FormalPara Key Summary Points

This case study details acute cerebellitis following SARS-CoV-2 infection in an immunocompetent adult.

There was an alarming clinical presentation challenged by normal paraclinical findings.

This shows that it is necessary to start the appropriate treatment (steroids, IgIV) as soon as possible.

Introduction

Neurological damage in the acute phase of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is well described, with a wide range of symptoms such as olfactory and gustatory disorders, headache or dizziness [1, 2]. Approximately 35% of the patients are neurologically impaired [3, 4], and this percentage further increases in case of severe infection under intensive care [5, 6]. Onset of neurological disorders may also appear several weeks after the acute phase and could be immune-mediated [7]. We report herein the case of an acute cerebellitis (AC), probably immune-mediated, following SARS-CoV-2 infection in an immunocompetent adult patient.

The patient’s written consent was obtained. We made sure to keep participant data confidential and in compliance with the Declaration of Helsinki of 1964 and its later amendments.

Case Presentation

A 32-years-old Caucasian man, with no past medical history, was admitted to the emergency department on 31 October 2023 because of acute dysarthria and gait disorder associated with fever (38.7 °C), without seizures or impaired consciousness or coma (Glasgow Coma Scale score 15), following headache and severe asthenia. Physical examination revealed a cerebellar syndrome, with ataxia, dysarthria and dysmetria. These appeared 2 weeks after a mild respiratory viral infection with similar cases in his family members with suspected coronavirus disease 2019 (COVID-19). The patient had no history of drug use or recent vaccination.

At admission, all routine laboratory findings were in normal ranges, including C-reactive protein (CRP) at 0.14 mg/dL. Two nasopharyngeal COVID-19 real-time polymerase chain reaction (RT-PCR) tests performed 2 days apart were weakly positive (E gene cycle threshold at 38.7 and 35.0) which confirmed a previous SARS-CoV-2 infection. Brain computed tomography angiography and subsequent brain magnetic resonance imaging (MRI) were normal (in T1, T2, fluid-attenuated inversion recovery [FLAIR] sequences, diffusion weighted imaging [DWI] and apparent diffusion coefficient [ADC] measurements).

Lumbar puncture (LP) showed clear cerebrospinal fluid (CSF) with normal pressure, minimal pleocytosis (6 white blood cells/mm3, 430 red blood cells/mm3), normal protein level (0.31 g/L), normal glucose and negative direct examination (Table 1). The FilmArray® meningitis/encephalitis panel was negative. An empiric treatment with intravenous (IV) infusions of amoxicillin 12 g daily and aciclovir 15 mg/kg/8 h was started.

Table 1 Blood and cerebrospinal fluid (CSF) analyses
Full size table

On day 3, the cerebellar syndrome worsened, with severe dysarthria and ataxia. A second LP was performed showing correction of pleiocytosis with 2 white blood cells/mm3, increased protein level (0.52 g/L), normal glucose level, and no malignant cells. Electroencephalogram (EEG) on day 3 and MRI with angiography on day 4 were normal. Thus, a post-infectious autoimmune cerebellitis was suspected, regarding the clinical presentation in the context of a recent COVID-19. IV methylprednisolone (1 g/day) was started on day 4. Amoxicillin was stopped after confirmation of negative CSF cultures at 72 h.

On day 7, the patient was transferred to the intensive care unit (ICU) because of swallowing disorders with a Scale for Assessment and Rating of Ataxia (SARA) score of 36/40. IV immunoglobulins (IgIV) were started at a dose of 0.4 g/kg daily (28 g/day) for 5 days.

On day 8, symptoms were improving. A whole-body [18F]-fluorodeoxyglucose positron emission tomography (18FDG-PET) was normal. Aciclovir was stopped following negative herpes simplex virus and varicella-zoster virus-specific PCR on follow-up LP, and steroids were also discontinued after 5 days.

On day 9, the patient was discharged from ICU to the neurology department. The only remaining symptom was ataxia, which had already started improving. Brain MRI and EEG follow-up were also normal, with no changes. He was transferred to a rehabilitation centre on day 23 with SARA score of 3/40. When he was fully discharged from hospital on day 30, he only had slight dysphonia with a SARA score of 1/40. On day 37 the patient had fully recovered, including from his dysphonia with a SARA score of 0/40. We did not observe any relapse afterwards, during a 5-month follow-up period.

Discussion

COVID-19-related AC must be suspected in case of acute cerebellar syndrome which appears several days or weeks (9 weeks at most) after SARS-CoV-2 infection [8, 9]. Our patient had initially a critical cerebellar syndrome with life-threatening risk that required critical care. Despite this fulminant critical presentation, the patient fully recovered in 37 days; our main assumption is that the patient have been quickly treated with high doses of steroids (day 4) and IgIV (day 7). This hypothesis is supported by other case reports where late initiation of treatment with steroids or IgIV (i.e. after day 7 of symptoms) affected the kinetics of symptom improvement and may lead to incomplete or delayed recovery [8,9,10].

Our case had an alarming clinical presentation challenged by normal paraclinical findings. Among the 20 patients reported with COVID-19-related cerebellitis in the Plumacker et al. cohort, 32% (6/19) had a normal brain MRI, and 61% (11/18) had no abnormality on CSF analyses [8]. Thus, AC following COVID-19 must be suspected even if laboratory and imaging findings are normal. In case of AC following COVID-19 with CSF pleiocytosis, differential diagnoses as viral or bacterial encephalitis are challenging [8, 9]. These diagnoses must be ruled out by CSF microbiological analysis, but without delaying treatment regarding the risk of neurological sequelae [8]. Since the first case of AC following SARS-CoV-2 infection reported by Fadakar et al. in 2020, several dozen cases have been described [8, 11,12,13,14], and various pathophysiological mechanisms have been described for cerebellum region damage, such as direct virus infection, immune-mediated mechanisms, or damage secondary to hypoxemia [8, 11,12,13]. A systematic review of post-COVID cerebellitis cases reveals a male predilection, indicating a possible gender-related susceptibility [14]. In our case, cerebellar symptoms occurred 2 weeks after COVID-19, and all blood and CSF parameters were normal (including COVID-19 RT-PCR in the CSF and immunological investigations). This can lead one to diagnose a post-viral AC but cannot confirm a viral invasion of the central nervous system. On the other hand, the chronology of events (delayed onset) and the almost immediate response to steroids and immunoglobulins are in favour of an immune-mediated mechanism, but this could not be strictly confirmed because of the lack of antibodies detected in blood and CSF. In other studies, in most cases, high doses of steroids and/or IV immunoglobulins are administered with favourable results [8].

This case highlights the need for clinicians to be aware of AC following COVID-19, despite normal laboratory, imaging and EEG findings and the importance to start appropriate treatment as soon as possible.