A disorder in which the child, having previously made normal progress in language development, loses both receptive and expressive language skills but retains general intelligence; the onset of the disorder is accompanied by paroxysmal abnormalities on the EEG, and in the majority of cases also by epileptic seizures. Usually the onset is between the ages of three and seven years, with skills being lost over days or weeks. The temporal association between the onset of seizures and loss of language is variable, with one preceding the other (either way round) by a few months to two years. An inflammatory encephalitic process has been suggested as a possible cause of this disorder. About two-thirds of patients are left with a more or less severe receptive language deficit.