Isolated Memory Loss in Anti-NMDAR Encephalitis

Abstract

Background and ObjectivesTo report a case of anti-NMDAR encephalitis presenting with isolated memory dysfunction.MethodsA 29-year-old woman was admitted to the Neurology Department referring memory impairment with a subacute onset. The initial assessment included EEG, neuropsychological tests, and brain MRI. Serum and CSF samples were collected for immunologic studies. The diagnostic evaluation was completed with a total body PET scan.ResultsPatient's neurologic examination was unremarkable apart from an episodic memory deficit, confirmed by neuropsychological examination. The EEG revealed epileptiform discharges in the temporal lobes, whereas brain MRI showed bilateral temporal lobes hyperintense lesions on fluid-attenuated inversion recovery images and T2-weighted images. NMDAR-IgG was detected in the patient's serum and CSF by cell-based assay confirming the diagnosis of definite anti-NMDAR encephalitis. The total body PET showed only a slight hypometabolism in the right temporal cortex and in the cerebellar hemispheres. After a course of IV immunoglobulin and corticosteroid therapy, a marked improvement of the memory deficit was observed.DiscussionThis case shows that anti-NMDAR encephalitis can present with isolated memory loss. Neural antibody testing in these patients could play a pivotal role in early diagnosis and prompt treatment.

Functional Cognitive Disorders in the Emergency Department

“…The possibility of drug-induced memory symptoms (e.g., due to hypnotics, sedatives, medications with anticholinergic effects) should always be considered but there is often concurrent evidence of impaired consciousness or encephalopathy, likewise with metabolic derangements such as acute alcohol withdrawal. Likewise, autoimmune encephalitides may be a cause of acute memory (and other cognitive) symptoms but these are usually associated with other features such as psychiatric symptoms, seizures, and movement disorders, although isolated memory impairment as the initial symptom of N-methyl-D-aspartatereceptor (NMDA-R) encephalitis has been described [29].…”