Localizing and Lateralizing Significance of Initial, Mid-Ictal, and Ictal-End Head Position in Versive Seizures With Secondary Generalization.

Background and Objective: The aim of this study was to assess the localizing and lateralizing significance of initial, mid-ictal, and ictal-end head position in versive seizures with secondary generalization. Methods: We analyzed video-EEG recordings of 65 patients with focal epilepsy for various head position changes during version evolving into secondary generalized tonic-clonic (GTC) seizure. We calculated the latency of version from seizure onset and the latency of secondary generalization from version. We excluded patients with generalized epilepsy. Results: The latency of version from seizure onset (T1) was 46.7 ± 8.8 sec and 24.1 ± 8.2 sec in temporal and frontal lobe groups, respectively (p < 0.0001). Occipital seizures had the longest latency of 77.8 ± 42.9 sec (p = 0.0002). The latency of secondary GTC seizures (T4) from initial version was 15.7 ± 3.2 sec in the temporal lobe group, compared with 18.3 ± 5.7 sec in the frontal lobe group (p = 0.03) and 18.8 ± 9.3 sec (p = 0.13) in the parietal lobe group. Occipital seizures had the shortest latency at 9.8 ± 3.9 sec (p = 0.0001). In 57 of 65 patients, the head position evolved to a primary midline position from the initial version. In 24 of 65 patients, the head position further evolved to an ictal-end position by the end of the GTC phase. In these 24 patients, the ictal-end head position was contralateral to the direction of initial version in 100% of cases, and hence ipsilateral to the epileptogenic zone. In total, 13 of these 24 patients also had corresponding ipsilateral ictal-end clonic movement. Discussion: Latency of onset of the initial version has a localizing significance for the epileptogenic zone, with the shortest latency for frontal seizures and the longest for occipital seizures. This is consistent with the relative distance of the frontal eye field from these seizure-onset zones. An ictal-end head position contralateral to the initial version occurs in approximately 37% of focal epilepsies and is always ipsilateral to the epileptogenic zone.