Abstracts

T cell-mediated cytotoxic reaction is postulated for severe cortical atrophy with marked neuronal loss in Rasmussen[rsquo]s encephalitis (RE).
We measured the percentage of lymphocyte subsets in peripheral blood and the concentrations of a proinflammatory cytokine, interleukin-6 (IL-6) in cerebrospinal fluid (CSF) and serum from three patients with RE. Magnetic resonance spectroscopy (MRS) and diffusion-weighted magnetic resonance (DW-MR) imaging were used to identify and quantify neuronal damage and loss in the affected hemisphere of the patients.
Before the immunomodulatory therapy (intravenous immunoglobulin plus steroid) all three patients had increased percentage of CD8⁺ cytotoxic T cells in peripheral blood according to the normal range for their age and markedly elevated concentration of IL-6 in CSF and serum compared to the mean values of age-matched controls. Serial MRS and DW-MRI examinations showed the progression of the disease in the patients despite the immunmodulatory therapy. Markedly decreased N-acetylaspartate to creatinine (NAA: Cr) ratios on MRS and increased mean apparent diffusion coefficient (ADC) on DW-MRI were measured in the affected hemispheres implying neuronal loss and atrophy in the brain. The magnitude of IL-6 response in the patients was correlated with the neuronal loss and atrophy on neuroimaging studies.
Elevated IL-6 response in patients with RE appears as an evidence of inflammation in the affected hemisphere. All these findings may be considered additional support to the cytotoxic T cell-mediated inflammatory reactions in RE.