What Is Landau Kleffner Syndrome?
Landau Kleffner Syndrome (LKS) is a rare epilepsy syndrome in which children lose language abilities.  This syndrome occurs most commonly in school-aged children in whom development was previously normal.  There is no known cause of LKS.  The child may or may not experience seizures, and these are usually controlled easily with medications.  However, the child then goes on to act as though he/she is not listening or does not hear others.  Hearing is often tested and is normal.  As the syndrome continues, the child starts speaking less and less and clearly has difficulty understanding what is being said to him or her.  The other name for LKS is “acquired auditory agnosia,” meaning the child no longer recognizes what he/she hears. 

What Other Symptoms Can I Expect In LKS?
In addition to the language regression, most children with LKS also have significant new-onset behavior, learning, and attention difficulties.  The behavior problems are not thought to be the direct result of the new communication difficulties.  Rather, the thought processes that control how we organize our thoughts, control our impulses, and react to changing situations are impaired in LKS.  Children are commonly diagnosed with attention deficit hyperactivity disorder (ADHD).  Going to sleep and staying asleep can also be a significant challenge.  Many of these symptoms improve when LKS is treated, but may not go away completely.  It is important to understand that these are symptoms of the disease, rather than intentional behaviors.

How Is LKS Diagnosed?
LKS is diagnosed based on the history you provide to your child’s neurologist and  your child’s electroencephalograph (EEG), a recording of electrical activity of the brain.  The EEG during wakefulness in children with LKS may or may not be normal.   When the child goes to sleep, there is a marked increase in discharges or excessive brain wave activities.  These increased discharges are not ongoing seizures during sleep.  When the child awakens, these discharges resolve.  This EEG pattern is called Electrical Status Epilepticus in slow wave Sleep (ESES).  An overnight EEG is typically required to confirm the ESES.  Language regression and an EEG demonstrating ESES must be present to make the diagnosis of LKS. 

It is important to ensure the behavior and language regression are not due to other pediatric disorders, such as epileptic encephalopathy, pervasive developmental disorders (autistic spectrum disorders), or developmental language disorders.  LKS should also be differentiated from a similar epilepsy syndrome, Continuous Spike Wave in slow wave Sleep syndrome (CSWS) Children with CSWS children lose significant abilities in a wide range of developmental skills not limited to language regression, including motor, memory, and visuospatial skills. 

How Is LKS Treated?
Because LKS is such a rare syndrome, there is no “best” treatment.  Although the seizures may be easily treated with seizure medications, the EEG abnormalities must also be treated to allow the child to learn and recover language function.  Many different treatments have been suggested, including high dose benzodiazepines (Valium/diazepam), high dose steroids (prednisone and ACTH), and some anti-seizure medications.  Rarely, intravenous gamma-globulin (IVIG) and ketogenic diet have been used.  It is important to recognize that some anti-seizure medications, such as phenytoin, carbamazepine, and oxcarbazepine, can make the EEG and learning problems worse.  Children with LKS do typically respond to treatment and the EEG pattern of ESES goes away. 

Recurrent relapses of language regression can occur in LKS.   With each relapse, the child once again has a decline in language skills and the EEG shows recurrence of the ESES pattern.  Each relapse needs to be treated aggressively to ensure resolution of the ESES.

In addition to the seizures and EEG abnormalities, the other symptoms of LKS must also be treated.  Medications typically used to treat ADHD, psychostimulants, often provide some benefit to improve poor impulse control and hyperactivity.  Melatonin may be used to help sleep difficulties.  Behavior modification is also important.  Consistent limits and routines are essential.  It is also important to work with the child’s school to ensure proper academic support is available.  Most children with LKS have Individualized Education Plans (IEP).  When children are working on academic tasks, distractions should be limited.

What Is The Long-Term Outcome for Children with LKS?  
Fortunately, the seizures in LKS improve as the child approaches adolescence and often resolve completely.  Similarly, the EEG abnormalities also resolve spontaneously.  However, the learning and cognitive problems remain a problem.  Normal language and learning is seen in only 10-44% of children.¹ Although language and learning improve with treatment, the recurrent episodes of relapse and ESES have a significant and lasting impact.  The most important predictive factor for learning outcome is how long the child has been exposed to ESES.  Therefore, those with onset at a younger age and those who do not respond to treatment, or have treatment delayed, are more likely to have abnormal language and learning in adulthood. 

How Is LKS Different From Continuous Spike-Wave in Slow Wave Sleep Syndrome?
Although there are many similarities between continuous spike-wave in slow wave sleep syndrome (CSWS) and Landau-Kleffner syndrome (LKS), these are recognized as two separate syndromes.  Both are rare epileptic syndromes that present with regression and behavior problems in school-aged children, but there are important differences in the cause of epilepsy, the type of developmental regression seen, and in the ability to treat seizures. 

Children with CSWS often have abnormal learning, brain formation, or other risk factors for epilepsy before onset of CSWS.  In contrast, children with LKS have normal development and have no epilepsy risk factors, making this truly a syndrome of unknown cause.  The regression in LKS is primarily in the ability to understand language, but other developmental abilities are essentially normal.  By comparison, the children with CSWS can understand language, but have trouble speaking.  They also lose developmental skills other than just language.  Finally, the seizures in LKS are typically infrequent and easily treated.  The seizures in CSWS can occur frequently and may be difficult to treat.

1. Nickels, K and Wirrell, E.  Electrical Status Epilepticus in Sleep.  Seminars in Pediatric Neurology.  15:50-60.  2008.