Hearing tests, however, show normal hearing. Children may also appear to be autistic or developmentally delayed. Children who have learned to read and write before the onset of auditory agnosia can often continue communicating through written language. Some children develop a type of gestural communication or sign-like language. The communication problems may lead to behavioral or psychological problems.
Intelligence usually appears to be unaffected.
The loss of language may be preceded by an epileptic seizure that usually occurs at night. The seizures usually stop by the time the child becomes a teenager. All LKS children have abnormal electrical brain activity on both the right and left sides of their brains. More than 160 cases have been reported from 1957 through 1990. The cause of LKS is unknown.