SUDEP
From EEG and ECG in Sudden Unexplained Death in Epilepsy, Epilepsia 45, Number 4
By Maromi Nei, Reginald T. Ho, Bassel W. Abou-Khaili, Frank W. Drislane, Joyce Liporace, Alicia Romeo and Michael R. Sperling
Sudden unexplained death in epilepsy (SUDEP) is a major cause of mortality in patients with epilepsy. Although SUDEP has been associated with generalized tonic-clonic seizures, young adult age, mental retardation, low anti-epileptic drug (AED) levels, use of multiple AEDs, and refractory epilepsy, no specific data can identify which patients are at greatest risk for SUDEP. Therefore targeted prophylactic interventions cannot be implemented.
The etiology for SUDEP remains elusive and may be multifactorial. Both cardiac rate and rhythm disturbances and respiratory-pattern abnormalities have been identified during seizures. Cardiopulmonary autonomic abnormalities have also been identified interictally in patients with epilepsy, they have not been identified in actual victims of SUDEP. Studies on SUDEP have historical data regarding cardiac and pulmonary status, including interictal 12 lead ECG data but no specific abnormalities have been identified. Many SUDEP victims have been found in bed, suggesting that the risk for specific etiologic mechanisms directly responsible for death may increase during sleep. Nonetheless, strong evidence implicates seizures as being directly responsible for SUDEP. Seizures have been noted shortly before death in many people with SUDEP, suggesting that seizures and their resulting systemic effects have a direct role in causing death. Additionally, surgical series report that mortality due to SUDEP declines when
epilepsy surgery is successful in eliminating seizures, also supporting an etiologic role of seizures in SUDEP.
No detailed analyses are found in the medical literature regarding the ictal EEG and ECG from patients who subsequently died with a diagnosis of SUDEP. This study examines these data and whether specific clinical features such as location or laterality of the epileptogenic zone, timing of seizures, or patterns of seizure activity are related to SUDEP. Identification of any such abnormalities before death may help to elucidate the etiology of SUDEP, aid in identification of those at greatest risk, and lead to strategies for its prevention.
This study suggests that patients with evidence of a great degree of change in autonomic tone during seizures might be at increased risk for SUDEP. Although the precise mechanism of death remains elusive, these data nevertheless suggest that prevention of nocturnal seizures and seizure clusters may be important in reducing the risk of SUDEP. Accurate diagnosis of nocturnal seizures and evaluation of their frequency, with either long-term ambulatory or impatient EEG monitoring, may be more important than has generally been considered. Aggressive treatment, even when seizures are only nocturnal, might help reduce the risk of SUDEP. Elimination of seizures is ideal, but when this cannot be accomplished, it is possible that other measures to reduce autonomic instability in specifically selected patients such as ß-blockers, might aid in preventing SUDEP. However, further investigation is needed to evaluate the role of such potential therapy, with caution regarding other possible mechanisms of SUDEP, including
increased parasympathetic activity of bronchoconstriction.
Electroencephalogram - (EEG)
A graphic record of the electrical activity of the brain as recorded by an electroencephalograph. Also called encephalogram.
Electrocardiograph (EKG or ECG )
An instrument used in the detection and diagnosis of heart abnormalities that measures electrical potentials on the body surface and generates a record of the electrical currents associated with heart muscle activity. Also called cardiograph.
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