Thursday, October 6, 2016

SUDEP without a seizure

Lhatoo SD, Nei M, Raghavan M, Sperling M, Zonjy B, Lacuey N, Devinsky O.
Nonseizure SUDEP: Sudden unexpected death in epilepsy without preceding epileptic
seizures. Epilepsia. 2016 Jul;57(7):1161-8.

To describe the phenomenology of monitored sudden unexpected death in epilepsy (SUDEP) occurring in the interictal period where death occurs without a seizure preceding it.
We report a case series of monitored definite and probable SUDEP where no electroclinical evidence of underlying seizures was found preceding death.
Three patients (two definite and one probable) had SUDEP. They had a typical high SUDEP risk profile with longstanding intractable epilepsy and frequent generalized tonic-clonic seizures (GTCS). All patients had varying patterns of respiratory and bradyarrhythmic cardiac dysfunction with profound electroencephalography (EEG) suppression. In two patients, patterns of cardiorespiratory failure were similar to those seen in some patients in the Mortality in Epilepsy Monitoring Units Study (MORTEMUS).
SUDEP almost always occur postictally, after GTCS and less commonly after a partial seizure. Monitored SUDEP or near-SUDEP cases without a seizure have not yet been reported in literature. When nonmonitored SUDEP occurs in an ambulatory setting without an overt seizure, the absence of EEG information prevents the exclusion of a subtle seizure. These cases confirm the existence of nonseizure SUDEP; such deaths may not be prevented by seizure detection-based devices. SUDEP risk in patients with epilepsy may constitute a spectrum of susceptibility wherein some are relatively immune, death occurs in others with frequent GTCS with one episode of seizure ultimately proving fatal, while in others still, death may occur even in the absence of a seizure. We emphasize the heterogeneity of SUDEP phenomena.

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…

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 report, “#AimForZero: Striving Toward a Future Free from Sudden Unexpected Death in Epilepsy.” These behaviors outlined in the report are

Take medication as prescribed
Get enough sleep
Limit alcohol
Strive to stop seizures

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