Landau-Kleffner Syndrome (cont.)

LKS occurs most frequently in normally developing children who are between 3 and 7 years of age. For no apparent reason, these children begin having trouble understanding what is said to them. Doctors often refer to this problem as auditory agnosiaor "word deafness." The auditory agnosia may occur slowly or very quickly. Parents often think that the child is developing a hearing problem or has become suddenly deaf. Hearing tests, however, show normal hearing. Children may also appear to be autistic or developmentally delayed.

The inability to understand language eventually affects the child's spoken language which may progress to a complete loss of the ability to speak (mutism). 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. At some time, 80 percent of children with LKS have one or more seizures. 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.

Source: MedicineNet.com
http://www.medicinenet.com/landau-kleffner_syndrome/article.htm