Diseases That Can Mimic Multiple Sclerosis

A differential diagnosis may be needed to pinpoint the actual cause

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If you are experiencing neurological symptoms, do not necessarily assume you have multiple sclerosis (MS), especially considering there are a number of other conditions that can mimic it. Seeing a healthcare provider for an evaluation is critical before jumping to any conclusions.

Depending on your symptoms, a proper diagnosis may be a fairly rapid process involving simple blood tests, or it may be more invasive, like requiring a biopsy.

Here are several medical conditions your healthcare provider may consider as alternative diagnoses to MS.

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Vitamin B12 Deficiency

In multiple sclerosis, the protective covering of nerve fibers in the brain and spinal cord (called the myelin sheath) is attacked by a person’s immune cells. Nerve impulses normally travel along these myelin-covered nerve fibers. When the nerve fibers are damaged, these impulses are slowed down or not received at all.

Similarly, in vitamin B12 deficiency, the myelin sheath surrounding nerve fibers is not formed properly, which impairs nerve signaling. This may cause MS-like symptoms, such as weakness, problems walking, cognitive dysfunction, and sensory disturbances like Lhermitte’s sign.

Be reassured, though, that for a healthcare provider it’s pretty straightforward distinguishing between MS and vitamin B12 deficiency. For one, the science behind the diseases is different.

Vitamin B12 deficiency affects nerves in the central and peripheral nervous system, whereas MS only affects the central nervous system (comprising the brain and spinal cord).

The peripheral nervous system includes nerves that carry information back and forth between your brain and spinal cord and the rest of your body (like your arms, legs, and internal organs).

Moreover, vitamin B12 deficiency usually manifests itself in a classic manner unlike MS, which may manifest itself in a variety of ways.

In vitamin B12 deficiency, the symptoms usually start with numbness, tingling, and loss of vibration sense, before progressing to muscle weakness or cramping.

Also in vitamin B12 deficiency, a person’s legs are generally affected more than the arms, and the disease is symmetric, affecting both sides of the body equally.

Finally, vitamin B12 deficiency tends to affect those who are middle-aged or elderly, whereas MS symptoms typically begin in young adults in their 20s and 30s.

Vitamin B12 deficiency may further cause problems like anemia, which can lead to paleness or a fast heart rate—something not associated with multiple sclerosis.

Differential Diagnosis

In terms of diagnosing vitamin B12 deficiency, a simple blood test can tell you the answer: a low vitamin B12 level in the bloodstream.

Another distinguishing diagnostic factor is that magnetic resonance imaging (MRI) scan of the brain and/or spinal cord in a person with vitamin B12 deficiency is normal, unlike that of a person with MS.

Still, it’s important to remember that both MS and vitamin B12 deficiency can coexist. In fact, many neurologists will check a vitamin B12 level in their patients with multiple sclerosis because of the overlapping symptoms.

Spinal Disorders

A herniated disc occurs when a disc located between two spinal bones (called vertebrae) is pushed out, irritating nearby nerves. This irritation of nearby nerves can lead to numbness or weakness in the area of the body that correlates with the affected nerves. These symptoms can mimic those of MS.

With a herniated disc, however, a person usually has acute pain, which is not seen in MS. Moreover, a herniated disc can generally be diagnosed on an MRI of the spine.

Like vitamin B12 deficiency, a herniated disc is usually a more benign condition than MS, and it’s common. A herniated disc can also coexist with MS; in fact, it would not be unusual for a healthcare provider to see a person with MS develop a herniated disc at some point in their life.

Another common condition of the spine that can cause neurologic symptoms similar to MS is cervical spondylosis, which is arthritis of the neck that occurs with normal aging.

Rarely, another structural problem within the spine like a tumor can mimic symptoms of MS. Again, an MRI of the spine can help differentiate these structural spine problems from an inflammatory disease like MS.


A variety of infections may cause neurologic symptoms that mimic those seen in MS. Two classic examples are Lyme disease and syphilis.

Lyme Disease

Lyme disease is a tick-borne illness that can affect the nervous system. Lyme disease can be confused with MS because an MRI of the brain of a person infected with Lyme disease may have some similar findings to the brain MRI of a person with MS.

In addition, findings from a spinal tap can be similar in MS and Lyme disease, as cerebrospinal fluid samples can be positive for a type of protein called an oligoclonal band.

Differentiating between the two requires a careful neurologic exam and additional tests, like testing for the antibody to Borrelia burgdorferi—the bacteria that causes Lyme disease—in the blood and/or cerebrospinal fluid.


Syphilis, a sexually transmitted infection, can cause neurologic symptoms like memory problems, slurred speech, tremors, sensory disturbances, and difficulties walking.

Syphilis-related antibodies in the bloodstream or cerebrospinal fluid can help distinguish this infection from MS.

Autoimmune Diseases

A number of autoimmune diseases may cause neurologic symptoms similar to those seen in MS. For example, sarcoidosis, Sjögren’s syndrome, and systemic lupus erythematosus can all cause transverse myelitis, which is a rare neurological condition characterized by inflammation spread across a segment of the spinal cord. Transverse myelitis is also seen in multiple sclerosis.


Myelin Sheath and the Role It Plays in MS

Sometimes it’s fairly simple for a neurologist to differentiate MS from another autoimmune disease. 

For instance, lupus as the cause of neurologic symptoms is more likely than MS if a person also tests positive for specific lupus-related blood tests, like antibodies to double-stranded DNA.

Lupus would also be more likely if that person had other lupus-related symptoms like joint pain, anemia, or kidney problems.

Other times the diagnosis is trickier and may require something more invasive, like a biopsy of the lip (as in the case of Sjögren’s syndrome) or the lung (as in sarcoidosis).

It is also not uncommon for multiple sclerosis to coexist with other autoimmune disorders. In fact, as many as 15% of people with MS will have at least one other autoimmune condition.

A Word From Verywell

It can be a scary time if you or a loved one is being tested for multiple sclerosis or other similar conditions. In the end, though, a thorough process will ensure the correct diagnosis, so you can move forward with a proper treatment plan.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.