Dravet syndrome is a severe inherited epilepsy disorder, characterized by seizures accompanied with fever, which appear in infancy.

There is currently no cure for Dravet syndrome. But there are several treatments to help manage its symptoms and improve patients’ quality of life. These include anticonvulsants (antiepileptic) medications.

Not all common antiepileptic medicines are suitable for Dravet syndrome patients, and some should be avoided because they can make the symptoms worse.

Sodium channel blockers

If a child is suspected of having Dravet syndrome, even before a concrete diagnosis from genetic evidence, certain antiepileptic agents should be avoided.

These mainly include sodium channel blockers that have been shown to worsen rather than improve seizures in most Dravet patients. This is especially common in patients with a mutation in the SCN1A gene, the most frequently affected gene in Dravet syndrome.

Why sodium channel blockers are unsuitable

Seizures are the result of overstimulation in the brain when too many “excitatory” signals are being fired by nerve cells and the brain cannot cope. Normally, this is balanced by inhibitory signals, but in the brain of people with epilepsy, this equilibrium has been lost.

Dravet syndrome can be the result of a loss-of-function mutation in the SCN1A gene, which provides instructions to make part of sodium channels. Sodium channels play a crucial role in nerve cell signaling.

Because of the SCN1A mutation, sodium channels cannot function properly, including in inhibitory nerve cells. This leads to reduced levels of inhibitory signals in the brain, and disrupts the balance between excitatory and inhibitory signals, ultimately resulting in overstimulation and seizures.

As the name suggests, sodium channel blockers work by preventing sodium channels from working by prolonging the time they are inactive.

In other epileptic disorders, this would prevent sodium channels in excitatory nerves from working and can restore balance in the brain. In patients with SCN1A mutations, however, this can block any remaining working sodium channels in the inhibitory nerves and further aggravate the condition.

What medications should be avoided?

There are several types of sodium channel blockers. These include Dilantin (phenytoin), Cerebyx (fosphenytoin), Tegretol (carbamazepine), Trileptal (oxcarbazepine), Lamictal (lamotrigine), Vimpat (lacosamide), and Banzel (rufinamide).

As Dilantin and Cerebyx may be given intravenously in an emergency situation in hospitals, it is important that the patients’ records reflect that these must be avoided because they may exacerbate rather than prevent status epilepticus.

Status epilepticus can develop from a prolonged seizure (lasting five minutes or more) and can cause permanent damage.

More about sodium channel blockers

In rare cases, some patients may benefit from sodium channel blockers despite having a mutation in the SCN1A gene, as demonstrated in a case study published in Developmental Medicine and Child Neurology.

However, this may not be the case for each person and a careful and controlled trial in the patient should be conducted. Sodium channel blockers should not be used in an emergency without clear evidence that the patient will react well to them.

Other medications to avoid

There are other antiepileptic medications that have appear to worsen seizures in Dravet syndrome and should be avoided.

These include Sabril (vigabatrin), Gabitril (tiagabine), Lyrica (pregabalin), and gabapentin. These drugs act on pathways involving GABA, a neurotransmitter or chemical messenger that passes signals between nerve cells in the brain.

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