Sleeping on the stomach may be a "major risk factor" for sudden unexpected death in patients with epilepsy, the researchers found.
Epilepsy is one of the most common neurological disorders in the US, affecting around 2.3 million adults and 450,000 children. Though epilepsy can occur at any age, onset is most common in young children and older adults.
The condition is characterized by seizures, caused by disturbances to electrical activity in the brain. An individual is usually diagnosed with epilepsy if they experience two or more seizures that are not triggered by an underlying medical condition.
There is currently no cure for epilepsy, but seizures can be managed with medication. However, some people do not respond to such treatment and continue to experience seizures. This is known as chronic uncontrolled epilepsy.
"Sudden unexpected death is the main cause of death in uncontrolled epilepsy and usually occurs unwitnessed during sleep," notes study author Dr. James Tao, of the University of Chicago.
For their research, Dr. Tao and colleagues set out to determine whether sleeping position may affect the risk of sudden unexpected death in epilepsy (SUDEP).
Prone position a 'major risk factor' for SUDEP
From analyzing 1,106 studies from the PubMed, Web of Science and Scopus databases, the team identified 25 studies that included 253 sudden unexpected death cases among patients with epilepsy, in which sleeping positions at time of death were documented.
The researchers found that in 73.3% of cases, patients died while sleeping on their stomach - known as the "prone" position - while the remaining 26.7% of patients died in other sleeping positions.
The team notes that 11 cases of sudden unexpected death identified in this study were monitored via video and electroencephalography (EEG). In all of these cases, patients died while sleeping in on their stomach.
By assessing a subgroup of 88 patients, the team found that patients under the age of 40 were four times more likely to be found in the prone position at time of sudden unexpected death than patients over the age of 40.
Although the researchers are unclear as to why younger people with epilepsy appear to be at higher risk of sudden unexpected death during sleep, they hypothesize that it may be because they are more likely to be single, so are less likely to have anyone with them while sleeping. Dr. Tao notes that if someone has a seizure while in the prone position during sleep, they should be turned onto their side.
Commenting on their results, the researchers say:
"There is a significant association between prone position and SUDEP, which suggests that prone position is a major risk factor for SUDEP, particularly in patients aged 40 years and younger."
Interventions for SIDS may also be effective for SUDEP
The team adds that their findings suggest the mechanisms behind SUDEP may be similar to those involved in sudden infant death syndrome (SIDS).
- Around 1 in 26 people in the US will be diagnosed with epilepsy at some point in their lives
- Causes of epilepsy include stroke, brain tumor, traumatic brain injury and central nervous system infections, though in many cases the cause is unclear
- Each year, the indirect and direct costs of epilepsy in the US total around $15.5 billion.
"In SIDS patients, impaired arousal secondary to serotonin deficiency can suppress auto-resuscitation mechanisms and prevent them from lifting or turning their heads when their airway is obstructed by soft bedding in a prone position ," the researchers explain. "As such, positioning susceptible children on their backs at bedtime, as in the 'Back-to-Sleep' campaign, has been highly successful for the prevention of SIDS."
Dr. Tao says adopting a similar strategy may be effective in reducing the risk sudden death in patients with epilepsy. "Our findings highlight an important strategy for preventing sudden unexpected death in epilepsy - that 'back is best,'" he notes. "Using wrist watches and bed alarms designed to detect seizures during sleep may also help prevent these deaths."
In an editorial linked to the study, Dr. Barbara Dworetzky, of Brigham and Women's Hospital in Boston, MA, and Dr. Stephan U. Schuele, of Northwestern University in Evanston, IL, say discovering that sleeping in a prone position may be a risk factor for SUDEP is of great importance.
"It implies the possibility of preventing a substantial number of deaths by having patients sleep on their back, as has been done with SIDS," they add. "The study underlines that simple measures may have a substantial effect on SUDEP risk and that our efforts to attend to patients and bring them out of a prone position are worthwhile."
Earlier this week, Medical News Today reported on a study published in the journal Epilepsia claiming almost 1 in 5 adults with epilepsy may also have symptoms of attention deficit hyperactivity disorder (ADHD).