Background: The aim of the study was to evaluate the magnetic resonance imaging (MRI) and planimetric computed tomography (CT) of brain lesions in patients with a history of tick-borne encephalitis (TBE); to assess the influence of steroid treatment on the brain and whether lesions were age-dependent.

Methods: A total of 19 patients with abnormal initial imaging in the acute stage of the disease had a follow-up MRI after 1 year; 34 patients hospitalized for TBE encephalitis/encephalomyelitis had planimetric CT after 10 years.

Results: On MRI cortico-subcortical atrophy with widening of anterior horns of the lateral ventricles and vascular changes was more marked on follow-up examination. Virchow-Robin spaces dilatation, widening of the lateral ventricles, periventricular lesions, and cortico-subcortical atrophy correlated with age. Results of planimetric CT study showed increased percentage of tracings, widened anterior horns, lateral ventricles, and III ventricle, which suggest new non-age-related atrophic lesions.

Conclusions: Radiological lesions in the acute phase of TBE and after recovery are non-specific. Cortico-subcortical atrophy with widening of the anterior horns of the lateral ventricles and vascular changes are most common. Long-term follow-up confirms the formation of new non-age-related cerebral atrophic lesions due to TBE. The logit model may serve as a background for the hypothesis concerning an accelerated local atrophy of the brain tissues in patients with a history of severe TBE.