# Opsoclonus-myoclonus following West Nile virus encephalitis: when the virus enters the equation

Flora Delamaire, Pierre Kergoat, Jean-Marc Tadie, Nicolas Terzi, Flora Delamaire, Pierre Kergoat, Jean-Marc Tadié

► To cite this version:

Flora Delamaire, Pierre Kergoat, Jean-Marc Tadie, Nicolas Terzi, Flora Delamaire, et al.. Opsoclonus-myoclonus following West Nile virus encephalitis: when the virus enters the equation. Travel Medicine and Infectious Disease, 2025, 68, pp.102942. 10.1016/j.tmaid.2025.102942. hal-05391120

HAL Id: hal-05391120

https://hal.science/hal-05391120v1

Submitted on 3 Dec 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

# Opsoclonus-myoclonus following West Nile virus encephalitis: when the virus enters the equation

Flora Delamaire<sup>a,b,*</sup>, Pierre Kergoat<sup>a</sup>, Jean-Marc Tadié<sup>a,b,c</sup>, Nicolas Terzi<sup>a,b,c</sup>

A 64-year-old man with no medical history, mathematics teacher living in the Algerian Sahara (near the oasis of Aougrout in Timimoune), presented to the emergency department of the local hospital in Timimoune with fever, headache, and confusion. His condition rapidly deteriorated into a coma. The hospital did not have access to a CT scanner or MRI for brain imaging. The lumbar puncture revealed 83 nucleated cells, of which 83 % were lymphocytes. He was treated with broad-spectrum antibiotics and aciclovir.

After being transferred to a French teaching hospital, a brain MRI showed diffuse involvement of the white matter, asymmetry signal of the basal ganglia and subtle small hyperintense signals involving the brainstem and oculomotor nerves. The electroencephalogram showed no epileptiform discharge nor diffuse slowing.

HSV RT-PCR and cerebrospinal fluid (CSF) culture were negative at 48-h intervals, as were tests for anti-neuronal and neuropil antibodies. Serologies for West Nile Virus (WNV) on both serum and CSF were strongly positive for IgM and IgG, with kinetics over one month indicating a recent infection. RT-PCR for WNV was not performed at the time of initial management; it was subsequently carried out on blood and urine samples eight days after symptom onset, with negative results. Other arbovirosis serologies were negative and cross-reactivity with other flaviviruses (Dengue, Zika, etc.) was excluded.

Clinically, after a 3-week period of coma, he exhibited opsoclonus, jaw clonus, and a paucireactive state (Video 1A).

Treatment with corticosteroid boluses (1 g per day for 3 days, followed by 1 mg/kg with a progressive taper over 3 weeks) and intravenous immunoglobulins at 30 g/day for 5 days did not improve his clinical condition. Two sets of five plasma exchanges resulted in a reduction in abnormal movements and a return to normal

consciousness, with the ability to speak and solve first-degree equations (Video 1B).

After six months of rehabilitation, the patient had recovered from ICU acquired weakness. He was able to walk independently and had returned home. He communicated clearly, but had not yet resumed his work as a teacher due to persistent concentration difficulties.

Although WNV neurotropism can directly affect cerebellar and brainstem circuits controlling saccadic inhibition, the delayed improvement after plasma exchange supports an antibody-mediated post-infectious mechanism, as reported in previous WNV-related opsoclonus-myoclonus syndrome cases.

## CRediT authorship contribution statement

**Flora Delamaire:** Writing – original draft, Data curation, Conceptualization. **Pierre Kergoat:** Writing – original draft. **Jean-Marc Tadié:** Writing – review & editing. **Nicolas Terzi:** Writing – review & editing.

## Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Appendix A. Supplementary data

Supplementary data related to this article can be found at https://doi.org/10.1016/j.tmaid.2025.102942.

<footnote><sup>a</sup> Médecine Intensive - Réanimation, CHU de Rennes, F-35033, Rennes, France</footnote>

<footnote><sup>b</sup> Université de Rennes 1, Faculté de Médecine, F-35043, Rennes, France</footnote>

<footnote><sup>c</sup> Inserm-CIC-1414, Faculté de Médecine, Université de Rennes 1, IFR 140, F-35033, Rennes, France</footnote>

<footnote>* Corresponding author. Médecine Intensive - Réanimation, CHU de Rennes, F-35033, Rennes, France. E-mail address: f.delamaire@ghbs.bzh (F. Delamaire).</footnote>