Summary: Purpose: To describe the long-term outcome of childhood-onset secondarily generalized epilepsies (SGEs).
Methods: Children were identified from the Nova Scotia population-based epilepsy study (n = 692). Onset of epilepsy was between 1977 and 1985, and follow-up was mainly in 2003. SGE was defined as having a mixture of more than one generalized seizure types including myoclonus, akinetic/atonic, tonic, or atypical absence, plus an interictal EEG with generalized spike–wave (irregular or slow) and/or multifocal spikes.
Results: SGE was identified in 80 children, 11.6% (80 of 692) of all childhood epilepsy. Forty percent did not fit into a currently accepted syndrome (such as Lennox–Gastaut, myoclonic–astatic or West). Seizure onset was in the first year of life in 60%, with only 9% later free of intellectual or physical handicap. Sixty-five percent (11 of 17) with Lennox–Gastaut had preceding West syndrome. During a median follow-up of 20 years, mortality was 24% (n = 19), and 53% (n = 42) had persistently intractable seizures. Surprisingly, 22 (28%) had ≥5 years of terminal remission (West, 31%, 10 of 32; Lennox–Gastaut, 0, none of four; myoclonic–astatic, 56%, five of nine; undefined, 31%, 10 of 32). At the end of follow-up, nearly 90% of patients fell into one of three outcome categories: death, 19 (24%); alive with intractable epilepsy, 31 (39%); or in remission for ≥5 years, 21 (26%).
Conclusions: Many children with SGE have ill-defined epilepsy syndromes. SGE is characterized by early age at onset, high rates of handicap, intractability, and death, although one third achieve complete seizure control with a long terminal remission.