Even neurologists who focus on or have special training in multiple sclerosis (MS) sometimes misdiagnose patients with migraine, fibromyalgia, and other disorders as having MS.

For the study, 24 neurologists reviewed records of patients for who had been misdiagnosed with MS. The misdiagnosis was confirmed with clinical and laboratory tests and imaging studies. They looked at 110 patients in total, 33% of whom had carried the misdiagnosis for more than 10 years and 29% were misdiagnosed for three to nine years. Most patients actually had one of these five conditions:

• Migraine (23%) 
• Fibromyalgia (15%) 
• Nonspecific or nonlocalizing neurologic symptoms with abnormal MRI findings (12%) 
• Conversion or psychogenic disorder (11%) 
• Neuromyelitis optic spectrum disorder (6%)

Researchers said that in 72% of cases, there was clear evidence that the patient did not have MS.

How could this happen? The study found that over-reliance on MRI findings is the likely cause of the problem. MS has pretty clear diagnostic criteria, including presence of lesions in at least two places in the central nervous system. In the misdiagnoses, neurologists either didn’t see at least two lesions or incorrectly identified an MRI abnormality as a lesion when it wasn’t. In addition, misdiagnosed patients’ symptoms were often considered atypical of MS.

It makes sense that migraine was the most common conditions diagnosed as MS. Relatively recent research shows that migraine can cause white matter lesions on the brain. Migraine and MS are comorbid—that is, they tend to occur together in people—and both occur more frequently in young women.

When other conditions are misdiagnosed as MS, patients don’t get the treatment appropriate for their condition. Instead, they are given expensive and potentially harmful treatments for a disease they don’t actually have. The emotional cost of repeatedly trying and failing treatments is also high. When misdiagnosed patients participate in clinical trials (4% in this study had), it could make the treatments seem less effective than they really are.

Ault, A. (2016, Jun 2). Migraine, Fibromyalgia Frequently Misdiagnosed as MS. Medscape. Retrieved 6/2/16 from http://www.medscape.com/viewarticle/864221.