Epilepsy • THEME Epilepsy syndromes in children Patrick W Carney BACKGROUND Understanding the common childhood epilepsy syndromes is valuable when approaching BSc, BMed, is a the diagnosis and management of a child presenting with seizures. neurology registrar, Austin Health, OBJECTIVE This article discusses the common epilepsy syndromes in children and provides a guide Melbourne, Victoria. to appropriate investigation and management of these syndromes. patrick.carney@ austin.org.au DISCUSSION A careful history and examination, supported by an electroencephalogram, are the cornerstones of epilepsy syndrome diagnosis. This, in turn, guides the need for further investigation such as magnetic Michael A Prowse resonance imaging, optimisation of therapy and prognostic counselling. Understanding the implications MBBS, FRACGP, is a of a specific syndrome diagnosis helps support families who are frequently overwhelmed by a diagnosis general practitioner, of epilepsy in their child. Berwick, Victoria. Ingrid E Scheffer PhD, FRACP, is pilepsy is defined as more than one unprovoked child, and Professor and E paediatric neurologist, 1 seizure and is essentially a clinical diagnosis based on • symptomatic – epilepsy occurs in the setting of Departments of an eye witness account of the attacks. When a child or a known or suspected abnormality of the central Medicine and Paediatrics, The adolescent presents with their first seizure, a detailed nervous system (Table 3).2,3 University of history should be sought for other seizure types that For example, a child with developmental delay has Melbourne, Austin may not have previously been appreciated (Table 1, symptomatic epilepsy, as does an individual with Health and Royal Children’s Hospital, 2). For example, an adolescent presenting with their hippocampal sclerosis. Melbourne, Victoria. first generalised tonic-clonic seizure (GTCS) may have The epilepsies are further subdivided into: had subtle absence or myoclonic seizures; diagnosis • generalised – seizures arise from both hemispheres of these seizure types is critical to diagnosis of the simultaneously, and specific epilepsy syndrome. An electroencephalogram • partial (or focal) epilepsy – which begins in one part of (EEG) provides supporting evidence for diagnosis the brain and may secondarily generalise. of a specific epilepsy syndrome; if a routine EEG is normal, a sleep deprived study should be considered. Generalised epilepsies In individuals with focal epilepsy not classified as idiopathic partial epilepsy, magnetic resonance Idiopathic generalised epilepsies Absence seizures are the hallmark of childhood imaging (MRI) should be performed. Investigations may be initiated by a general practitioner, but more absence epilepsy (CAE) and juvenile absence epilepsy sophisticated syndrome diagnosis would usually be (JAE) (Table 3). Typical absence seizures, or ‘staring made by a paediatrician or neurologist. spells’, have an abrupt onset without warning and rapid offset with resumption of previous activities (Table 1, Classification of the epilepsies 2). The events are brief, lasting less than 20 seconds, The International League Against Epilepsy (ILAE) and awareness is impaired. Other features may include classifies epilepsy syndromes as: mild clonic, myoclonic, atonic or tonic movements, and • idiopathic – epilepsy develops in an otherwise normal oral and manual automatisms.4,5 Reprinted from Australian Family Physician Vol. 34, No. 12, December 2005 4 1009 Theme: Epilepsy syndromes in children Table 1. Common generalised seizure types Seizure type Clinical features Postictal Duration Usual epilepsy syndrome Absence Abrupt onset of staring Abrupt return to <30 seconds CAE, JAE with cessation of normal motor activity Myoclonic Brief contraction of Abrupt return to <5 seconds IGE, Lennox- muscle/muscle groups normal Gastaut, progressive, either singularly or myoclonus epilepsies repetitively Tonic-clonic seizure May begin with a cry Drowsiness may Usually <5 minutes May be generalised or fall to the ground be prolonged with from onset, secondarily followed by tonic recovery taking generalised with flexion. This is followed minutes to hours. focal onset or occur by a clonic phase Postictal confusion and due to an acute involving symmetrical agitation is common metabolic disturbance. movement of all limbs. Associated with Autonomic features a broad range of are common as are epilepsies including incontinence and IGE and SGE tongue biting Tonic Tonic extension of 10 seconds SGE especially the all limbs with semi- Lennox-Gastaut flexed arms (bear syndrome hug). Patients often fall backward Atonic Classic drop attacks Few seconds SGE including Lennox- with sudden loss Gastaut syndrome of postural tone Table 2. Common partial (focal) seizure types and adversely affect school performance. Absence seizures may be triggered by stress, fatigue, and Location Clinical features hyperventilation. The EEG shows bilaterally synchronous Temporal Aura may involve epigastric sensation, olfactory 3 Hz spike and wave discharges (generalised spike or gustatory hallucinations, autonomic features, wave [GSW]) on a normal background. Trains of 3 Hz dysmnestic changes such as déjà vu followed by loss GSW correlate with a clinical absence seizure on EEG; of awareness and automatisms involving the mouth hyperventilation is used to trigger GSW and absence or upper limbs. Duration 30–300 seconds with a brief period of postictal confusion seizures during an EEG (Figure 1). Childhood absence epilepsy may be accompanied by GTCS, which tend to Frontal May be hyperkinetic with motor automatisms or an asymmetric tonic seizure depending on the location occur later in adolescence. Seizures resolve in 60% of in the frontal cortex; may be incontinent children by mid adolescence.4,5 Occipital Visual symptoms including hallucinations, field Juvenile absence epilepsy defects, and flashing lights; may vomit Juvenile absence epilepsy differs from CAE not only Childhood absence epilepsy because of a later age of onset (after the age of 10 Childhood absence epilepsy begins between 3 and years and occasionally as late as 20 years), but also 12 years of age with peak onset at 6 years. Absence because of the seizure pattern. Absence seizures seizures occur frequently, often 20 times per day,5 are less frequent, perhaps once per week, and less 1010 3Reprinted from Australian Family Physician Vol. 34, No. 12, December 2005 Theme: Epilepsy syndromes in children severe impairment of awareness may occur. Other Table 3. ILAE classification of epilepsy syndromes2 seizure types, such as GTCS, are more common. The EEG shows faster GSW, usually at 3.5–4.0 Hz and Generalised occasionally faster, and generalised polyspike wave Idiopathic generalised epilepsy syndromes with age related onset is often seen.6 (in order of age) Juvenile myoclonic epilepsy Benign neonatal convulsions – sporadic and familial forms Childhood absence epilepsy Juvenile myoclonic epilepsy (JME) accounts for up to Juvenile absence epilepsy a quarter of idiopathic generalised epilepsies (IGE). Juvenile myoclonic epilepsy Onset is in adolescence (8–20 years of age) and is Epilepsy with generalised tonic-clonic seizures alone characterised by isolated myoclonic seizures, especially Symptomatic generalised epilepsies (in order of age) after awakening (see Case study 1). Other seizure West syndrome types are common including GTCS in up to 80% of Lennox-Gastaut syndrome patients and absence seizures in 30%. Seizures often Epilepsy with myoclonic-astatic seizures occur following sleep deprivation, fatigue and alcohol use.8 The EEG shows 4–6 Hz polyspike wave and Focal/partial seizure disorders photosensitivity is common; occurring in more than Idiopathic focal epilepsies 30% of individuals.7 Benign epilepsy with centro-temporal spikes Treatment of IGE Childhood epilepsy with occipital paroxysms Valproate is the drug of first choice for IGE.8 Although Symptomatic focal epilepsies generally well tolerated, common side effects include Temporal lobe epilepsy weight gain and fatigue. Another concern for teenage Frontal lobe epilepsy girls is teratogenesis, as valproate is associated Parietal lobe epilepsy with an increased incidence of neural tube defects. Occipital lobe epilepsy Contraceptive advice should be provided and specialist advice sought before conception. Lamotrigine is an Epilepsies or syndromes undetermined as to whether focal effective second line agent, especially in combination or generalised with valproate. The principal side effect of lamotrigine Neonatal seizures is rash, which is more likely when on valproate co- Dravet syndrome (severe myoclonic epilepsy of infancy therapy. Therefore, lamotrigine should be started at a Epileptic-aphasia syndromes low dose and slowly increased over several months. Other medications include topiramate, clobazam and Special syndromes clonazepam.9,10 Febrile seizures Isolated seizures or isolated status epilepticus Symptomatic generalised epilepsies Acute symptomatic seizures (associated with acute metabolic or toxic event) The symptomatic generalised epilepsies are characterised by multiple seizure types and other neurological deficits including intellectual disability. West syndrome West syndrome usually begins at 6 months of age (range 3–12 months years) and is sometimes mistaken for infantile colic. The baby has clusters of epileptic spasms, developmental arrest or regression. The EEG shows hypsarrhythmia with continuous multifocal epileptiform activity. Cerebral malformations