Secondarily generalized seizures in mesial temporal epilepsy: Clinical characteristics, lateralizing signs, and association with sleep-wake cycle

Purpose: Secondarily generalized seizures (SGSs) are often considered to be stereotyped, presumably sharing a common electrical pathway. We examined w hether SGSs are uniform in a homogeneous group of patients with mesial temp oral epilepsy, and whether certain clinical signs associated with generaliz ation are lateralizing with regard to seizure origin. Methods: A comprehensive, standardized video/EEG analysis was performed of the clinical characteristics of 29 patients (69 SGSs) with mesial temporal seizure onset. Results: The sequence of tonic postures, as well as the sequence of tonic a nd clonic activity, was variable in SGSs of mesial temporal origin. The seq uence of tonic activity, followed by vibratory and then clonic activity alo ne, was seen only in 51.7% of patients. Tonic and clonic activity could occ ur simultaneously. The most common clinical signs were forced head deviatio n (89.7%) and vocalization (75.9%). The most common tonic posture was bilat eral arm extension (72.4%). All other clinical signs occurred in < 60% of p atients. Among these, early forced head deviation, asymmetric tonic facial contraction, tonic arm abduction with elbow flexion, and tonic arm extensio n combined with opposite arm flexion had lateralizing significance. The pre ceding partial seizure in SGSs (mean, 43.6 s) was significantly shorter tha n partial seizures without generalization (mean, 105.2 s; p <0.001). SGSs o ccurred more often out of steep (p < 0.01). Conclusion: Secondarily generalized seizures of mesial temporal origin are not uniform in their clinical presentation. The final phases of SGSs are mo re stereotyped than the initial clinical signs of generalization. This sugg ests variable electrical spread patterns, which may end in a common pathway . Some asymmetric motor signs have lateralizing significance. SGSs were ass ociated with sleep and abbreviated partial seizures.