Question: What is (are) Landau-Kleffner syndrome ?
Answer: Landau-Kleffner syndrome (LKS) is a rare, childhood neurological disorder characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electro-encephalogram (EEG). The disorder usually occurs in children between age 2 and 8. Typically, children with LKS develop normally but then lose their language skills for no apparent reason. While many of the affected individuals have seizures, some do not. The disorder is difficult to diagnose and may be misdiagnosed as autism, pervasive developmental disorder, hearing impairment, learning disability, auditory/verbal processing disorder, attention deficit disorder, intellectual disability, childhood schizophrenia, or emotional/behavioral problems. Treatment for LKS usually consists of medications, such as anticonvulsants and corticosteroids, and speech therapy, which should be started promptly. The prognosis varies. Some children may have a permanent language disorder, while others may regain much of their language abilities (although it may take months or years).
Source: GARD

Question: What are the symptoms of Landau-Kleffner syndrome ?
Answer: What are the signs and symptoms of Landau-Kleffner syndrome? Landau-Kleffner syndrome is characterized by the sudden or gradual development of aphasia (the inability to understand or express language) in previously normal children along with an abnormal electro-encephalogram (EEG). It most frequently occurs in children between the ages of 2 and 8. The condition affects the part of the brain that controls comprehension and speech. Some children with Landau-Kleffner syndrome develop behavioral problems, including hyperactivity, attention deficits, temper outbursts, impulsivity, and/or withdrawn behaviors. Seizures occur in up to 2/3 of affected children. These complex partial, generalized clonic and atypical absence seizures are generally easy to control and often resolve spontaneously before adolescence. The Human Phenotype Ontology provides the following list of signs and symptoms for Landau-Kleffner syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Intellectual disability 5% Agnosia - Aphasia - Attention deficit hyperactivity disorder - Autosomal dominant inheritance - Delayed speech and language development - Dysphasia - EEG with centrotemporal focal spike waves - Incomplete penetrance - Seizures - Speech apraxia - Variable expressivity - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: How to diagnose Landau-Kleffner syndrome ?
Answer: How is Landau-Kleffner syndrome (LKS) diagnosed? LKS is diagnosed based on clinical features and the results of an electroencephalogram (EEG), a recording of the electric activity of the brain. All LKS children have abnormal electrical brain activity on both the right and left sides of their brains.
Source: GARD