Data from: Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP)

Objective: To characterize peri-ictal apnea and post-ictal asystole in generalized convulsive seizures (GCS) of intractable epilepsy. Methods: Prospective, multi-center epilepsy monitoring study of autonomic and breathing biomarkers of SUDEP in patient's ≥18 years old with intractable epilepsy and monitored GCS. Video EEG, thoraco-abdominal excursions, nasal airflow, capillary oxygen saturation and electrocardiography were analyzed. Results: We studied 148 GCS in 87 patients. Nineteen patients had generalized epilepsy, 65 had focal, one had both and in two, the epileptogenic zone was unknown. Ictal central apnea (ICA) preceded GCS in 49/121 (40.4%) seizures in 23 patients, all with focal epilepsy. Post-convulsive central apnea (PCCA) occurred in 31/140 (22.1%) seizures in 22 patients, with generalized, focal or unknown epileptogenic zones. In two patients, PCCA occurred concurrently with asystole (near-SUDEP), with an incidence rate of 10.2/1000 patient-years. One PCCA patient died of probable SUDEP during follow up, suggesting a SUDEP incidence rate 5.1 per 1000 patient-years. No cases of laryngospasm were detected. Rhythmical muscle artifact synchronous with breathing was present in 75/147 seizures, and related to stertorous breathing (OR 3.856, 95%CI 1.395-10.663, p=0.009). Conclusions: PCCA occurred in both focal and generalized epilepsies, suggesting a different pathophysiology from ICA, which only occurred in focal epilepsy. PCCA was seen in two near-SUDEP and one probable SUDEP case, suggesting that this phenomenon may serve as a clinical biomarker of SUDEP. Larger studies are needed to validate this observation. Rhythmical post-ictal muscle artifact is suggestive of post-GCS breathing effort, rather than a specific biomarker of laryngospasm.