MS vs. Ankylosing Spondylitis: What Are the Differences?

Despite both being autoimmune diseases, multiple sclerosis (MS) and ankylosing spondylitis (AS) are unrelated conditions. They rarely coexist, and they differ significantly in symptoms, diagnosis, and treatment.

In MS, the immune system attacks nerve fibers in the brain and spinal cord and their protective myelin covering. This may lead to neurological symptoms like numbness, weakness, and vision problems.

In AS, the immune system attacks the spine, including the sacroiliac joints, which connect your lower spine to your pelvis. Even though it's considered a type of arthritis, AS can also affect multiple other organs in your body, including your heart, eyes, skin, intestines, and kidneys.

This article will provide a brief overview of MS and AS. Key differences in symptoms, causes, diagnosis, treatment, and prevention between the two autoimmune diseases will be highlighted.

Symptoms

The symptoms of both MS and AS usually start in early adulthood. They range in severity from being a mild nuisance to being severe and debilitating. Apart from these general similarities, AS and MS are unique conditions.

Multiple Sclerosis

MS symptoms are neurological in nature because the disease only affects the central nervous system. Your central nervous system (CNS) consists of your brain, spinal cord, and the optic nerves of your eyes.

The specific symptoms a person with MS has depends on which nerve-signaling pathways are affected within the CNS.

Common MS symptoms include:

• Fatigue
• Pain
• Weakness and muscle spasms
• Vision problems (e.g., blurry or double vision)
• Constipation
• Cognitive dysfunction (problems with thinking and memory)
• Bladder problems (e.g., urinating frequently)
• Trouble walking
  

Ankylosing Spondylitis

People with AS initially experience lower-back pain from inflamed sacroiliac joints. This aching pain comes on gradually over a period of weeks to months and usually worsens with inactivity and improves with exercise.

Over time, the inflammation moves from the sacroiliac joints to the spinal joints. Chronic inflammation of the spine may eventually cause the bones within the spine to fuse or stick together, resulting in a rigid, immobile spine that is severely disabling.

Other symptoms of AS may include:

• Inflammation and pain of the hip and shoulder joints
• Swelling of the heels or elbows from enthesitis (inflammation of the site where tendons and ligaments attach to bone)
• Systemic (whole-body) symptoms like fatigue or loss of appetite

In some cases, people with AS experience symptoms related to other organs besides the joints. For example, AS can damage the eyes, causing eye pain and blurry vision, or the heart, leading to heart failure or abnormal heart rhythms.

Causes

The exact cause of both MS and AS remains unknown. However, both diseases involve the immune system launching misguided attacks on healthy tissues in the body.

Multiple Sclerosis

Experts suspect that genetics and certain lifestyle factors, like vitamin D deficiency or obesity in early childhood, may play a potential role in the development of MS.

Hormones whose levels are higher in females, such as estrogen, probably also contribute, considering females are 2 to 3 times more likely to be diagnosed with MS than males.

Ankylosing Spondylitis

Like MS, AS onset is likely due to the interaction of multiple factors, including genes, lifestyle habits, and environmental exposures.

One gene variant known as HLA-B27 is positive in 90% of people diagnosed with AS. Experts have found other genes linked to AS as well, including a gene called the ERAP-1 gene. This gene codes for a protein involved in the normal functioning of the immune system.

Other factors that may influence AS development include:

• Certain infections
• Drug or toxin exposure
• Bacterial changes within your gut
• Mechanical stress to affected joints
• Bowel inflammation
  

Diagnosis

The diagnosis of both MS and ankylosing spondylitis can be challenging because there is no single test to determine if a person has the disease. Moreover, symptoms in both conditions can be subtle or nonspecific, which can delay the diagnosis for years.

The diagnostic process for both conditions involves obtaining results from a person's medical history, physical examination, and various blood and imaging tests. Results from these tests ultimately guide healthcare providers into ruling the disease in or out.

Multiple Sclerosis

When making a diagnosis of MS, a neurologist—a doctor who specializes in diseases of the nervous system—will ask you questions about your symptoms and perform a neurological exam.

Results from the following tests will also be evaluated:

• Magnetic resonance imaging (MRI) of the brain and/or spinal cord
  
• Laboratory tests, mostly to rule out mimicking conditions like vitamin B12 deficiency
• Other diagnostic tests, such as a spinal tap (lumbar puncture) or evoked potential tests (measure the electrical activity of the nerves of the eye)

Taking all the above information into account, your neurologist will determine if you meet the McDonald criteria—a formal set of guidelines intended to help neurologists diagnose MS accurately and timely.

The premise of the McDonald criteria is that it provides evidence of damage to the CNS at different dates and to different parts—referred to as "dissemination in time and space."

Ankylosing Spondylitis

A rheumatologist—a doctor who specializes in diseases of the joints and muscles—usually makes the diagnosis of AS. Your provider would start by asking you questions about your symptoms and performing a physical exam.

During the physical exam, your spine, hip, and sacroiliac joints will be moved around to assess for range of motion. Your joints will also be examined for signs of inflammation like warmth, swelling, and tenderness.

Results from these tests will also be gathered and carefully evaluated:

• The HLA-B27 blood test
• Inflammatory blood tests like C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR or sed rate)
• Imaging tests, like X-ray studies or an MRI of the spine

Keep in mind that you may be referred to another specialist if you are having non-joint-related symptoms. For instance, a condition called uveitis (inflammation of the uvea at the center of the eye) is a possible symptom of AS and can be diagnosed by an ophthalmologist—a doctor specializing in conditions of the eyes.

Treatment

There is no cure for MS or AS. However, there are therapies that can help alleviate symptoms and medications that can improve the long-term outcomes of both diseases.

Multiple Sclerosis

Disease-modifying treatments (DMTs) in MS are intended to decrease the number and severity of MS relapses a person may experience and slow the natural course of the disease.

There are numerous DMTs available, and they come in three different forms—injections, oral therapies, and intravenous (IV) infusions. Selecting a DMT requires careful discussion and depends on many factors, including how aggressive your disease is and the drug's safety profile.

Of note, DMTs do not treat relapses or specific MS symptoms, like bladder dysfunction, pain, or fatigue. MS relapses can be treated with a corticosteroid, like Solu-Medrol (methylprednisolone) or prednisone, whereas MS symptoms are treated with lifestyle changes, medications, and/or rehabilitation therapies.

Ankylosing Spondylitis

The treatment of AS involves both physical therapy and medication to ease pain and improve everyday functioning.

Depending on the specific symptoms and severity of a patient's AS, a physical therapy program often entails a combination of gentle range of motion and muscle stretching and strengthening exercises.

Two types of medications used to treat AS include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs) work to ease inflammation and are available over-the-counter or by prescription.
• Tumor necrosis factor (TNF) blockers inhibit the production of a protein involved in AS-related inflammation.

Prevention

MS and AS cannot necessarily be prevented. This is because there are factors that contribute to the diseases' development that are out of a person's control. These factors include genetic makeup and immune system response.

Nevertheless, there are some lifestyle changes that may be helpful in preventing or combating each disease.

Multiple Sclerosis

Lifestyle behaviors that may help prevent MS onset or reduce the severity/progression if you have already been diagnosed include:

• Maintaining a healthy weight
• Ensuring a sufficient vitamin D level
• Avoiding smoking
• Engaging in regular physical activity

Ankylosing Spondylitis

Lifestyle behaviors that can optimize your functioning and well-being while living with AS include:

• Avoiding smoking and excess alcohol intake
  
• Engaging in a regular exercise program (e.g., gentle stretching, balance, and muscle strengthening exercises)
• Maintaining a healthy weight
  

Summary

While both multiple sclerosis and ankylosing spondylitis are autoimmune diseases, they are otherwise unrelated and rarely coexist. MS is a disease of the brain and spinal cord, whereas ankylosing spondylitis is a type of inflammatory arthritis that mainly affects the spinal and sacroiliac joints.

The therapies for each condition are also unique; although, treatment goals are similar (e.g., relieving symptoms and delaying disease progression).