Children with Dravet syndrome are at risk of coma after prolonged epileptic seizures, especially when associated with high fever, according to a large Chinese retrospective study.
The study, “The clinical outcome and neuroimaging of acute encephalopathy after status epilepticus in Dravet syndrome,” was published in the journal Developmental Medicine and Child Neurology.
Dravet syndrome is a rare and severe type of epilepsy characterized by prolonged seizures within the first year of a child’s life. Seizures often are triggered by warm weather, fevers, or sunlight, and are highly resistant to many existing treatments for epilepsy.
While most seizures stop within a minute or two, if the seizure lasts more than a couple of minutes, it is unlikely to stop by itself. The longer the seizure continues, the more difficult it is to control it with antiepileptic medication and the greater the brain damage.
Seizures lasting more than five minutes, or consecutive seizures without recovery of consciousness in between, are defined as status epilepticus — life-threatening seizures that require urgent medical treatment.
Although prolonged seizures can lead to acute encephalopathy — generalized brain damage or malfunction that occurs abruptly — which is a cause of early death for patients with Dravet syndrome, it remains an underdiagnosed and misunderstood complication of this disease.
To better understand the frequency and clinical outcome of this complication in Dravet syndrome, researchers analyzed data of Dravet patients at Peking University First Hospital, in Beijing, from February 2005 to December 2016.
In this analysis, acute encephalopathy was defined as an event of coma lasting more than 24 hours.
Among a total of 624 individuals with Dravet syndrome, 35 patients (20 women and 15 men) had a record of a coma for more than 24 hours after prolonged seizures. Patients were followed-up for a median of 2 years and 1 month.
The patients’ median age when the coma event occurred was 3 years and 1 month, and the coma lasted from two to 20 days. The duration of the associated prolonged seizures varied between 40 minutes and 2 hours, and in 35 patients (97%) the seizures occurred during a high fever.
“Acute encephalopathy after status epilepticus is more prone to occur in patients with Dravet syndrome who had a high fever,” the researchers wrote.
Twenty-three patients survived, but all showed a massive regression in brain function. Analysis of brain data from the recovery phase revealed that 20 of those patients had diverse degrees of brain damage.
The study also showed that the mortality rate is high in severe cases of coma after prolonged seizures, and that although survivors show severe brain damage, seizures become absent or less frequent.
As this is a misunderstood cause of early death in patients with Dravet syndrome, there is an increasing need of a management protocol at the earliest onset of these prolonged epileptic seizures, where several parameters are monitored and antiepileptic medication is given, to better understand this condition and prevent severe consequences.