Dravet Syndrome

What is Dravet Syndrome?

Dravet syndrome is a rare genetic epileptic disorder that is due to a brain dysfunction. It usually begins in the first year of an otherwise healthy infant and remains throughout life. Approximately, 80% of people with this disorder have mutations in genes that cause dysfunction of sodium ion channels in the brain.

This mutation is considered new in the child and is not inherited from parents. The main presentation is epileptic seizures, which do not respond well to conventional seizure medications. Almost all children with this syndrome exhibit some developmental disability and have other medical conditions.

Neurodevelopment is normal prior to the onset of seizures, and the first seizure occurs with fever. Generalized seizures involving the whole body or only one side are common. Multiple drug therapy and aggressive seizure management along with the implementation of global therapies is advocated to control seizures and improve the outcome of this disorder.

Incidence of Dravet Syndrome

• This is a rare disorder, which approximately affects 1:20000 to 1:40000 births, but the incidence may be more prevalent once the syndrome is better recognized.
• A total of 3-8% children who develop their first seizure by 12 months may have Dravet syndrome.
• Myoclonic seizures develop between 1 and 5 years in 85% children with Dravet syndrome.
• Seizures lasting for more than 10 minutes, occurring on one side and seizures that are triggered by warm baths in children less than a year old are considered significant risk factors.

What are the Causes of Dravet Syndrome?

In about 80% patients, mutations in the gene SCN1A are considered to be the cause. This gene carries the code or set of instructions for proteins that regulates the function of sodium ion channels.

A mutation or sudden change in this gene may cause the abnormal functioning of these sodium ion channels, leading to seizures.

Studies have shown mutations in this gene; however, not all mutations cause Dravet syndrome. These gene mutations occur spontaneously and are new to the individual; rarely are they passed from parents to children.

Much needs to be known about the causes of this rare genetic disorder. Genetic and environmental factors contributing to this disorder are also not well understood.

What are the Symptoms and Triggers of Dravet Syndrome?

• Seizures occur within the first year of life. The first seizure is associated with fever causing severe jerking movements of one side of the body.
• Seizures often last more than 2 minutes in the early years.
• Children with Dravet syndrome can exhibit different type of seizures such as:
• Atonic seizures
• Partial seizures
• Absence seizures
• Myoclonic seizures
• Tonic clonic seizures
• Children who develop fever with seizures (febrile seizures) are often prone to infections.
• A slight change in temperature can also trigger a seizure even when they do not have fever. A hot or warm bath can also act as a trigger.
• Flashing lights or patterns can also stimulate a seizure in children with this syndrome.
• Excitement and emotional stress can be another trigger for childhood epilepsy
• After the age of 2 years, these children generally do not achieve their developmental milestones as their typical peers do.
• Cognitive development will be slow; however, some cases might show improvement in cognitive functioning after the age of 6 years.
• Children with this syndrome might also develop certain other symptoms such as:
• Unsteady walk
• Low immunity
• Growth and nutrition issues
• Older children might develop a crouch gait and joint deformities with significant functional impairment
• Motor tone issues causing foot problems
• Autism and other behavioral problems
• Intellectual disability

How do you Diagnose Dravet Syndrome?

Accurate diagnosis and effective treatment make a huge difference in the outcome of this syndrome. Most cases of Dravet syndrome remain underdiagnosed and do not receive proper treatment. Requesting for early testing is crucial to reduce the burden of the disease.

SCN1A testing is recommended when an infant presents with seizures before the age of 12 months. This is more so if the medical history reveals the following:

• Frequent seizure episodes
• Epilepsy is resistant to drugs
• Pattern of seizure changes with age
• Mild change in temperature triggers an attack
• Sensitivity to light causes seizures
• Initial EEG, MRI, and other metabolic tests are normal
• As the child reaches the 2nd year, developmental disabilities become apparent

If Dravet syndrome is suspected, refer to a neurologist who has expertise in epilepsy and ask for SCN1A testing. Even if SCN1A test comes out negative, Dravet syndrome should not be ruled out, if symptoms are clinically relevant.

How do you Treat Dravet Syndrome?

Early diagnosis is the key for prompt treatment and better prognosis of this syndrome. A multi-disciplinary approach is required for the patient, as well as family members. Treatment of seizures is based on choosing the best combination of drugs to control seizures and prevent any kind of epileptic emergencies. Achieving this can promise better developmental outcomes in children as well as reduce risk of death.

Usually, two or more medications are required to control seizures and prevent multiple seizure. It is important to avoid sodium channel blockers as they can aggravate or worsen seizures associated with this syndrome. Sodium channel blockers to avoid include:

• Phenytoin
• Rufinamide
• Lamotrigine
• Fosphenytoin
• Oxcarbazapine
• Carbamazepine

A ketogenic diet is also helpful in many patients. This diet is a high-fat, adequate protein, and low-carb diet. This is primarily used to treat cases of epilepsy in children that are difficult to control. Treatment plan should also include how to treat children when they are experiencing a seizure or fever or illness.

Developmental assessments and checks should be started as early as possible.

Children with Dravet syndrome should receive physical, speech, occupational, and social therapies for a fulfilled life.

How do you Prevent Dravet Syndrome?

Prevention of Dravet syndrome is not possible because it is a genetic mutation, with no known causes. However, if your child is diagnosed with this syndrome you can prevent potential triggers such as fever, illness, or any change of temperature. The most important aspect is to control triggers enabling the child to lead a good quality of life without disabling their daily activities.

What is the Prognosis for Dravet Syndrome?

Treatment of Dravet syndrome is complicated as most seizures are not responsive to medications. Currently available medications are not able to fully control seizures because this syndrome has many associated health issues that need to be identified and addressed immediately.

Patients with epilepsy that has following features might be suffering from Dravet Syndrome:

• Hard to treat
• Seizures associated with developmental delays
• Patients who are treated with multiple medications
• Patients who experience tonic clonic seizure activity

Health Tips

If your child experiences seizures due to high temperature, the following first aid is recommended:

• Lay the baby on a flat surface
• Provide access to fresh air
• Clear mucus from the baby's mouth
• Turn the child's head to the left side
• To reduce body temperature, hold the baby under a cold water shower

If your child experiences severe tonic clonic seizures, apart from the above mentioned actions also take the following steps and seek immediate medical care:

• Tie a knot in a cloth and hold it between the teeth to prevent the child from biting his tongue and lips
• Wipe foam from his mouth
• Ensure that the child does not hit or bang against something during the seizure attack

References:

1. Scheffer I, Berkovic S. Generalized (genetic) Epilepsies with Febrile Seizures Plus. In: Engel J, Pedley T. Epilepsy: A Comprehensive Textbook. Philadelphia, PA: Lippincott, Williams & Wilkins; 2007: 2553-2662.
2. Sijbet AE, Sithinamsuwan P, et al. Does an SCN1A gene mutation confer earlier age of onset of febrile seizures in GEFS+? Epilepsia. 2009;50(4):953-56.
3. Korff C, Laux L. Dravet syndrome: a Retrospective study of 16 patients. Jour Child Neur. 2007; 22:185-94.
4. Caraballo R, Cersosimor R. et al. Ketogenic Diet iin patients with Dravet syndrome. Epilepsia. 2005;46:1539-44.

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