Abstracts

Rationale:
Sudden unexpected death in epilepsy patients (SUDEP) is the most common cause of death in refractory epilepsy patients. Despite this importance and prevalence the pathophysiology remains unknown. Multiple potential post-ictal phenomena have been suggested to contribute including immobility, postictal generalized EEG suppression (PGES), arousal deficits, central apneas, and obstructive apneas due to laryngospasms. Cases of SUDEP and near-SUDEP in monitored EMU settings have occured, but are rare. We present a case of near SUDEP in a patient undergoing intracranial EEG monitoring with a bilateral stereotactic EEG (sEEG) implantation, which is to our knowledge the first near SUDEP case occurring during a SEEG evaluation.
Method:
 Case report.
Results:
We report a case of a 51 year old right handed female with medically refractory temporal lobe epilepsy who experienced a near-SUDEP event following a convulsive seizure during a bilateral SEEG investigation. Clinical onset involves patient glancing at hand and then pressing the event button followed by imparied awareness and automatisms (lip smacking) as the nurse walks into the room before the ultimate progression to tonic-clonic convulsion. The clinical onset precedes the EEG onset by 1-3 seconds, which is characterized by 6Hz rhythmic activity in the left mesial temporal structures with an evolution to low voltage fast in these regions with rapid spread to all left temporal structures prior to spread to right mesial structures and generalization. The electroclinical seizure lasts 2 minutes with an ictal offset characterized by striking diffuse global EEG voltage suppression in all intracranial electrodes. This diffuse PGES lasts for 4.5 mins, during this time the patient's oxygen saturation drops to 65%, with 5L/min oxygen by nasal cannula placed on the patient at seizure offset. Due to equipment issues, no inductive plethysmography belts were on the patient at the time of the event. However, from video observation, the patient has loud sonorous labored breaths for ~30 seconds after seizure offset followed by apparent cessation of breathing during remainder of the extended period of PGES. There is a return again to low amplitude and low frequency bilateral cerebral activity and a return to visible breathing with a recovery of her oxygen saturation, however, the cerebral activity does not last longer than 30 seconds and there is again diffuse PGES with cessation of breathing. She becomes tachycardic followed by an irregular heart rhythm with her confirmed oxygen saturation reaching below 60% before she is bag masked and eventually intubated. Throughout the postictal period efforts by the nurse and medical staff to arouse the patient were unsuccessful. The patient was admitted to the neurointensive care unit and medications restarted, with this seizure the only ictal event captured. Spectral power analysis of iEEG was used to determine areas of diffuse EEG suppression and respiratory effort was graded by expert video observation.
Conclusion:
This case suggests multiple suspected post-ictal phenomena are important markers in SUDEP, foremost the striking PGES and post-ictal apnea. The return to cerebral activity and spontaneous breathing after the first extended PGES period and then subsequent return to diffuse suppression suggest a failure in the brainstem arousal networks. The nature of the SEEG allowed us to record this brief return of cerebral activity, likely to be missed on surface EEG. Finally, this case exhibits measures postulated to prevent SUDEP like early attempts to arouse the patient and early oxygen administration are not going to be successful in all cases.
Funding:
:American Epilepsy Society Junior Investigator Award Vanderbilt Faculty Research Scholars Award (VFRS)