Ictal changes in parasympathetic tone: Prediction of postictal oxygen desaturation.
OBJECTIVE
To measure changes in parasympathetic tone before, during, and after temporal seizures, and to determine whether changes in high-frequency heart rate variability are correlated with postictal oxygen desaturation.


METHODS
We recorded the electrocardiogram and peripheral oxygen saturation during 55 temporal lobe seizures and calculated a high-frequency variability index (HFVI) as a marker of parasympathetic tone for periods of 20 minutes (centered on seizure onset). We then compared HFVI values in seizures with and without postictal hypoxemia, and looked for correlations between HFVI changes and the risk of sudden unexpected death in epilepsy (SUDEP) (as assessed with the SUDEP-7 Inventory).


RESULTS
Parasympathetic tone decreased rapidly at the onset of temporal lobe seizures, reached its minimum value at the end of the seizure, and then gradually returned to its preictal value. Changes in parasympathetic tone were more intense and longer-lasting in older patients with a longer duration of epilepsy. The HFVI was significantly lower during seizures with hypoxemia, and remained significantly lower 5 minutes after the end of the seizure. The change in the HFVI slope over the first 30 seconds of the seizure was predictive of postictal oxygen desaturation. Postictal autonomic changes were correlated with the SUDEP-7 scores.


CONCLUSIONS
Our results showed that ictal autonomic dysfunction is correlated with postictal hypoxemia. A prolonged impairment of parasympathetic tone might expose a patient to a greater risk of postictal sudden unexpected death. The real-time measurement of parasympathetic tone in patients with epilepsy may be of value to medical staff as an early warning system.
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland. william.szurhaj@chru-lille.fr.
William
W
Szurhaj
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Anne-Cécile
AC
Troussière
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Régis
R
Logier
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Philippe
P
Derambure
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Louise
L
Tyvaert
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Franck
F
Semah
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Philippe
P
Ryvlin
From the Epilepsy Unit (W.S., A.-C.T., P.D., L.T.), INSERM CIC-IT 1403 (R.L., J.D.J.), Department of Nuclear Medicine and Molecular Imaging (F.S.), Lille University Medical Center; INSERM U1171 (W.S., P.D., L.T., F.S.), University of Lille, France; and the Department of Clinical Neuroscience (P.R.), Lausanne, Switzerland.
Julien
J
De Jonckheere
D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D003645:Death, Sudden / Q000209:etiology / Q000517:prevention & control*; D004562:Electrocardiography / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D012640:Seizures / Q000503:physiopathology
D010100:Oxygen