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.