While the vast majority of seizures stop on their own without lasting harm, a seizure can lead to death, though this outcome is uncommon. Mortality related to seizures generally falls into two categories: a prolonged, life-threatening seizure event that fails to stop, and a sudden, unexpected death that occurs shortly after a seizure. These two mechanisms represent the primary ways a person’s life can be endangered by their seizure disorder.
Status Epilepticus: The Acute Emergency
A seizure is medically defined as a life-threatening emergency when it persists for an extended period, a condition known as Status Epilepticus (SE). This state is formally defined as a seizure lasting five minutes or longer, or when a person experiences multiple seizures without regaining full consciousness in between episodes. The five-minute mark is used because seizures that do not stop within this timeframe are unlikely to terminate naturally and require immediate medical intervention.
The danger of this prolonged electrical activity stems from the massive physiological stress it places on the body. The continuous muscle contractions during a convulsive SE cause an extreme increase in metabolic demand, leading to the rapid depletion of oxygen and glucose stores in the brain and muscles. This hypermetabolic state results in severe lactic acidosis and hyperthermia, where the body temperature rises dangerously high.
If the seizure continues, the body’s compensatory mechanisms begin to fail, leading to systemic organ dysfunction. The prolonged stress can trigger cardiac arrhythmias and a massive catecholamine surge, causing damage to the heart muscle. Simultaneously, the sustained seizure activity can depress the respiratory drive, leading to respiratory failure and hypoxia—a lack of oxygen reaching the brain and other organs.
This cascade of events, particularly the lack of oxygen and the excitotoxic neuronal injury from over-firing brain cells, rapidly causes irreversible brain damage after about 30 minutes. Therefore, the goal of emergency treatment is to stop the seizure well before this 30-minute mark to minimize the risk of permanent neurological injury and death. SE requires prompt, aggressive medical treatment.
Understanding SUDEP
The second major category of seizure-related mortality is Sudden Unexpected Death in Epilepsy, commonly referred to as SUDEP. SUDEP is defined as the sudden, non-traumatic, and non-drowning death of a person with epilepsy, where an autopsy does not reveal a clear alternative cause. This event often occurs during sleep and is typically unwitnessed, making it difficult to determine the precise sequence of events.
The mechanism of SUDEP is not fully understood, but current evidence points to a failure of the body’s life-sustaining systems immediately following a seizure, most often a generalized tonic-clonic seizure. The leading hypotheses focus on severe post-seizure central nervous system shutdown, affecting both breathing and heart function.
In the respiratory system, a generalized seizure can cause central apnea, where the brain’s control centers stop sending signals to breathe, leading to a dangerous reduction in blood oxygen levels. The cardiac system can also be severely affected, with seizures triggering life-threatening heart rhythm abnormalities, such as severe bradycardia (slow heart rate) or asystole (complete cessation of heart activity).
SUDEP is estimated to affect about 1 in 1,000 adults with epilepsy each year. The single most significant risk factor identified is the occurrence of generalized tonic-clonic seizures, especially when they are frequent or poorly controlled. Individuals whose seizures occur predominantly at night are also considered to be at a higher risk, likely because the event goes unobserved and no immediate intervention is possible.
Reducing Mortality Risk and Secondary Injuries
The most effective strategy for reducing the risk of both Status Epilepticus and SUDEP is achieving optimal seizure control. Consistent adherence to prescribed antiseizure medication regimens is the most important action a person can take to lower their mortality risk. Preventing generalized tonic-clonic seizures, in particular, is directly linked to a substantial reduction in the incidence of SUDEP.
For individuals who continue to experience seizures, particularly nocturnal tonic-clonic seizures, additional measures can mitigate risk. Discussing seizure safety plans and considering devices that monitor physiological changes, such as heart rate or movement, can alert caregivers to an event in progress. Nocturnal supervision, where appropriate, can also allow for timely intervention.
Beyond the direct physiological causes of death like SE and SUDEP, seizures also carry an increased risk of death from secondary injuries and accidents. These indirect causes include fatal falls, burns, and, most frequently, drowning, often occurring during a seizure in a bathtub or pool. Simple safety precautions, such as avoiding bathing alone or ensuring a shower is used instead of a tub, can significantly reduce the potential for these secondary injuries.