Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP).

Vilella, Laura; Lacuey, Nuria; Hampson, Johnson P; Rani, M R Sandhya; Sainju, Rup K; Friedman, Daniel; Nei, Maromi; Strohl, Kingman; Scott, Catherine; Gehlbach, Brian K; Zonjy, Bilal; Hupp, Norma J; Zaremba, Anita; Shafiabadi, Nassim; Zhao, Xiuhe; Reick-Mitrisin, Victoria; Schuele, Stephan; Ogren, Jennifer; Harper, Ronald M; Diehl, Beate; Bateman, Lisa; Devinsky, Orrin; Richerson, George B; Ryvlin, Philippe; Lhatoo, Samden D

OBJECTIVE To characterize peri-ictal apnea and postictal asystole in generalized convulsive seizures (GCS) of intractable epilepsy. METHODS This was a prospective, multicenter epilepsy monitoring study of autonomic and breathing biomarkers of sudden unexpected death in epilepsy (SUDEP) in patients ≥18 years old with intractable epilepsy and monitored GCS. Video-EEG, thoracoabdominal excursions, nasal airflow, capillary oxygen saturation, and ECG were analyzed. RESULTS We studied 148 GCS in 87 patients. Nineteen patients had generalized epilepsy; 65 had focal epilepsy; 1 had both; and the epileptogenic zone was unknown in 2. Ictal central apnea (ICA) preceded GCS in 49 of 121 (40.4%) seizures in 23 patients, all with focal epilepsy. Postconvulsive central apnea (PCCA) occurred in 31 of 140 (22.1%) seizures in 22 patients, with generalized, focal, or unknown epileptogenic zones. In 2 patients, PCCA occurred concurrently with asystole (near-SUDEP), with an incidence rate of 10.2 per 1,000 patient-years. One patient with PCCA died of probable SUDEP during follow-up, suggesting a SUDEP incidence rate 5.1 per 1,000 patient-years. No cases of laryngospasm were detected. Rhythmic muscle artifact synchronous with breathing was present in 75 of 147 seizures and related to stertorous breathing (odds ratio 3.856, 95% confidence interval 1.395-10.663, p = 0.009). CONCLUSIONS PCCA occurred in both focal and generalized epilepsies, suggesting a different pathophysiology from ICA, which occurred only in focal epilepsy. PCCA was seen in 2 near-SUDEP cases and 1 probable SUDEP case, suggesting that this phenomenon may serve as a clinical biomarker of SUDEP. Larger studies are needed to validate this observation. Rhythmic postictal muscle artifact is suggestive of post-GCS breathing effort rather than a specific biomarker of laryngospasm.