Long‐term Prognosis for Symptomatic (Secondarily) Generalized Epilepsies: A Population‐based Study

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Abstract
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.