Reversible dementia and insomnia in ABGA related encephalitis

ABGAs are historically associated with Encephalitis Lethargica (EL). Typically ABGAs are also found in children resulting in a variety of neuropsychiatric and extrapyramidal disorders, rare cases are reported in adults with atypical movement disorders. No description of basal ganglia reversible lesions related to ABGAs are reported and these antibodies are not included in the list of autoimmune encephalitis.

A 55 years old female presented sub-acute onset of an anxious-depressive disorder and obsessive-compulsive behavior associated with intractable insomnia affecting sleep onset and sleep maintenance. Brain-MRI showed diffuse hyperintensities on FLAIR sequences in the basal ganglia. A therapy with IV-immunoglobulin was started and the clinical condition improved dramatically and insomnia and psychiatric symptoms resolved completely.

Our case highlights the importance of making a fast diagnosis. When caught early ABGAs-related encephalitis is susceptible of a good outcome and response to treatment. Reversible insomnia and dementia in our case expand ABGA clinical presentation in adults and favors the hypothesis of an immune pathogenesis for Encephalitis Lethargica, especially in the hyperkinetic form as previously suggested, as in our case.