Dravet syndrome symptoms
Fact-checked by The hallmark of Dravet syndrome, a severe infantile-onset epilepsy, is recurrent seizures that usually begin within the first year of life. Developmental delays, cognitive and behavioral problems, and movement difficulties also characterize the rare disorder.
Specific Dravet syndrome symptoms can vary, but the disease generally begins in infancy with prolonged seizures, often triggered by fevers. The signs of Dravet syndrome tend to evolve with age to include a wider range of seizure types and non-seizure symptoms.
Identifying and tracking all Dravet symptoms can facilitate an early, accurate diagnosis and appropriate treatment.
Early symptoms
Seizures are the first symptom of Dravet syndrome. They typically begin between 3 and 9 months of age in an otherwise healthy infant, but can occur as early as 1 to 2 months or as late as 15 to 20 months. After the initial incidence, seizures will usually recur over the next several months.
In about 55% of cases, these early symptoms of Dravet syndrome are triggered by a fever, which is known as a febrile seizure. Early seizures in Dravet are also often:
- prolonged, lasting over five minutes, with up to a third of children having seizures that last longer than 30 minutes
- resistant to standard anti-seizure treatments
- convulsive, involving abnormal movements like twitching or jerking
Before around age 1, seizures are typically the most noticeable symptoms of Dravet syndrome in infants. However, delayed achievement of motor milestones, such as the ability to sit, may become obvious between 6 and 12 months of age.
Common types of seizures
There are several types of Dravet syndrome seizures, and patients may experience multiple types throughout life. Dravet syndrome seizures may take the form of:
- generalized tonic-clonic seizures (GTCS): whole body convulsions with a loss of consciousness
- hemiclonic seizures: convulsions limited to one side of the body
- myoclonic seizures: brief muscle jerks, often lasting only a few seconds
- atonic seizures: sudden loss of muscle tone and falling
- absence seizures: episodes of lost awareness, often involving staring off into space, usually without major body movements
GTCS and hemiclonic seizures are the most common initial seizure types in infants, with other seizure types usually emerging between the ages of 1 and 4 years.
At some point in their lives, up to 90% of people with Dravet may experience a life-threatening medical emergency called status epilepticus, when a seizure lasts over five minutes or several seizures happen close together without recovery time between them.
Developmental and cognitive symptoms
Most developmental delays in Dravet syndrome emerge after age 1. They may include:
- language and speech delays
- intellectual and learning disabilities
- autism or autism-like symptoms, including irritability, impulsivity, and other behavioral challenges
- problems with attention or concentration, including attention-deficit/hyperactivity disorder
The cognitive and behavioral symptoms of Dravet syndrome may be a direct consequence of the genetic mutations that cause the disease, but can also be exacerbated by seizures and the medications used to treat them.
While most adolescents and adults have moderate to severe cognitive impairment, some may have milder symptoms.
Movement, balance, and muscle tone changes
Movement and balance problems in Dravet syndrome can emerge during childhood and generally worsen through adolescence and adulthood. Motor symptoms in children with Dravet syndrome include:
- low muscle tone (hypotonia)
- poor muscle coordination (ataxia)
- gait abnormalities, such as excessive knee bending (crouch gait)
- stooped or hunched posture
In adulthood, motor symptoms may resemble those seen in Parkinson’s disease. Called parkinsonian symptoms, they include:
- slowed movement (bradykinesia)
- muscle rigidity
- small steps
- difficulty staying upright and balancing
- difficulty speaking (dysarthria)
Other symptoms
Other possible non-seizure symptoms of Dravet syndrome include
- autonomic dysfunction: problems with involuntary body functions, such as digestion, temperature regulation, heart rate, and blood pressure
- growth and nutritional issues: difficulty swallowing, appetite and weight loss, and growth disturbances
- sleep disturbances: difficulty falling or staying asleep, daytime sleepiness; sleep problems in Dravet syndrome can exacerbate other symptoms and trigger seizures
- frequent infections: ear, nose, throat, lung, or digestive infections
People with Dravet are also at risk of sudden unexpected death in epilepsy, a type of death that occurs in people with epilepsy during sleep and which has no clearly identifiable cause. Accidental injuries, drowning, or choking due to seizures can also increase the risk of early death in Dravet.
How symptoms may change over time
The symptoms of Dravet syndrome commonly evolve through childhood, adolescence, and adulthood. Some Dravet syndrome symptoms that differ by age include:
- Seizure type: Tonic-clonic or hemiclonic seizures are common in infancy, with other types developing during childhood. For adults, tonic-clonic seizures during sleep are particularly common. Fever-triggered seizures are less common in older patients.
- Seizure severity: Prolonged seizures in Dravet syndrome are frequent in infancy and early childhood, but less common in older patients. Seizure frequency and severity also generally decline with age.
- Other symptoms: Infants with Dravet are usually developmentally normal, with cognitive, behavioral, and motor problems emerging in early childhood and worsening over time. Cognitive function may stabilize in adulthood, while motor symptoms continue to get worse.
Careful long-term monitoring of symptoms over time is important for tracking disease progression and treatment responses.
Dravet Syndrome News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
