What is Absence Seizure (Absence (Petit Mal) Seizure)?
Absence seizures are brief seizures that result in a pause in behavior, and they show up as 3-Hz spike and wave discharges on an EEG, a test that monitors brain activity. These seizures are found in various types of genetic generalized epilepsies, such as childhood absence epilepsy (CAE), juvenile absence epilepsy (JAE), and juvenile myoclonic epilepsy (JME). About 25% of all epilepsy cases are classified as genetic generalized epilepsies. Moreover, up to 60% of the patients with Lennox-Gastaut syndrome, a rare type of epilepsy, have reported atypical absence seizures.
In the past, absence epilepsy was often referred to as “pyknolepsy,” from a Greek word meaning “very frequent” or “grouped.” It was also called a “petit mal” seizure, but this term is no longer preferred. According to the International League Against Epilepsy Classification of 2017, absence seizures are classified as “generalized nonmotor seizures,” although this isn’t entirely accurate as epilepsy often shows physical symptoms.
While these seizures have often been termed “benign” due to their lack of convulsive symptoms, up to 60% of children with these seizures can have serious mental and psychological effects. These effects can include issues with attention, cognition, memory, and mood, impacting a child’s social skills and academic performance. Thus, it’s important that absence epilepsy is treated.
What Causes Absence Seizure (Absence (Petit Mal) Seizure)?
There is a genetic aspect to all types of generalized epilepsy, including absence epilepsy. This means that these conditions can run in families. But it’s not straightforward, their inheritance isn’t just strictly from one dominant or recessive trait. It actually involves multiple genes and factors. Twin studies from 1951 showed that if one identical twin had a specific pattern of brain activity seen in epilepsy, the other twin had a 66% chance of showing the same pattern.
Various genes can play a role in epilepsy. For instance, certain genes (CACNA1H, CACNG3, CLCN2) affect how electrical signals move through nerve cells. These are called voltage-gated genes. Others (CHRNA4, GABRA1, GABRB3, GABRG2, GRM4) control chemicals in the brain that influence electrical signals, known as ligand-gated genes.
Specifically, in some people with epilepsy, there are variations in the following genes: calcium-channel genes (CACNA1H and CACNG3), GABA-A and GABA-B receptors genes (GABRA1, GABRB3, and GABRG2), a gene involved with the glutamate receptor (GRM4), the µ-Opioid Receptor gene (OPRM1), and the Solute transfer receptor genes (SLC6A3/DAT1).
Additionally, certain genetic variations known as copy number variants (CNVs) have been found in people with this type of epilepsy, including the 15q11.2, 15q13.3, and 16p13.11 microdeletion. However, there’s still a lot we don’t understand about the genes involved in epilepsy and how it’s inherited.
Risk Factors and Frequency for Absence Seizure (Absence (Petit Mal) Seizure)
Childhood Absence Epilepsy (CAE) is a type of pediatric epilepsy syndrome. Each year, around 6.3 to 8.0 out of every 100,000 kids get diagnosed with CAE. It is one of the most common epilepsy types found in school-going children, accounting for 10% to 17% of all epilepsy cases. Most kids start showing signs of CAE between the ages of 4 and 10, with a peak occurrence between 5 and 7 years old. While it seems girls are more likely to get CAE than boys, the evidence is not entirely clear on this.
- Childhood Absence Epilepsy is generally diagnosed in approximately 6.3 to 8.0 out of every 100,000 children per year.
- This type of epilepsy contributes to 10% to 17% of all epilepsy cases in children of school age.
- The usual age when CAE begins is between 4 and 10 years, particularly common between ages 5 and 7.
- Girls get CAE more frequently than boys, but there is conflicting evidence on this.
Signs and Symptoms of Absence Seizure (Absence (Petit Mal) Seizure)
Childhood Absence Epilepsy (CAE) usually begins between the ages of 4 and 10, peaking between 5 and 7. If symptoms appear before age 4, there might be a concern for an underlying condition known as glucose transporter type 1 deficiency. Around 10% to 15% of children with CAE have had seizures triggered by high fevers.
Common symptoms of CAE include brief spells of unresponsiveness or behavioral arrest, occurring 10 to 30 times a day, where the child might appear to ‘zone out’ or stare blankly. Some children may experience eyelid fluttering or display oral automatisms (unconscious or involuntary motor behavior), particularly during longer seizures or hyperventilation. Other symptoms can include mild clonic movements (rapid muscle contractions), pallor (pale skin), and rarely, urinary incontiness. These spells typically last between 4 and 30 seconds and are not preceded by an aura or followed by any postictal state (confusion or grogginess).
During a physical exam, a doctor might trigger absence seizures by asking the child to hyperventilate for at least two minutes. Hyperventilation, as well as arousal, lack of sleep, and certain medications, may affect the duration of the seizure.
Juvenile Absence Epilepsy (JAE) generally begins between the ages of 10 and 19, peaking at age 15. Seizures in JAE are less frequent than in CAE but tend to last longer.
A condition known as Absence Status involves long-lasting seizures with impaired awareness, sometimes exhibiting occasional involuntary muscle movements or changes in body functions. Such a seizure can last from half an hour to several days, often ending suddenly. However, it should be treated with seizure medications as soon as it is diagnosed.
Testing for Absence Seizure (Absence (Petit Mal) Seizure)
EEG, or Electroencephalogram, is the primary tool used to diagnose absence epilepsy. In kids who have absence seizures, this test displays a particular kind of brain wave activity. This activity is characterized by symmetrical and synchronized 3-Hz spike and wave discharges, which start and end suddenly. Sometimes, these discharges may be stronger at the front of the brain or start with one-sided focal spikes.
Still, in about 50% of seizures associated with this type of epilepsy, the initial discharges seen are the conventional spike and wave pattern. The other half may present a singular spike, multiple spikes, or an abnormal, irregular spike wave pattern on a normal background.
Atypical absence seizures, though, show a more subtle start and finish, slower spike and wave bursts (slower than 3 Hz), and an abnormal brain wave pattern in between seizures. In Juvenile Absence Epilepsy (JAE), EEG shows 3 to 4-Hertz spike-and-wave or multiple spike and wave discharges.
Interestingly, cognitive tests have revealed that patients with this type of epilepsy tend to have more cognitive issues, particularly in areas such as attention, executive function, and verbal and visual memory. Problems with language and reading are also common. Disorders such as depression, anxiety, and attention-deficit/hyperactivity disorder are more frequently reported in these patients too.
In the situation of continuous or near-continuous seizures, known as absence status, the EEG shows continuous or nearly continuous generalized spike and wave discharges, or multiple spike and wave discharges at 2 to 4 Hz. For patients newly diagnosed with absence seizures, brain imaging is recommended to check for any abnormal structures in the brain.
Treatment Options for Absence Seizure (Absence (Petit Mal) Seizure)
The first choice for treating absence epilepsy is a medication called ethosuximide. A study in 2010 involving 446 kids with a common form of absence epilepsy showed that ethosuximide and another drug called valproic acid worked better than a third drug, lamotrigine. However, the rates of people whose seizures were completely stopped were low: 53% for those taking ethosuximide, 58% for those on valproic acid, and only 29% for people taking lamotrigine.
People taking valproic acid scored noticeably lower in tests of attentiveness compared to those on ethosuximide or lamotrigine. Due to this, and its effectiveness, ethosuximide is often the preferred drug for treating absence epilepsy. Another study found that only one out of four kids with absence epilepsy stopped having seizures after starting a medication called levetiracetam. However, if levetiracetam does work, it can manage absence epilepsy at a relatively small dose. Increasing the dose isn’t helpful if the medication doesn’t initially work.
The most common side effects of ethosuximide are stomach pain and sickness. To help with this, people are advised to take it with meals. Other drugs that can help manage this type of epilepsy include valproate, lamotrigine, and topiramate while second-choice drugs that can be added to the first-choice treatment include valproic acid, zonisamide, and levetiracetam. It’s important to note that certain drugs like phenytoin, carbamazepine, gabapentin, pregabalin, and vigabatrin can actually make absence seizures worse.
Women who could become pregnant and are not on birth control should not use valproic acid; ethosuximide is the preferred drug in these cases.
Some experts think that certain diets, like the ketogenic diet or medium-chain triglyceride diet, could be beneficial. However, there isn’t strong evidence to back up this claim yet.
What else can Absence Seizure (Absence (Petit Mal) Seizure) be?
When a child has staring spells, there are a few conditions that doctors consider. These include absence epilepsy, focal seizures with altered awareness, and nonepileptic episodes that resemble seizures. Here are some details about these conditions:
- Focal epilepsy with an altered awareness, formerly known as complex partial epilepsy, is one such condition. It is characterized by a pause in behavior and automatic movements. However, these seizures happen less often than absence seizures, but patients can experience generalized seizures as well. The behavior during these seizures can vary based on the part of the brain where the seizures start.
- A study found that nonepileptic staring spells often feature a halt in all movements, vague facial expressions, and a fixed gaze without blinking. These episodes last between 3 and 74 seconds. For most children, it’s hard to say when the episode begins and ends. Waving hands in front of them doesn’t usually get their attention, but louder noises like clapping can stop the episode. Interestingly, 41% of children were inactive at the start of the episode, and 18% were watching TV.
Reports from an epilepsy center showed that only 11% of 276 patients in an epilepsy monitoring unit had seizures. This means most staring spells in children are not due to epilepsy. Therefore, it’s crucial that health providers don’t assume staring spells are “absence seizures” without an EEG evaluation. The study also created a tool to estimate the likelihood of seizures in kids with staring spells, considering factors like prior EEG results, past use of seizure medication or psychiatric treatments, and how long the spells last.
What to expect with Absence Seizure (Absence (Petit Mal) Seizure)
Typical Childhood Absence Epilepsy (CAE) usually begins during early years and tends to resolve by the teenage years. Approximately 57% to 74% of patients reportedly become seizure-free. There are reports suggesting a higher risk of accidental injuries during absence seizures, compared to individuals without this condition.
It’s been noted that individuals with CAE often face challenges related to attention, executive function (the skills needed to control and manage other abilities), as well as verbal and visuospatial memory (the ability to remember verbal and visual information). Struggles with language and reading are also common.
In addition, these patients tend to experience conditions like depression, anxiety, and Attention Deficit Hyperactivity Disorder (ADHD) more frequently than those without CAE.
Possible Complications When Diagnosed with Absence Seizure (Absence (Petit Mal) Seizure)
People who experience absence seizures need to be careful with certain activities due to the temporary loss of awareness they might experience during an episode. Activities such as swimming, using dangerous machinery, or driving could cause accidents or even lead to drowning. For this reason, it might be necessary to avoid these activities until the seizures are well-managed. Laws in some locations also determine how long a person must be seizure-free before they can resume driving.
Preventing Absence Seizure (Absence (Petit Mal) Seizure)
If a patient, often a child, tends to blank out or stare often, it doesn’t automatically mean they’re having a seizure. When parents bring kids with this condition to the doctor, it’s crucial for the medical provider to explain that, yes, it could be seizures, but it’s best not to jump to conclusions. Instead, doctors will want to run an EEG, a type of test, to get a clearer picture. Parents can also help by recording videos of these staring episodes and keeping track of how often they happen and what seems to trigger them.
Parents of kids with a specific type of seizure called Childhood Absence Epilepsy (CAE) should know that it’s uncommon for their kids to have severe seizures that affect the whole body. So, there usually isn’t a need for emergency medications. Still, it’s important that parents know what to do if their child does have a more severe seizure.
It’s a common misconception that these “absence seizures” are harmless because of how short they are. Parents sometimes question whether medication is necessary, fearing that the side effects could be worse than the brief seizures. However, doctors advise that these frequent, short episodes of unresponsiveness can be risky, possibly causing accidents. They can also disrupt learning and school performance. That’s why kids with uncontrolled seizures should not partake in risky activities like swimming, diving, or rock climbing unless they’re properly supervised. Driving restrictions also apply and may depend on the regulation in the specific area.
