(050) An “Unforgettable” Case of Patchy Memory Loss Due to Human Herpesvirus-6 Encephalitis after Stem Cell Transplant for Acute Myeloid Leukemia

Abstract:

Background: Reactivation of human herpesvirus-6 (HHV-6) is common following stem cell transplantation (SCT) for acute myelogenous leukemia (AML), and can infrequently present with encephalitis. We present an even rarer case of patchy memory loss initially incorrectly hypothesized to be functional neurologic disorder (FND), and eventually diagnosed as HHV-6 encephalitis.

Case: A 36-year-old woman with AML was admitted for SCT fourteen months after initial diagnosis and following two rounds of chemotherapy. Twenty-four days following SCT, patient endorsed amnesia and was oriented to name only. Psychiatry was consulted for suspected FND due to preserved insight/cognition and the inconsistent nature of memory loss. Specifically, she demonstrated forgetfulness of select events from past years, was able to provide detailed information with cues, and appeared to recall past mundane events to a greater degree than traumatic events from the same time periods. Electroencephalography (EEG) and head computed tomography (CT) were unremarkable. Cerebrospinal fluid (CSF) was later found to be positive for HHV-6. Subsequently, brain magnetic resonance imaging (MRI) showed symmetric diffusion signal abnormality involving the bilateral hippocampi and amygdala concerning for viral encephalitis. Patient was treated with antiviral therapy for 21 days with subsequent improvement in clinical symptoms.

Discussion: Although amnesia is a common symptom of HHV-6 encephalitis (Frey, 2017) and symptoms presented within the appropriate timeframe of HHV-6 encephalitis (Zerr, 2006), timely diagnosis of this patient’s illness presented several challenges. Namely, the patchy nature of her memory loss inconsistent with either anterograde or retrograde amnesia and lack of other common symptoms of encephalitis raised suspicion for FND. However, HHV-6 encephalitis was eventually diagnosed based on consistent lab and imaging findings. To our knowledge, there is only one prior case report describing a patient with AML following SCT who exhibited patchy memory loss for personal events in the previous few years, while maintaining the ability to provide further information when given cues (Kapur, 1999).

Conclusion: Patchy memory loss is a rare expression of HHV-6 encephalitis and may delay potentially life-saving antiviral treatment. Therefore, it is important for consultation-liaison psychiatrists to consider HHV-6 encephalitis as a potential etiology of delirium in patients demonstrating various memory loss phenotypes, particularly in patients following SCT for AML.

References:

1. Frey, JW, Cherabie, JN, Assi, MA: Human herpesvirus-6 encephalitis following chemotherapy induction for acute myelogenous leukemia. Transplant infectious disease 2017; 19(6).

2. Zerr DM: Human herpesvirus 6 and central nervous system disease in hematopoietic cell transplantation. Journal of clinical virology 2006; 37:S52–S56.

3. Kapur, N, Brooks, DJ: Temporally-specific retrograde amnesia in two cases of discrete bilateral hippocampal pathology. Hippocampus 1999; 9(3):247–254.

Presenting Author(s)

Ariana Zargarian, MD

Resident Physician
Keck School of Medicine of the University of Southern California
Los Angeles, CA, United States

Co-Author(s)

Cody A. Bryant, MD (he/him/his)

Assistant Program Director, USC/LAC+USC Consultation-Liaison Psychiatry Fellowship Clinical Assistant Professor of Psychiatry and the Behavioral Sciences
Keck Medicine of USC & LAC+USC Medical Center
Los Angeles, CA, United States

SR

Stephanie Rademeyer, MD

Resident Physician
Keck School of Medicine of the University of Southern California
Los Angeles, California, United States

Patrick Baumgart, MD

Clinical Assistant Professor of Psychiatry and the Behavioral Sciences
University of Southern California
Los Angeles, California, United States

Bo Fu, MD

Clinical Assistant Professor of Psychiatry
Keck School of Medicine of USC
Los Angeles, California, United States