The First Afebrile Seizure

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You are the paeds reg in a regional base hospital when a five year old girl is referred to you by the emergency department following a seizure.  She is afebrile and not known to have a seizure disorder.  By the time of your assessment she is alert and interactive.

 

Bottom line:

  • A detailed understanding of exactly what happened is crucial
  • Distinguish seizure from seizure mimic (see below for definition)
  • Distinguish primary from secondary seizure
  • Don’t miss a potentially fatal arrhythmia
  • Check a BSL and strongly consider an ECG
  • Ensure parents (and child if age appropriate) have received advice about what to do in the event of another seizure and safety regarding environmental hazards

How do I know if it was a seizure?

Your history should enable you to imagine a video clip of the event occurring – what was happening before hand? How did it start? Was it symmetrical? How long did it go on for? What were the patients eyes doing? What was the recovery period like?

This detailed understanding of what happened may enable you to see a pattern that you recognise as a particular form of seizure or seizure mimic (any other process, pathological or not, which may mimic and thus be confused with a true seizure). In reality the more experience you have in this area the more likely you are to recognise a particular pathology but even if you don’t a good history will also enable you to describe the event more usefully to a specialist. Watch out for DFTB’s upcoming seizure quiz for descriptions of some common seizure patterns and classic seizure mimics.

Tongue biting, incontinence of urine, a drowsy post-ictal period and occurrence during sleep or on waking are all strongly associated with seizures. When observing a patient with intermittent seizure episodes you may also see an increase in heart rate and blood pressure and pupillary dilatation during periods of seizure activity. While providing useful information unfortunately none of these observations are diagnostic in isolation. It is worth noting that tonic clonic activity can occur following vasovagal syncope so a history of jerking movements is also not diagnostic of a seizure.

Serum prolactin is elevated immediately and at 20 minutes following many seizures, returning to baseline within an hour.  This is often discussed but NICE recommend against using it to diagnose a seizure as it is neither sensitive nor specific enough to be used for that purpose.    Consider it circumstantial evidence only and note the importance of the timing of the test in relation to the episode.

Was it a primary or secondary seizure?

i.e. was this a seizure that occurred as the primary pathology or was it a symptom of another problem?

Occurrence during exercise, after a sudden surprise or with a family history of arrhythmia, pacemaker or sudden death which may have been due to a cardiac cause are big red flags for a dangerous cardiac arrhythmia as a cause of the event and warrant urgent assessment by a cardiologist.  This is the big one not to miss in the context of a child who has made a full recovery by the time you see them.

Intracranial bleeds, meningitis and ingestions are other things to consider in every case and may be relatively straightforward to exclude on the history or may warrant further investigation such as a CT head, LP or a tox screen and a discussion with child protection.

Careful physical exam is important looking for stigmata of a neurocutaneous syndrome, subtle neurological deficits as well as evidence of any traumatic injury which may be a cause or an effect of the seizure.

What investigations are required?

This is heavily dependent on the clinical context however a few general principles apply.

Anyone with any altered level of consciousness should get their BSL checked whatever the presumed cause.

The utility of checking electrolytes decreases with age and degree of recovery.  NICE suggest that checking electrolytes is at the discretion of the practitioner but what does this mean?  Infants are at risk of many congenital causes of electrolyte abnormality as well as errors in formula preparation.   When seizures are caused by electrolyte problems the patient is unlikely to make a full recovery until you identify and treat that abnormality.    I think it is essential to check the electrolytes (paying particular attention to Na and Ca) in anyone under 12 months of age, anyone who has not stopped seizing by the time you see them or does not go on to make a full and timely recovery and anyone who has findings on history or examination which suggest they may be at particular risk of an electrolyte disorder.  Our patient in this case is 5yrs old, alert and interactive so Us and Es in her case are unlikely to be helpful.

An ECG is non-invasive and harmless so worthy of a look for evidence of LQTS, Brugada syndrome, HOCM or pre-excitation in all but those episodes with an obvious alternate cause.

Other investigations are dictated by the history and exam, it may be appropriate to look for infections, metabolic problems, trauma or other pathologies as suggested by the clinical circumstances.

Do note, however, that a WCC may be elevated by a primary seizure with or without an infectious trigger.

Who needs a CT?

This is not required routinely unless there is a persistently altered level of consciousness, new focal neurological abnormality or particular reason to suspect an intracranial bleed.

Focal episodes are more likely to be associated with structural pathology than generalised episodes but are not a hard indication for immediate CT (provided they fully resolve).

MRI is a better test for parenchymal abnormalities so patients with seizure disorder who do not have a clear clinical/EEG based diagnosis will need an MRI regardless of whether they have had a CT.  Whether you chose to CT in some circumstances (e.g. a focal seizure with full resolution and a normal neuro exam) may be heavily influenced by your speed of access to MRI.

As alluded to above those with more experience in this area are likely to be more comfortable making a clinical diagnosis of a seizure syndrome and will consequently order less imaging. So don’t be shy about discussing the patient with your senior colleagues prior to requesting a CT in a child who has made a full recovery.

Who needs an EEG?

In reality most people who have had a seizure or seizure like episode without clear diagnosis will need an EEG.

It is important to bear in mind that it is not a screening test for epilepsy as some people with epilepsy will have normal inter-ictal EEGs and many without epilepsy will have baseline EEG abnormalities.

There is a reasonable degree of interpreter variability with paediatric EEGs and it is worth considering who will be interpreting the EEGs you request and how much experience they have in paediatrics before taking the conclusions as absolute, especially if your clinical assessment does not leave you confident about the underlying aetiology of the episode.

The NICE guideline suggests EEG should usually be undertaken after the second seizure like event, should not be performed unless you think this was a seizure on clinical grounds and should be taken to neither exclude or confirm a diagnosis of epilepsy.

The chain of events in which a non-specific episode leads to the requesting of an EEG which turns out to be abnormal and results in a child who does not have epilepsy being started on AED medication is something to be wary of.

Who should I start on anti-epileptic medications?

Acutely very few people should be started on anti-epileptic drugs (AEDs) after a single seizure.

There is a significant reported rate of over-diagnosis of epilepsy in the community and all anti-epileptic medications have significant side effect profiles including subtle impairment of cognitive function to which the developing brain is particularly sensitive.

Some AEDs are more effective for certain seizure types and contraindicated in others, they have different side effect profiles and these need to be considered in light of the individual patients lifestyle and co-morbidities.

An RCT of 1443 adult patients showed no significant long term differences in seizure control or quality of life measures with treatment at the time of the first episode versus later on.

If you are entirely confident about the diagnosis of a particular epilepsy syndrome and are sure that your patient will require AED medication it is essential you discuss this with whoever will be following the patient up as switching to a different AED will require a weaning process.  Outpatient follow up should be arranged in a relatively short time frame, NICE recommend within 2 weeks.

What else should I tell the family?

Anyone who has had a seizure is more likely than the average person to have another one.

There are some places that a seizure could prove fatal because of the environment in which they occur, a bathtub, a swimming pool, unfenced heights, on a bike in traffic. Families should be aware of the need to avoid these situations which, in the case of a 3 yr old, may not require any change to the level of supervision the child would normally receive but older children may need to start taking showers instead of baths and so on.

Obviously someone with a potentially uncontrolled seizure disorder should not be driving and while this is not relevant to most paediatric practice the required seizure free period for gaining a drivers licence is worth considering when reviewing teenagers with epilepsy in clinic.

Many parents have smartphones with video recording capability and it is really helpful if parents can get a video of these events if they are to recur.

References

NICE CG137 The epilepsies: the diagnosis and management of the epilepsies in adults and children in primary and secondary care. Modified Dec 2013 http://www.nice.org.uk/nicemedia/live/13635/57779/57779.pdf accessed 22/12/13

Wilden J and Cohen-Gadol A. Evaluation of first non-febrile seizures. Am Fam Physician. 2012;86(4):334-340

Marson A, Jacoby A, Johnson A, Kim L, Gamble C, Chadwick D; Medical Research Council MESS Study Group. Immediate versus deferred anti-epileptic drug treatment for early epilepsy and single seizures: a randomised controlled trial. Lancet. 2005;365(9476):2007-2013.

Luef G. Hormonal alterations following seizures. Epilepsy behav 2010 Oct;19(2):131-3.

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About 

Paediatric emergency physician interested in education, retrieval medicine and simulation. Lives in Brisbane where he enjoys falling off his mountain bike and being outsmarted by his pre-teen children.

@paedsem | + Ben Lawton | Ben's DFTB posts

One Response to "The First Afebrile Seizure"

  1. Eric Jaeger
    Eric Jaeger 3 years ago .Reply

    Thanks Ben for the terrific article.

    I would amplify the advice given to parents as follows:

    Learn first aid for a seizure. While most children who experience a seizure will continue to breath, some will experience apnea and will require rescue breathing. Parents experiencing their first or second seizure are often distracted by the convulsions and do not understand the need to assess their child’s respiratory status and provide rescue breathing in the event of apnea or agonal respirations.

    Call 911 immediately in the event of another seizure. While most seizures terminate in one to two minutes, prolonged seizures are dangerous and the effectiveness of seizure termination is time sensitive. Even the most effective EMS system will require 8 to 10 minutes from 911 call to arrive on scene and begin care.

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