Seizures and Epilepsy
A seizure is a set of transient signs and symptoms that arise due to abnormal excessive or synchronous activity in the brain.
Epilepsy describes a person’s tendency to have seizures and is defined as:
- At least two unprovoked seizures occurring more than 24 hours apart
- One unprovoked seizure and a probability of further seizures similar to the general recurrence risk after two unprovoked seizures over the next 10 years
- Diagnosis of an epilepsy syndrome
Non-epileptic seizures are seizures that do not occur due to epilepsy and abnormal neuronal discharge.
Provoked and unprovoked seizures
In general, seizures associated with epilepsy and have no identifiable reversible cause are called unprovoked seizures. Seizures that are caused by a reversible stimulus (e.g. drugs or toxins) are called provoked seizures.
Therefore, not all seizures are due to epilepsy.
Status epilepticus
Status epilepticus describes a seizure lasting 5 minutes or longer, or recurrent seizures without recovery in between. It is a medical emergency that is discussed more here.
Febrile Convulsions
Overview
Febrile convulsions are seizures accompanied by fever (>38°C) without signs of central nervous system (CNS) infection.
Febrile convulsions can be classified according to the type of seizure, duration, clinical features, and patterns of recurrence:
- Simple febrile convulsions:
- Isolated, generalised tonic-clonic seizures lasting <15 minutes
- They do not recur within 24 hours or within the same febrile illness
- There is complete recovery within 1 hour
- Complex febrile convulsions:
- One or more of the following features are present:
- Partial seizure (e.g. limited to one side of the body or limb)
- Duration >15 minutes
- Recurrence within 24 hours or within the same febrile illness
- Incomplete recovery within 1 hour
- One or more of the following features are present:
Febrile status epilepticus describes a febrile convulsion lasting 30 minutes or longer or if there are consecutive seizures without full recovery in between that last 30 minutes or longer.
Epidemiology
- Febrile convulsions tend to occur in children aged 6 months to 5 years
Risk Factory
- Family history – around 1/3 have a positive family history
- Viral infection – the cause in 80% of cases, especially roseola infantum (an infection due to human herpes virus 6, HHV-6) and influenza
- Other infections including urinary tract infections and gastroenteritis are risk factors as well
Presentation
There are no features of a CNS infection (e.g. headache, neck stiffness, and photophobia suggesting meningitis). Features of a simple febrile seizure include:
- Most febrile convulsions occur during the first day of a fever as the temperature rises quickly
- Most seizures are generalised tonic-clonic seizures and are brief, lasting <5 minutes
- There may be foaming at the mouth, difficulty breathing, pallor, or cyanosis
- There may be a brief post-ictal period of drowsiness, irritability, or confusion
Features of a complex febrile seizure include:
- Partial seizures
- >15 minutes duration
- Seizure recurrence within 24 hours or within the same febrile illness
- Incomplete recovery after 1 hour, prolonged post-ictal period, or Todd’s paresis
Diagnosis
The child should be examined for features of an alternate diagnosis, especially CNS infections such as meningitis or encephalitis. If there are no features suggestive of another diagnosis, febrile convulsions can be diagnosed clinically.
Although investigations are not routinely necessary, some may be appropriate such as:
- Blood glucose:
- If the child is having an acute seizure, is drowsy, or cannot be roused
- Urinalysis:
- If the underlying cause of infection is unknown
Management
Acute management of a febrile convulsion involves:
- Immediate first aid:
- Monitor duration of seizure
- Protect the child from injury – cushion head with hands or soft material and move harmful objects away
- Check the airway and put the child in the recovery position after the seizure has stopped
- Do not restrain the child
- Observe the child until they have recovered and examine for, and manage, any injuries
- If the seizure lasts >5 minutes call an ambulance
In children with recurrent febrile convulsions, rescue buccal midazolam or rectal diazepam may be prescribed only on the advice of a paediatrician.
Patient Advice
Advice regarding the nature of febrile convulsions:
- Febrile convulsions are not the same as epilepsy and the risk of the child developing epilepsy is relatively low
- Short-lasting seizures are not harmful to the child
- Around 1 in 3 children have another febrile convulsion
- The risk of febrile convulsions decreases with age as the brain matures and they are rare after 6 years of age
Advice regarding the management of febrile convulsions:
- Intermittent antipyretic use does not reduce the risk of or prevent a febrile convulsion. They should be given to reduce fever if the child is uncomfortable, or distressed, or to prevent dehydration
- A written action plan should be given with advice regarding:
- First aid
- How and when to use benzodiazepine rescue medication
- When to call an ambulance
Complications
- Parent/carer anxiety
- Febrile status epilepticus – occurs in around 5% of children with febrile convulsions
- Epilepsy – the risk of developing epilepsy is relatively small
- The risk is higher if any of the following are present: family history of epilepsy, complex febrile convulsions, neurodevelopmental problems such as cerebral palsy, and short duration of fever (<1 hour) before the seizure
- Without risk factors, the risk is around 2.4%
Prognosis
- The risk of febrile convulsions decreases with age and they are rare after 6 years old
- Without risk factors, the risk of developing epilepsy is around 2.4%
Infantile Spasms (West Syndrome)
Overview
Also known as West syndrome, infantile spasms are a form of epilepsy that presents in the first 4-7 months of life, with most cases starting under 1 year of age.
West syndrome has 3 main components, however, it can still be diagnosed in the absence of one:
- Infantile spasms
- Learning disabilities
- Hypsarrhythmia – a characteristic electroencephalogram (EEG) finding
Epidemiology
- Infantile spasms are rare and have an incidence of 4.5 in 10,000 live births
- Infantile spasms are confined to infancy and the majority of cases occur in <1-year-olds
Cause
The cause is not entirely known, however, many infants with infantile spasms have structural abnormalities on neuroimaging. Infantile spasms can be idiopathic.
Risk Factors
- Neurological disorders
- Antenatal or perinatal neurological complications such as hypoxic-ischaemic encephalopathy
- Intrauterine infections
- Genetic disorders such as Down’s syndrome
Presentation
- Spasms – sudden, rapid contraction of the trunk and limbs with gradual relaxation over 2 seconds
- These spasms occur in clusters and may repeat up to 50 times
- They tend to occur just before sleep or on awaking
- ‘Salaam’ attacks – a type of infantile spasm characterised by flexion of the head, trunk, and arms, followed by extension of the arms
- Learning disabilities and developmental milestone delays/regression
Diagnosis
If infantile spasms are suspected, seek advice from, and urgently refer the child to a paediatric neurologist within 24 hours for rapid assessment. Investigations a specialist may perform include:
- Sleep electroencephalogram (EEG):
- Shows characteristic hypsarrhythmia
- This may be found even between attacks
- Neuroimaging (e.g. CT/MRI head):
- Identifies structural abnormalities in many, but not all, cases of infantile spasms
Management
Treatment is initiated by a specialist and may involve:
- Combination therapy with high-dose oral prednisolone and vigabatrin
Prognosis
- The prognosis is generally poor, around 1/3 of infants are seizure-free, up to 50% have long-term developmental and neurological problems, and mortality is high throughout life
Lennox-Gastaut Syndrome
Overview
Lennox-Gastaut syndrome (LGS) is a rare childhood epilepsy characterised occurring in children aged 3-5 years. Around 20% of patients with LGS have prior infantile spasms.
Epidemiology
- Around 20% of LGS have prior infantile spasms
- LGS is around 5 times more common in boys than girls
Causes
LGS can be divided into:
- Secondary LGS – around 80% of cases, and causes such as brain injury and genetic mutations are identified
- Idiopathic LGS – no cause is known
Presentation
LGS has a triad of features that present over time at different ages:
- Seizures – axial tonic (flexion of the head, upper trunk, and head), atonic, and absence seizures, and drop attacks
- Learning difficulty – such as developmental milestone delay/regression
- Characteristic electroencephalogram (EEG) findings: slow spike waves.
Diagnosis
LGS is diagnosed by a neurologist and involves the use of an electroencephalogram (EEG) which shows slow spike waves.
Management
Treatment is initiated by a specialist and may involve:
- 1st-line: sodium valproate
- 2nd-line: lamotrigine
Prognosis
- The prognosis of LGS is generally poor but variable
- Epilepsy may improve in a minority of patients, however, learning difficulties still persist and complete resolution of epilepsy is rare
Benign Rolandic Epilepsy
Overview
Also known as self-limited epilepsy with centrotemporal spikes, benign Rolandic epilepsy (BRE) is the most common childhood epilepsy syndrome. The seizures begin in the central sulcus of the brain around the Rolandic fissure, hence its name, and most children outgrow BRE by adolescence, hence the term ‘benign’. The Rolandic area controls the face and oropharynx.
Epidemiology
- Benign Rolandic epilepsy is the most common childhood epilepsy syndrome
- BRE typically presents in children under 15 years old
- BRE is around 1.5 times more common in boys
Causes
BRE is thought to be a genetic disorder and around 1 in 4 patients have a family history.
Presentation
BRE tends to present with partial seizures that characteristically occur at night. The Rolandic area controls the face and oropharynx, explaining some of the symptoms seen:
- Unilateral facial twitching and stiffness with or without associated numbness/tingling
- There may be drooling and problems with speech
- The child is fully aware and does not lose consciousness and seizures only last 2-3 minutes
- The child is otherwise unaffected (i.e. no neurodevelopmental delays etc.)
The symptoms may go unnoticed as they can be subtle and occur at night. There may go on to become generalised tonic-clonic seizures and may be unnoticed until this happens.
Diagnosis
BRE is diagnosed by a neurologist and involves the use of an electroencephalogram (EEG) which shows characteristic centrotemporal spikes.
Management
Treatment is initiated by a specialist and may involve:
- 1st-line: lamotrigine or levetiracetam
- 2nd-line: carbamazepin
- e, oxcarbazepine, or zonisamide
Prognosis
- The prognosis of benign Rolandic epilepsy is generally excellent and most children stop having seizures 2-4 years after their onset.
- In nearly all cases, complete remission is seen by age 15 and children remain developmentally normal.
Juvenile Myoclonic Epilepsy (Janz Syndrome)
Overview
Also known as Janz syndrome, juvenile myoclonic epilepsy (JME) is an inherited childhood generalised epilepsy. It may be inherited in an autosomal dominant manner.
Epidemiology
- JME is one of the most common childhood/adolescent epilepsy syndromes
- JME usually presents between 12-18 years of age
Presentation
The majority of patients with JME have myoclonic seizures, followed by generalised tonic-clonic seizures, and then absence seizures.
- Sudden myoclonic jerks – especially early in the morning, following sleep deprivation, or after drinking too much alcohol
- Consciousness is preserved
- As time goes on, increasing frequency and intensity of these myoclonic jerks evolve into generalised tonic-clonic seizures:
- This tends to occur after a few months after the onset of myoclonic seizures
- Many patients may present with a GCTS after having myoclonus for many years
- Absence seizures are the least common type seen but may occur independently of the other seizures patients experience
- Around 40% of patients with JME have photosensitive epilepsy, where flashing lights can trigger seizures
Diagnosis
JME is diagnosed by a neurologist and involves the use of an electroencephalogram (EEG) which may show 3-6 Hz generalised polyspike and wave discharges.
Management
Treatment is initiated by a specialist and may involve:
- 1st-line: sodium valproate or lamotrigine for female patients of childbearing potential
Prognosis
- Seizures in JME are generally well-responsive to medication in most patients
- JME generally improves after the fourth decade of life, however, treatment is most likely to be lifelong as withdrawal of antiepileptic drugs may risk seizure recurrence
Breath-Holding Spells
Overview
Breath-holding spells (BHS) describe involuntary episodes of apnoea in children triggered by an emotional stressor such as when a child is hurt, frustrated, or frightened. They are not an attention-seeking behaviour and are involuntary. BHS is not epileptic.
BHS can occur in children with a normal neurological examination and normal developmental milestones, and they do not increase the risk of epilepsy or cause harm in the long term.
Epidemiology
- BHS is most common in children aged 6 months to 6 years
Cyanotic breath-holding spells
Cyanotic breath-holding spells are the most common type. They usually occur when the child is worked up, crying, or having a tantrum.
- The child cries for a brief period, becomes silent, stops breathing, and becomes cyanotic
- They then regain consciousness within a minute and may gasp for air and be tired
Pallid breath-holding spells (reflex anoxic seizures)
Also known as reflex anoxic seizures, pallid breath-holding spells generally occur after the child experiences pain. The child turns pale (pallid), loses consciousness, and goes into asystole.
The child regains consciousness after around 30 seconds. There is not usually any incontinence or a post-ictal phase, however, some muscle jerking may be present and the child may be sleepy after. There is no tongue-biting.
Pallid breath-holding spells are thought to be due to stronger signals from the vagus nerve to the heart causing it to stop beating.
Diagnosis
Diagnosis is made based on the history, normal ECG, and a normal electroencephalogram (EEG). Since breath-holding spells are associated with iron deficiency anaemia, the child may have iron studies performed.
Management
Management involves giving reassurance and advising the parents to place the child in the recovery position. In frequent and severe cases, pacemaker insertion may be considered.
Prognosis
- Breath-holding spells usually resolve by the time the child is 4-5 years old
