Increased working memory related fMRI signal in children following Tick Borne Encephalitis

•We measured the brain activity with fMRI in pediatric patients with status post Tick Borne Encephalitis during a Working Memory task.•Compared with age matched controls the patients show increased activity in parietal cortices during the task.•Working Memory function in the sample was reduced, in line with previous reports.•The results indicate cortical hyperactivation as a compensatory mechanism after TBE in children.

ObjectiveTick Borne Encephalitis (TBE) is a viral infection in the central nervous system endemic in Europe and Asia. While pediatric infection may carry a lower risk for serious neurological sequelae compared to adults, a large proportion of children experience long term cognitive problems, most markedly decreased working memory capacity. We explored whether task related functional magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) could reveal a biological correlate of status-post TBE in children.MethodsWe examined 11 serologically verified pediatric TBE patients with central nervous system involvement with 55 healthy controls with working memory tests and MRI.ResultsThe TBE patients showed a prominent deficit in working memory capacity and an increased task related functional MRI signal in working memory related cortical areas during a spatial working memory task performed without sedation. No diffusion differences could be found with DTI, in line with the reported paucity of anatomical abnormalities.ConclusionThis study is the first to demonstrate functional MRI abnormalities in TBE patients that bears similarity to other patient groups with diffuse neuronal damage.