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Editor-In-Chief: C. Michael Gibson, M.S., M.D.  ; Associate Editor(s)-in-Chief: Aditya Govindavarjhulla, M.B.B.S. 
Synonyms and keywords: Infantile acquired aphasia; acquired epileptic aphasia; aphasia with convulsive disorder
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.
This syndrome was first described in 1957 by Dr. William M. Landau and Dr. Frank R. Kleffner, who identified six children with the disorder.
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.
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.
|Disease||Clinical Features||EEG Patterns|
|Autistic epileptiform regression||Global regression during the second year that encompasses social skills||Centrotemporal spikes|
|Acquired epileptic aphasia||Developmental language disturbance, autistic features||Epileptic spikes, electrical status epilepticus of sleep|
|Electrical status epilepticus of sleep||Global regression or auditory agnosia||Electrical status epilepticus of sleep|
Epidemiology and Demographics
Since description, almost 200 cases have been reported.
Over 50% of the affected children present between the ages of three and eight years.
There appears to be a male preponderance in an approximate male: female ratio of 2:1.
Natural History, Complications and Prognosis
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
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.
A directed history has to be obtained to ascertain the onset of symptoms, duration and their prognosis.
- Auditory agnosia or word deafness
- Hearing loss
- Hearing impairment
- Mental retardation
- If acquired aphasia is secondary to stroke, hemiparesis can be noticed
- Signs of increased intracranial tension in case of tumor
- Erratic respirations
- Overnight sleep EEG is beneficial.
- Findings of EEG
- Activation and generalization of discharges
- Continuous spike-and-wave discharges during slow-wave sleep
- 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.
- Magnetoencephalography 
- 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.
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.
- ↑ "Landau-Kleffner Syndrome Information Page: National Institute of Neurological Disorders and Stroke (NINDS)".
- ↑ Canitano R, Zappella M (2006). "Autistic epileptiform regression". Funct. Neurol. 21 (2): 97–101. PMID 16796825.
- ↑ Deonna T, Roulet-Perez E (2010). "Early-onset acquired epileptic aphasia (Landau-Kleffner syndrome, LKS) and regressive autistic disorders with epileptic EEG abnormalities: the continuing debate". Brain Dev. 32 (9): 746–52. doi:10.1016/j.braindev.2010.06.011. PMID 20637551. Unknown parameter
- ↑ Nickels K, Wirrell E (2008). "Electrical status epilepticus in sleep". Semin Pediatr Neurol. 15 (2): 50–60. doi:10.1016/j.spen.2008.03.002. PMID 18555191. Unknown parameter
- ↑ Bhardwaj P, Sharma VK, Sharma R, Gautam P (2009). "Acquired epileptic aphasia: Landau-Kleffner syndrome". J Pediatr Neurosci. 4 (1): 52–3. doi:10.4103/1817-1745.49114. PMC 3162843. PMID 21887181. Unknown parameter
- ↑ Sobel DF, Aung M, Otsubo H, Smith MC (2000). "Magnetoencephalography in children with Landau-Kleffner syndrome and acquired epileptic aphasia". AJNR Am J Neuroradiol. 21 (2): 301–7. PMID 10696012. Unknown parameter
- ↑ Zouari N, Choyakh F (1997). "[Early, middle-latency and late auditory evoked potentials in a case of acquired epileptic aphasia (Landau-Kleffner syndrome)]". Rev Laryngol Otol Rhinol (Bord) (in French). 118 (4): 267–70. PMID 9637098.