Reviewed by SIAHMSR Medical team

Written by Dr. Sanjana V.B Bhms,dbrm,cdn
Founder & medical director of siahmsr wellness.in

all rights reserved with siahmsr digital healthcare[siahmsr wellness]

Overview

Ankylosing spondylitis [AS] is one of the common types of spondyloarthropathies affecting young people [ age <45] and it is often linked to genes as well as autoimmunity.

Spondyloarthropathy refers to a heterogeneous group of rheumatic diseases that present common clinical and genetic features, which are categorized as peripheral or axial based on what parts of the body are mainly affected.

  Ankylosing spondylitis [AS] is a chronic inflammatory autoimmune disease that mainly affects spine joints and over the time involving other joints of the body also. AS is characterized by the involvement of the spine and sacroiliac (SI) joints and peripheral joints, digits, and entheses.

 The arthritis can cause spinal fusion as the disease progresses over the years. Chronic inflammation can lead to fibrosis and calcification, resulting in the loss of flexibility and the fusion of the spine, resembling “bamboo” with an immobile position.

Etiology & pathogenesis

AS is an autoimmune disease and the exact etiology of it remains unclear to certain extent. It is believed that genetic and environmental factors play synergistic role in the pathogenesis of the disease.

Human leukocyte antigen (HLA)‑B27 and the interleukin‑23/17 axis play crucial role in the pathogenesis of ankylosing spondylitis.

  Various studies demonstrates that 90%–95% of AS patients are HLA-B27 positive, while 1%–2% of HLA-B27-positive populations develop AS. This shows 15%–20% predominance in those with an affected first-degree relative.

Acute anterior uveitis [ A symptom of AS affecting eyes] is more prevalent in HLAB27 positive cases of AS.

Clinical presentation

The main clinical presentation is back pain and progressive spinal rigidity and spreading inflammation of the hips, shoulders, peripheral joints and fingers/toes.

 AS is associated with impaired spinal mobility and can result in postural abnormalities. It can also cause severe buttock pain and hip pain.

The extra-articular manifestations of ankylosing spondylitis include acute anterior uveitis and inflammatory bowel disease (IBD). The inflammatory bowel disease affects up to 50% of individuals, acute anterior uveitis has been found in 25%-35% of cases and psoriasis is linked with AS in around 10% of the people.

However, these extra-articular manifestations vary slightly in East Asian and Caucasian populations. In Western countries, 5%–10% of AS patients present with inflammatory bowel disease while it is quite low in Asian populations.

Complications of ankylosing spondylitis 

Ankylosing spondylitis is associated with an increased risk of cardiovascular diseases which probably stem from the systemic inflammation present in people with AS.

Pulmonary complications of AS include restrictive lung diseases due to diminished chest wall expansion and limited spinal mobility.

AS also affects bone health adversely causing osteoporotic fractures.  AS associated spine fractures are estimated to be 4 times greater than fragility fractures in the general population.

It is due to the synergistic effect of rigidity and osteoporosis that may develop in these patients [4,5]. Spine fracture can be severe even after minor trauma and 75% of these fractures occur in the cervical spine, particularly at the C5-T1 cervicothoracic junction [6].

 Ankylosing spondylitis may affect spinal vertebra and it may lead to atlantoaxial subluxation, spinal cord injury and cauda equina syndrome.

Diagnosis

A detailed medical history is very crucial to identify or rule out associated conditions such as psoriasis, inflammatory bowel disease, and uveitis as AS may be presenting with these disease symptoms outside joints.

The inflammatory back pain in AS is characterized by at least 4 of the following 5 features:

onset of symptoms before the age of 40, gradual and insidious onset, relief with exercise, lack of improvement with rest, and nocturnal pain with improvement upon arising.

 Also spinal stiffness, limited mobility, and postural changes, particularly hyper kyphosis, are frequently observed.

Radiography [X- ray]

Ankylosing spondylitis is characterized by a series of distinct radiographic changes o characteristics which can progressively develop.

In the initial phase of the disease, a notable sign is the "squaring" of vertebral bodies, which is best visualized on lateral X-rays. This squaring occurs due to inflammation and bone deposition, resulting in the loss of normal concavity of the anterior and posterior borders of the vertebral body.

Furthermore, early-stage radiographs may show Romanus lesions, also known as "shiny corner signs," characterized by small erosions and reactive sclerosis at the corners of the vertebral bodies.

In the advanced stages radiographic findings include ankylosis (fusion) of the facet joints of the spine, the presence of syndesmophytes, and calcification of the anterior longitudinal ligament, supraspinous ligaments, and interspinous ligaments.

This calcification may be seen on imaging as the "dagger sign," appearing as a single radio dense line vertically running down the spine on frontal radiographs.

The classic radiographic finding in late-stage AS is the "bamboo spine sign," which refers to vertebral body fusion by syndesmophytes.

 The bamboo spine typically involves the thoracolumbar or lumbosacral junctions. This spinal fusion predisposes the patient to progressive back stiffness.

MRI

Although plain radiography is the first-line imaging modality in AS, further imaging with MRI may be helpful to detect more subtle abnormalities, such as fatty or inflammatory changes.

MRI can reveal active inflammatory lesions in the sacroiliac [SI ]joints. These appear as bone marrow edema (BME) on short tau inversion recovery (STIR) and T2-weighted images with fat suppression.

It should be noted that the presence of BME on MRI can also be seen in up to 23% of patients with mechanical back pain and 7% of healthy individuals. It is important to rule out other clinical conditions mimicking AS.

Differential diagnoses

·       Mechanical low back pain

·       Lumbar spinal stenosis

·       Rheumatoid arthritis

·       Diffuse idiopathic skeletal hyperostosis (DISH)

Various diseases listed above may mimic  AS, and therefore for accurate diagnosis these have to be eliminated by differentiation.

·    Management

Pharmacological treatments

The goal of treatment is to improve and maintain spinal flexibility and normal posture, relieve symptoms, decrease functional disability, and reduce complications.

 A permanent cure is not possible in AS and flare ups and remissions continue. The pharmacological treatment chiefly includes nonsteroidal anti-inflammatory medications (NSAIDs) and TNF-α inhibitors (TNFis) and these medications help to relieve joint pains.

Glucocorticoid injections into involved peripheral joints, sacroiliac joints, or entheses is found to be helpful in providing immediate symptom relief.

According to some previous studies long-term treatment with systemic glucocorticoids is relatively contraindicated probably due to the increased risks of osteoporosis, hyperlipidemia and insulin resistance. However, a recent study reported that AS patients achieved relief from signs and symptoms after short-term treatment with high doses of glucocorticoids (50 mg/day).

In patients with stable AS, using NSAID treatment on-demand is recommended. Continuing treatment with TNFi alone is suggested rather than treatment with TNFi and NSAID or DMARD.

 The continued use of NSAIDs or DMARDs has uncertain therapeutic effects  along with increased risks of gastrointestinal, cardiovascular, renal and hematological toxicity [2].

Surgical management

Untreated ankylosing spondylosis can cause spinal deformity. Around more than 30% of AS patients suffering from thoracolumbar kyphosis. Corrective osteotomy and stabilization is recommended as surgery in these people [3].

Complementary and alternative system of medicine

Homeopathy

 The commonly used remedies include  cimicifuga, natrum muriaticum, kalium carbonicum, rhus toxicodedron, silicea etc. Homeopathic medications mostly act as a supportive therapy to manage the severe pain associated with arthritis.

Medications may help to manage the pain and stiffness associated with chronic joint inflammation. Constitutionally chosen medications may be potentiated to control the autoimmune trigger associated with ankylosing spondylitis in the initial phase.

References

1.    Moltó A, Nikiphorou E. Comorbidities in spondyloarthritis. Front. Med. 2018;5:62–62. doi: 10.3389/fmed.2018.00062. https://pubmed.ncbi.nlm.nih.gov/29594122/
2.    A systematic review and meta-analysis of efficacy and toxicity of disease modifying anti-rheumatic drugs and biological agents for psoriatic arthritis https://pubmed.ncbi.nlm.nih.gov/17827183/
3.    American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network 2015 Recommendations for the Treatment of Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis https://pubmed.ncbi.nlm.nih.gov/26401991/
4.    Finkelstein JA, Chapman JR, Mirza S. Occult vertebral fractures in ankylosing spondylitis. Spinal Cord. 1999;37:444–447. doi: 10.1038/sj.sc.3100837 https://pubmed.ncbi.nlm.nih.gov/10432265/
5.    The management of spinal injuries in patients with ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis: a comparison of treatment methods and clinical outcomes. J. Spinal Disord. Tech. 2009;22:77–85. https://pubmed.ncbi.nlm.nih.gov/19342927/
6.    Hunter  T, Forster B, Dvorak M. Ankylosed spines are prone to fracture. Can. Fam. Physician. 1995;41:1213–1216. https://pubmed.ncbi.nlm.nih.gov/7647627/
7.    Watad A, Cuthbert RJ, Amital H, McGonagle D. Enthesitis: Much More Than Focal Insertion Point Inflammation. Curr Rheumatol Rep. 2018 May 30;20(7):41 https://pubmed.ncbi.nlm.nih.gov/29846815/
8.    https://www.ncbi.nlm.nih.gov/books/NBK470173/
9.    The homeopathic medical repertory Murphy