15 Conditions Commonly Mistaken for Multiple Sclerosis

MS is a chronic disease that affects the central nervous system. When you have MS, your immune system attacks the protective sheath (myelin) that covers nerve fibers, and this can lead to communication problems between your brain and the rest of your body.

Errors in diagnosis likely result from the absence of a test that can conclusively determine an MS diagnosis. Also, not everyone with the disease experiences the most common symptoms, such as numbness, tingling, pain, fatigue, and heat sensitivity. To complicate matters further, many symptoms people do have may resemble those of some other conditions.

There are situations when it's fairly clear that someone does — or doesn't — have MS, says Devon Conway, MD, a neurologist at the Mellen Center for Multiple Sclerosis in Cleveland. “Then sometimes there are cases where it's a little more ambiguous; we are considering the possibility of MS but haven't come to a definitive decision yet,” says Dr. Conway. “Sometimes it's necessary to observe the patient and their imaging to try to make a more definitive decision on whether they have MS or not.”

To figure out what's causing possible MS symptoms, doctors look at a person's medical history, the results of a neurological exam, and a magnetic resonance imaging (MRI) scan. Sometimes, they also do a spinal tap (also called a lumbar puncture). To accurately diagnose MS, it’s important to consider and exclude the many other possible causes that exist.

There are many conditions that may be misdiagnosed as MS, with some being more likely than others.

Diseases More Likely to Be Misdiagnosed as MS

Similar symptoms may lead to confusion between MS and the following diseases. In most cases — but not always — an MRI scan of the brain can rule out MS.

1. Fibromyalgia

Fibromyalgia and MS share some symptoms, including headaches, joint and muscle pain, numbness and tingling of extremities, memory problems, and fatigue. Like MS, fibromyalgia is more common in women than in men. But Conway says fibromyalgia is unlikely to cause the types of brain or spinal lesions that typically show up on an MRI scan of a person with MS. That said, sometimes people with fibromyalgia do have abnormal MRI results for other reasons.

2. Neuromyelitis Optica Spectrum Disorder (NMOSD)

NMOSD is an inflammatory disease that, like multiple sclerosis, attacks the myelin sheaths — the protective covering of the nerve fibers — of the optic nerves and spinal cord, says Conway. But unlike MS, it usually spares the brain in its early stages.

3. Small Vessel Ischemic Disease

Small vessel ischemic disease is a “cousin” of stroke, says Conway. “It's basically injury that occurs to areas of the brain because of hardenings of the small arteries,” he says.

“On an MRI, the changes that small vessel ischemic disease causes can look like spots that could be mistaken for MS spots,” says Conway.

4. Sarcoidosis

Sarcoidosis is another inflammatory autoimmune disease that shares some symptoms with MS, including fatigue and decreased vision. But sarcoidosis most commonly affects the lungs, lymph nodes, and skin, causing a cough or wheezing, swollen lymph nodes, and lumps, sores, or areas of discoloration on the skin.

“Although this condition primarily affects the lungs, it can sometimes cause inflammatory changes in the brain and spinal cord, which can be mistaken for MS,” says Conway.

5. Vitamin B12 Deficiency or Copper Deficiency

A vitamin B12 deficiency can cause MS-like symptoms, says Conway. These symptoms can include fatigue, mental confusion, and numbness and tingling in the hands and feet. That's because vitamin B12 plays a role in the metabolism of fatty acids needed to maintain the myelin sheath. Vitamin B12 deficiency can be identified with a simple blood test.

A deficiency of the mineral copper can also cause symptoms similar to those of a vitamin B12 deficiency.

Diseases Somewhat Likely to Be Misdiagnosed as MS

While overlapping symptoms may lead doctors to think the following diseases might be MS, the conditions are generally less likely to be misdiagnosed as MS than those listed above.

6. Migraine

Migraine is a neurological disease that can cause intense, throbbing headaches; sensitivity to light, sounds, or smells; nausea and vomiting; blurred vision; and lightheadedness and fainting.

Migraine can also be difficult to diagnose; doctors use some of the same tools to diagnose migraine and MS, including taking a medical history and performing a thorough neurological examination.

An MRI can help distinguish between the two diseases, but not always, says Conway. “Both MS and migraine patients can have white matter changes on their MRI, although we can usually, but not always, distinguish between these,” he says.

7. Spondylopathies

Spondylopathies are a collection of disorders of the vertebrae that usually involve inflammation, such as ankylosing spondylitis. “These conditions are basically degenerative changes in the back and sometimes exert pressure on the spinal cord,” says Conway.

Although spondylopathies may cause symptoms such as joint pain and fatigue that are similar to MS, the MRI images are usually not particularly consistent with MS, and that's often how the distinction is made, Conway adds.

8. Functional Neurologic Disorders (FND)

9. Acute Disseminated Encephalomyelitis (ADEM)

Diseases Less Likely to Be Misdiagnosed as MS

While these diseases may have some symptoms that are similar to those of MS, they also have enough characteristics that are different from MS that misdiagnosing one for the other should happen only rarely.

10. Lyme Disease

Lyme disease is a bacterial infection transmitted by tick bites. Early symptoms include fatigue, fever, headaches, and muscle and joint aches. Later symptoms can include numbness and tingling in the hands and feet, as well as cognitive problems, such as short-term memory loss and speech issues. If you live in an area that's known to have Lyme disease in it, or if you have recently traveled to one, your doctor will want to rule out the possibility.

11. Neuropathy

Both MS and neuropathy involve nerve damage, but whereas MS impacts the central nervous system (CNS), neuropathy usually refers to peripheral neuropathy, or damage to the nervous system outside the brain and spinal cord (which make up the CNS). Peripheral nerves connect the brain and spinal cord to the rest of the body.

Peripheral neuropathy is particularly common in people with diabetes, because high blood glucose levels damage the peripheral nerves.

People with neuropathy may experience loss of coordination, muscle weakness, or difficulty walking or moving their arms or legs, similar to people with MS. However, there are several kinds of neuropathy — sensory, motor, and autonomic — each with its own set of symptoms, and it's usually fairly easy for a neurologist to distinguish between those two, says Conway. “Although they can produce similar symptoms, the clinical picture is usually a lot different,” he says.

12. Lupus

Lupus is a chronic autoimmune disorder that, like MS, affects more women than men. It can cause muscle pain, joint swelling, fatigue, and headaches. The hallmark symptom of lupus is a butterfly-shaped rash covering the cheeks and bridge of the nose that shows up in about half of people who are diagnosed. There is no single diagnostic test for lupus, and because its symptoms are similar to those of many other conditions, it is sometimes called “the great imitator.”

Rheumatologists (physicians specializing in diseases of the muscles and joints) typically diagnose lupus based on a number of laboratory tests and the number of symptoms characteristic of lupus that a person has.

“Although lupus can affect the nervous system, it's rare. The changes that we would see in an MRI are usually a little different than what we would see with MS,” says Conway.

13. Stroke

A stroke occurs when a portion of the brain stops receiving a steady supply of blood and consequently doesn't get the oxygen and nutrients it needs in order to survive. Symptoms of a stroke generally evolve rapidly and include loss of vision; loss of feeling in the limbs, usually on one side of the body; difficulty walking; and difficulty speaking. All of these signs can also occur as part of an MS flare, or exacerbation, but there's a crucial difference.

“The presentation of stroke tends to be very different, because it's very acute in its onset, and MS is usually a slower process,” says Conway.

The age of the person experiencing the symptoms can also help to pin down the correct diagnosis. While MS can occur at any age, the likelihood of having a stroke goes up with age, while the likelihood of developing MS goes down.

14. Sjögren's Syndrome

With the autoimmune disorder Sjögren's syndrome, the immune system mistakenly attacks the glands that produce tears and saliva, which in turn causes the hallmark symptoms of dry eyes and mouth.

The condition does share symptoms with MS, including fatigue and musculoskeletal pain, and, like MS, it is more common in women than in men.

However, this misdiagnosis is unlikely because Sjögren's is a fairly rare condition, and it would only be a subset of patients whose Sjögren's symptoms would mimic MS, says Conway.

15. Myasthenia Gravis

Myasthenia gravis is a chronic autoimmune disease that causes muscle weakness that typically comes and goes but tends to progress over time. A defect in the transmission of nerve impulses to the muscles is what causes the weakness.

In many people, the first signs of myasthenia gravis are drooping eyelids and double vision. Like MS, it can also cause difficulty with walking, speaking, chewing, and swallowing. If a doctor suspects that you have myasthenia gravis, a number of tests can help to confirm or rule out the diagnosis.

How a person responds to certain medicines can also aid in the diagnosis. If an anticholinesterase medicine dramatically improves muscle weakness for a brief period, it confirms a diagnosis of myasthenia gravis.

“Myasthenia gravis is a disease of the peripheral nervous system,” says Conway. “It's fairly rare that this condition would be mistaken for MS, [because] patients who have it would present differently in a physical exam.”

Additional reporting by Beth W. Orenstein and Brian P. Dunleavy.