COMMON PRESENTATION WITH AN UNCOMMON ETIOLOGY: THYMOMA-ASSOCIATED AUTOIMMUNE ENCEPHALITIS INDUCED BY COVID-19 BOOSTER VACCINE

ABSTRACT

SESSION TITLE Issues After COVID-19 Vaccination Case Posters SESSION TYPE Case Report Posters PRESENTED ON 10/19/2022 1245 pm - 0145 pm INTRODUCTION: Thymoma-associated autoimmune encephalitis (TAAE) is an understudied and overlooked diagnosis in patients presenting with abrupt altered mental status. Described as inflammation of brain tissue, autoimmune encephalitis is seen in 5-10 cases per 100,000 across all age groups per year. A rare subtype involves neuronal surface antibodies to alpha-amino-3-hydroxyl-5-methyl-4isoxazolepropionic acid receptors (AMPA-R) encephalitis is seen even less commonly. Given the "unicorn” nature of presenting cases and difficulty of diagnosis, prompt identification and treatment are critical as prolonged courses without treatment are irreversible and deadly. CASE PRESENTATION A 47-year-old male with no past medical history presented 3 days after a Johnson & Johnson coronavirus-2019 (COVID-19) booster vaccine due to worsening acute altered mental status over the past week. He complained of episodes of fever & chills prior to this. The patient's wife reported abrupt changes in memory and personality. Upon admission, the patient had a Glasgow Coma Scale of 4. The patient was intubated and transferred to the intensive care unit. Intravenous (IV) vancomycin, ceftriaxone and acyclovir was initiated for meningitis. Computed tomography (CT) scan of the head without contrast was unremarkable. Magnetic resonance imaging (MRI) showed enhancements of the right anterior and medial temporal lobe suggesting encephalitis. Cerebrospinal fluid analysis (CSF) revealed lymphocytic pleocytosis. A CT scan of the chest, abdomen and pelvis showed an anterior mediastinal mass measured 1.8 x 2.3 cm (Figure 1). FilmArray Meningitis polymerase chain reaction was negative as well as Herpes Simplex Virus (HSV) 1 and 2. Autoimmune encephalitis antibody was positive for Anti-AMPAR. Pulse dose steroids and intravenous immunoglobulin were initiated but failed. Rituximab was initiated and cardiothoracic surgery completed a thymectomy. DISCUSSION: TAAE is a rare disease, permanently debilitating, and deadly if unrecognized or treatment is delayed. Autoimmune encephalitis is an umbrella disease process seen in 0.00005% of patients per year. AMPA-R positive encephalitis is even less commonly seen with only 22 cases reported between the years 2009 and 2014 [1]. A rapidly progressive cognitive decline or psychiatric disorders are early features of this disease.Our patient had prodromal symptoms of fever and cognitive decline days after receiving his COVID-19 booster vaccine. CONCLUSIONS: Post-vaccine encephalomyelitis has been described in other settings[2]. This patient was free of symptoms prior to the COVID-19 vaccine booster, and demonstrated altered mental status hours after receiving it. This furthers the possibility of an association of the COVID-19 booster vaccine, development of encephalitis, and in this case a thymoma. Despite this, conclusions can not be made on the account of one report, but introduces a new area of focus to study. Reference #1 Höftberger, R., van Sonderen, A., Leypoldt, F., Houghton, D., Geschwind, M., Gelfand, J., Paredes, M., Sabater, L., Saiz, A., Titulaer, M. J., Graus, F., & Dalmau, J. (2015). Encephalitis and AMPA receptor antibodies Novel findings in a case series of 22 patients. Neurology, 84(24), 2403–2412. https//doi.org/10.1212/WNL.0000000000001682 Reference #2 Huynh, W., Cordato, D. J., Kehdi, E., Masters, L. T., & Dedousis, C. (2008). Post-vaccination encephalomyelitis literature review and illustrative case. Journal of clinical neuroscience official journal of the Neurosurgical Society of Australasia, 15(12), 1315–1322. https//doi.org/10.1016/j.jocn.2008.05.002 DISCLOSURES No relevant relationships by Matthew Frank No relevant relationships by Justin Ilagan No relevant relationships by Danielle Mahon No relevant relationships by Danielle Mahon No relevant relationships by Harshini Sahani No relevant relationships by Kameron Tavakolian No relevant relationship by Ndausung Udongwo