Why multiple sclerosis is often misdiagnosed

Multiple sclerosis misdiagnosis remains a stubborn problem because there is no one test that can conclusively identify the disease. Clinicians must weigh a person’s symptoms, examination, MRI scans and sometimes spinal-fluid findings, while ruling out conditions that can look remarkably similar.

A 2019 review in Frontiers in Neurology found that MS signs, MRI findings and oligoclonal bands in spinal fluid all have limited specificity. The disease can also look different from one person to another, and change over time, adding more moving parts to an already difficult call.

Why is multiple sclerosis misdiagnosed?

MS diagnosis depends on the full clinical picture, not an abnormal brain scan alone. Cedars-Sinai says doctors assess whether symptoms came as distinct attacks or progressed gradually, conduct a neurological examination, and use MRI to look at the brain and spinal cord.

The trouble is that other illnesses can produce overlapping symptoms or white-matter lesions on MRI. The 2019 review lists migraine, cerebral small-vessel disease, fibromyalgia, functional neurological disorders and neuromyelitis optica spectrum disorders among the conditions that may be mistaken for MS. Cedars-Sinai also names lupus and myelin oligodendrocyte glycoprotein antibody-associated disease as potential look-alikes.

Dr. Lokesh Rukmangadachar of SLUCare said in a 2022 video that nonspecific neurological symptoms can be incorrectly treated as a typical MS attack, while MRI findings from other conditions may be read as MS-like lesions. That is a high-stakes mix when a scan result is separated from a patient’s wider medical history.

The McDonald criteria, used to help diagnose MS, were designed to identify MS or a high likelihood of it in people with a typical clinically isolated syndrome after other diagnoses have been judged unlikely, according to the 2019 review. The authors cautioned that the criteria were not created as a stand-alone tool for excluding every alternative disease.

How common are wrong MS diagnoses?

There is no single population-wide misdiagnosis rate. The 2019 review says the true incidence and prevalence are unknown. Reports from specialist MS centers found that roughly 30% of people referred with suspected MS were ultimately found to have another condition, a figure that reflects a selected group rather than everyone with symptoms or an abnormal MRI.

Cedars-Sinai summarized a separate 2019 study as finding that nearly one in five patients with an established MS diagnosis had been misdiagnosed. In a narrower 2025 study of 46 patients with confirmed neurogenetic diseases or coexisting MS seen at tertiary centers, researchers found overlapping clinical and imaging features could lead to confusion; atypical MRI features were common among those initially diagnosed with MS.

Why getting the diagnosis right matters

A wrong MS diagnosis can mean exposure to therapies that alter or suppress the immune system without the expected benefit. Cedars-Sinai says those drugs can carry side effects, including infection. The 2019 review reported that, in one study across four academic MS centers, 70% of misdiagnosed patients had received disease-modifying treatment and 31% experienced unnecessary harm attributed directly to the error.

The risk runs both ways. Cedars-Sinai says a person who has MS but receives another diagnosis can face delayed treatment, with greater risks of relapses, worsening or new symptoms, and later disability. For cases that remain uncertain or have atypical features, reassessment by a clinician with MS expertise may help clarify the diagnosis.

This story draws on original reporting from Rolling Stone.