Oxygen desaturations triggered by partial seizures: Implications for cardiopulmonary instability in epilepsy

Purpose: The occurrence of hypoxemia in adults with partial seizures has no t been systematically explored. Our aim was to study in detail the temporal dynamics of this specific type of ictal-associated hypoxemia. Methods: During long-term video/EEG monitoring (LTM), patients underwent mo nitoring of oxygen saturation using a digital Spo(2) (pulse oximeter) trans ducer. Six patients (nine seizures) were identified with oxygen desaturatio ns after the onset of partial seizure activity. Results: Complex partial seizures originated from both left and right tempo ral lobes. Mean seizure duration (+/-SD) was 73 +/- 18 s. Mean Spo(2) desat uration duration was 76 +/- 19 s. The onset of oxygen desaturation followed seizure onset with a mean delay of 43 +/- 16 s. Mean (+/-SD) Spo(2) nadir was 83 +/- 5% (range, 77-91%), occurring an average of 35 +/- 12 s after th e onset of the desaturation. One seizure was associated with prolonged and recurrent Spo(2) desaturations. Conclusions: Partial seizures may be associated with prominent oxygen desat urations. The comparable duration of each seizure and its subsequent desatu ration suggests a close mechanistic (possibly causal) relation. Spo(2) moni toring provides an added means for seizure detection that may increase LTM yield. These observations also raise the possibility that ictal ventilatory dysfunction could play a role in certain cases of sudden unexpected death in epilepsy in adults with partial seizures.