E-doc interactive – managing seizures in children brain anoxia

David W. Webb

MRCPI, MRCP

Childhood seizures may cause distress to children and their parents. In this article, the authors describe the forms of seizure, highlight some of the diagnostic pitfalls and suggest an approach to assessment and management.

Seizures in children are common and frequently cause anxiety. There is a risk of diagnostic confusion. The general practitioner, who is often first on the scene, is best placed to gather `fresh` descriptive information and provide informed reassurance. Most children appear normal between seizures and if the nature of the event is not clear from the history, investigations are unlikely to be helpful.


Several other events may mimic seizures. True seizures may not be epileptic, and epileptic seizures may be symptomatic of a concurrent illness or represent the onset of epilepsy.Brain anoxia

Forms of seizure

A seizure is a paroxysmal clinical event which may be convulsive or non convulsive. A convulsion is an attack of involuntary muscle contraction which can be `shock-like` (myoclonic), sustained (tonic) or interrupted (clonic). Clonic movements have fast and slow components and are characterised by their rhythmic nature. Non convulsive seizures take the form of vacant spells (absences), drop attacks (atonic seizures) and transient sensory, autonomic or psychic symptoms.

It is most important to distinguish between epileptic and non epileptic seizures. Epileptic seizures occur because of transient abnormal and excessive activity of the brain. Generalised epileptic seizures occur if there is involvement of both cerebral hemispheres with loss of consciousness from the onset.Brain anoxia partial seizures have a focal onset in a single hemisphere with or without loss of consciousness, either at onset or with time. They may be symptomatic of a concurrent illness (occasional seizures) or recur spontaneously (epilepsy).

Non epileptic seizures may be psychogenic, or occur because of a reduction in cerebral oxygenation with a decrease in brain activity and a flattened EEG (anoxic seizures). Both epileptic and non epileptic seizures are more frequent in childhood and the potential for misdiagnosis is considerable. However, it is important to distinguish epileptic and non epileptic seizures, as management and outcome are very different. In addition, other episodes may mimic seizures and cause diagnostic confusion.Brain anoxia A practical approach to taking the history of a possible seizure is given in box 1.

Episodes which mimic seizures

Some of the childhood episodes which can be mistaken for seizures are given in box 2. They may be usefully divided into those with and without abnormal movements.

Episodes with abnormal movements

Jitteriness is characteristically seen in newborn babies. There is a tremulous rhythmic movement which is very sensitive to stimuli and not associated with abnormal eye movements. It can be stopped by moving the affected limb.

Sleep myoclonus, hypnagogic and hypnopompic jerks occur in sleep, on falling asleep, and on waking up. They are characterised by brief muscle contractions producing regular or irregular movements at a joint or of the face.Brain anoxia

Rigors take the form of intensive shivering with a rapid rise or fall in temperature. The associated delirium may be mistaken for altered consciousness. Tics are sudden, stereotyped, complex, repetitive, normally co-ordinated movements, performed inappropriately. They may be to some degree under voluntary control.

Episodes without abnormal movements

Daydreams, unlike absence seizures, can be interrupted and are not associated with confusion or amnesia. Uncontrollable daytime sleepiness combined with episodic loss of muscle tone and falling provoked by laughter or excitement is known as narcolepsy-cataplexy. In children under 5 years old, brief (seconds to minutes) attacks of unsteadiness and falling associated with pallor and sometimes nystagmus, but without loss of consciousness, are likely to be caused by benign paroxysmal vertigo.Brain anoxia this may be an early manifestation of migraine.

Night terrors are a benign often familial condition involving a partial arousal from non rapid-eye-movement sleep. They usually occur in children between 18 months and 5 years old, who appear terrified and unable to recognise their parents. Outbursts of aggressive behaviour can be mistaken for periods of confusion associated with partial seizures, but unlike seizures are usually situation specific and provoked. Self-stimulation and behaviour disturbances are not associated with a change in consciousness and can be interrupted.

Non epileptic seizures

Anoxic and epileptic self-induced seizures and `psychogenic seizures` are well recognised.

Psychogenic seizures

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Psychogenic seizures are uncommon but do occur in a significant minority of children referred with intractable epilepsy and may be seen in children who also have epilepsy. There may be convincing stereotypical movements, but incontinence and postictal drowsiness are uncommon. Close observation or video surveillance and EEG monitoring is helpful. A normal EEG during an episode is common.

Anoxic seizures

An abrupt depletion in cerebral cortex perfusion or oxygenation is commonly followed by a non epileptic seizure. This may include alteration in tone, limb jerking, eye movements, urinary incontinence and postictal drowsiness.

Breath-holding attacks

Breath-holding attacks occur in about 5 percent of children and are commonly familial. 1 they are provoked by anger or fright and follow a sequence of crying, expiratory apnoea, cyanosis or pallor and loss of consciousness.Brain anoxia there may be associated tonic posturing of the body, head and back hyperextension, eye rolling, and clonic movements of hands and arms. The episodes are followed by a brief period of confusion and then full recovery. Cyanotic and pallid attacks may occur in the same child. 2

Reflex anoxic seizures

Reflex anoxic seizures result form brief stoppage of the heart (asystole) through excess activity of the vagus nerve, usually in response to minor injury, or an unpleasant stimulus such as a bump on the head. The pathophysiology is similar to, but distinguishable from, pallid breath-holding attacks. 2 the seizure starts with a momentary loss of tone, followed by a tonic stiffening which may also be brief.Brain anoxia the upper limbs usually flex and may jerk, the eyes can jerk or deviate upwards. On recovery, there is often an inspiratory snort and facial flushing and occasionally confusion, agitation and postictal sleep. 2 urinary incontinence, vomiting, salivation and sweating may also occur.

The provocation, sequence of events and brevity of unconsciousness (often less than 1min) provide the diagnostic clue. If there is any doubt about the diagnosis, referral for ocular compression of head-up tilt testing can reproduce attacks and confirm their non epileptic nature. Reflex anoxic seizures do not usually respond to anti-epileptic drugs or require treatment. Frequent or serious attacks may require treatment with atropine. 3

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Syncope

The vasovagal syncope or `faint` is a sudden reversible loss of consciousness with hypotension and bradycardia often occurring after shock or prolonged periods of inactive standing (eg at school assembly). Light-headedness usually precedes fainting and the child appears pale and sweats profusely. Tonic stiffening, with or without limb jerking, is not unusual. Seizures with an associated migraine and attack are probably ischaemic and are more likely to be anoxic than epileptic seizures. 2

Suffocation

Induced anoxia (munchausen syndrome by proxy) should be considered when the child`s mother is always present during an episode and is the only witness to the onset of the seizures. She may also have a medical history. 4

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Cardiac arrhythmias

Seizures precipitated by exercise or excitement may follow cerebral anoxia in children with paroxysmal tachy-arrhythmias. Clues to the diagnosis include a family history of arrhythmias or deafness, and a prolonged QT interval on ECG. Ambulatory EEG/ECG and exercise testing can aid diagnosis.

Epileptic seizures

Most children with epileptic seizures have occasional provoked seizures probably caused by a genetic predisposition. The most common provocation in children is a fever, although there are many others (box 3). Other children have spontaneously recurring seizures, ie epilepsy, either because of an underlying brain abnormality (secondary epilepsy) or for an unknown reason (idiopathic epilepsy).Brain anoxia

Febrile seizures

Seizures can occur in a child of any age with a fever of any cause. The term “febrile seizures“ is limited to an epileptic seizure occurring in a child ages 6 months to 5 years old, precipitated by a fever arising from infection outside the central nervous system in a child who is otherwise neurologically normal. 5 they present the most common problem in paediatric neurology with a lifetime incidence of about 3 percent. Most are brief bilateral clonic or tonic-clonic seizures. The temperature of the child is usually more than 38.5°C, the peak age is 18 months and there is a family history in a first-degree relative in about 20 percent of children.

It is very important to identify children who may have an underlying neurological abnormality or central nervous system infection requiring further investigation.Brain anoxia guidelines for admission to hospital of children with febrile seizures are given in box 4.

Parents should administer an antipyretic and ensure regular fluid intake during subsequent fevers. About one-third of children have a subsequent febrile seizure, one-sixth have three more, and one-tenth have more than three. Long-term prophylaxis is too often ineffective and rarely indicated, but having rectal diazepam available helps the family deal with repeated seizures. 6,7 an EEG after the episode is unhelpful in predicting the future risk of epilepsy and has no place in management. 8

The risk of developing epilepsy after febrile seizures is increased by a number of factors (box 5, figure 1).

Febrile status epilepticus most often occurs with the first febrile seizure, is uncommon in a child over 2 years old, and while it increases the risk of subsequent afebrile seizures (21 percent) in an otherwise normal child, it does not appear to have a significant effect on intellectual development. 9,10 the prognosis following afebrile status in childhood is less optimistic and appears to be determined by the underlying neurological problem rather than the status itself.Brain anoxia

Figure 1: risk of developing epilepsy in children with and without febrile seizures.

Epilepsy

An unprovoked seizure may be a single lifetime event or may herald the onset of epilepsy. In one study the incidence of an unprovoked seizure in the first 10 years of life was 0.57 percent, with 0.43 percent having repeated unprovoked seizures (epilepsy). 11 thirty percent of those with epilepsy had an identifiable secondary cause and were more likely to have both onset in the first year and delayed development. The most common causes include cerebral dysgenesis leading to malformations or phakomatoses, and early cerebral insults from asphyxia, trauma, infection or metabolic defects. If children with absence epilepsy, infantile spasms and myoclonic seizures are excluded, the risk of recurrence after a single unprovoked seizure has been reported to be 36 percent. 12

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Assessment of epilepsy

The assessment of a child with a first unprovoked epileptic seizure should include a detailed birth and developmental history. Examination should include a search for dysmorphic features, the cutaneous stigmata of tuberous sclerosis (figure 2), neurofibromatosis and sturge weber syndrome and evidence of focal neurology and papilloedema. Potential new cases of epilepsy should be seen by a paediatrician.

Figure 2: A shagreen patch on the lower back of a child with tuberous sclerosis.

We request an EEG for children who have had two or more unprovoked seizures. An interictal EEG can neither exclude nor prove a diagnosis of epilepsy and offers considerable potential for misunderstanding.Brain anoxia it may, however, help define the type of seizure and identify a specific epileptic syndrome. If an episode occurs during the EEG, this may prove or disprove an epileptic basis for the seizure and identify possible precipitant or epileptogenic foci.

Management of epilepsy

If anti-epileptic medication is appropriate, then sodium valproate is the first choice drug for generalised seizures and carbamazepine for partial seizures. Routine measurement of blood levels of these first-line drugs in unnecessary. Levels of sodium valproate in the blood do not relate to tissue levels which determine efficacy. A programme of combined follow-up by the general practitioner and hospital specialist is usually possible, so that alterations to medication and use of second-line drugs can be undertaken in consultation.Brain anoxia

A goal oriented approach helps in monitoring treatment progress. It is important to be vigilant for adverse effects on behaviour and cognitive function. Children who are free of seizures for more than 2 years should be considered for a trial of medication.

Many families feel that they have not been given sufficient information to understand their child`s epilepsy. Written information from the epilepsy clinic and/or from patient support groups is extremely valuable.

GP`s perspective

It is alarming for both parent and general practitioner when a child has a convulsion. General practitioners rarely witness an attack as most settle down before the general practitioner arrives at the home.

If a seizure is still in progress, rectal diazepam is a useful first-line approach.Brain anoxia diazepam can be used in a dose of 500 micrograms per kg and repeated as necessary. Absorption is achieved within minutes. Diazepam should be in all emergency bags. It is the treatment of choice in status epilepticus.

If the attack has settled down, a decision has to be made about whether referral should be immediate or through outpatients. This decision should be based on an assessment of the cause of the convulsion. If the child is a known epileptic, appropriate adjustments in the medication can be suggested. If not, a full history is necessary and will most likely identify the problems. An examination should focus on possible causes such as a fever which may be caused by meningitis. If there are no problems requiring immediate attention an outpatient appointment can be requested.Brain anoxia

Practical points

• the history is the most reliable guide to the nature of the seizure.

• febrile convulsions are the most common problem in paediatric neurology.

• the peak age is 18 months and there is often a family history. An antipyretic and adequate fluids are recommended during subsequent fevers.

• potential new cases of epilepsy should be seen by a paediatrician.

• sodium valproate is the first choice for generalised seizures and carbamazepine for partial seizures. Routine blood monitoring is unnecessary.

Conclusion

Seizures in children are common events which can only be classified after a careful history from an eyewitness. Not all seizures are epileptic and among those that are, many are symptomatic of a concurrent illness.Brain anoxia only spontaneously recurring epileptic seizures require long-term anti-epileptic medication and this should be prescribed in consultation with a paediatrician.

References available upon request