Landau-Kleffner syndrome

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Overview
Landau-Kleffner syndrome (LKS), also called infantile acquired aphasia, acquired epileptic aphasia or aphasia with convulsive disorder, is a rare, childhood neurological syndrome characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electroencephalogram (EEG). Landau-Kleffner syndrome affects the parts of the brain that control comprehension and speech. The disorder usually occurs in children between the ages of 5 and 7 years. Typically, children with LKS develop normally but then lose their language skills. While many of the affected individuals have clinical seizures, some only have electrographic seizures, including electrographic status epilepticus of sleep (ESES).

Approximately 80 percent of the children with LKS have one or more epileptic seizures that usually occur at night. Behavioral disorders such as hyperactivity, aggressiveness and depression can also accompany this disorder. LKS may also be called infantile acquired aphasia, acquired epileptic aphasia or aphasia with convulsive disorder.

Etymology
This syndrome was first described in 1957 by Dr. William M. Landau and Dr. Frank R. Kleffner, who identified six children with the disorder.

Etiology
The cause of LKS is unknown. Some experts think there is more than one cause for this disorder. All of the children with LKS appear to be perfectly normal until their first seizure or the start of language problems. There have been no reports of children who have a family history of LKS. Therefore, LKS is not likely to be an inherited disorder.

Signs and Symptoms
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.

Differential diagnosis
The syndrome can be difficult to diagnose and may be misdiagnosed as autism, pervasive developmental disorder, hearing impairment, learning disability, auditory/verbal processing disorder, attention deficit disorder, mental retardation, childhood schizophrenia, or emotional/behavioral problems.

Treatment
Treatment for LKS usually consists of medications, such as anticonvulsants and corticosteroids, and speech therapy, which should be started early.

Medication to control the seizures and abnormal brain wave activity (anticonvulsants) usually has very little effect on language ability. Corticosteroid therapy has improved the language ability of some children. Sign language instruction has benefited others.

A controversial treatment option involves a surgical technique called multiple subpial transection in which multiple incisions are made through the cortex of the affected part of the brain, severing the axonal tracts in the subjacent white matter.

Prognosis
There have not been many long-term follow-up studies of children with LKS. This lack of evidence, along with the wide range of differences among affected children, makes it impossible to predict the outcome of this disorder.

Complete language recovery has been reported; however, language problems usually continue into adulthood. The continued language problems can range from difficulty following simple commands to no verbal communication. If recovery takes place, it can occur within days or years. So far, no relationship has been found between the extent of the language impairment, the presence or absence of seizures and the amount of language recovery. Generally, the earlier the disorder begins, the poorer the language recovery.