Focal seizure symptoms in idiopathic generalized epilepsies

Objective: We sought to study the frequency and prognostic value of focal seizure symptoms (FSS) in idiopathic generalized epilepsies (IGE) using a validated tool: Epilepsy Diagnostic Interview Questionnaire and Partial Seizure Symptom Definitions. 

Methods: Participants with IGE were recruited from epilepsy clinics at 2 tertiary hospitals. The diagnosis was validated and classified into syndromes according to the International League Against Epilepsy criteria by 2 epileptologists independently with discordance resolved by consensus. The Epilepsy Diagnostic Interview Questionnaire utilizes both open- and closed-ended questions to elicit FSS in association with generalized tonic-clonic seizures, myoclonus, and absences. The elicited FSS were classified according to the Partial Seizure Symptom Definitions. Regression analysis was conducted to examine the relationship between the duration of seizure freedom and FSS. 

Results: A total of 135 patients were studied, of whom 70 (51.9%) reported FSS. Those symptoms occurred in association with generalized tonic-clonic seizures (53.1%) as well as myoclonus and absences (58%). FSS were reported with similar frequency in juvenile absence epilepsy (62.5%) and juvenile myoclonic epilepsy (60%), and with a lesser frequency in generalized epilepsy with tonic-clonic seizures only (39.5%) and childhood absence epilepsy (33.3%). A strong relationship between FSS and duration of seizure freedom was found (regression coefficient -0.665, p 0.037). 

Conclusions: FSS are frequently reported by patients with IGE. A shorter duration of seizure freedom is associated with FSS. Recognition of the presence of FSS in IGE is important to avoid misdiagnosis and delayed diagnosis as well as to choose appropriate antiepileptic drug therapy.