Absence seizure, also called petit mal seizure, is a type of nonconvulsive seizure involving episodes of staring spells that last for a brief period, usually less than 15 seconds. A child can be unresponsive during this type of seizure.
The symptoms of absence seizure are barely noticeable, and an electroencephalogram (EEG) is mandatory for the diagnosis.
If a child has recurrent absence seizures, it is diagnosed as childhood absence epilepsy (CAE). CAE affects two to eight in 100,000 children younger than 15 years of age every year and is more common in girls than boys (1). Absence seizure often occurs in people younger than 20 years and is more common in children aged four to 12 (2).
Read this post to know about the causes, clinical features, types, complications, diagnosis, and treatment options for absence seizures in children.
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. 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.
3. 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). Many 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).
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 doctors’ 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.
Never ignore the symptoms of absence seizures assuming it to be daydreaming. Proper management can help prevent complications and improve the quality of life in children with absence seizures. Also, seek support and reassurance from medical home providers, support groups, or local offices of national organizations such as the Epilepsy Foundation.