LATERALIZING SIGNIFICANCE OF HEAD AND EYE DEVIATION IN SECONDARY GENERALIZED TONIC-CLONIC SEIZURES

We studied 92 secondary generalized tonic-clonic seizures (SGTCS) in 2 9 patients with a clearly lateralized seizure focus using video-EEG te lemetry. An examiner, blind to the EEG, reviewed direction and type (f orced versus nonforced) of head/eye deviation (HD). Forced HD consiste d of sustained, unnatural tonic or clonic movements. Nonforced HD cons isted of sustained deviations that were neither tonic nor clonic and w ere similar to volitional head movements. Eighty-three of the 92 SGTCS (26 of 29 patients) had lateralized and sustained HD. The direction o f HD was contralateral in over 90% of seizures when the movement eithe r (1) continued as the seizure generalized, or (2) occurred in the 10 seconds prior to generalization. The direction of HD was ipsilateral i n over 90% of seizures if the movement ended before the seizure began to generalize (in all cases, the movement ended more than 10 seconds b efore generalization). HD occurring within the first 10 seconds after seizure onset was not of lateralizing significance. Forced HD was 89% contralateral, while nonforced HD was not of lateralizing significance . HD in SGTCS provides information on seizure focus lateralization.