Why hundreds of patients a year are misdiagnosed with MS

Relying too much on brain scans appears to be one reason doctors each year misdiagnose multiple sclerosis in hundreds of patients whose symptoms are caused by some other disease.

Researchers at Oregon Health & Science University and the Portland Veterans Affairs Medical Center surveyed 242 multiple sclerosis specialists in the U.S. to find out how often they see patients who have been misdiagnosed. Among the 122 respondents, more than 95 percent said they saw at least one patient in the past year diagnosed with MS by another medical provider, but the specialist "strongly felt" the patient had some other disease. Three out of four specialists said they saw three or more misdiagnosed patients within the past year.

The authors estimate that the 122 specialists saw 600 patients in a year who had been given an incorrect diagnosis of MS. An estimated 280 of the misdiagnosed patients were receiving therapy for MS with a disease-modifying drug, which can cause serious side effects and cost $40,000 or more per patient per year.

"Some of these patients have had this diagnosis for years," says lead author Dr. Andrew Solomon, an assistant professor at the University of Vermont College of Medicine, who began the research while he was at OHSU. "All of us had seen patients like this, who had a diagnosis of MS but we felt sure they did not have MS. That's what prompted this study."

MS is a chronic disease that attacks the central nervous system. Symptoms vary from mild numbness in the limbs to severe paralysis and loss of vision. The severity and progress of the disease vary unpredictably.

Doctors have no definitive blood test or imaging scan to confirm the diagnosis. They must take into account the patient's health history and performance on tests of movement, balance, vision, and mental function. Spinal fluid tests and MRI brain scans can be helpful.

The pattern of misdiagnosis revealed by the survey suggests that doctors are leaning too much on MRI findings, Solomon says.

"MRIs are not a substitute for a good history and neurological examination in the diagnosis of MS," cautioned Dr. John R. Corboy of the University of Colorado Multiple Sclerosis Center and co-authors.

'Therapeutic frenzy'

Back then, Poser speculated that marketing of the newly approved -interferon had created a "therapeutic frenzy" that further propelled misdiagnosis. "I found that some patients referred to me with the diagnosis of multiple sclerosis had already been given these drugs, irrespective of the clinical characteristics of their disease," he wrote. "I have also noted that many patients who receive -interferon do not have multiple sclerosis, and some patients started to take the drugs even after they were told that I could not confirm the diagnosis of multiple sclerosis."

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Why hundreds of patients a year are misdiagnosed with MS