Absence Epilepsy: A Subtle Form of Epilepsy
When you hear the word epilepsy, the image that comes to your mind is a man who suddenly falls on the floor, twisting uncontrollably as if he is being possessed by a demon. Epilepsy, in our minds, is a condition characterized by convulsions which often appear as uncoordinated twitching and abnormal movements in the body. However, while this is the conventional portrayal of epilepsy, there are certain types of epilepsy which presents more subtly.
Absence epilepsy presents with seizures where you blank out or stare into space for a few seconds. These seizures are also called “petit mal seizures” an old naming, literally means “small bad” in comparison to “Grand Mal” which is “big bad”. This condition commonly affects children. Childhood Absence Epilepsy (CAE) is one of the most common types of generalized epilepsy and happens in school aged children, with predominance in children from 4 to 10 years of age.
Children will start staring into space with eyes rolling up lasting for a few seconds and this can happen several times a day. These children are typically developmentally normal, doing well at school. However, their performance might be affected because they’re having difficulties in concentration and are experiencing fragmented lectures. Even though the development is normal, many kids will have ADHD, anxiety, depression and learning disability which should be identified and treated promptly. Quite often, absence seizures might be missed as daydreaming or just being an unresponsive or ignorant kid in the classroom, until someone pays more attention and consult a doctor.
How to Diagnose Absence Epilepsy?
The diagnosis of Absence Epilepsy sometimes can be done in the convenience of one’s own home through simple tests. We can make the child blow on a pinhole or a tissue. The hyperventilation that follows will trigger the staring spell in 90% of patients. They can have mouth movement or some body movements as well.
EEG is another critical test. A sleep deprived EEG is best which needs the child to wake up early in the morning and come to the EEG tired, so they can sleep during the EEG. Best to do the EEG with hyperventilation, blowing a pinhole and photic stimulation, shining light on the eyes, which can provoke seizures. Here, we must make sure that the child goes to sleep, because sometimes the only changes we see will be during sleep.
Brain imaging like MRI is not necessary in typical cases of absence epilepsy with typical EEG and seizures. So, there is no need for MRI of the brain, unless there is a suspected alternative diagnosis suspected by the treating neurologist.
What is the Cause for Childhood Absence Epilepsy?
The cause of CAE is polygenic, meaning there are multiple genes controlling the electricity flow in the brain affected. The genes make proteins, and the proteins control the electricity flow in the brain via channels and receptors. In this case, there will be mutations in these genes causing issues with the channel proteins and receptor proteins, leading to seizures.
About 20% of children have a history of febrile seizures and about half will have first- or second-degree relatives with seizures.
What are the Available Treatment for Childhood Absence Epilepsy?
The best doctor to treat this condition would be a pediatric neurologist. The goal of treatment is to stop the seizures to help with school performance, quality of life and social acceptance.
The first line of treatment and the best medicine is Ethosuximide based on multiple studies. We start with 5 to 10 mg per kg per day in two divided doses in children younger than 6 years and in 6 years and older we give 250 mg twice a day. We gradually increase to reach a dose of 15 to 40 mg/kg per day in two divided doses. We check the serum levels of the medicine and should be between 40 and 100 micrograms/mL. We can also do EEG to evaluate response to treatment. The most common side effects of Ethosuximide include nausea, vomiting, sleep disturbance, drowsiness, and hyperactivity. This medicine is heavy on the stomach and is therefore better to be given with food.
Ethosuximide only treats staring spells and absence seizures and does not treat generalized tonic-clonic or shaking seizures. If they occur the treatment regime should be revised accordingly, mostly by adding a second medicine that cover the generalized seizures like the medications following below.
The second line of treatment is Valproic acid. The third line is Lamotrigine. Some medications worsen generalized epilepsy and absence seizures, that is why not all anti-seizure medications work and we need a neurologist to manage this. Sodium channel blockers like carbamazepine, phenytoin should be avoided. Other medications to be avoided are vigabatrin, gabapentin, tiagabine and phenobarbital.
Other potential treatments for more resistant cases are ketogenic diet and vagus nerve stimulation.
What is the Outlook for Childhood Absence Epilepsy?
Most children with CAE do well and stop having seizures with treatment and “outgrow” the seizures as they get older. An estimated 70 to 90 percent of them will stop having seizures. There will be some patients who need long term treatment, and these are the ones who will go into juvenile myoclonic epilepsy or have generalized tonic clonic seizures or have poor response to treatment.
Not All Staring Spells are Absence Epilepsy
Some other types of epilepsy syndromes also cause staring spells, and they include juvenile myoclonic epilepsy with myoclonic jerks, staring spells and generalized tonic clonic seizures. This usually starts later in life after age of 12 years and stays lifelong. Other types are juvenile absence epilepsy starting at a later age and can also last for a longer time.
Not all staring spells are absence seizures. There are some focal seizures that cause pauses or staring spells and they are focal, likely coming from the left side of the brain where you communicate and talk from and the temporal lobe epilepsy, that will have pause and sometimes move movements like lip smacking and picking on your own body and head turning to one side. So, not all staring spells are generalized epilepsy or absence epilepsy, some are focal epilepsy and that requires a different treatment.