Autoimmune limbic encephalitis related to SARS-CoV-2 infection: Case-report and review of the literature

Abstract

Background: SARS-CoV-2 infection is associated with a wide spectrum of neurological complications, including encephalitis. Most cases showed features consistent with a central nervous system (CNS) cytokine-mediated damage. However, few cases arguing for an autoimmune mechanism have been described, mainly as single reports or sparse in large case series involving other CNS manifestations. In this paper, we described a case of definite autoimmune limbic encephalitis (LE) COVID-19 related and reviewed the existing literature on other reported cases.

Case report: Two weeks after the onset of COVID-19 infection, a 74-year-old woman presented with subacute confusion and focal motor seizures with impaired awareness, starting from left temporal region. Cerebrospinal fluid analysis revealed hyperproteinorrachia. Brain MRI showed bilateral T2/FLAIR hyperintensities in both hippocampi and total body PET/TC scan revealed hypermetabolism in basal ganglia bilaterally. A diagnosis of autoimmune LE was made. Thus, high dose corticosteroids and antiseizure medications were started, with a marked improvement of neurological conditions.

Literature review: We systematically reviewed the literature to identify all well-documented cases of definite autoimmune LE (according to Graus criteria) in patients with COVID-19 infection, identifying other five cases exhibiting a good response to immunomodulating therapy.

Conclusion: A very limited number of autoimmune LE have been described until now. It is important to monitor neurological symptoms in COVID-19 patients and to consider the possibility of an autoimmune LE, in particular when altered mental status and seizures appear late in the disease course. This allows to promptly start the appropriate treatments and avoid unnecessary delays.

Keywords: Autoimmune limbic encephalitis; COVID-19; Memory deficits; Post-infectious encephalitis; SARS-CoV-2; Seizures.

Fig. 1

Box 1. Brain MRI features: axial (a) and coronal (b) T2 weighted images and axial (c) and coronal (d) Flair images show hyperintensity and mild expansion of both medial temporal lobes. The study of medial temporal lobes with diffusion weighted images demonstrates high signal in DWI b1000 (e) and no diffusivity restriction in ADC maps (f), denoting the presence of vasogenic edema. T1 weighted images acquired before (g) and after (h) contrast administration demonstrate no contrast enhancement. FDG-PET of the brain shows hypermetabolic foci in basal ganglia (i), while no metabolic alteration on both hippocampi (l) is detectable. Box 2. Ictal EEG: a theta rhythmic activity starts on the left temporal region, then spreads bilaterally and evolves to a delta activity mixed with sharp waves, persisting predominantly on bi-temporal region for a total length of 63 ​s. Clinically, the patient presents behavioral arrest, right head and eyes deviation, chewing automatisms.

Fig. 2

Flowchart showing our literature search.