What are the symptoms? LKS have what is known as auditory agnosia, whereby they experience a loss of language understanding, and which also severely limits speech. A wide range of additional symptoms are found, including problems with social communication (see entry Autism Spectrum conditions), a reduction in learning abilities (see entry Learning Disability), and in more than half of cases, difficulties with coordination of walking, feeding and hand function. Many children also have behaviour problems, including impulsivity, hyperactivity, distractibility and behaviour that challenges. Three quarters of children with LKS also have epileptic seizures (see entry Epilepsy), though a significant minority do not at least initially have obvious seizures. All, however, show epileptic activity on electroencephalogram (EEG) in the central region of the brain (temporal lobe: language reception); this activity is particularly increased during sleep, which is a key symptom of the condition. What are the causes? The causes of LKS are largely unknown, but it is thought to be due to abnormal electrical activity of the parts of the brain responsible for processing language, particularly the language receptive (Wernicke’s) area. How is it diagnosed? LKS can be difficult to diagnose if seizures are absent and it is essential that EEGs are used to confirm the high level of epileptic activity in sleep. How is it treated? Treatment with routine antiepilepsy drugs is usually quite effective in seizure control, but much less so for the encephalopathy (regression related to seizure activity). Corticosteroid drugs are often much more effective and help more than half of those treated and can be continued after an early daily course on a weekly basis. Occasionally there is a dramatic spontaneous or drug-induced total recovery but, more commonly, problems continue and some long-term impairments persist. Occasionally, surgical treatment by multiple subpial transections (severing horizontal connections controlling seizure spread in the brain; surgical intervention that was developed after research showed that the normal structural organisation of the brain relied on vertical connections) is used. Such treatment requires the accurate identification of the source of seizure activity using a range of neurophysiological techniques, which may include a methohexitol suppression test and magnetoencephalography. The aim of the methohexitol suppression test is to suppress all electrical activity in the brain and then to see in which area of the brain the abnormal electrical activity returns first. This area may be the one that is primarily responsible for the problem. In those children with multiple communication and behavioural impairments, major educational, medical and care support may be required. The active phase of the condition usually burns out in the early part of the second decade, but may leave the child with long-term disability. In addition to the above clinical presentation, there are ‘variants’ with a younger age of onset, and some with abnormal MRI scans, which may require different management. There is, as yet, no evidence to regard the more common presentations of autism in the first two years of life as an early type of LKS. Inheritance patterns and prenatal diagnosis Inheritance patternsNone are known. Prenatal diagnosisNone. Is there support? There is no support group for Landau-Kleffner syndrome in the UK. Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.