Introduction

Epilepsy is a chronic neurological condition of recurrent seizures in the absence of a precipitating event.  A seizure is an abormal paroxysmal period of neuronal discharge in the brain that can result in a variety of signs and symptoms dependent on the type and location of the abnormal firing.  The main seizure types are shown in the table below.

Aetiology

The majority (approximately 80%) of childhood epilepsies are idiopathic, though genetic predisposition to abnormal neuronal regulation does play a role.  Epilepsy may also be secondary to a variety of central nervous system insults, the most common of which is hypoxic injury, such as that following a difficult birth or trauma.  This is also known as symptomatic epilepsy.

Other causes of secondary epilepsy include:

  • Cerebral dysgenesis/malformation
  • Cerebral damage resulting from infection
  • Cerebral tumour
  • Neurodegenerative disorders, e.g. tuberous sclerosis
  • Neurocutaneous syndromes, e.g. neurofibromatosis or ataxia telangiectasia.

 

Epilepsy that is presumed to arise from a lesion that has not yet been found is often referred to as cryptogenic epilepsy.

Classification

The classification of epilepsy follows a multi-axial diagnostic scheme encompassing not only the seizure type, but also the aetiology and whether symptoms fit a known syndrome.  Failure to classify a child's epilepsy can lead to incorrect or ineffective management, and prevents the giving of an accurate prognosis.  Most children will have their epilepsy classified based on the cause and localisation of the seizures, but some fit more specific syndromes describing non-seizure related symptoms.

Important syndromes to be aware of are:

  • Typical absence epilepsy: an idiopathic generalised epilepsy occuring in prepubescent children.  The child predominately suffers absence seizures, though some also develop tonic-clonic seizures.  There are no neurodevelopmental deficits.
  • Infantile spasms: presents in infants aged 4-6 months as violent flexor spasms of the body, followed by extension of the arms.  The majority of cases are due to an underlying abnormality, and individuals may show delayed development or even developmental regression.
  • Lennox-Gestaut syndrome: presents in children aged 1-3 years as multiple generalised seizure types.  Individuals show developmental arrest/regression.
  • Juvenile myoclonic epilepsy: presents in adolescence or early adulthood as myoclonic or tonic-clonic seizures shortly after waking.  Other generalised seizure types may be present but there are no other deficits.
  • Benign rolandic/centrotemporal lobe epilepsy of childhood: presents in prepubescent children as focal seizures affecting the facial muscles during sleep.
The main types of seizure.

Differential Diagnosis

The differential diagnosis of epilepsy is shown below.  Diagnosis of epilepsy should only be made by a specialist paediatrician, and is only considered after a second seizure (except in rare cases).

The differential diagnosis of epilepsy.

Investigations

Investigatons in cases of suspected epilepsy have three main purposes:

 

1) To rule out other causes of seizure.

  • Blood and urine biochemistry
  • Assessment of fever or infection status

 

2) To determine whether the epilepsy is idiopathic or secondary.

  • Neuroimaging: this is particularly important if the child is under 2 years of age, experiencing focal seizures, or if seizures continue despite treatment with first line medications.
  • MRI is the first choice, but CT can be used if an MRI is unsuitable (e.g. if the child would require sedation for an MRI).

 

3) To support a diagnosis of epilepsy following a second seizure, or allow classification of epilepsy.

  • A common misconception is that an EEG will determine whether an individual has epilepsy or not.  However, some patients with epilepsy will have a normal EEG, and some individuals who have never had a seizure will show epileptiform activity.  As such they should not be used in isolation to make a diagnosis (if you order an EEG for that purpose, your request form is likely to be returned attached to a snarky note from an unimpressed EEG technician!).
  • EEGs may be used to help determine seizure type and syndrome in those with suspected epilepsy.  This enables them to be given the correct prognosis.
  • When a standard EEG has not contributed to the diagnosis, a sleep EEG or ambulatory EEG can be used if there are diagnostic difficulties.

 

Despite these investigations being available to aid in diagnosis, the most important diagnostic tool in epilepsy is the history; this is covered in the Fastbleep 'Suspected Seizure' article.  Video recording of seizures can also help the doctor form a diagnosis.

Up to one third of children diagnosed with epilepsy actually suffer non-epileptic attacks.  Considering the toxicity of anti-epilepsy drugs and the dangers of labelling a child as having epilepsy, great care must be taken with history and investigations to ensure the correct diagnosis.

Management

Seizures are not only unpleasant for the child and carers, but can also lead to serious problems.  Recurrent seizures increase the risk of developing intractable epilepsy, cognitive impairment, physical injury and psychological problems, including loss of self esteem and mood disturbance.  Absence seizures during school time, or time away from school as a result of epilepsy, can lead to academic underperformance.  Seizures (or fear of seizures) can result in restrictions in social and sporting activities.

Sudden Unexplained Death in Epilepsy (SUDEP) is a rare but obviously important condition, in which a sufferer dies from sudden respiratory or cardiac arrest following a seizure but no abnormality is seen on post mortem.  Risk of SUDEP can be minimised by optimising seizure control.

 

Conservative/lifestyle measures

The importance of giving the child and family appropriate and comprehensive information about epilepsy is not be be underestimated.  Issues to be discussed include:

  • Treatment options
  • Seizure triggers and their avoidance
  • Safety and injury prevention at home/school/during social activities
  • SUDEP
  • Status epilepticus (see below)
  • Benefits and social service support available
  • Support groups

When the child is older, other lifestyle issues need to be discussed, such as those surrounding recreational drugs, alcohol, sleep deprivation, family planning, and the impact of epilepsy on driving and career options.

Epilepsy specialist nurses (EPNs) support paediatricians and GPs in providing information, training and support to the child and those involved in their welfare.  This includes visits to homes and schools.

 

Pharmacological management

Pharmacological management of epilepsy must be tailored to the individual's seizure type, syndrome, lifestyle, comorbidity and the wishes of the child and their carers.  It is usually split into two categories: preventative medications, which includes the anti-epilepsy drugs (AEDs), and rescue medications, which stop seizures once they have already begun.

AED treatment is not able to cure epilepsy, but aims to deliver 'freedom from seizures', with minimal side effects, thus improving quality of life.  AEDs are only prescribed following a diagnosis of epilepsy (except in rare cases) and must always be initiated by a specialist.

The seizure type will determine the best medications for the child.  First line treatments (as recommended by NICE) are shown in the table below.  Drugs in bold type (the 'new' AEDs) are to be tried first, before switching to 'old' AEDs (in normal type).  * indicates the AED is a hepatic enzyme-inducing drug, and so care needs to be taken to avoid interactions with other medications.

 

Acute management

*see Fastbleep article 'Suspected seizure'

 

The first line treatments for epilepsy.

Monotherapy is to be used where possible - if monotherapy with one drug doesn't work, monotherapy with another drug is tried.  Combination therapy should only be used when attempts at monotherapy have not been successful.  However, if seizures remain refractory to two or more drugs children should be referred to tertiary services for consideration of surgical treatment.

The ketogenic diet may also be considered in children who are not achieving seizure control on medications alone.  It was widely used before anticonvulsants became available, but is now beginning to be used again as a treatment option following some promising results of clinical trials.  It is a high fat, low carbohydrate diet resulting in ketosis, which significantly reduces the frequency of seizures in 50% of patients.

First line rescue mediation is rectal diazepam; however in some instances this may not be acceptable, and buccal midazolam can be used (off licence).  Anyone who may be needed to administer rescue medicines (e.g. carers, teachers) must receive comprehensive instructions on when and how to give them, and when to call for emergency services.

 

Surgical management

Resective surgery may be considered in those with intractable epilepsy secondary to a cerebral lesion.  This surgery may be curative or palliative.

A more common surgical intervention is the implantation of a Vagal nerve stimulator.  A device similar to a cardiac pacemaker is implanted in the neck, and sends electrical impulses along the Vagus nerve at regular intervals.  How this reduces seizure frequency is unknown, but it is effective in approximately 50% of patients.

 

Follow-up

The frequency of epilepsy reviews is determined by the child's epilepsy and the wishes of their carers, but the maximum acceptable length of time between reviews with a specialist is 1 year.

 

Prognosis

Epilepsy is a chronic condition, and many individuals will need lifelong AED treatment.  However, medication withdrawal may be attempted in those who have been seizure-free for 2 years, as epilepsy may go into remission.

Childhood epilepsy has higher remission rates than adult epilepsy, but is dependent on seizure type, syndrome and aetiology.  For example, 95% of those with typical absence epilepsy will go into remission, although 5-10% will go on to develop tonic-clonic seizures later in life.  Juvenile myoclonic epilepsy, however, is almost always lifelong.

 

 

Suggested OSCE Revision Tasks

  • Sit in with a physician explaining the diagnosis of epilepsy with a concerned carer / discuss pharmacological management of epilepsy with a carer.
  • Speak to parents about their child's epilepsy, seizures and challenges of treatment.
  • Explain the purpose of an EEG and gain consent from a carer.

 

 

Further Reading

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