Seizures in Dravet Syndrome
Seizures in Dravet Syndrome change over time. Some individuals may experience periods of seizure freedom, but most will continue to experience seizures throughout their lifetime.
Below is a summary of how you might expect seizure patterns to change - from infancy through to adulthood.
A seizure in an otherwise healthy baby is one of the first signs of Dravet Syndrome. This is usually accompanied by a normal interictal EEG.
In Dravet Syndrome, the first seizures typically occur between threeand nine months of age, with an average of six months old. Rare cases can happen as early as one month of age, or as late as 20 months. Typically, this first seizure is generalised tonic-clonic, focal clonic or hemiclonic and in just over half of cases is febrile.
Other typical characteristics of early seizures include prolonged seizures and recurrent or cluster seizures that occur close together without time for recovery in-between. Both are common in Dravet Syndrome, especially in the early years. They usually require emergency medical intervention to provide rescue medication and reduce the risks of status epilepticus. In these situations, hospital admission may also be required.
All children and adults with Dravet Syndrome should have home rescue medication and an emergency protocol, which includes instructions for administering rescue medication.
Seizures in early childhood
Between the ages of one and five years old, seizures typically become more frequent and persistent. Additional seizure types can occur including: myoclonic, focal impaired awareness, tonic-clonic, atypical absence, atonic and non-convulsive status epilepticus. These seizures may happen with or without a fever, and at any time of the day and night. In addition, tonic and tonic-clonic seizures may occur in sleep and in clusters. An interictal EEG may remain normal or (usually after two years of age) start to demonstrate an abnormal EEG background activity.
Generally, as children get older, typically around four years of age, status seizures begin to settle. However, children and adults with Dravet Syndrome remain prone to status seizures, particularly when they are ill or have an infection.
Seizures may become more frequent around the time status seizures begin to settle. So, someone with Dravet Syndrome may have more seizures but they may last a shorter time and not always require emergency medication.
Another change is that children may begin to xperience nocturnal seizures, particularly as they transition through nightly sleep phases. For some families, this feels like a positive change, as children is less likely to sustain injuries from falling, but for others, it may cause additional anxieties and fears.
Later childhood and teenage years
As children grow older, the seizure pattern may change further. Overall, seizure frequency is high in the first decade of the patient’s life, including myoclonic, atypical absence, and focal impaired awareness.
Prolonged seizures may continue to be a risk and may still be more likely to happen when a child/adult is ill or has a fever.
The onset of puberty may trigger a change in seizures. Monthly periods may also affect seizures.
Seizure types often change in adulthood and may become less frequent. However, it is a misconception that seizures disappear in adulthood. The misconception is because Dravet Syndrome is typically seen as being a childhood condition and most studies have been conducted in a paediatric setting. So, there is only a limited evidence base for adults.
The majority of adults with Dravet Syndrome still experience regular seizures (particularly generalised tonic-clonic seizures), and these often occur during sleep. Sensitivity to increased body temperature and fever continue, but the impact of these triggers on seizure frequency and severity is generally milder than in infancy.
When adults have seizures, the injuries they experience can be more severe. Injuries are a part of Dravet Syndrome and can be really upsetting for families of people of all ages.
Overall, we need more research into seizures in adults with Dravet Syndrome. There’s still much we don’t know about the changing patterns of seizures in adulthood. What we do know is that improving seizure control has benefits at anyage. As newer treatments become available, we hope that they improve life for adults, as well as children.
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