Diseases That Can Mimic Multiple Sclerosis

A diagnosis of MS requires that other conditions are ruled out

Lyme Disease Can MImic MS
Lyme Disease Can Mimic MS. ROYALSTOCKPHOTO/Getty Images

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. This is why seeing a doctor 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 a few of the medical conditions that your doctor may consider as alternative diagnoses to MS.

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' sign.

Be reassured, though, that for a doctor 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 (comprised of 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 also cause other problems like anemia, which can lead to paleness or a fast heart rate—something not associated with multiple sclerosis.

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 the MRI 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 co-exist. In fact, many neurologists will check a vitamin B12 level in their patients with multiple sclerosis because of the overlapping symptoms, and the fact that vitamin B12 is an easy fix—not something your doctor wants to miss.

Herniated Disc

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.

That being said, with a herniated disc, a person usually has acute pain, which is not seen in MS. Moreover, a herniated disc can usually 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 co-exist with MS. In fact, it would not be unusual for a doctor to see a person with MS, who also at some point in their lifetime developed a herniated disc.

As an aside, it's good to mention that an MRI done on a person with MS (for purposes related to their MS) may incidentally show a herniated disc. Not all herniated discs cause symptoms, and in these cases, you just leave it alone.

Other Structural Spine Problems

Another common condition of the spine that can cause neurologic symptoms similar to MS is cervical spondylitis, 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 multiple sclerosis.


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 affects the nervous system in about 10 to 15 percent of people infected with it. 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 diseases, 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 some 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, tremor, 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, Sjogren'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.

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 pains, 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 Sjogren's syndrome) or the lung (as in sarcoidosis).

A Word From Verywell

It can be a scary time if you or a loved one are in the process of being ruled out or in 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.

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Article Sources

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  • Brinar VV, Habek M. Rare infections mimicking MS. Clin Neurol Neurosurg. 2010 Sep;112(7):625-8.
  • Langan RC & Zawistoski KJ. Update on Vitamin B12 Deficiency. Am Fam Physician. 2011 Jun 15;83(12):1425-30.