Ankylosing spondylitis

Overview

Ankylosing spondylitis (AS) is a kind of arthritis that causes chronic (long-term) inflammation of the spine. Ankylosing spondylitis causes inflammation of the sacroiliac joints, which are positioned between the base of the spine and the pelvis. Sacroiliitis, or inflammation of the sacroiliac joints, is one of the initial symptoms of AS. Inflammation frequently extends to the joints between the vertebrae, the bones that form the spinal column. Spondylitis is the medical term for this condition.

Some persons with AS report significant, ongoing back and hip discomfort and stiffness. Others get lesser symptoms that come and go. Over time, new bone forms may fuse vertebral portions together, making the spine stiff. This is known as ankylosis.

Ankylosing spondylitis definition

Ankylosing spondylitis (AS) is a chronic, inflammatory disease of the axial spine that causes a variety of clinical indications and symptoms. The most prevalent symptoms of the condition are chronic back pain and growing spinal stiffness. The condition is characterized by involvement of the spine and sacroiliac (SI) joints, peripheral joints, fingers, and entheses. AS is linked with impaired spinal mobility, postural irregularities, buttock discomfort, hip pain, peripheral arthritis, enthesitis, and dactylitis ("sausage digits").

AS is a type of spondyloarthropathy. The condition is frequently observed in conjunction with other spondyloarthropathies, such as ReA, PsA, ulcerative colitis (UC), and Crohn’s disease. Patients frequently have a family history of AS or another kind of spondyloarthropathy.

Epidemiology

Ankylosing spondylitis (AS) is frequently diagnosed in adults under the age of 40, with around 80% of patients experiencing their first symptoms when they are under the age of 30. Less than 5% of patients present when they are above the age of 45.

According to radiographic survey surveys, the prevalence of AS is almost similar in men and women. Males, on the other hand, exhibit more severe radiographic abnormalities in the spine and hips than women, and clinical AS is more frequent in men than in women, with a male-to-female ratio of about 3:1. Females may have a milder or subclinical form of the condition.

Approximately 1-2 percent of those who are HLA-B27 positive acquire AS. If they have a first-degree family with HLA-B27 positive AS, this rises to 15-20%.

Diagnosis is frequently delayed, generally happening many years after the beginning of inflammatory rheumatic symptoms. In a study of German and Austrian individuals with AS, the average age of beginning of illness symptoms was 25 years in HLA-B27–positive patients and 28 years in HLA-B27–negative patients, with an 8.5-year delay in diagnosis in HLA-B27–positive patients and 11.4 years in HLA-B27–negative patients.

Ankylosing spondylitis Causes

The etiology of ankylosing spondylitis (AS) is mostly unknown, however there appears to be a link between the incidence of AS and the prevalence of human leukocyte antigen (HLA)-B27 in the same population.

The prevalence of AS is roughly 5% to 6% among those who are HLA-B27 positive. HLA-B27 prevalence varies by ethnic group in the United States. According to a 2009 poll, non-Hispanic Whites had a prevalence rate of 7.5 %, Mexican-Americans had a prevalence rate of 4.6 %, and non-Hispanic Blacks had a prevalence rate of 1.1 %.

Because AS does not develop in every HLA-B27 positive individual, it is clear that environmental factors play a role. Even first-degree relatives who are HLA-B27 positive do not always suffer the sickness. In actuality, only 15-20% of such persons develop the illness.

HLA-B27–positive transgenic rats develop a spondyloarthropathy-like sickness with symptoms such as sacroiliitis, enthesitis, arthritis, skin and nail lesions, ocular inflammation, cardiac inflammation, and inflammation of the gastrointestinal and male genitourinary tracts. The number of copies of HLA-B27 expressed in the transgenic animal corresponds with the severity of the clinical condition.

Transgenic HLA-B27–positive rats maintained in a germ-free environment do not acquire clinical illness. When rats are placed in a normal environment (i.e., not germ-free) and exposed to germs, they acquire clinical signs of spondyloarthropathy.

Patients with AS may develop exacerbations following a traumatic event. However, no scientific research has been conducted to suggest trauma as a cause of AS.

Pathophysiology

Ankylosing spondylitis (AS) is a chronic inflammatory illness that develops gradually. The condition is characterized by progressive musculoskeletal and, in some cases, extraskeletal signs and symptoms. The pace of advancement varies from patient to patient. Enthesitis with chronic inflammation, including CD4 and CD8 T cells and macrophages, is the main pathophysiology of spondyloarthropathies.

Cytokines, notably tumor necrosis factor- (TNF-) and transforming growth factor- (TGF-), play a significant role in the inflammatory process by causing inflammation, fibrosis, and ossification at enthesitis sites.

The SI joints are usually involved in the initial presentation of AS; involvement of the SI joints is essential to establish the diagnosis. Following SI joint involvement, the discovertebral, apophyseal, costovertebral, and costotransverse joints, as well as the paravertebral ligaments, are involved.

Early lesions include subchondral granulation tissue, which erodes the joint and is progressively replaced by fibrocartilage, followed by ossification. Enthesitis is a condition that arises in ligamentous and capsular attachment sites to bone.

This first phase happens in the spine at the junction of the vertebrae and the annulus fibrosus of the intervertebral discs. The outside fibers of the discs gradually ossify, becoming syndesmophytes. As the illness worsens, it takes on the look of a bamboo spine.

Acute anterior uveitis and aortitis are examples of extra-articular involvement. Anterior uveitis affects 25-30% of people and is usually acute and unilateral. Pain, lacrimation, photophobia, and hazy vision are some of the symptoms. Cardiac involvement, including aortic insufficiency and conduction abnormalities, is often discovered late and infrequently.

Inflammation of the costovertebral and costotransverse joints, which reduces chest wall range of motion, causes pulmonary involvement (ROM). In most cases, pulmonary fibrosis is an asymptomatic incidental radiography finding. Neurologic impairments are caused by spinal fractures or cauda equina syndrome caused by spinal stenosis. Cervical spine fractures are the most prevalent type of spinal fracture.

Ankylosing spondylitis symptoms

Because of the disease's pervasiveness and propensity to multi-organ system involvement, individuals suspected of having (AS) should undergo a complete, full-body assessment. Almost all patients will have back discomfort to some extent.

The typical type of back pain in AS is "inflammatory" in nature. Inflammatory back pain generally has at least four of the five features listed below: age of onset less than 40 years, insidious onset, improvement with activity, no improvement with rest, and discomfort at night with relief upon waking up.

Spinal stiffness, immobility, and postural abnormalities, particularly hyperkyphosis, are all prevalent. Because AS can have numerous axial and peripheral musculoskeletal symptoms, as well as extra-articular characteristics, the history and physical exam should cover all systems. A thorough medical history should be collected in order to rule out any linked diseases.

Ankylosing spondylitis diagnosis

Although laboratory results in ankylosing spondylitis (AS) are often nonspecific, they can aid in diagnosis. Acute phase reactants, such as erythrocyte sedimentation rate (ESR) and C-reactive protein, are raised in 50–70% of individuals with active AS (CRP). A normal ESR and CRP, on the other hand, should not rule out the illness.

Plain radiographic changes in the SI joints might be quite mild in the early stages of AS, but they generally become more visible during the first decade. The most visible abnormalities are subchondral erosions, sclerosis, and joint fusion, and these radiographic alterations are usually symmetric.

A sequence of simple radiographic abnormalities that are diagnostic of AS might occur gradually throughout the course of the disease. The "squaring" of the vertebral bodies, best observed on lateral x-ray, is an early indicator. This is characterized by a lack of normal concavity of the vertebral body's anterior and posterior borders as a result of inflammation and bone deposition. In the early stages, Romanus lesions, commonly known as the "shiny corner sign," can be detected on this radiographic picture.

These lesions are distinguished by tiny erosions and reactive sclerosis at the vertebral body corners. Ankylosis (fusion) of the facet joints of the spine, syndesmophytes, and calcification of the anterior longitudinal ligament, supraspinous ligaments, and interspinous ligaments are late-stage abnormalities. This calcification can be observed on imaging as the "dagger sign," which is displayed on frontal radiographs as a single radiodense line extending vertically down the spine.

The "bamboo spine sign," which refers to vertebral body fusion by syndesmophytes, is a characteristic radiographic finding in late-stage AS. The thoracolumbar or lumbosacral connections are commonly involved in a bamboo spine. This spinal fusion predisposes the patient to increase back stiffness.

While conventional radiography is the first-line imaging modality in AS, MRI may be required to detect more subtle abnormalities such as fatty or inflammatory alterations. On short tau inversion recovery (STIR) and T2-weighted images with fat suppression, active SI joint inflammatory lesions present as bone marrow edema (BME). It should be mentioned that the presence of BME on MRI can be found in up to 23% of mechanical back pain patients and 7% of healthy persons.

Aside from the disorders stated in the differential diagnosis, the following considerations should be addressed into account:

Inflammatory bowel disease (IBD)–associated spondyloarthropathy (SpA)
Juvenile idiopathic arthritis
Diffuse idiopathic skeletal hyperostosis

Genetic testing

Although it is not a diagnostic test, variations in the HLA-B gene increase the likelihood of getting ankylosing spondylitis. Those with the HLA-B27 variation are at a greater risk of acquiring the illness than the general population. The presence of HLA-B27 in a blood test can occasionally aid in the diagnosis, but it is not diagnostic of AS in a person with back pain.

Over 85 percent of persons with AS are HLA-B27 positive, while this ratio varies by community, with roughly 50 percent of African Americans with AS having HLA-B27, compared to 80 percent of those with AS of Mediterranean descent.

Ankylosing spondylitis treatment

There is no specific disease-modifying therapy for ankylosing spondylitis (AS), however biologic medicines show signs of such action. Early detection is critical. As with any chronic condition, patient education is critical to getting acquainted with the patient with the disease's symptoms, progress, and therapy. Pharmacologic, surgical, and physical therapy treatments are available.

Treatment objectives should include reducing pain and stiffness, preserving axial spine mobility and functional ability, and avoiding spinal problems. Regular exercise, posture training, and physical therapy should all be part of non-pharmacologic therapies.

Long-term, daily nonsteroidal anti-inflammatory medications are used as first-line pharmaceutical treatment (NSAIDs). If NSAIDs are ineffective, they can be supplemented with or replaced with tumor necrosis factor inhibitors (TNF-Is) such as adalimumab, infliximab, or etanercept. Response to NSAIDs should be evaluated four to six weeks after starting them, and TNF-Is should be evaluated twelve weeks after starting them.

Although systemic glucocorticoids are not advised, local steroid injections may be tried. Referrals to specialists may be necessary based on the patient's clinical picture, probable consequences, and extra-articular symptoms of the illness. Rheumatologists can help with official diagnosis, therapy, and monitoring, while dermatologists, ophthalmologists, and gastroenterologists can help with non-musculoskeletal AS symptoms.

In general, people with AS do not require in-patient treatment. Patients with comorbid or extra-articular illness, as well as those requiring surgery, are exceptions to this rule.

The following are examples of extra-articular presentations that may necessitate professional referral for optimal care:

Acute anterior uveitis
Aortitis
Conduction defects
Pulmonary fibrosis
Amyloidosis
Neurologic deficits, including cauda equina
Associated inflammatory bowel disease

Laboratory measurements such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level can be used to track disease progression and response to medication.

Surgical treatment

Surgical therapy is aimed at resolving the issues associated with AS; it is seldom used to repair injured peripheral joints and is rarely utilized to fix spinal abnormalities due to the high morbidity involved. Patients with AS-related spinal fusion who report a change in supine position should be treated with caution and should be considered to have incurred a spinal fracture. To fix the fracture and prevent neurologic damage, surgical intervention may be required.

Outpatient treatment should focus on providing appropriate pain relief while also maximizing mobility and functional abilities. Pain medicines, fitness programs, recreational therapy, and vocational rehabilitation are all examples of such care. Regular exercise reduces symptoms and may decrease the progression of the condition. In general, individuals with AS are not subjected to food restrictions; however, patients with concurrent disorders, such as inflammatory bowel disease (IBD), are subjected to dietary restrictions.

Ankylosing spondylitis diet

Ankylosing spondylitis is a kind of arthritis that mostly affects the spine and major joints. The Mediterranean diet, or a diet high in lean protein, vegetables, and fruit that avoids refined flour, sugar, alcohol, and processed foods, is the ideal diet for ankylosing spondylitis.

Differential Diagnosis

Certain disorders and ailments can cause symptoms similar to ankylosing spondylitis (AS) and must be ruled out. Among these include, but are not limited to:

Mechanical low back pain
Lumbar spinal stenosis
Rheumatoid arthritis
Diffuse idiopathic skeletal hyperostosis (DISH)

Each of these diagnoses has similarities to AS, but their differences must be ruled out for an accurate diagnosis.

Mechanical back pain can be distinguished from Since by the age at which symptoms appear, as mechanical back pain can appear at any age, but AS often appears before the age of 40. In contrast to AS, pain improves with rest, and morning stiffness is minimal and transient. Mechanical back pain, unlike AS, is not accompanied with peripheral arthritis or extraskeletal symptoms.

The term lumbar spinal stenosis (LSS) refers to a narrowing of the spinal canal that puts pressure on the spinal cord. It, like AS, can cause chronic back pain and morning stiffness. Unlike AS, LSS often manifests in people over the age of 60, is not linked with peripheral arthritis or extraskeletal symptoms, and responds inconsistently to NSAIDs.

Rheumatoid arthritis (RA) is another chronic inflammatory joint illness that, like AS, commonly manifests as escalating back pain and morning stiffness in persons aged 40 or younger. Peripheral arthritis, on the other hand, is particularly frequent in RA, as opposed to AS. Furthermore, rheumatoid nodules are pathognomonic for RA but are seldom seen in AS.

Diffuse idiopathic skeletal hyperostosis (DISH) is a degenerative condition characterized by ossification in the spine, most notably in the anterior longitudinal ligament, paravertebral tissues, and the peripheral side of the annulus fibrosus. DISH, like AS, may appear with a history of postural abnormalities and back discomfort.

Unlike AS, which is an inflammatory illness, DISH lacks inflammatory features such as morning stiffness or improvement with activity but not with rest. On radiographs, DISH also displays no indication of sacroiliitis.

Prognosis

While the young age of onset is related to worse function results in ankylosing spondylitis (AS) patients, significant physical impairment is uncommon. The majority of patients are totally functioning and able to work. Patients with severe, long-term illness have a higher death rate than the overall population, owing mostly to cardiovascular problems.

Indicators of poor prognosis include the following:

Peripheral joint involvement
The young age of onset
Elevated erythrocyte sedimentation rate (ESR)
Poor response to nonsteroidal anti-inflammatory drugs (NSAIDs)

Symptoms are often unilateral and intermittent during the outset of the condition. Pain and stiffness grow more intense and consistent as the condition advances. Adequate exercise can help to improve symptoms and range of motion.

Some people have minimal or no symptoms. A considerable proportion of AS patients acquire chronic progressive illness and disability as a result of spinal inflammation leading to fusion, which is frequently associated with thoracic kyphosis or erosive disease involving peripheral joints, particularly the hips and shoulders. Patients who have had spinal fusion are more likely to experience spinal fractures, which can result in neurologic impairments. The majority of functional decline in AS happens within the first ten years of the disease.

Severe physical handicap is uncommon in AS sufferers. Mobility issues affect around 47 percent of patients. The length of the disease, peripheral arthritis, cervical spine involvement, younger age at beginning of symptoms, and concurrent disorders all contribute to disability. Long durations of exercise or surgical treatment of peripheral joint and cervical spine involvement have been shown to ameliorate disability.

After the beginning of symptoms, the majority of patients remain totally functioning and continue to work. Vocational counseling has been shown to reduce the probability of work handicap by more than 60%. Although the majority of patients are able to continue working, when symptoms worsen, up to 37% move employment to less physically demanding jobs.

Complications

Ankylosing spondylitis (AS) can cause both articular and extra-articular problems. These are some examples:

Chronic pain and disability
Aortic regurgitation
Pulmonary fibrosis
Cauda equina syndrome
Mood disorders

Patients with severe long-standing AS may acquire major extra-articular symptoms such as cardiovascular illness, including cardiac conduction abnormalities and aortic regurgitation; pulmonary fibrosis; neurologic sequelae (e.g., cauda equina syndrome); or amyloidosis in rare cases. Patients with severe long-term AS are at a higher risk of death than the general population. Extra-articular symptoms or concomitant disorders increase the likelihood of death.

Emotional issues relating to the condition are noted by 20% of patients. Women are more likely to suffer from depression, and contributing variables include the severity of pain and functional handicap involved.

Ankylosing spondylitis in Children

Juvenile ankylosing spondylitis (JAS) is a less prevalent variant of the illness than the more common adult version. Enthesopathy and arthritis of major joints of the lower limbs are more frequent in adult AS than the typical early-morning back pain.

Ankylosing tarsitis of the ankle is a typical finding, as are seronegative ANA and RF, as well as the presence of the HLA-B27 allele.

Although primary appendicular joint engagement may explain the delay in diagnosis, additional frequent AS symptoms such as uveitis, diarrhea, pulmonary illness, and heart valve disease may shift attention away from other juvenile spondyloarthropathies.

Conclusion

The condition is characterized by involvement of the spine and sacroiliac (SI) joints, peripheral joints, fingers, and entheses. AS is linked with impaired spinal mobility, postural irregularities, buttock discomfort, hip pain, peripheral arthritis, enthesitis, and dactylitis ("sausage digits").

Patient education is critical in the treatment of ankylosing spondylitis (AS). Patients should be informed on the long-term nature of their condition, as well as the use and side effects of drugs.

Inform patients that while correct exercise regimens are beneficial in lowering symptoms, physical therapy is strongly necessary in order to remain functioning. Swimming and water therapy are both recognized to aid in the maintenance of fitness and the reduction of morbidity. Smoking cessation is advised due to the role of the lungs in AS.