Lennox-Gastaut Syndrome is an uncommon form of epilepsy and occurs between one and five in every 100 individuals. However, it is the most common cause of intractable (difficult to treat) epilepsy. The most common time for it to start is between three and five years of age.
The seizures experienced can vary.
- atonic seizures or ‘drop attacks’. During these, the individual will suddenly fall to the ground which may at first be mistaken as tripping up or poor balance. These seizures usually happen many times a day and are very upsetting as the individual may be injured.
- Another common seizure type is atypical absence seizures, which can last from 10 seconds to several minutes. During these seizures the individual will appear vacant or blank. They may have other features like head nodding, or rapid blinking. The individual may have some awareness of what is going on around them. These seizures can be frequent and merge to constant, forming a state called ‘non-convulsive status epilepticus’. During these episodes the individual may drool, be unable or slow to speak, need help with feeding and be floppy or wobbly.
- Another frequent seizure type is tonic seizures. They may only happen at night. There is a general stiffening of the arms and legs.
Individuals with Lennox-Gastaut syndrome may have other types of seizures including generalised tonic-clonic seizures, partial motor seizures, complex partial seizures and myoclonic seizures.
All individuals with Lennox-Gastaut syndrome will develop learning difficulties which will be moderate to severe. Some individuals will have developmental delay or learning difficulties before the seizures start.
About two out of ten individuals will develop Lennox-Gastaut syndrome after having West syndrome (infantile spasms).