MS Misdiagnosis in the Era of McDonald Criteria
In more than 30% of cases, an erroneous determination of juxtacortical or periventricular lesion location was thought to have contributed to misdiagnosis. In 60%, the study neurologists cited misdiagnosis related to overreliance on MRI abnormalities, meaning dissemination in time, to confirm a diagnosis of MS in a patient with nonspecific neurologic symptoms.
“We all know the differential diagnosis of MS is broad, and a number of rare disorders can mimic MS,” Dr. Solomon said. “But here it was migraine, fibromyalgia, and a number of other disorders that are quite common that mimicked MS and were mistaken for MS.” Most of these diagnoses, with the exception of NMO, lack a specific biomarker. “What this means is that the correct diagnosis in many of these cases relies on our clinical skills and critical thinking, not just MRI. The problem is not confined to nonspecialists. MS specialists can also make mistakes.”
Study neurologists reported that in almost two-thirds of cases, atypical symptoms for a demyelinating attack contributed to misdiagnosis. “Perhaps this reflects a misunderstanding of what constitutes a typical demyelinating attack and when we should rely on our diagnostic criteria alone,” Dr. Solomon said. In half, historical episodes of neurologic dysfunction, without corroborating objective findings, contributed to misdiagnosis. “This means that patients came in and they had reported historical episodes—episodes of numbness or tingling or blurry vision—where there were no objective exam findings, evoked potentials, imaging findings, to corroborate those symptoms, yet perhaps these episodes were used to meet dissemination in time.”
MRI abnormalities incorrectly attributed to MS in patients without typical demyelinating symptoms contributed to more than half of the misdiagnoses. “It is important to highlight that our MRI criteria, as part of our MS diagnostic criteria, were not developed to differentiate MS from other disorders. The MRI criteria for MS were meant to identify patients at high risk for MS after typical clinical presentations for demyelination,” Dr. Solomon said.
The Importance of Diagnostic Criteria
“Making a diagnosis of MS is challenging. It is important to acknowledge that,” Dr. Solomon said. Common diagnoses and syndromes are often mistaken for MS. But there is significant risk and morbidity associated with misdiagnosis. “The best way to prevent misdiagnosis may be strict adherence and proper use of our MS diagnostic criteria. In patients with atypical clinical presentations or in patients with nonspecific MRI abnormalities, we may need to do more. We may need to monitor longer, do more imaging, make sure we get CSF. That may prevent misdiagnosis in a number of cases.”
Dr. Solomon also stressed the need for continued vigilance for misdiagnosis in patients with an existing MS diagnosis. “We should be thinking, ‘Is this really MS?’ each time we see a new patient, rather than simply accepting that diagnosis.” And lastly, Dr. Solomon recommended that future MS diagnostic criteria should balance the benefit of prompt diagnosis and initiation of DMT versus the potential risks of misdiagnosis.
—Glenn S. Williams
