The sudden unexpected death in epilepsy (SUDEP)

SUDEP (sudden unexpected death in epilepsy) is a sudden event in a person suffering from epilepsy that is associated with the death of the patient. In a SUDEP, 90% of people suffer a fatal cardio-respiratory or cerebral dysfunction.

The incidence of SUDEP is an average of 3 cases per year in 1,000 patients who have persistent seizures. In people with difficult-to-treat epilepsies, the incidence increases to up to 9 cases per 1,000 patient-years. The lifetime risk of SUDEP is particularly high in people who have had epilepsy since childhood or adolescence: it is about 7 to 8%. Overall, SUDEP is the cause of 5% to 20% of premature deaths in epilepsy patients.


SUDEP is the cause of 20%
premature death from epilepsy

There are different risk factors for a SUDEP:

Male gender
Beginning of epilepsy at a young age (<16 Years)

Symptomatic cause of epilepsy
Pathological changes in the brain, e.g. due to acute brain diseases, craniocerebral traumas, intracerebral haemorrhages, cerebral infarctions, brain abscesses

Longer epilepsy duration
Nightly epileptic seizures
Prone position during sleep
Irregular medication use

The risk of SUDEP increases with the number of epileptic seizures per year. However, the most relevant and the strongest risk factor is the occurrence of bilateral tonic-clonic seizures.

What are tonic-clonic epilepsy seizures?

Epileptic seizures can be primarily generalized or focal in onset. The spread of epileptic activity over the entire brain in a bilateral tonic-clonic seizure (also known as a “grand mal”), represents the most dangerous form of epileptic seizures.

Tonic-clonic epileptic seizures occur in three phases:

1. Tonic phase

Unconsciousness, fall, stiffening of the entire body, short respiratory
arrest (<1 minute) and fixed pupils.

2. Clonic phase

Rough twitching in the face and arms, legs and trunk.

3. Post-phase

Return of consciousness, resumption of breathing and state of exhaustion.

„Generalized tonic-clonic seizures occur in two phases: In the first phase the affected person loses consciousness, his extremities, but also his breathing becomes tense. In the second phase, rhythmic twitching occurs, which is also associated with a high risk of injury. However, it is critical that in both phases breathing does not function normally, which can lead to a lack of oxygen – especially in the brain”.


Prof. Dr. med. Andreas Schulze-Bonhage
Head of Department at the Epilepsy Center of the University Medical Center Freiburg (European Reference Center)

In general, a tonic-clonic seizure can also develop from a focal seizure. Generalized tonic-clonic seizures can lead to suppression of cardiorespiratory functions in the early post-ictal phase and are therefore considered a relevant risk factor for SUDEP, as they can lead to death within about 10 minutes after the end of the seizure.

The role of cardiac dysfunction in epileptic seizures

In connection with epileptic seizures, a large number of different cardiac dysfunctions of varying severity occur very frequently. In most cases (in 80-90% of all seizures) an increase in heart rate is already measurable at an early stage. In generalized tonic-clonic seizures, the heart rate increases to 150 beats per minute on average.

„Tonic-clonic seizures usually last 80 to 120 seconds. However, breathing and heart rate can still be severely disturbed afterwards, which can result in SUDEP. Therefore, rapid assistance – preferably within 3 minutes – is important in the case of a nocturnal tonic-clonic seizure“.

Prof. Dr. med. Andreas Schulze-Bonhage

Recommendations to avoid a SUDEP

Frequently, a generalized tonic-clonic seizure – and thus also a SUDEP – can be prevented by drug control. In this context, comprehensive education of the epilepsy patient about the risks is an important instrument that can contribute to improving patient adherence. If drug therapy is not an effective option, successful epilepsy surgery or vagus nerve stimulation can reduce the risk of SUDEP. An additional measure is the nocturnal monitoring (supervision) of epilepsy patients. This can be done either by having another person sleep in the patient‘s room or by using electronic warning devices (e.g. NightWatch). In addition, relatives, as well as nursing staff, should be trained in performing cardiopulmonary resuscitation.

SUDEP – Key Facts

Unexpected death in epilepsy
Especially high risk for patients with generalized tonic-clonic seizures
Risk reduction through seizure control, patient education and monitoring

„Uncontrolled patients who continue to suffer many seizures are particularly at risk. This can be caused by a lack of adherence, but patients who have to take many drugs at the same time are also at risk. If these patients suffer many nocturnal tonic-clonic seizures and are poorly monitored, there is a high risk of a fatal event“.

Prof. Dr. med. Andreas Schulze-Bonhage

Opportunities for patients and relatives to reduce SUDEP risk

Successful drug therapy is crucial for seizure control. Although this is prescribed by the treating physician, patients and relatives make an important contribution by ensuring that the medication is taken regularly (compliance).

In addition, comprehensive education about epilepsy and SUDEP is important. Furthermore, relatives and also nursing staff can enable the rapid initiation of life-sustaining measures in the case of SUDEP by monitoring the endangered epilepsy patient at night (e.g. using warning devices). This is because 86% of SUDEP cases occur when those affected are unobserved, 90% of them at night, in the period between 10 p.m. and 6 a.m.

The risk of SUDEP can be reduced by 69% by not allowing epilepsy patients to sleep unattended.

Examples of technical monitoring methods for seizure control

Bed sensors: To monitor the nightly sleep of people with epilepsy, mattresses are equipped with a so-called bed sensor as standard. These sensors detect movements of the person concerned during sleep and can trigger an alarm if necessary via a special control unit. However, since tonic-clonic seizures in particular often with a stiffening of the body, such critical events are often registered by the bed sensors too late or not at all.

Surveillance wearables: The novel wearables (e.g. NightWatch) are attached to the upper arm of the affected person before falling asleep. NightWatch not only registers the nightly movements during sleep but also the heart rate. Thus it detects 9 out of 10 potentially dangerous seizures – in particular, tonic-clonic seizures – at an early stage. Compared to bed sensors, NightWatch detects potentially dangerous nocturnal seizures 3 times more frequently.

„Recently, there have been good, new developments in the field of night-time surveillance. Particularly noteworthy here are devices that the patient can wear while sleeping. These are similar to a Smartwatch and measure movements as well as heart rate. If a nocturnal tonic-clonic seizure is registered, the devices immediately trigger an alarm and inform caregivers. Compared to conventional bed sensors, these wearables are much more sensitive. The sensitivity is very high with an average of 90% detected tonic-clonic seizures“.

Prof. Dr. med. Andreas Schulze-Bonhage

„My son‘s attending physician had recommended NightWatch to us because my son repeatedly has tonic-clonic as well as tonic seizures, which the bed sensor used until then did not reliably register. Thanks to NightWatch this has now changed. The detection rate is many times better – finally, almost every seizure is detected. Not only we but also the nursing staff is enthusiastic about the device. It is easy to use so that my son can also handle it. I would advise every affected person to apply for such a device“.


Katja B.
Mother of a 30-year-old son suffering from generalized epilepsy

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NightWatch epilepsy detection system

NightWatch is a detection system that warns parents or caregivers of a potentially severe epilepsy seizure during sleep. The person with epilepsy wears an arm module around the upper arm at night. This arm module measures the wearer’s heart rate and movements all night long. 

A corresponding base station is in the room of the parents or caregivers and alerts if the arm module detects a potentially dangerous seizure. The parent or caregiver can then go and have a look and offer help where necessary.

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