By Pat Anson, PNN Editor

Nearly one in five patients who are told they have multiple sclerosis are misdiagnosed with the autoimmune disease, according to a new study of patients referred to two MS treatment centers in Los Angeles. The patients spent an average of four years being treated for MS before receiving a correct diagnosis.

MS is a chronic disease that attacks the body’s central nervous system, causing pain, numbness, difficulty walking, paralysis, loss of vision, and fatigue. The symptoms are similar to those of several other chronic conditions – including neuropathy, migraine and fibromyalgia – which often leads to a misdiagnosis.

Researchers at the Cedars-Sinai Multiple Sclerosis and Neuroimmunology Center analyzed the cases of 241 patients who had been diagnosed by other physicians and then referred to the Cedars-Sinai or UCLA MS clinics.

Their findings, published in the journal Multiple Sclerosis and Related Disorders, indicate that 43 of the 241 patients (18%) with a previous diagnosis of MS did not meet the criteria for the disease.

"The diagnosis of MS is tricky. Both the symptoms and MRI testing results can look like other conditions, such as stroke, migraines and vitamin B12 deficiency," said lead author Marwa Kaisey, MD. "You have to rule out any other diagnoses, and it's not a perfect science."

The most common correct diagnoses was migraine (16%), radiologically isolated syndrome (RIS) (9%), spondylopathy (7%), and neuropathy (7%). RIS is a condition in which patients do not experience symptoms of MS even though their imaging tests look similar to those of MS patients.

The misdiagnosed patients received approximately 110 patient-years of unnecessary MS disease modifying drugs. Nearly half received medications that carry a known risk of developing progressive multifocal leukoencephalopathy, a potentially fatal brain infection.

"I've seen patients suffering side effects from the medication they were taking for a disease they didn't have," Kaisey said. "Meanwhile, they weren't getting treatment for what they did have. The cost to the patient is huge — medically, psychologically, financially."

The cost of disease modifying medications for an MS patient in the U.S. exceeds $50,000 a year. Investigators estimated that the unnecessary treatments identified in this study alone cost almost $10 million. 

Researchers hope the results of the study will lead to new biomarkers and improved imaging techniques to help prevent future MS misdiagnoses.

A similar study in 2016 also found that MS patients were often misdiagnosed. One third of the patients were misdiagnosed for a decade or longer, most took unnecessary and potentially harmful medication to treat a disease they didn't have, and some even participated in clinical trials for experimental MS therapies. About a third suffered from morbid thoughts of death.