History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include genetic predisposition or family history, antenatal or perinatal insults, metabolic/neurodegenerative disorders, traumatic brain injury, structural abnormalities of the central nervous system, history of febrile seizures, and neurocutaneous syndromes.
staring spells or inattention
Usual characteristics of absence seizures.
Brief impairment of consciousness that may be associated with motor arrest or with stereotyped movements. Often first noted by teachers.
It is important to differentiate between the two types of absence seizure, as they occur in different epileptic syndromes.
Typical absence seizure: behavioural arrest or staring, lasting 5-10 seconds, interrupting otherwise normal activity. Can be hyperventilation-induced.
Atypical absence seizure: less distinct beginning and end, not usually precipitated by hyperventilation.
May occur in the following syndromes: Dravet syndrome, epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, childhood absence epilepsy, epilepsy with myoclonic absence, juvenile myoclonic epilepsy, and juvenile absence epilepsy.
tonic-clonic seizures
Tonic phase involves the patient falling unconscious, possibly falling to the ground, and extension or flexion of extremities. May be preceded by aura. Clonic phase consists of usually violent muscle contractions, shaking, or vibrating. Eyes may roll back in head, tongue may be bitten, and incontinence may occur. Often followed by post-ictal phenomena.
May occur in the following syndromes: Dravet syndrome, epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, epilepsy with myoclonic absence, epilepsy with eyelid myoclonia, juvenile myoclonic epilepsy, and epilepsy with generalised tonic-clonic seizures alone.
Clonic or tonic seizures may also occur in isolation.
Early infantile developmental and epileptic encephalopathy usually presents with tonic spasm, and seizures often come in clusters.
brief, arrhythmic muscular jerking movements
Typical characteristics of myoclonic seizures.
Dominant seizure type in early infantile developmental and epileptic encephalopathy, which can also be associated with tonic spasms or focal motor seizures.
May also occur in the following syndromes: Dravet syndrome, epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, epilepsy with myoclonic absence, epilepsy with eyelid myoclonia, juvenile myoclonic epilepsy, and juvenile absence epilepsy.
eyes rolling back in head
Often observers will see the patient's eyes rolling back in the head during tonic-clonic seizures.
intercurrent illness
Many people who have recurrent seizures will experience increased frequency of seizures at times of intercurrent minor illness, especially if associated with increased temperature.
uncommon
unexplained falls
Brief loss of muscle tone followed by falling episodes is a typical characteristic of atonic seizures.
May occur in the following syndromes: epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, and epilepsy with myoclonic absence.
Other diagnostic factors
common
incontinence
Urinary or faecal incontinence may occur during tonic-clonic seizures.
tongue biting
Patient may bite tongue during tonic-clonic seizures.
post-ictal phenomena
Some patients may experience post-ictal phenomena such as sleepiness, headaches, amnesia, or confusion.
Usually occurs only with generalised tonic and/or clonic seizures.
precipitated by fatigue or lack of sleep
Fatigue may increase likelihood of seizures in a person with recurrent seizures.
Lack of sleep is a well-known precipitating factor for seizures in juvenile myoclonic epilepsy and in epilepsy with generalised tonic-clonic seizures only.[7]
precipitated by light or noise
Sometimes seizures can be induced by light. The following syndromes are known to be photosensitive: epilepsy with eyelid myoclonia, juvenile myoclonic epilepsy, epilepsy with generalised tonic-clonic seizures alone, Dravet syndrome, and progressive myoclonic epilepsies.[7][31][32]
Seizures may be provoked by external stimuli such as noise.
developmental delay
May be present in patients with epilepsy syndromes, and may first become apparent either before or after first seizure occurrence.
Children with Dravet syndrome have normal development before onset of seizures, but intractable seizures lead to developmental delay, intellectual disability, and sometimes also development of neurological abnormalities such as ataxia.[31]
Around two-thirds of children with epilepsy with myoclonic-atonic seizures have normal development prior to the onset of epilepsy; developmental delay occurs following onset. Development progresses, but some children will have a degree of intellectual disability.[32]
Most children with Lennox-Gastaut syndrome have developmental delay, which may be apparent before seizure onset. Over 90% of patients with a diagnosis of Lennox-Gastaut syndrome ultimately have moderate to severe intellectual disability.[32]
Patients with epilepsy with myoclonic absence may have intellectual impairment at seizure onset, and intellectual disability is ultimately found in around 70% of patients.[32]
It may be difficult to identify absence seizures or even absence status epilepticus in a child with developmental delay.
uncommon
neurocutaneous stigmata
Conditions with neurocutaneous signs can manifest with seizures.[12]
Tuberous sclerosis complex: depigmented macules, shagreen patches, periungual fibromas, adenoma sebaceum, and ash-leaf macules.
Neurofibromatosis type 1: cafe au lait spots, axillary and inguinal freckling, and plexiform neurofibromas.
Sturge-Weber syndrome: port wine-coloured haemangiomas on the face or trunk.
Risk factors
strong
genetic predisposition or family history
Most (but not all) recurrent generalised seizures are due to epilepsy syndromes with a genetic or presumed genetic aetiology.[3]
Some epilepsies are the result of monogenic inheritance; the genes responsible have been identified for some of the epilepsies in this group, such as familial neonatal seizures.[6]
However, for many epilepsies the patterns of inheritance are complex. Examples include the idiopathic epilepsies childhood absence epilepsy, juvenile absence epilepsy, and juvenile myoclonic epilepsy.[6]
antenatal or perinatal insults
Antenatal and perinatal insults are the most common cause of preventable aetiologies of epilepsy. These include fetal distress or asphyxia, and neonatal infection.[10]
metabolic/neurodegenerative disorders
Abnormal metabolic states (e.g., hypoglycaemia, hypocalcaemia) can often provoke seizures.
Recurrent seizures are part of a clinical picture of many metabolic/neurodegenerative disorders in childhood, although the background of this association is often not fully understood.
traumatic brain injury
Moderate or severe traumatic brain injuries may lead to recurrent seizures, which are known as post-traumatic epilepsy; however, focal seizures are more common in this setting.[10]
Estimates of how many people will develop post-traumatic epilepsy after brain trauma vary depending on the population studied. In one UK study, 9% of children who received inpatient rehabilitation for head injury went on to develop post-traumatic epilepsy.[11] The proportion of epilepsy among children that is attributable to traumatic brain injury is greater in low- and middle-income than in high-income countries.[10]
structural abnormalities of the central nervous system (CNS)
Structural lesions of the brain often lead to recurrent seizures; however, they are usually focal rather than generalised seizures, although in some cases there may be rapid bilateral spread leading to generalised seizure. Diffuse structural abnormalities, such as lissencephaly, can be associated with generalised seizures.
neurocutaneous syndromes
Conditions with neurocutaneous signs can manifest with seizures. These include tuberous sclerosis complex (depigmented macules, shagreen patches, periungual fibromas, adenoma sebaceum, and ash-leaf macules), neurofibromatosis type 1 (cafe au lait spots, axillary and inguinal freckling, and plexiform neurofibromas), and Sturge-Weber syndrome (port wine-coloured haemangiomas on the face or trunk).[12]
history of febrile seizures
Many studies show that a history of febrile seizures increases the risk of epilepsy, and this increased risk persists into adult life.[13]
Most common seizure types after febrile seizures are generalised tonic-clonic seizures, absence seizures, and focal motor seizures.
A genetic component has been suggested for febrile seizures.[14] Among children with a history of febrile convulsions, those who had complex febrile seizures, have a family history of epilepsy, or have developmental delay are at most risk of developing epilepsy.[15]
weak
autistic spectrum disorder
CNS infection
CNS infections such as meningitis, encephalitis, or parasitic infections may result in recurrent seizures beyond the setting of the acute infection. These are often focal in onset.[10]
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