MS Diagnoses Can Be Wrong: What the 20% Headline Means Here

Why MS Can Be Difficult to Diagnose

Multiple sclerosis occurs when the immune system attacks the central nervous system, according to the National Multiple Sclerosis Society. Symptoms and the course of the disease can differ widely, and there is no one test that establishes an MS diagnosis.

Dr. Josef Gutman of NYU Langone said the range of symptoms linked to MS can make the condition challenging to diagnose. Dr. Robert Brumel of Cleveland Clinic said misdiagnoses often stem from brain scan abnormalities being read as signs of MS when they may have another explanation.

Brain Scans and Other Causes

Lesions seen on brain scans are associated with MS, but they can also result from issues such as migraines, smoking or high blood pressure, Brumel said. More advanced MRI sequences may help doctors distinguish MS-related lesions from those linked to other conditions.

An international panel issued revised MS diagnostic criteria in 2025. Brumel said the updated standards are more precise than earlier criteria, particularly in how clinicians assess brain lesions.

What Patients Can Do

When doctors determine that an MS diagnosis was incorrect, they investigate other possible explanations for the patient's symptoms, Brumel said. In some cases, he added, a person may have more than one condition, and an inaccurate diagnosis can delay progress in understanding the problem.

Brumel said seeking a second opinion may be appropriate when someone is facing an MS diagnosis. Gutman said MS specialists tend to know current diagnostic standards, recognize conditions that resemble MS and have access to more specific tests.

Applegate's Unanswered Symptoms

Applegate announced Tuesday that she had been misdiagnosed after years of thinking she had MS. On her podcast, she said the news has made matters more difficult because the debilitating symptoms affecting her everyday life and mobility still have no explanation. Brumel said getting the diagnosis right from the beginning matters so patients can move toward effective MS treatment with confidence.