Isolated reversible splenial lesion in tick-borne encephalitis: a case report and literature review

Here, we demonstrate a first case of tick-borne encephalitis (TBE) associated with an isolated reversible splenial corpus callosum lesion (IRSL) and highlight the wide range of different clinical entities in which such alterations have been observed. A 42-year-old man showed fever, cephalgia and mild disturbance of coordination and gait. Diagnosis was ascertained by slight CSF-pleiocytosis and positive TBE-IgG as well as by positive intrathekal specific antibody index on follow-up. MRI demonstrated a single ovoid hyperintensity in T2 and DWI with reduction in ADC in the splenium of corpus callosum which was abrogated in follow-up after 6 weeks. Most entities of IRSL presented with excellent prognosis, including our novel case of TBE. We discuss different possible pathomechanisms and the so far unexplained propensity of the splenium for such alterations. Clinicians should be familiar with this phenomenon to avoid unnecessary diagnostic or therapeutic efforts.