Does a Seizure Always Occur in SUDEP?

A few recent cases where a person with epilepsy was undergoing video-EEG monitoring and died suddenly indicate that seizures may not be absolutely necessary in SUDEP.

Challenging SUDEP Assumptions

Experts have assumed that seizures are a necessary trigger for sudden unexpected death in epilepsy, known as SUDEP. In all of the published SUDEP and near-SUDEP cases that have occurred during video-EEG monitoring, death followed a seizure, usually a tonic-clonic seizure. In addition, the vast majority of sudden deaths occurring outside the epilepsy monitoring unit that have been witnessed by an observer were preceded by an obvious seizure. 

However, there have been reports of cases of SUDEP where the death was witnessed but there was no obvious preceding seizure. Some have speculated that some of these patients had unrecognized or subclinical seizures leading to death. However, a recent case series of people living with epilepsy that had sudden death while undergoing video-EEG monitoring demonstrates that seizures may not be absolutely necessary.

Three Cases Where Seizures May Not Have Been Involved in SUDEP

Lhatoo and colleagues report on three cases of sudden death in people with epilepsy with no clinical or EEG evidence of a preceding seizure. 

• Two of these patients were definite SUDEP; the autopsy did not reveal an anatomical or toxicological cause of death.
• One case was probable SUDEP. There was no alternate cause of death, but an autopsy was not performed per the family’s wishes.
• In all cases, there was a near sudden onset of diffuse, generalized EEG suppression followed by breathing abnormalities and slowing of the heart rhythm. This same pattern was seen among people who had SUDEP following seizures while undergoing EEG monitoring in the MORTEMUS study.

What can be learned from these cases?

Lhatoo and colleagues conclude that the mechanism for SUDEP may involve pathways that are independent of seizures. While seizures are the strongest trigger for these mechanisms, they can rarely be activated in the absence of seizures. The presence of EEG suppression and breathing abnormalities suggests that that the brainstem may be critical for both seizure-related and seizure-independent forms of SUDEP.

This study is important because seizure detection and alert devices are being developed with the hope that they can be used to prevent SUDEP. However, in all three cases, such a device would not have alerted a caregiver that a life-threatening event was in progress. While SUDEP occurring without a seizure is likely very rare, these cases suggest that novel preventative strategies are needed to prevent these deaths.

In addition, the study highlights how much more research is needed to fully understand causes of SUDEP and the importance of initiatives like the Epilepsy Foundation SUDEP Institute’s challenge initiative. The fourth and final challenge, worth $1 million, seeks to prove a biomarker can predict the risk for SUDEP and serve as an intervention for seizures that compromise cardiac or respiratory function. The first milestone for this challenge closes October 10.

• Learn more about the challenge initiative.
• Enter the fourth challenge. 

So what can I do to minimize my risk for SUDEP?

Experts agree that having a generalized tonic-clonic seizure increases the risk of SUDEP for a person with epilepsy. To help people with epilepsy reduce their risk of seizures and SUDEP, experts have identified four actionable behaviors in a special epilepsy.com report, “#AimForZero: Striving Toward a Future Free from Sudden Unexpected Death in Epilepsy.” These behaviors outlined in the report are

1. Take medication as prescribed
2. Get enough sleep
3. Limit alcohol
4. Strive to stop seizures

Learn more about how to #AimForZero and find practical tips for these behaviors at epilepsy.com/aimforzero.

If you’re living with seizures and already following the #AimForZero recommendations, we urge you to seek out an epilepsy specialist now. Talk with them about your options, including participating in medical research that can lead to new treatments. Reach out to your local Epilepsy Foundation for services, support, and referrals, or call our 24/7 Helpline at 800-332-1000.