How Dravet Syndrome Is Diagnosed

Dravet syndrome is a rare neurological disorder that begins to cause seizures and developmental decline during early childhood. There is no definitive diagnostic test that is used to confirm this condition. The diagnosis is made based on a clinical evaluation that can involve ruling out other similar conditions. 

Mother looking concerned and putting her hand on child's forehead

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Self-Checks/At-Home Testing 

Parents are usually the first to notice signs of Dravet syndrome. The signs can begin within the first year of life, but they can start up to age 3. The first sign is usually a prolonged febrile seizure (a seizure associated with a fever). 

Other signs that can develop with Dravet syndrome include:

  • A loss of cognitive (thinking) skills 
  • A decline in communication abilities 
  • Impaired balance and coordination 
  • A loss of motor skills, such as walking 
  • Crouching when walking 
  • Limp or weak limbs 
  • Behavioral changes 
  • Hyperactivity 

It can be difficult for parents to recognize subtle changes, especially because Dravet syndrome is not associated with a family history of the disorder or any specific risk factors.

Once the condition begins to have effects, it can progress rapidly over the course of about a year, with a child losing abilities that they had gained earlier.

Physical Examination 

Your child’s pediatrician will do a comprehensive physical examination if symptoms of Dravet syndrome emerge. This will include a neurological examination and an assessment of age-appropriate cognitive and motor milestones. Sometimes the physical findings can be apparent during a routine physical checkup as well.

Some physical examination signs that can be present when a child has Dravet syndrome include: 

  • Hypotonia: Children who have Dravet syndrome may develop diminished muscle tone, which can be detected with a physical examination. Hypotonia can make it feel like a child’s limbs are too easy for someone else to move.
  • Crouched gait: Children who have already started walking before showing signs of Dravet syndrome may begin to crouch when they walk. This can be seen at home, but your child’s doctor may recognize it as part of the condition during the examination. 
  • Impaired coordination: Your child’s doctor will examine their coordination by evaluating their ability to walk, use their arms, and use small objects compared to what is expected for their age. These abilities will be impaired with Dravet syndrome, although diminished coordination can begin to develop and progress a few months after the first seizure occurs. 
  • Cognitive abilities and communication: These skills will be evaluated in light of your child’s age and expected skills. Cognitive skills in a child who has not yet learned to speak can be evaluated by a child’s attention to objects, sounds, and other people. 

These features will be re-examined and re-evaluated over time to determine whether your child is improving or declining. A decline is expected with Dravet syndrome. 

Labs and Tests

Several diagnostic tests are used to evaluate seizures, motor changes, and cognitive decline. Depending on the pattern of your child’s symptoms and physical examination, their doctor might order tests to rule out other potential conditions.

Tests your child might have during their assessment include:

  • Complete blood count (CBC): This blood test can show signs of infection, cancer, or metabolic disease. This test is expected to be normal in Dravet syndrome.
  • Electrolyte tests: This blood test can identify serious systemic problems. It is expected to be normal in Dravet syndrome.
  • Metabolic testing: Metabolic diseases can cause seizures and developmental problems. If any metabolic conditions are suspected, your child might have blood or urine tests to identify whether a metabolic problem could be the cause of their symptoms. 
  • Electroencephalogram (EEG): This noninvasive test records the electrical activity of the brain. It may identify areas of the brain that can be causing seizures and certain changes in the brain's electrical activity that can occur due to structural or metabolic issues. The EEG can be normal early in the course of the disease. It may later show an altered pattern.
  • Special EEG testing: Sometimes photosensitivity is apparent. This is a change in the EEG pattern or a clinical seizure resulting from light stimulation. 
  • Electrocardiography (ECG): Children who have Dravet syndrome can have changes in heart function, which may be detected with a noninvasive test of heart rhythm. This test is not diagnostic of Dravet syndrome, but it can be important in guiding the management of a heart problem caused by Dravet syndrome.
  • Lumbar puncture (LP): Also called a spinal tap, it samples cerebrospinal fluid (CSF) with a needle placed in the lower back, below the level of the spinal cord. This test can detect signs of infections or inflammation of the nervous system. Dravet syndrome is not specifically associated with changes in CSF. 
  • Genetic testing: While genetic testing is not considered a definitive method of diagnosing Dravet syndrome, genetic changes are associated with the condition. About 80% of people diagnosed with the condition have a mutation on the SCN1A gene. However, other conditions are associated with mutations of this gene.

The mutation often seen in Dravet syndrome is not usually inherited, so genetic testing is not a useful method of assessing risk for family planning purposes.

Imaging 

Dravet syndrome does not typically cause alterations that would appear on imaging studies of the brain, such as brain computerized tomography (CT) scan and magnetic resonance imaging (MRI). Sometimes mild atrophy (shrinking) is noted.

However, a child who develops symptoms of the condition might have a brain imaging study to rule out other causes, such as a structural-developmental problem, a tumor, or an infection. 

Brain imaging studies are safe, but the images have to be obtained while a child is not actively moving, so your child might need medical sedation when undergoing a brain imaging test. 

Differential Diagnosis 

The effects of Dravet syndrome can resemble those of several other conditions. Your child’s pediatrician might consider some of the other possible diagnoses based on the signs and symptoms that your child has developed. 

Common considerations in the differential diagnosis of Dravet syndrome include:

  • Febrile seizures: The seizures of Dravet syndrome can be associated with a fever, and febrile seizures might be considered the cause, especially if other clinical signs and symptoms are not apparent. 
  • Meningitis or encephalitis: Inflammation or an infection of the brain (encephalitis) or inflammation or infection of the meninges that cover the brain (meningitis) can cause fevers, along with motor and cognitive changes. These conditions can cause changes that are detectable with diagnostic brain imaging and LP.
  • Cerebral palsy (CP): CP is a congenital condition (present from birth). It is associated with a range of symptoms, including some that resemble those of Dravet syndrome. One major difference is that CP generally shows signs at an earlier age than Dravet syndrome. However, sometimes mild cases of CP are not apparent until a child is a few years old. 
  • Lennox-Gastaut syndrome (LGS): This neurological disorder is characterized by seizures and developmental delay. Children who have LGS have a characteristic EEG pattern that is often helpful in diagnosing the disorder.
  • Inborn errors of metabolism: A number of disorders can affect a child's ability to metabolize certain substances—potentially leading to seizures, developmental issues, and organ dysfunction.
  • Mitochondrial disease: Rare inherited disorders that cause mitochondrial dysfunction can cause seizures and a range of other effects, including motor and cognitive problems. These conditions can be diagnosed with a clinical evaluation, muscle biopsy, and sometimes genetic testing.

A Word From Verywell

Because there is no definitive or specific test used to confirm a diagnosis of Dravet syndrome, it can take several months for the diagnosis to be established. Throughout the diagnostic process, medication will be prescribed to help reduce symptoms, especially to control seizures.

Once your child has a definitive diagnosis, you will be able to discuss the prognosis and treatment plan with a multidisciplinary medical team.

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