Neurology and Neurosurgery

Dec. 30, 2022

Patients mistakenly given a diagnosis of autoimmune encephalitis can experience harm from inappropriate treatment. A multicenter study led by Mayo Clinic and published in JAMA Neurology outlines the most common autoimmune encephalitis mimics and the potential reasons for misdiagnosis.

Key findings:

• Approximately half of the case series of 107 outpatients who were misdiagnosed with autoimmune encephalitis had functional neurological or psychiatric disorders.
• Misdiagnosis is frequent and occurs in many settings, including specialized centers.
• One-fifth of the misdiagnosed patients experienced morbidity related to unnecessary immunotherapy.

Clues that a patient's presentation might not be due to autoimmune encephalitis include:

• Insidious rather than acute onset of symptoms.
• Lack of MRI or cerebral spinal fluid test findings suggestive of inflammation.

Over-interpretation of serum nonspecific antibodies was also a major contributor to misdiagnosis.

The researchers note that autoimmune encephalitis is increasingly diagnosed but remains rare.

"It's important that neurologists have a good eye out for autoimmune encephalitis. But it's important also to consider the possibility of alternatives," says Eoin P. Flanagan, M.B., B.Ch., the study's first author and an autoimmune neurologist at Mayo Clinic.

For more information

Flanagan EP, et al. Autoimmune encephalitis misdiagnosis in adults. JAMA Neurology. In press.

Refer a patient to Mayo Clinic.