Episode 100: Autoimmune encephalitis testing with Tammy Smith

Autoimmune encephalitis testing requires a strategic, phenotype-driven approach rather than a broad, indiscriminate diagnostic method. Because these tests are expensive and prone to false positives, clinicians must first identify the patient's specific clinical phenotype—such as epilepsy, movement disorders, or encephalopathy—to select the appropriate antibody panel. Testing should ideally include both serum and cerebrospinal fluid, though serum often provides higher sensitivity for specific conditions like LGI1 encephalitis. While empirical treatment with steroids, plasma exchange, or IVIG is often necessary for critically ill patients, clinicians should avoid over-testing and consult with subspecialty experts at reference laboratories to ensure accurate interpretation. Ultimately, treating the patient’s clinical presentation and response to initial immunotherapy remains more critical than relying solely on antibody titers, which do not always correlate with disease severity or the presence of an undiscovered antibody.