“Blanking out” or “zoning out” is a behaviour that is commonly reported to paediatricians by parents who are concerned about their children.  As a parent myself, I know how difficult it is to tell if a child is not responding because they are

• Tired and just not hearing you
• Too absorbed in something else (eg reading, television etc)
• Ignoring you because you are asking them to do something they would prefer not to do (actually my husband is pretty good at this one too – ha ha… no seriously it’s actually true – sorry babe ;D )
• Actually unresponsive due to something like an absence seizure

For teachers, sometimes it may appear that a child has poor attention, is a daydreamer or it may even first become apparent that the child’s academic performance is dropping even before it is realised that absence seizures are occurring.  The poor attention and concentration can persist even once the absence seizures are adequately treated (and as an aside, the medications we often use to help attention/concentration can theoretically lower seizure threshold and make seizures MORE likely… but that is another story for another day).  Children can be “snapped out” of a daydream, but the same cannot be done for an absence seizure.

What ARE absence seizures?

TYPICALLY, absence seizures are a sudden loss of consciousness where the child will suddenly stop what they are doing and stare blankly into space.  The episode can sometimes be accompanied by some involuntary, recurrent and purposeless movements of the face (eg eyelid flickering, eyes drift upwards, lip smacking) called ‘automatisms.’ During this time (usually around 5-20 seconds) the child will not respond (at all) to voice or other types of stimulation.

They are a type of GENERALISED seizure (which means it affects the WHOLE brain – as opposed to just PART of the brain (which is called a partial seizure; we’ll blog about this another day as it is too huge a topic to cover today) and thus the whole body) and often occur many times a day (up to 200 in some cases!).  Typically, the child returns to normal immediately after the seizure (or will take about 2-3 seconds at most to return to normal) and often have no idea that they have just had the episode.

They are also sometimes called:  petit mal seizures or absences (pronounced “ab-son-ses”).

More UNUSUAL types of absence seizures can also occur. These are called “atypical absence seizures.”  They are different from typical absence seizures in a few ways,

1. The child is often confused for a longer period of time after the seizure
2. The child might fall down during the seizure, or if they are sitting, they might slump forwards, or objects may drop from their hands (due to a sudden loss in muscle tone).
3. The start and the end of the seizure may not be very clear
4. There may be other unusual features that involve the autonomic nervous system (ie the part of your nervous system that you have no control over) for example, the child might
   1. Become pale around the mouth
   2. Get goosebumps on their skin
   3. Become flushed in the face
   4. Drool
   5. Lose control of their bladder or bowel
   6. Have a fast heart rate
5. They are more often seen in kids who have other problems with their nervous system like a developmental disability, and often occur alongside other types of seizures as well

 

How do we diagnose absence seizures and how do we know what TYPE of absence epilepsy/epileptic condition the child has?

If typical absence seizures are the only type of seizure type experienced by that child, AND the child has otherwise normal development and no structural abnormalities of their brain, then the child is said to have “Childhood Absence Epilepsy (CAE).”[i] In this diagnosis, the onset of the absence seizures starts between the ages of 3 and 11 years and about a third of children will have a family history of absence seizures.  It accounts for about 2-8% of people with epilepsy.  By contrast, if the absence seizures occur in a child who has other types of seizures as well then other diagnoses might apply such as, “Juvenile Absence Epilepsy (JAE)” (about 2% of all cases of epilepsy; first seizure starts between 9-13 years of age; absence seizures go for longer – see below under prognosis), “Juvenile Myoclonic Epilepsy (JME)” or potentially some other type of epilepsy syndrome.

Absence seizures can look a bit like other seizures called complex partial seizures (because these have the same “automatisms” that absence seizures can have and are also characterised by the child being unresponsive).  Absence seizures appear different from complex partial seizures because the child tends to not be drowsy afterwards and also because they tend to have a more defined start and end point.

If you are worried that your child is experiencing absence seizures, then you will need to see your GP and get a referral to see a paediatrician and/or paediatric neurologist.  Your paediatrician/neurologist will take a thorough history around what the episodes look like, how often they occur and about other aspects of your child’s health and development.  During this consultation, your child may be asked to breathe quickly or blow on a pinwheel to make it turn for a few (hyperventilate), to see if this will bring on an absence seizure (it does in over 80% of children with childhood absence epilepsy).  It helps if you have managed to capture an event on a camera or phone to show the doctor.

If the doctor thinks that absence seizures are a possibility, he/she will order an EEG (electroencephalogram).  This is a non-painful, non-invasive test where a bunch of little electrodes are stuck to your child’s scalp to read brain waves/activity (and during the EEG, your child may be asked to breathe quickly again and or be subjected to a flashing light).  The EEG will show a pattern typical of absence seizures called a “spike and wave” pattern at about 3-6 Hz (or 3-6 cycles per second).

A brain scan is not always ordered in the case of typical absence seizures, but if it is (for example a CT scan or an MRI), the result is usually normal.

 

How common are absence seizures?

In all children who have epilepsy, about 10% of seizures are typical absence seizures.  Depending where you source your information, absence seizures are said to occur in anywhere between 6 to 8 per 100,000 children between the ages of 0 and 15 years.[ii]^,[iii]

That’s roughly about 1 kid in every 12,500-16,600.

What do I do if I see my child have an absence seizure?

• Keep an eye on them (especially if you know they have a history of falling) to make sure they are safe.
• If you remember, try to time the episode (this is an important diagnostic clue for the doctor) or record the event on your phone to show the doctor.
• Note down any involuntary movements (and which side of the body they occurred on) or if there was any other associated features like loss of bladder/bowel continence, pallor (child looking pale), goosebumps etc
• If you are unsure if they are daydreaming or actually having a seizure, gently touch them on the arm to see if you can “bring them out of it.”
• Don’t shout or shake them, they cannot hear you and are not aware of what is going on
• Wait – they will come out of it on their own, no other intervention is usually needed.

 

Prognosis for children with absence seizures

Prognosis (or in other words – the outlook) for the child really depends on the underlying diagnosis for their absence seizures.  It can sometimes be hard to know the difference between diagnoses (especially between childhood absence epilepsy and juvenile absence epilepsy because of the age overlap and other common features), but there are subtle differences that your doctor will look for on history to help with making a diagnosis.

JAE usually begins a bit later in childhood (9-13 years as mentioned above) and the absences can last  longer (up to 45 seconds) than those that occur in CAE (around 10-20 seconds but usually less than 10).  The cause of both these conditions is thought to be genetic and both are associated with problems with attention and concentration (and therefore learning), but JAE is considered a life-long condition (meaning that anti-epileptic medication will be needed long-term to control seizures) whereas the seizures from CAE can stop 2-5 years after they start, and if they don’t – will usually spontaneously resolve by the child’s mid-late teens.  In BOTH conditions, the response to anti-epileptic medication is very good (80-95% in CAE, and about 70-75% in JAE) but there is a higher risk of generalised tonic-clonic seizures (the kind you see in the movies where a person will fall down and shake all 4 limbs) in JAE (80%) as compared to CAE (10-15%).

Juvenile myoclonic epilepsy has a different outlook again, and for other rare and more severe epilepsy syndromes such Lennox-Gastaut syndrome, the seizures can be very difficult to control indeed and children will commonly also have intellectual impairment.  It is too much to go into these in today’s blog, but it is on my list of “topics to do” in future!

 

How do we treat absence seizures?

Absence seizures are treated with certain anti-seizure medications.  Your doctor will select the one that is most appropriate for your child, and the choice will depend on the underlying seizure disorder diagnosis.

For example, a medication called ethosuximide (brand name “Zarontin”) is used to very good effect to treat absence seizures.  However, in children who have a high risk of other types of seizures (eg generalised tonic-clonic seizures (GTCS)) as in JAE, it may make more sense to use a different medication such as sodium valproate (brand name “Epilim”) that will be effective in treating BOTH the absences and the GTCS.  Valproate has been shown in studies to be equally as effective as ethosuximide, but it can have a higher incidence of side effects (eg it can cause problems with attention and concentration amongst other things).

Sometimes if one medication alone fails to control the seizures, a combination of two or more medications might help.  Other medications that are used to treat absence seizures include lamotrigine [Lamictal], topiramate [Topamax] and levetiracetam [Keppra] as well as others, but these are generally not used first-line because they are either less effective, or not adequately studied in children when used for this reason.

Usually when a child has been seizure free for 2-3 years, we think about gradually discontinuing their medication.

 

Well that was a massive topic!!  I actually started writing this blog thinking it would be fairly easy and 4 pages later we are still going (**eye roll** sorry about that!).

We’ll have to do “Epilepsy” as a totally separate topic (or several separate topics) another time.

I hope at the very least you have found this post informative.

 

As always – don’t forget to hit SHARE for me.  It makes all of this staying-up-late to write free blogs worthwhile 😉

 

xxDr Megs

 

 

 

 

 

 

[i] Posner E.  Absence seizures in children. BMJ Clin Evid. 2008; 2008:0317.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2907950/ .   Accessed on 3 June 2018.

[ii] Olsson I. Epidemiology of absence epilepsy. I. Concept and incidence. Acta Paediatr Scand 1988; 77:860.

[iii] Loiseau J, Loiseau P, Guyot M, et al. Survey of seizure disorders in the French southwest. I. Incidence of epileptic syndromes. Epilepsia 1990; 31:391.