Around 85% of individuals with Angelman Syndrome (AS) will experience epileptic seizures. The most common age of onset is between 1 and 3 years old, with less than 25% experiencing seizures during the first year. As with all young children, the likelihood of seizures increases if your child has a temperature or is unwell.
Seizure frequency generally lessens with increasing age of the child and may disappear completely after adolescence. However, some report that seizure frequency may increase at this time (possibly due to rapid growth and the need to adjust medication). Some reports also suggest that seizures may return later in adulthood.
Types of Seizure
There are many different types of seizure, the most frequent being atypical absences, generalized tonic-clonic, atonic or myoclonic seizures. Drop attacks and reflux induced seizures have also been reported. Multiple seizure types occur in 50% of patients with the deletion form of AS.
- Status epilepticus is a single epileptic seizure lasting more than five minutes, or two or more seizures within a five-minute period without the person returning to normal between them.
- Non-convulsive status epilepticus consists of repeated or prolonged periods of absence, atypical absence or partial seizures and happens more often than status epilepticus. Frequent or prolonged episodes of non-convulsive status epilepticus, if left untreated, can lead to a poor cognitive outcome for children with AS.
What to do in the event of a seizure
- If your child has not experienced a seizure before, or you are unsure what to do, or the seizure lasts for longer than 5 minutes, call an ambulance.
- An ambulance should also be called if they have one tonic-clonic seizure after another without regaining consciousness between or they are injured during the seizure.
- If your child experiences a seizure, or you suspect they have, keep a record of the event, how and when it happens, what you observe, length of episode. If possible try to film it so that medical experts can better evaluate the seizure type.
- Make sure your child is safe – remove harmful objects from nearby and cushion their head. Time the seizure. Stay with them and speak calmly and reassuringly to them.
- Don’t restrain movement, don’t put anything in their mouths (including food or drink) or try to move them (unless it is unsafe to not do so).
Anti-epileptic drugs (AEDs)
These are the most commonly used treatment and help to control seizures in around 70% of people. The person with AS may be prescribed one or more of these and it may take a while to ensure the correct combination or dose. It is very important to follow dosage instructions carefully, as with many of these, you need to build up the dose gradually. Never stop taking a treatment without the advice of your medical practitioner, even if the person with AS has not experienced a seizure for many years.
Commonly prescribed AEDs include: sodium valproate (also known as Epilim); lamotrigine; levetiracetam (also known as Keppra); ethosuximide; topiramate; clobazam. Some AED’s are contraindicated for people with Angelman Syndrome: carbamazepine, oxcarbazpine and vigabatrin should be avoided as they are known to make seizures worse. Seek further advice from your medical professional.
VNS (Vagus Nerve Stimulation)
This is where a small electrical device, similar to a heart pacemaker, is fitted under the skin of the chest. A wire attached to the device connects, under the skin, to a nerve in the neck called the vagus nerve. The device sends burst of electricity through this wire to the nerve and this can change the electrical signals in the brain, helping to control seizures. VNS does not stop seizures completely and AEDs may also still be prescribed, it will however, decrease the frequency and severity of seizures.
The battery for the device will need changing after approximately 10 years.
This is a specific diet, high in fats and low in carbohydrate and protein, very similar to the Atkins diet. It has been very beneficial in controlling seizures, particularly in children, as it changes the levels of chemicals in the brain. For older individuals, high–fat diets are associated with other risks such as heart disease and diabetes and may not be as suitable. Therefore it should be used under the guidance of your GP and a dietician.
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