How Many People Diagnosed With MS Don’t Actually Have the Disease?

brain scan, MS
brain scan, MS
Researchers sought to find out how frequently MS is mistaken for another condition.

Multiple sclerosis is difficult to diagnose accurately. Not only is there no proof-positive test for the disease, but symptoms are often unspecific and vary from one patient to the next. How frequently is MS mistaken for another condition?

Researchers Study MS Misdiagnosis

Researchers from Cedars-Sinai Multiple Sclerosis and Neuroimmunology Center and the University of California, Los Angeles (UCLA) sought to find out how frequently the disease is incorrectly diagnosed and identify common characteristics in these patients. Their findings were published in Multiple Sclerosis and Related Disorders.1

Over 12 months, the investigators analyzed the cases of 241 patients who were diagnosed with MS and referred to the Cedars-Sinai or UCLA MS clinics. They found that 18% of patients who were diagnosed with MS by a referring clinician did not actually have the disease.

Not a Perfect Science

Migraines (16%) were the most common condition mistakenly diagnosed as MS, followed by radiologically isolated syndrome (9%), spondylopathy (7%), and neuropathy (7%).

“The diagnosis of MS is tricky,” said Marwa Kaisey, MD, MS specialist at Cedars-Sinai and lead author of the study, in a press release. “Both the symptoms and MRI testing results can look like other conditions, such as stroke, migraines, and vitamin B12 deficiency. You have to rule out any other diagnoses, and it’s not a perfect science.”2

The Cost of MS Misdiagnosis

Among the patients who received an incorrect diagnosis, 72% had received treatment for MS. Of those patients, 48% received therapies that can lead to progressive multifocal leukoencephalopathy (PML), an infection of the central nervous system that causes demyelination of the nerves.

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Kaisey noted that there are significant physical, psychological, and financial costs associated with misdiagnosis. “I’ve seen patients suffering side effects from the medication they were taking for a disease they didn’t have,” she said. “Meanwhile, they weren’t getting treatment for what they did have.”2

On average, patients with misdiagnosed MS were found to spend 4 years undergoing treatment for MS before receiving the correct diagnosis. The unnecessary treatments identified in the study resulted in a healthcare cost of nearly $10 million combined.1

Looking Ahead

The researchers are hopeful that their findings will help improve diagnostic procedures for MS. “The first step, which is what we’ve done here, is to identify the problem, so now we’re working on potential solutions.”2


  1. Kaisey M, Solomon AJ, Luu M, Giesser BS, Sicotte NL. Incidence of multiple sclerosis misdiagnosis in referrals to two academic centers. Mult Scler Relat Disord. 2019;30:51-56.
  2. Study of multiple sclerosis patients shows 18 percent misdiagnosed [Press Release]. Los Angeles, CA; EurekAlert!; April 8, 2019.