What is Landau Kleffner syndrome?

• Landau Kleffner syndrome usually starts between the ages of three and eight. It may develop slowly over many months or very suddenly. 
• Approximately 50 per cent of children with Landau Kleffner syndrome have a behavioural disorder. 
• There have been approximately 200 cases reported since the condition was identified in 1957. Due to the nature of the syndrome, there may be more cases that are undiagnosed.  
• Landau Kleffner syndrome is twice as common in males as in females. 

A major feature is the loss of ability to understand and use spoken language. When it develops in young children who have not yet learnt to talk it may be mistaken for a developmental language disorder, deafness or autism. Some language problems may include:  

• Unintelligible speech, or voice quality that sounds similar to a person with a hearing impairment 
• Deleting final consonant sounds and interchanging letters 
• Using only single words, jargon or total mutism 
• Language problems such as dysnomia (difficulty in remembering names for items or recalling words), semantic paraphasia (using a different word with a similar meaning eg. saying cut for scissors) or reverse compounds (saying lightstop for stoplight) 

References:
Understanding Epilepsy Syndromes
Epilepsy Action Australia