Rationale:
Despite its rarity, sudden unexpected death in epilepsy (SUDEP) remains the leading cause of mortality among persons with chronic refractory epilepsy. While previously published case series and retrospective studies have described cases of SUDEP occurring during long-term video electroencephalogram monitoring (VEEG) recorded with scalp electrodes, there is limited literature regarding cases of SUDEP recorded with intracranial electrodes.
Methods: Case Report.
Results:
The patient was a 44 year-old with a history of medically intractable epilepsy presumed to be secondary to a right temporal dysembryoplastic neuroepithelial tumor which had previously undergone resection. Their seizures did not have electrographic correlate on scalp VEEG monitoring, prompting phase two monitoring. Seven stereotactic intracranial depth electrodes were placed in the right hemisphere in the temporal lobe, frontal lobe, superior parietal lobe, and insula. A focal to bilateral tonic-clonic (FBTC) seizure occurred on day seven of monitoring with resulting SUDEP. The recorded FBTC seizure had focal onset in the right temporal region, followed by diffuse voltage suppression (all amplitudes < 10 microvolts) postictally. Terminal apnea occurred approximately eight minutes postictally, followed by loss of intracerebral pulse artifact five minutes later. Concurrent with the loss of intracerebral pulse artifact was the onset of bradyarrhythmia, intermittent asystole, and changes in QRS morphology. Terminal asystole occurred approximately 35 minutes postictally.
Conclusions:
Previous studies have found generalized postictal voltage suppression on scalp EEG in cases of SUDEP. A recent study demonstrated that regional EEG suppression can be seen on intracranial EEG despite generalized suppression on concurrent scalp EEG,
1 raising the question of whether postictal EEG suppression is regional or generalized in cases of SUDEP. Although electrodes in this case were limited to the right hemisphere, all electrodes were suppressed postictally; there was no evidence of regional suppression alone despite the seizure’s focal onset.
Little is known regarding cerebral hemodynamics in cases of SUDEP. In this case, pulse artifact seen on intracranial EEG electrodes indicated a loss of cerebral perfusion concurrent with the onset bradyarrhythmia and changes to QRS morphology on ECG. We postulate this change in cerebral hemodynamics reflects changes in cerebral vascular compliance and systemic vascular resistance in the setting of hypoxia/hypercapnia that occur prior to the onset of significant cardiac arrhythmias and decreased cardiac output.
Ultimately, this case adds to our understanding of postictal EEG suppression in SUDEP, providing intracranial EEG data concordant with previous scalp EEG data. Additionally, this case adds to our understanding of cerebral hemodynamics in SUDEP, demonstrating cerebral hypoperfusion prior to the onset of bradyarrhythmia and periods of asystole.
References:
1 Esmaeili B, Weisholtz D, Tobochnik S, et al. Association between postictal EEG suppression, postictal autonomic dysfunction, and sudden unexpected death in epilepsy: Evidence from intracranial EEG. Clin Neurophysiol. 2023;146:109-117.
Funding: None