A severe form of epilepsy with developmental delays and behavioral disturbances.
Lennox-Gastaut syndrome (LGS) is a severe form of epilepsy. The syndrome consists of the following primary characteristics: multiple types of seizures (e.g., tonic, atonic, myoclonic, and atypical absence), a diffuse spike, or poly-spike, slow waves (< 2.0 Hz) pattern on electroencephalogram (EEG), and severe mental retardation. LGS accounts for at least 3-5% of all childhood epilepsies. The age of onset is between 1 and 8 years, with a peak incidence between 3 and 5. The syndrome is slightly more common in males, with a male-to-female ratio of 1.5 to 1. More than one third of all cases involve children who had a prior history of infantile spasms. A family history of epilepsy is a risk factor, however, there is no known single cause of LGS (and about one third of all cases are idiopathic). Etiological factors related to LGS include hypoxic ischemic encephalopathy (i.e., lack of oxygen) at birth, intrauterine infections (cytomegalovirus, rubella, toxoplasmosis), traumatic brain injury, meningitis, tuberous sclerosis, brain tumors, and metabolic disorders.