological deficits like nerve impingment.
The doctor will take a thorough medical history looking for distinct features of AS and conduct a physical examination.
Blood tests
There is no confirmatory blood tests for Ankylosing spondylitis. Tests are done to rule put other conditions and to test any genetic predisposition. Blood tests that are ordered are inflammatory markers like ESR, CRP and full blood count and HLA B27 genetic testing .
Imaging tests
1. X-rays : to look for early and advanced changes to the spine and pelvis. Early radiographic signs include squaring of the vertebral bodies caused by erosions. The inflammatory lesions at vertebral entheses may result in sclerosis of the superior and inferior margins of the vertebral bodies, called shiny corners (Romanus lesion). Ossification of the anulus fibrosus leads to the radiographic appearance of syndesmophytes. Over time, the syndesmophytes bridge together to form the classical "bamboo spine". Radiographs of the pelvis may show ossification of various entheses, such as the iliac crest, ischial tuberosity, and femoral trochanter, which is termed whiskering.
2. MRI/CT scans: may reveal early sacroiliitis, erosions, and enthesitis that are not apparent on x-rays. Also for neurological deficits like nerve impingment.
Treatment for Ankylosing Spondylitis
There is currently no cure for AS , treatment is just to relieve symptoms and prevent/delay complications. Any damage cannot be reversed thus early diagnosis is important.
Drug therapy
Physical therapy
Surgery
Usually surgery is unnecessary unless in severe cases, to correct severe deformity. Three surgical interventions for AS are:
There is currently no cure for AS , treatment is just to relieve symptoms and prevent/delay complications. Any damage cannot be reversed thus early diagnosis is important.
Drug therapy
- Nonsteroidal anti-inflammatory drugs (NSAIDs) : reduce inflammation, pain and stiffness
- Disease-modifying anti-rheumatic drugs (DMARDs): For example Sulfasalazine are prescribed people who do not respond to NSAIDs or have contraindications. It is helpful those with coexisting IBD and peripheral joint involvement.
- Biologics such as a tumor necrosis factor (TNF) blocker or an interleukin 17 (IL-17) inhibitor. TNF blockers are injectable medicine that target a cell protein that causes inflammation in the body. TNF blockers (humira, cimzia, enbrel, simponi and remicade) help reduce pain, stiffness, and tender or swollen joints.Toxicities associated with TNF-α antagonists include injection-site and infusion reactions. Increased risks of bacterial infections, reactivation of latent tuberculosis, and certain fungal infections. IL-17 plays a role in your body's defense against infection and inflammation.
- Corticosteroids: Local corticosteroid injections are useful for symptomatic sacroiliitis, peripheral enthesitis, and arthritis. Oral steroids can be used short term for control of disease but long terms usage is not recommended due to its adverse effects.
Physical therapy
- Physiotherapist will design exercise to strengthen and increased flexibility of joints.
- Water therapy and swimming are excellent activities for maintaining mobility and fitness.
- Maintains good posture and relief pain and stiffness
- Spinal extension and deep-breathing exercises help to maintain spinal mobility, encourage erect posture, and promote chest expansion.
- Maintaining a good posture, sleeping on a firm mattress with a thin pillow will reduce the tendency towards thoracic kyphosis.
Surgery
Usually surgery is unnecessary unless in severe cases, to correct severe deformity. Three surgical interventions for AS are:
- Vertebral osteotomy: Patients who has fusion of the cervical or upper thoracic spine will experience significant impairment in line of sight, eating and psychosocial well-being. Extension osteotomy of the cervical spine but this procedure will have risk of significant neurological mmorbidity.
- Fracture stabilization: for patients who suffered from complications of fracture vertebrae
- Joint replacement: Patients with significant hip joint involvement of the hips may benefit from total hip arthroplasty and occasionally, total shoulder replacement for those with severe shoulder involvement. The surgeries is useful for reducing pain and improving function of the joints.
Prognosis of Ankylosing spondylitis
The prognosis of AS is difficult to predict as the disease progression varies between individuals. Important factors for measuring outlook include levels of functional ability, spinal mobility, joint damage and extra-articular involvements. Patients usually require long term NSAIDs and physical therapy. Most patients remain fully functional and continue working after the onset of symptoms.
Indicators of poor prognosis include the following:
The prognosis of AS is difficult to predict as the disease progression varies between individuals. Important factors for measuring outlook include levels of functional ability, spinal mobility, joint damage and extra-articular involvements. Patients usually require long term NSAIDs and physical therapy. Most patients remain fully functional and continue working after the onset of symptoms.
Indicators of poor prognosis include the following:
- Peripheral joint involvement
- Young age of onset
- Elevated erythrocyte sedimentation rate (ESR)
- Poor response to NSAIDS