Sjögren Syndrome Associated Limbic Encephalitis and Its Longitudinal Brain FDG PET Manifestations.

Soni, Kriti; Cicero, Steven; Syed, Rizwana; Horan, Nicolas; Mansharamani, Naresh; Delgrosso, Janine; Singhal, Tarun · Clin Nucl Med · 2026

case_report · Level V

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Abstract

A 62-year-old woman with Sjögren syndrome, rheumatoid arthritis, and autoimmune hepatitis presented with subacute confusion and generalized seizures. MRI revealed bilateral mesial temporal T2/FLAIR hyperintensity. Serology revealed anti-SSA and anti-SSB antibodies elevated at 5 times above the upper limit of normal. FDG-PET demonstrated marked relative mesial temporal hypermetabolism with widespread hypometabolism in the rest of the brain; z-score mapping confirmed focal mesial temporal hyperactivity. They received immunotherapy and antiseizure therapy. After 1 year, cognition improved, though memory deficits persisted. Follow-up FDG-PET showed a transition from mesial temporal hypermetabolism to relative hypometabolism, with recovery of cortical metabolism, highlighting FDG-PET's role in diagnosing and monitoring autoimmune limbic encephalitis in Sjögren syndrome.

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