Landau-Kleffner syndrome
Synonyms and keywords: Infantile acquired aphasia; acquired epileptic aphasia; aphasia with convulsive disorder

# Overview
Landau-Kleffner syndrome 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(LKS) affects the parts of the brain that control comprehension and speech. 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.

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

# Pathophysiology
All of the children with LKS appear to be perfectly normal until their first seizure. There have been no reports of children who have a family history of LKS. Therefore, LKS is not likely to be an inherited disorder.

# Causes
The cause of LKS is unknown. Some experts think there is more than one cause for this disorder.

# Differentiating Landau-Kleffner Syndrome from other Diseases
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.  It can be confused with other epileptic disorders and can be differentiated depending upon the cognitive and behavioral regression.

# Epidemiology and Demographics
Since description, almost 200 cases have been reported.

## Age
Over 50% of the affected children present between the ages of three and eight years.

## Gender
There appears to be a male preponderance in an approximate male: female ratio of 2:1.

# Natural History, Complications and Prognosis

## Natural History
Generally, earlier manifestation of the disease correlates with poorer language recovery, and with the appearance of night seizures that last for longer than 36 months.  LKS has a wide range of symptom differences and lacks a uniformity in diagnostic criteria between cases, and many studies don't include follow-ups on the patients, so no other relationships between symptoms and recovery have been made known

## 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.

# Diagnosis

## History
A directed history has to be obtained to ascertain the onset of symptoms, duration and their prognosis.

## Symptoms
- Autism
- Auditory agnosia or word deafness
- Aphasia
- Seizures
- Hearing loss

## Physical Examination

### Neurologic
- Hearing impairment
- Mental retardation
- If acquired aphasia is secondary to stroke, hemiparesis can be noticed
- Signs of increased intracranial tension in case of tumor
Bradycardia
Papilledema
Erratic respirations
- Bradycardia
- Papilledema
- Erratic respirations

## Laboratory Findings

### Electroencephalogram
- Overnight sleep EEG is beneficial.
- Findings of EEG
Activation and generalization of discharges
Continuous spike-and-wave discharges during slow-wave sleep
- Activation and generalization of discharges
- Continuous spike-and-wave discharges during slow-wave sleep

### MRI
- Useful in excluding other causes of acquired aphasia like stroke, neurocysticercosis, tumors and  cns infections

### Other Imaging Findings
- PET Scan
Decreased metabolism of one or both temporal lobes.
- Decreased metabolism of one or both temporal lobes.
- Magnetoencephalography 
Evaluation of the aphasia
Presurgical localization of the electrical spike
- Evaluation of the aphasia
- Presurgical localization of the electrical spike
- Brain stem evoked potential 
The amplitude of the middle latency and late cortical responses were decreased.
- The amplitude of the middle latency and late cortical responses were decreased.

# 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.