Getting a correct diagnosis of multiple sclerosis (MS) can be a challenge. In fact, a study published in May 2019 in the journal Multiple Sclerosis and Related Disorders suggested that nearly 1 in 5 people with other neurologic conditions are mistakenly diagnosed with MS.

These errors in diagnosis likely result from the fact that there is no single test that can determine an MS diagnosis conclusively. Also, not everyone has all of the common symptoms of MS, such as numbness, tingling, pain, fatigue, and heat sensitivity. And to complicate matters, the symptoms you do have may resemble those of some other conditions.

To figure out what’s causing possible MS symptoms, doctors look at your medical history, the results of a neurological exam, and a magnetic resonance imaging (MRI) scan — and sometimes do a spinal tap (also called a lumbar puncture). To accurately diagnose MS, many other possible causes must be considered and excluded.

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 MS Center 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. 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,” says Dr. Conway.

“Misdiagnosis in MS has been an issue that’s been talked about for 40 years,” adds Jeffrey Cohen, MD, director of experimental therapeutics at the Mellen MS Center of the Cleveland Clinic in Ohio. “And even with refinement of diagnostic criteria and the availability of technologies like MRI, it’s still a problem. There are a significant number of people getting misdiagnosed with MS in part because there’s no single test for it, like a blood test.”

Conway agrees, saying, “It’s fairly common to have a misdiagnosis of MS; there’s been a fair amount of research about the need to sometimes ‘undiagnose’ patients.”

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

Diseases More Likely to Be Misdiagnosed as MS

Similar symptoms may lead to confusion between MS and these diseases, although in most cases, an MRI scan of the brain can rule out MS as the diagnosis — but not always.

1. Fibromyalgia

Fibromyalgia and MS have some similar 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, says Conway, fibromyalgia wouldn’t be expected to cause the types of brain or spinal lesions seen on an MRI scan of a person with MS — but sometimes people with fibromyalgia 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.

Symptoms of NMOSD can be similar to MS but can also include sudden vision loss or pain in one or both eyes, numbness or loss of sensation in the arms and legs, difficulty controlling the bladder and bowels, and uncontrollable vomiting and hiccups, according to Oregon Health and Sciences University.

Treatments for MS are ineffective for and can even worsen NMOSD, so getting an accurate diagnosis is extremely important. A blood test known as the NMO IgG antibody test can help to differentiate between MS and NMOSD.

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.

Also called cerebral small vessel disease, this condition can cause disability, abnormal gait, urinary incontinence, and cognitive decline. “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, they 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 light-headedness and fainting.

In the study published in Multiple Sclerosis and Related Disorders in May 2019, researchers from Cedars-Sinai Medical Center and the University of California in Los Angeles (UCLA) found that migraine was the most common correct diagnosis in study subjects who had been misdiagnosed with MS, occurring in 16 percent of the group.

That said, headaches — and headaches caused by migraine in particular — can be the first manifestation of MS, according to a study published in December 2017 in Brain and Behavior.

Migraine can also be difficult to diagnose, and doctors use some of the same tools to diagnose migraine as they do for 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 really consistent with MS, so that’s how we often make the distinction, he says.

In the Cedars-Sinai-UCLA research reported in May 2019, as many as 7 percent of MS misdiagnoses were really spondylopathies

8. Conversion and Psychogenic Disorders

Conversion and psychogenic disorders are conditions in which psychological stress is converted into a physical problem — such as blindness or paralysis — for which no medical cause can be found. In a study published in September 2016 in the journal Neurology, 11 percent of subjects definitely or probably misdiagnosed with MS actually had a conversion or psychogenic disorder.

Although this misdiagnosis can be made, generally these disorders don’t have MRI changes associated with them, so that would argue against MS, says Conway. “Some of these patients might have incidental MRI changes that are not really consistent with MS, but they have the spots and they have the symptoms, and so they can get misdiagnosed.”

9. Vasculitis

Vasculitis is an inflammation of the blood vessels that, depending on the type of vasculitis, can cause symptoms often seen in MS, such as fatigue; headache; numbness, tingling, and weakness in the hands and feet; and double vision.

However, other symptoms of vasculitis, such as fever, stomach pain after eating, swelling or hardening of the palms of the hands and soles of the feet, and bleeding under the skin, would not be characteristic of MS.

Vasculitis affecting the skin or bodily organs, like the kidneys, can be diagnosed by examining samples of tissue collected from that area. Some types of vasculitis can also be diagnosed via X-rays or blood tests.

Vasculitis is a rare condition, which makes misdiagnosing it as MS less likely, says Conway. “The changes on the MRIs of people with vasculitis are different from the changes we would see in MS. We can usually distinguish between the two,” he says.

10. Acute Disseminated Encephalomyelitis (ADEM)

ADEM is a severe inflammatory attack affecting the brain and spinal cord. Symptoms include fever, fatigue, headache, nausea, vomiting, vision loss, and difficulty walking. A very rare condition, ADEM typically comes on rapidly, often after a viral or bacterial infection.

ADEM can appear very similar to MS, but ADEM is most commonly a disease of childhood and usually fairly easily distinguishable for MS at presentation, says Conway.

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.

11. Lyme Disease

Lyme disease is a bacterial infection transmitted through a tick bite. 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 or have recently traveled to one, your doctor will want to rule out the possibility.

12. Neuropathy

In the Cedars-Sinai-UCLA study, neuropathy, or nerve damage, was the correct diagnosis for 7 percent of those misdiagnosed with MS.

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 their 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.”

13. 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, but only about half of people with lupus develop this rash. 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.

14. 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 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.

A stroke requires immediate attention; if you think you’re experiencing a stroke, call 911.

15. Sjogren’s Syndrome

In the autoimmune disorder Sjogren’s syndrome, the glands that produce tears and saliva are mistakenly attacked by the immune system, which in turn causes the hallmark symptoms of dry eyes and mouth.

The condition does have shared symptoms with MS, including fatigue and musculoskeletal pain, and, like MS, it is more commonly found in women than in men, says Cohen.

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

16. Myasthenia Gravis

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

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 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 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.

16 Conditions Commonly Mistaken for Multiple Sclerosis