The long-term prognosis for Lennox-Gastaut syndrome (LGS) is variable but, overall, unfavorable. Four cohort studies have followed up children with LGS over time and found that a minority of patients eventually could work normally, but 47–76% still had typical characteristics (mental retardation and treatment-resistant seizures) many years after onset and required significant help such as home care or institutionalization.43–46

Patients with symptomatic LGS had a worse prognosis. Groups particularly affected included those with:

• a history of West syndrome (infantile spasms)27
• early onset of seizures27
• higher frequency of seizures20
• constant slow EEG background activity28

In one report, tonic seizures became more difficult to control over time and persisted in 97.8% of the patients. Myoclonic seizures persisted in only 22.5% and atypical absence seizures persisted in 39.3% of the patients.47

Mortality rates range from 3% (mean follow-up of 8.5 years) to 7% (mean follow-up of 9.7 years).28

Adapted from: Glauser TA and Morita DA. Lennox-Gastaut syndrome. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;65–78.
With permission from Elsevier (www.elsevier.com).