Abstracts

Rationale: Seizure onset determines seizure classification as well as effective therapy. Generalized-onset seizures with focal evolution are uncommon and frequently misdiagnosed as complex partial seizures, leading to ineffective therapy. We describe generalized absence seizures with alternating focal evolution to either right or left frontal regions in different seizures of the same patient. Methods: Video-EEG monitoring was used for evaluation of a 12 year old girl with drug-resistant seizures. Results: Epilepsy started at age 7 years. There was a prior history of febrile seizures at 18 months. Routine EEGs always showed interictal generalized polyspike-and-wave activity and brain MRI was said to be normal. Her seizures at presentation involved staring and eye blinking for 5-10 seconds with daily clusters in the morning. Two years prior to evaluation she developed generalized tonic clonic seizures that started with eye deviation to one side. She was diagnosed with absence and generalized tonic-clonic seizures. However, she failed to respond to multiple anti-epileptic medications including lamotrigine, zonisamide, topiramate and levetiracetam and she was referred for a second opinion. Her neurological exam was normal. Video-EEG monitoring captured frequent episodes of behavioral arrest and eye fluttering in prolonged clusters. On two occasions there was evolution, once with head and eye deviation to the left for 20 seconds then generalized tonic-clonic activity, and once with recurrent head and eye deviation to the right and intermittent right face and right arm twitching for 24 minutes before eventual secondary generalization. The electrographic onset for the first seizure (Figure 1) was 2.5-6 Hz generalized spike-and-wave and polyspike-and-wave activity that evolved to right frontal rhythmic alpha activity, which then became bilateral after 25 seconds. The second seizure electrographic onset was similar to the first (Figure 2), but there was evolution to left hemisphere focal activity that was slower in frequency and wider in field. The prolonged focal activity was repeatedly punctuated by generalized spike-and-wave and polyspike-and-wave bursts. The behavioral arrest and eye fluttering was associated with generalized 2.5-6 Hz spike-and-wave and polyspike-and-wave activity. The interictal discharges was consistently generalized. She was diagnosed with idiopathic generalized epilepsy with generalized absence seizures, and generalized absence seizures with focal evolution and later secondary generalization. She was discharged on levetiracetam 3000 mg per day and valproic acid titration to 2500 mg per day. She was seizure-free at her clinic visit three months following discharge. Conclusions: Generalized-onset seizures may have focal evolution and be misdiagnosed as partial seizures. Alternating left and right hemisphere evolution of the ictal pattern may occur in idiopathic generalized epilepsy. This phenomenon may be similar to the interictal phenomenon of focal fragments of generalized spike-and-wave discharges, which alternate between the two hemispheres.