Absence Seizures In Children: Causes, Risk And Symptoms

Absence seizure or petit mal seizure is a nonconvulsive seizure that is characterized by occurrences of staring spells lasting for a short period, mostly for a duration of fewer than 15 seconds. Absence seizures in children can make them unresponsive to sound or touch during episodes of staring spells.

Some cases of absence seizures may be barely noticeable to the caregivers. Frequent occurrences of such seizures in a child are diagnosed as childhood absence epilepsy (CAE).

Every year CAE affects about two to eight in every 100,000 children of age younger than 15 years. Girls are more commonly affected by it than boys (1). Children between four and 12 years of age are most susceptible to it (2).

Read on to know more about absence seizures in children, including their causes, symptoms, complications, and treatments.

Symptoms And Signs Of Absence Seizure

A blank stare lasting for a few seconds is one of the most common symptoms of absence seizure in children. An absence seizure doesn’t typically cause your child to fall, but they may fail to hear, understand, or speak during the time of seizure. Then, the child can suddenly snap out of the episode and continue their activities as before (3).

Other common symptoms and signs of absence seizure may include (3)

• Being still
• Fluttering the eyelids
• Smacking the lips
• Chewing motion of the mouth

Absence seizures often have sudden onset without warning signs and usually last less than 15 seconds. The child might appear to zone out mid-sentence. However, in a few rare cases, it may last longer than 15 seconds (4). Seizures such as grand mal seizures (generalized tonic-clonic seizures), atonic seizures (sudden loss of muscle tone), and myoclonus (muscle jerks or twitches) may also occur along with absence seizure, and jerky movements are a sign of it.

Types Of Absence Seizure

Based on the EEG pattern and seizure characteristics, absence seizure is classified into the following types (5) (6).

1. Typical absence seizure

This type of absence seizure is characterized by generalized seizure with sudden onset and offset of altered awareness. Usually, the electrocardiogram (EEG) may show frequencies at 3Hz (Hertz) in this type of seizure. The severity of the seizure may vary, and the child may not have a memory of the events during the seizure. However, some children, especially adolescents, may retain some awareness.

Clonic movements of the head, eyelid, eyebrows, chin, and other facial parts are usually seen during this type of seizure. Some children may display brief unconscious behaviors (automatisms) such as oral or manual movements before the seizure episode. Muscle spasms (myoclonus) of limbs may also be seen in typical absence seizures in some rare cases.

2. Atypical absence seizure

An atypical absence seizure may have a slower onset and offset of the loss of awareness than a typical absence seizure. Loss of muscle tone of the head, trunk, and limbs is often seen in this type of absence seizures. A gradual slump or subtitle myoclonic jerks are also seen in some cases.

Although the loss of awareness may be minimal, the child may continue doing their activity more slowly or with mistakes. These seizures are often difficult to determine in children with slow (less than 2.5Hz) EEG frequencies; therefore, a careful correlation between the clinical state and EEG is a must for diagnosis.

Causes And Triggers Of Absence Seizure In Children

Like in other types of seizures, absence seizures are caused by abnormal electrical activity in the brain. The exact causes of abnormal brain activity are not known in many cases (4). kMany children with absence seizures have a positive family history, indicating a genetic association.

Absence seizure can also be due to childhood absence epilepsy (CAE), which accounts for 10-15% of childhood epilepsy. The following types of epilepsies may be responsible for absence seizures in children (2).

• Juvenile absence epilepsy (JAE): In this condition, absence seizure may begin after ten years of age. Although absence seizure is common in JAE, it can be of short duration and less frequent than CAE. Most children with JAE may develop generalized tonic-clonic seizures.

• Juvenile myoclonic epilepsy (JME): Absence seizure is less frequently seen in JME, and it is often associated with myoclonic seizures of the upper limbs on awakening.

• Lennox-Gastaut syndrome (LGS): Atypical absence seizures are seen in up to 60% of children with this syndrome. It is a severe and rare childhood epilepsy with periodic convulsions with or without loss of consciousness.

The following factors may trigger any kind of seizure or epilepsy in children (2).

• Sleep deprivation
• Improper treatment
• Use of medications such as antipsychotics and isoniazid that lower seizure threshold
• Withdrawal from benzodiazepines and other CNS drugs
• Flashing lights
• Hyperventilation (breathing faster and more deeply than usual)

Complications Of Absence Seizure In Children

Most children outgrow absence seizures within a few years of treatment. However, some children may eventually develop convulsions (involuntary movements or muscle spasms) such as generalized tonic-clonic seizures. Life-long anti-seizure medications may be required to control seizures in some cases (7).

The other complications of absence seizure in children may include (7):

• Social isolation
• Learning difficulties
• Behavioral issues

Children with absence epilepsy may also have an increased risk of the following comorbidities and secondary conditions (8).

• Anxiety
• Depression
• Other mood disorders
• Attention-deficit hyperactivity disorder (ADHD)

If left untreated, your child could have hundreds of absence seizures a day, which could impair their life significantly. It could also impact the child’s motor activities and result in physical injuries. For example, a child walking on the footpath can step into traffic during an absence seizure episode, or they can be in danger if the absence seizure occurs while doing activities such as cycling and swimming.

When To See A Doctor?

Any seizure lasting more than five minutes is a medical emergency. You may also seek emergency help if your child displays any involuntary behavior such as eating or moving without awareness and prolonged confusion lasting for minutes to hours.

Diagnosis Of Absence Seizures

Pediatricians may refer a child with suspected absence seizures to an epilepsy specialist or pediatric neurologist for detailed evaluation and treatment. The clinical features, age of onset, and electroencephalogram (EEG) can help diagnose absence seizures in children. Doctors may also ask for a detailed medical history, including family history and developmental history (8).

Usually, a child with absence epilepsy and normal development may not require neuroimaging. Doctors may order imaging tests to identify cases of developmental or other issues associated with seizures.

Regular screening for complications and side effects due to medications is recommended after initiating treatments. Complete blood count (CBC) and liver function tests (LFTs) are also often ordered, and family screening may be recommended in some cases.

Treatment For Absence Seizure In Children

Antiseizure medications are prescribed for children with absence seizures depending on the severity. The doctor may usually start the medications from the lowest dose and increase the dosage as required. Anti-seizure medications are usually stopped under the doctors’ supervision if your child has been seizure-free for at least two years.

The following medications are usually prescribed for absence seizure in children (7),

• Zarontin (ethosuximide): Many doctors begin absence seizure treatment with Zarontin, as most children respond well to it. However, this drug can be associated with side effects such as sleepiness, insomnia, nausea, vomiting, and hyperactivity in some children.

• Depakene (valproic acid): This drug is used in monotherapy (using a single drug) or adjuvant therapy (with other drugs) for seizures. Depakene is effective in managing absence seizures and other types of seizures in all age groups.

• Lamictal (lamotrigine): This drug is also prescribed for absence seizure Although it is less effective than other drugs, it has fewer side effects. Rash and nausea are common side effects of lamotrigine in children.

Your child’s doctor may also recommend dietary therapy to improve seizure control. For example, a ketogenic diet, a diet low in carbs and high in fat, is usually recommended if medications fail to control seizures.

Variations of high fat and low-carbohydrate diets such as modified Atkins diet and low glycemic index diet are also recommended for some children. However, these diets can have major setbacks on a child’s nutrition, so try them only under a dietician’s supervision.

Prognosis Of Absence Seizure In Children

Typical childhood absence seizures usually resolve by adolescence. Research indicates that 57-74% of children with absence seizure report having seizure freedom (2). Unfortunately, initial therapy with ethosuximide alone may not be enough to control seizures in children who have associated generalized tonic-clonic seizures.  They may require more medications to control seizures and often fail to achieve long-term remission.

A 16% recurrence risk exists for childhood absence epilepsy in children who have been seizure-free for two years after stopping antiseizure medications. In addition, accidental injuries and comorbidities such as anxiety, depression, and ADHD are frequently reported in cases of childhood absence epilepsy (CAE) (8).

Absence Status Epilepticus

Absence status epilepticus (AS) is a highly rare condition characterized by prolonged generalized absence seizure. This may usually last at least more than half an hour to hours or even for days. Loss of consciousness can be associated with subtitle myoclonus and automatisms in this condition (9).

Children with absence (nonconvulsive) status epilepticus may look like they are daydreaming and may behave irrationally and find it challenging to speak. They may also not respond to touch, voice, or eye contact during the seizure episode (10).

How To Help A Child With Absence Seizure

The following steps may help control seizure episodes and ensure the safety of a child with absence seizure.

• Take medications correctly: Do not skip or adjust the antiseizure medication dosage and duration without the doctor’s knowledge, even if your child does not have seizures for a few weeks. It is recommended to seek a doctor’s prescription to change seizure

• Wear a medical alert bracelet: Medical ID bracelets can help emergency personnel know what treatment to give your child if they have seizures outside the home.

• Inform teachers: You may inform your child’s teachers about their condition, medications, and if they have any learning or attention issues. This may help the teachers understand and give special attention to the child if required.

• Encourage children to sleep well: Lack of sleep can trigger seizures. Ensure that your child gets adequate sleep every day.

• Know the restrictions: You may ask the doctor if your child has any restrictions with regard to motor activities. Swimming or the use of bathtubs can be restricted due to the risk of drowning in some cases. You may let your child do activities with supervision as per doctors’ recommendations.

• Do regular follow-ups: Never skip scheduled follow-up visits. It is necessary to monitor comorbidities, complications, improvement, and side effects of medications as early as possible to improve outcomes.

You may also keep an eye on your child’s school performance since a decline in academic performance may be an indication that the medication dose needs to be increased.

References

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Reviewer

Dr. Neha Bhave SalankarMD

 

Dr. Neha Bhave Salankar is a consultant psychiatrist at Bhave Institute of Mental Health based in Nagpur and has around 11 years of experience in the field. Having been a meritorious student throughout, she bagged the prestigious gold medal for medicine in MBBS and MD psychiatry.

Read full bio of Dr. Neha Bhave Salankar