Abstracts

Rationale: The association between PGES and sudden unexpected death in epilepsy (SUDEP) Is controversial. Lhatoo and colleagues, 2010, found that PGES duration greater than 20 sec. was associated with increased risk of SUDEP following GTCS. Another study failed to demonstrate an association between PGES and SUDEP (Surges et al. 2011). There is an association between PI and PGES (Semmelroch et al. 2012; Seyal et al. 2012). PI may be a relevant factor predisposing to SUDEP following GTCS. Most patients with SUDEP are found dead in the prone position. An inability to move and reposition the head following a GTCS likely increases the risk of suffocation. Hypoxemia and hypercapnia commonly occur with seizures recorded in the epilepsy monitoring unit (EMU) (Bateman et al 2008; Seyal et al. 2010). Respiratory effort resumes in the postictal period whether or not there is PGES (Seyal et al 2012). In a prior study of 32 patients, we did not find an association between the total seizure duration or the duration of the convulsive component (tonic and clonic) and PGES (Seyal et al. 2012). Subsequently, Tao et al. 2013, found that the tonic phase of the GTCS was a predictor of PGES but detailed respiratory information was not available. We now report on a large group of consecutive patients who had GTCS undergoing VET. We studied the association between seizure duration, duration of the tonic phase, total convulsive duration, respiratory dysfunction, postictal immobility and PGES.Methods: Patients had synchronized recording of end-tidal CO2 (ETCO2) and SpO2 during VET. Total seizure duration, duration of the tonic component of the GTCS, duration of the entire convulsion (tonic and clonic), presence and duration of PGES > 2 sec, duration of PI, duration and change in ETCO2 and SpO2 were recorded. The Mann-Whitney Rank Sum Test was used to compare data in seizures with and without PGES.Results: 182 seizures with GTCS were available in 70 patients. Comparing seizures with PGES to those without, there were no significant differences in the total seizure duration (128 v 146 sec), duration of the convulsive component (tonic plus clonic) (73 v 75 sec), or the tonic phase alone (22 v 21 sec ). The duration of PI was longer following seizures with PGES (200 v 139 sec, p=0.002). In seizures with PGES, the duration of ETCO2 elevation above preictal baseline was longer (353 v 188 sec, p=0.033) and peak ETCO2 was higher (64 v 56 mm Hg, p=0.011). The SpO2 nadir was marginally lower in seizures with PGES (72 v 76%, p=0.055).Conclusions: The duration of postictal immobility is significantly longer following GTCS with PGES than in GTCS without PGES. There is a more profound disturbance of respiratory function in GTCS followed by PGES. Comparing seizures with or without PGES there is no difference in total seizure duration, duration of the convulsive phase (tonic and clonic) or the duration of the tonic phase.