Tick-Borne Encephalitis in a 6-Year-Old Patient: A Case Report

Abstract

Background: Tick-Borne Encephalitis virus (TBEV) is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family. TBEV transmission typically occurs through infected Ixodes tick bite or by consumption of unpasteurised milk from infected cattle. Case report: We report the clinical, neuroimaging, electroencephalogram (EEG), and laboratory (microbiological tests and spinal tap) data of a 6- year-old boy with Tick-borne encephalitis. Our patient presented with a biphasic course, initially with a myositis-like picture on his first admission to the emergency department, and after a few days with an encephalitic picture, resulting in a second hospitalization. EEG showed focal slow activity, while his brain magnetic resonance imaging (MRI) showed a signal abnormality, which completely resolved on repeat MRI after 3 months. Conclusion: To our knowledge, this is the youngest patient presenting with myositis in the first phase of Tick-borne encephalitis (TBE). In the presence of a biphasic clinical course, with previous myositis, aspecific MRI changes in the thalamic and midbrain regions and an EEG documenting slowed bioelectrical activity should prompt suspicion of TBEV infection.

Keywords: biphasic; encephalitis < central nervous system infections; tick-borne; virus.

Figure 1.

A EEG showing background asymmetry due to slowing of background activity in the left posterior regions (20s/pg, 14 μV/mm, 0.1 s, 15 Hz, Notch 50 Hz). B EEG on the sixth day since hospitalization, devoid of frank abnormalities (20s/pg, 14 μV/mm, 0.1 s, 15 Hz, Notch 50 Hz).

Figure 2.

(A-B) Brain MRI, axial FLAIR images, showed signal anomalies in the thalami (A) on both sides (green arrows) and midbrain (B) with main involvement of cerebral peduncles/black matter bilaterally, predominantly on the right (blue arrows). (C-D). 3-months follow-up. Complete resolution of signal anomalies.

Figure 3.

Timeline.