MS diagnosis requires attention to signs, symptoms of other neurological diseases

SAN DIEGO - Clinicians must rule out several neurological diseases that often mimic MS when making a diagnosis, according to a presenter at ACTRIMS 2023.

“For medical students or trainees involved in MS diagnosis, it’s important to show these are not the zebras that are misdiagnosed but are actually common conditions that we see in our clinics,” Eoin P. Flanagan, MB, BCh, professor of neurology at the Mayo Clinic, told attendees.

Flanagan cited five common diagnoses often mistaken for MS: migraine alone or with other diagnoses, fibromyalgia, nonspecific or nonlocalizing neurologic symptoms with abnormal MRI, conversion or psychogenic disorders and neuromyelitis optica spectrum disorder (NMOSD).

Clinicians can work around a potential misdiagnosis, Flanagan said, by considering the five steps of MS diagnosis, which include identifying classic clinical features such as subacute attacks related to optic, speech or cerebral dysfunction or signs of progressive disability; neurological examination for signs consistent with MS; imaging of the brain, cervical or thoracic spinal regions; measurement of cerebrospinal fluid for low white blood cell counts; and further evaluation for atypical signs of disease or disease progression.

Regarding CSF and related serology, Flanagan noted, higher white blood cell counts are more likely an indicator of myelin oligodendrocyte glycoprotein antibody disease (MOGAD), NMOSD or lymphoma, while higher protein counts are likely to indicate Susac syndrome or Guillain-Barre syndrome.

For proper MS diagnosis, length and axial location of a spinal MRI are also crucial to prevent misdiagnosis, as the lesion size, length, location and axial positioning of the scan may rule out other syndromes, while the pattern of enhancement is likely to provide clearer clues regarding lesion etiology.

Malnutrition, areflexia, fatiguability, intractable nausea or vomiting, encephalopathy and symptoms consistent with immunosuppression should guide clinicians away from an MS diagnosis and toward brainstem or cerebellar syndromes, Flanagan said.

Ataxia, symmetric myelopathies and immunosuppression, along with family history of leukodystrophies or mitochondrial disease, also are crucial measures that point away from MS.

The principal difference, Flanagan noted, between a diagnosis of MS compared with MOGAD or aquaporin-4 antibody positive NMOSD is a progressive phase in MS, along with a well-defined ovoid, periventricular shape to lesions found on MRI at the time of an attack.

“It’s important (to remind clinicians of) risk of misdiagnosis in patients with migraine, fibromyalgia and other nonspecific symptoms,” Flanagan said.