Paediatric medicine - Epilepsies in infants and children

Epilepsies are not usually missed; but differential diagnoses may be overlooked.

An abnormal ECG does not always diagnose epilepsy
An abnormal ECG does not always diagnose epilepsy

Epilepsy is a susceptibility to recurrent spontaneous seizures.

It occurs in 0.5 to 1 per cent of the population and 60 per cent of cases start in childhood.

Epilepsy is unresponsive to medication in 20 to 25 per cent of cases and diagnosis can be difficult. The epilepsies comprise many different seizure types and syndromes, with different prognoses for responding to medication, remitting, or for associated comorbidities.

The patient's history should alert GPs to the possibility of epilepsy and, in particular, certain epileptic syndromes (common or rare, but crucial not to miss).

Clinical features
The history and age of the child are vital to diagnosis (see below).

Eye-witness reports are valuable, and can now be captured on mobile phones. History-taking and video reviews should focus on:

  • onset of the event, although it is often not seen. Identify whether there was a trigger;
  • how the seizure evolves;
  • laterality;
  • degree of unresponsiveness/loss of awareness;
  • any colour change and when it occurred;
  • limb movement;
  • postictal behaviour.

Differential diagnoses
Epilepsies are not usually missed; we are more likely to forget other possibilities. Fewer than 25 per cent of all children in whom epilepsy is considered will actually have epilepsy; conversely, the false-positive diagnosis rate can be as high as 15 per cent. The box (bottom, left) lists differential diagnoses for 'fits, faints and funny turns'.

Clinical features to rule in or rule out epilepsy

Features making an epileptic seizure more likely:

Features making an epileptic seizure less likely:

  •  Stereotyped event (looks the same each time).
  • Posture sustained for several seconds.
  • Head turned to one side and eyes looking in the same direction.
  • Shock-like jerks of limbs.
  • Subtle flickering around eyes and mouth.
  • Brief duration (seconds to minutes).
  • Postictal tiredness and sleep.
  • Violent thrashing movements.
  • Prolonged limb unresponsiveness.
  • Context-specific (for example, only happens at school).
  • Preceded by frustration or irritation.
Remember, none of these features are absolute and there are plenty of exceptions. Diagnosis should not be based on the presence or absence of single features.

Epilepsies at different ages
Early childhood (up to four years old)
Be aware of rare, but serious, aggressive and often progressive conditions that need specialist referral. Spasms and myoclonic seizures indicate these, often with developmental problems.

  • Infantile spasms (West syndrome). Onset is around four months with tonic spasms every five to 10 seconds.

Parents may complain of colic or reflux, or lack of visual interest or social interaction. There may be a characteristic chaotic EEG (hypsarrhythmia) and cortical abnormalities on brain imaging. Early treatment may lead to better developmental outcomes.

Middle childhood (four to 10 years)
Characterised by more benign conditions with good developmental and educational outcomes and greater likelihood of spontaneous remission.

  • Childhood absence epilepsy. This makes up 12 per cent of epilepsies, and is usually treatment responsive. Children have sudden behavioural arrest and impaired consciousness lasting seconds, with immediate resumption of activity at offset. Other features include jerks of the eyelids and the corner of the mouth, automatisms, head-droop or relaxation of grip.
  • Benign rolandic epilepsy with centrotemporal spikes. The most common idiopathic epilepsy, with onset between five and eight years. Seizures are usually clonic with paresthesia affecting one side of the face, bulbar muscles and upper limb. They occur on waking, are infrequent and may not require treatment.
  • Febrile convulsions. Occur in about 5 per cent of children and are associated with fever. While not epilepsy, all children with complicated febrile convulsions (duration longer than 15 minutes, multiple seizures in 24 hours and focal features) should be referred to a paediatrician to consider underlying structural lesions or the onset of genetic epilepsy.

Later childhood epilepsies (from 10 years)
Idiopathic life-long syndromes often emerge after 10 years of age including idiopathic generalised epilepsy, juvenile myoclonic epilepsy and juvenile absence epilepsy.

  • Juvenile myoclonic epilepsy (JME). This makes up about 10 per cent of all epilepsies and is characterised by myoclonic jerks while awake (unlike hypnopompic/hypnogogic sleep jerks). Triggers include sleep deprivation, stress and menses. Later infrequent generalised tonic-clonic seizures emerge. JME is easy to diagnose but easy to miss. Diagnosis is often delayed until the first generalised tonic-clonic seizure and even then can be misdiagnosed as idiopathic generalised epilepsy. The wrong diagnosis may lead to the wrong drug aggravating the myoclonic jerks.

Referrals
The NICE guidelines recommend that 'all children with a recent onset suspected seizure should be seen urgently by a specialist'. The diagnosis should then be established by a specialist paediatrician with expertise in epilepsy.

In your referral letter, outline the clinical features and, if possible, the perinatal history, family history and school progress.

The area of EEG is difficult to navigate. An abnormal EEG does not always diagnose epilepsy and a normal EEG does not rule out the diagnosis (60 per cent false-negative on first EEG). Investigations, including blood and urine, to exclude other diagnoses or determine an underlying cause, should be undertaken at the discretion of the specialist.

Children with epilepsy should be under the care of a GP and a consultant paediatrician. Children with pharmacologically unresponsive epilepsy will also see a consultant paediatric neurologist.

  • Dr Varadkar is a consultant paediatric neurologist at Great Ormond Street Hospital
Differential diagnoses of paroxysmal events
Age groupDifferent diagnoses
Babies 
  • Normal movements (sleep myoclonus, primitive reflexes, jitters).
  • Gastro-oesophageal reflux (Sandifer syndrome, back arching after feeds, cyanosis).
  • Head-banging.
Toddlers and
pre-schoolers 
  • Parasomnias: night terrors (before midnight); nightmares (early hours of morning); confusional
    arousals.
  • Breath-holding attacks/reflex anoxic seizures.
  • Overflow movements (with excitement).
  • Stereotypies.
  • Gratification phenomena.
  • Rigors.
School-age 
  • Daydreaming (child won't blink on confrontation if having an absence seizure).
  • Tics.
  • Ritualistic behaviour (children with learning difficulties).
Adolescents 
  • Vasovagal episodes.
  • Parasomnias.
  • Cardiac syncope (can be at any age).

 

  • Migraine (usually comes after a seizure rather than at onset).
  • Recreational drug use.
  • Primary psychiatric disorder.

Do not miss cardiac clues, such as sudden drop to ground, pallor or cyanosis at onset. In epilepsy, pallor and cyanosis is late and non-specific.

Breath-holding, reflex-anoxic attacks and faints may be followed by true epileptic phenomena (jerking) secondary to cerebral hypoxia.

This list is not exhaustive. There are many more causes of 'funny turns', such as the movement disorders.

 

Key Points
  • Description of the seizure is the main diagnostic tool.
  • All children with an epilepsy should be seen by a paediatrician.
  • Don't miss infantile spasms.
  • Ask about early morning jerks in teenagers.
  • Consider cardiac causes and, if suspected, refer promptly.
  • EEG does not always diagnose epilepsy.

Further Information

  • NICE Clinical guidelines and evidence review for the epilepsies: diagnosis and management in adults and children in primary and secondary care. CG20. London: NICE; 2004.

 

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