When can an EEG typically be performed?
Click to see answer
On an outpatient basis when patients are otherwise well.
Click to see question
When can an EEG typically be performed?
On an outpatient basis when patients are otherwise well.
What is the effect of immediate antiseizure medication treatment in adults with a first unprovoked seizure?
It reduces the absolute risk of recurrence by about 35% for a subsequent seizure within the next 2 years.
Why must EEG interpretation be done in the context of clinical history?
Because approximately 3% of people without epilepsy may show epileptiform discharges, making an abnormal EEG not equate to epilepsy.
Did immediate antiseizure medication treatment improve quality of life or sustained seizure remission in adults?
No, it did not alter quality of life or improve the chance of obtaining sustained seizure remission over the longer term.
What caution should be taken regarding normal EEG variants?
Caution must be taken to not overinterpret normal variants as pathogenic.
What is crucial for excluding seizure mimics and provoked seizures in new-onset seizures?
A careful clinical history.
What is the yield of genetic testing in infants and young children with developmental and epileptic encephalopathies of unknown cause?
Approximately one-third to one-half of these patients have a pathogenic variant found.
What does the ILAE recognize as important in the definition of epilepsy?
The importance of comorbidities.
What misinterpretation can occur with vertex sharp waves in young children?
They may appear spiky and lead to misdiagnosis of central spikes.
Why is accurate classification of epilepsy important?
It assists with the choice of cost-effective investigations, optimal treatment, and accurate prognosis.
When should genetic testing be considered in patients?
In patients whose examination or investigations suggest a probable genetic cause.
What are the consequences of epilepsy according to the ILAE?
Neurobiologic, cognitive, psychological, and social consequences.
What should be addressed in all cases of new-onset seizures?
Counseling regarding seizure safety and first aid.
What is hypnagogic hypersynchrony often misinterpreted as?
Generalized spike and wave.
What are some conditions that may indicate a genetic-structural cause on neuroimaging?
Tuberous sclerosis complex or double cortex.
What is the consensus regarding treatment in children with new-onset seizures?
A similar consensus was reached as in adults, but few data are available from studies limited to children.
Why is it important to address cognitive and psychological comorbidities in epilepsy management?
They can have a greater impact on quality of life than seizures.
What are wicket waves and rhythmic temporal theta of drowsiness often miscalled in adolescents and adults?
They are often miscalled as epileptiform.
What are the medical implications of genetic testing?
Some genes may have implications for symptoms other than epilepsy, affecting relatives as well.
What does rhythmic temporal theta of drowsiness indicate in an EEG?
It can be a normal variant seen during light sleep, especially in children with a history of absence epilepsy.
What types of cognitive disorders are common in people with epilepsy?
Cognitive disorders that often precede seizure onset.
What reproductive implications arise from genetic testing?
The risk of passing on an abnormal variant.
What factors may contribute to cognitive disorders in epilepsy?
Underlying pathology, frequent seizures, and treatment-related effects.
Which neuropsychiatric disorders are more prevalent in individuals with epilepsy?
Attention deficit hyperactivity disorder and mood disorders.
What psychological implications should be considered before genetic testing?
The impact of potentially carrying an abnormal variant that could result in disease or increase risk in one's child.
Why is early identification of comorbidities critical in epilepsy?
They are treatable and can significantly worsen cognitive function if left untreated.
What financial implications may arise from genetic testing?
Insurance and financial implications related to the testing and potential findings.
What is the frequency of focal impaired awareness seizures in untreated patients?
Typically less than daily to monthly.
What was the diagnosis for the 9-year-old boy in the case study?
Self-limited epilepsy with centrotemporal spikes.
What types of genetic investigations are possible for epilepsy?
Karyotype, chromosomal microarray, single-gene sequencing, epilepsy gene panel, and whole-exome sequencing.
What is the duration of focal impaired awareness seizures?
Usually minutes.
What did the EEG show for the boy in the case study?
Occasional right centrotemporal discharges that became more frequent in sleep.
What is the postictal state like for focal impaired awareness seizures?
Usually present with confusion and possible language dysfunction if it affects the dominant temporal lobe.
What counseling was provided to the family regarding the boy's condition?
Teaching on seizure safety and counseling on the low risk of sudden unexpected death in epilepsy (SUDEP).
What are some clinical features of focal impaired awareness seizures?
Often contralateral head or eye deviation, contralateral dystonic posturing with ipsilateral automatisms.
What does the interictal EEG show in untreated patients with focal impaired awareness seizures?
Normal, focal slowing, or focal discharges.
What defines genetic epilepsy?
It is caused by a known or presumed genetic variant.
What is the frequency of absence seizures in untreated patients?
Often daily or more.
Which genes are associated with single-gene disorders in genetic epilepsy?
KCNQ2, CDKL5, and STXBP1.
What is the duration of absence seizures?
Usually less than 10-30 seconds.
What type of epilepsy is often associated with drug-resistant, early-onset developmental and epileptic encephalopathies?
Single-gene disorders.
What is the postictal state like for absence seizures?
Absent.
What is the underlying etiology of idiopathic generalized epilepsies?
Polygenic, with or without environmental factors.
What does the interictal EEG show in untreated patients with absence seizures?
Usually shows generalized spike-and-wave discharge, which may activate with hyperventilation or photic stimulation.
What should patients with new-onset seizures and focal neurologic deficits be considered for?
Urgent imaging, preferably MRI over CT.
What are common infectious etiologies of epilepsy?
Neurocysticercosis, HIV, cerebral malaria, Zika virus, and cytomegalovirus.
What other seizure types may be associated with absence seizures?
May have associated myoclonic or generalized tonic-clonic seizures.
Why is MRI preferred over CT for imaging in new-onset seizures?
MRI avoids radiation exposure and enhances detection of lesions.
What distinguishes infectious etiology from acute symptomatic seizures?
Infectious etiology implies epilepsy and seizures are core symptoms of the disorder.
What other seizure types may evolve from focal impaired awareness seizures?
May evolve to bilateral tonic-clonic seizure.
What factors may influence the choice of genetic testing in epilepsy cases?
Whole-genome sequencing and specific clinical features.
What is the sensitivity of CT for detecting small cortical epileptogenic lesions?
CT has low sensitivity for many small cortical lesions.
What is the purpose of investigations in the context of seizures?
To confirm epilepsy or provide information on the underlying cause.
What specific syndrome might be tested for in a child with global developmental delay and new-onset epilepsy?
Angelman syndrome.
What does a metabolic etiology imply in relation to epilepsy?
Epilepsy and seizures result from biochemical changes due to a known metabolic disorder.
What percentage of adults with new-onset seizures have a clinically relevant structural lesion on neuroimaging?
Approximately 10%.
What initial genetic tests are suggested for patients with epilepsy when the phenotype does not suggest a specific gene?
An epilepsy gene panel or whole-exome sequencing study.
What is an example of a treatable metabolic disorder related to epilepsy?
Glucose transporter disorder, treatable with a ketogenic diet.
What is the relative risk of seizure recurrence in individuals with imaging abnormalities?
Relative risk of 2.44.
What guidelines has the American Academy of Neurology developed?
An evidence-based guideline for managing a first seizure in adults and a practice parameter for evaluating a first nonfebrile seizure in children.
What counseling should be provided to individuals presenting with a first unprovoked seizure?
Counseling on lifestyle issues, seizure safety, and what to do if further seizures occur.
What characterizes immune epilepsy?
It results directly from an underlying immune disorder.
What laboratory studies are commonly done for patients with new-onset seizures?
Complete blood cell count, glucose, electrolytes, blood urea nitrogen, and creatinine.
What is the highest risk period for seizure recurrence after a first seizure?
The first 1 to 2 years after the seizure.
What percentage of children with new-onset seizures show an epileptiform abnormality on routine EEG?
Between 18% and 56%.
When should toxicology screening be considered?
If toxin exposure or substance abuse is a concern or if clinical findings suggest possible exposure.
What is the distinction between immune-mediated epilepsy and acute symptomatic seizures?
Immune-mediated epilepsy has an enduring predisposition to seizures, while acute symptomatic seizures occur secondary to autoimmune encephalitis.
What is the most important lifestyle modification for patients with new-onset seizures?
Safety around water.
What percentage of adults with new-onset seizures show an epileptiform abnormality on routine EEG?
Between 12% and 50%.
What clinical circumstances suggest a higher likelihood of underlying provoked seizures?
Failure to return to baseline alertness, vomiting, diarrhea, dehydration, and certain medical conditions.
What clinical signs suggest the need for a lumbar puncture?
New, unexplained fever with seizures, encephalopathy, or meningeal signs such as nuchal rigidity.
What percentage of patients with new-onset unprovoked seizures have no clear etiology found?
Approximately 30% to 50%.
What should patients be counseled about regarding driving after experiencing seizures?
Guidance varies depending on the place of residence; the Epilepsy Foundation provides updated driving laws for each state.
What additional testing should be considered in children with concerning clinical features and seizures?
Screening for inborn errors of metabolism.
What is the recommendation for lumbar puncture in children aged 6 months to 5 years with simple febrile seizures?
It should be performed if meningeal signs are present or if there is a suggestion of central nervous system infection.
Why is an EEG recommended for patients with a first unprovoked seizure?
It may impact management decisions.
What is the role of a qualified electroencephalographer in interpreting EEG results?
They are key in interpreting temporal epileptiform discharges and distinguishing between epileptic and nonepileptic events.
What is an example of a condition that has both structural and genetic etiology?
Tuberous sclerosis complex.
What common trigger for seizures should patients manage?
Sleep deprivation.
What should be done before a lumbar puncture if there are signs of increased intracranial pressure?
A brain imaging study should precede the lumbar puncture.
When is the diagnostic yield of EEG highest?
If performed within the first 24 hours after a seizure.
What should be done if a lesion is found on MRI?
Establish whether it is the underlying etiology for the seizures using clinical and electrophysiologic data.
What can routine EEG recordings capture?
Both epileptic and nonepileptic events.
What should patients understand about seizure rescue medication?
When and how to administer it, especially in emergencies.
Why might MRI studies in children under 3 years be limited?
Ongoing brain myelination often limits detection of lesions.
What phenomenon may cause transient focal slowing on an EEG after a seizure?
Postictal phenomena.
What are some clinical features that suggest an autoimmune etiology in seizures?
Frequent, drug-resistant seizures, cognitive/behavioral dysfunction, dysautonomia, and specific seizure types like faciobrachial dystonic seizures.
What activation parameters are typically used during routine EEG?
Hyperventilation and photic stimulation.
What is the significance of detecting specific antibodies in autoimmune encephalitis?
They result in acute symptomatic seizures and should be distinguished from immune-mediated epilepsies.
What potential risks should patients be informed about regarding recurrent seizures?
Status epilepticus, aspiration, and sudden unexpected death in epilepsy (SUDEP).
When should genetic testing be considered in epilepsy?
If the result will likely lead to a change in evaluation procedures, treatment choice, or prognosis.
How does sleep deprivation affect EEG yield?
It increases the yield, particularly for those with focal discharges.
What does focal epileptiform discharges in an EEG suggest?
A diagnosis of focal epilepsy.
When is antiseizure medication typically started?
In cases of new-onset epilepsy, but not in most cases of first unprovoked seizure with normal EEG and imaging.
What is the recommendation for neuroimaging in patients with new-onset, unprovoked seizures?
Neuroimaging is recommended for all patients except those with well-defined, drug-responsive idiopathic generalized epilepsy or self-limited focal epilepsy of childhood.
What does the case illustrate about the diagnosis of specific syndromes?
It provides key information for choosing optimal investigations, treatment, and prognosis.
What EEG finding is consistent with generalized epilepsy?
Generalized spike-and-wave discharges.
What is the yield of routine blood and urine studies in new-onset, unprovoked seizures?
They are commonly obtained but of low yield.
What EEG findings were consistent with a diagnosis of self-limited epilepsy in the case study?
Very frequent right centrotemporal sharp waves.
What is the risk of seizure recurrence after a first unprovoked seizure?
Approximately 40% to 50% within the next 2 years.
What is the risk of meningitis in children presenting with convulsive febrile status epilepticus?
Approximately 17%.
What does an EEG with epileptiform abnormalities indicate regarding seizure recurrence?
It is associated with a relative rate increase for seizure recurrence.
When should prolonged video-EEG monitoring be considered?
To exclude frequent subtle seizures or status epilepticus in specific clinical scenarios.
What is the recommendation regarding MRI for patients with epilepsy?
All patients should undergo MRI, except those with clearly defined, drug-responsive idiopathic generalized epilepsy syndromes.
Why is it important to diagnose cognitive and psychiatric comorbidities in people with epilepsy?
They often have a greater impact on quality of life than seizures.
What is the usual age at onset for Genetic epilepsy with febrile seizures plus?
Childhood.
What type of seizures are associated with Genetic epilepsy with febrile seizures plus?
Febrile seizures, which may persist after 6 years, and other focal or generalized seizures.
What does the interictal EEG typically show for Genetic epilepsy with febrile seizures plus?
Usually normal but may show generalized or focal discharge.
What is the prognosis for Genetic epilepsy with febrile seizures plus?
Usually remits with age.
What is the usual age at onset for Early infantile developmental and epileptic encephalopathy?
Less than 3 months.
What type of seizures are seen in Early infantile developmental and epileptic encephalopathy?
Tonic and/or myoclonic seizures.
What does the interictal EEG show for Early infantile developmental and epileptic encephalopathy?
Severely abnormal with diffuse slowing, multifocal discharges, and/or burst suppression.
What are common comorbidities associated with Early infantile developmental and epileptic encephalopathy?
Moderate or greater intellectual disability, hypotonia.
What is the prognosis for Early infantile developmental and epileptic encephalopathy?
Usually drug-resistant and lifelong.
What is the usual age at onset for Epilepsy with myoclonic-atonic seizures?
Preschool age.
What is the usual age at onset for Infantile epileptic spasms syndrome?
1-24 months.
What are the characteristic seizure types in Epilepsy with myoclonic-atonic seizures?
Myoclonic-atonic seizures, generalized tonic-clonic, absence, myoclonic, atonic, and occasionally tonic seizures.
What type of seizures are associated with Infantile epileptic spasms syndrome?
Clusters of epileptic spasms.
What does the interictal EEG show for Epilepsy with myoclonic-atonic seizures?
Slow background with high-amplitude generalized spike and wave.
What does the interictal EEG show for Infantile epileptic spasms syndrome?
Severely abnormal; usually high-amplitude background slowing with focal or multifocal discharge or hypsarhythmia.
What is the prognosis for most patients with Epilepsy with myoclonic-atonic seizures?
Two-thirds remit but may have mild attention or cognitive concerns; 1/3 do not remit and often have more severe learning and attention problems.
What is the prognosis for Infantile epileptic spasms syndrome?
High risk of drug-resistant epilepsy; may evolve to focal/multifocal epilepsy or Lennox-Gastaut syndrome.
What is the usual age at onset for Lennox-Gastaut syndrome?
Mostly preschool to school age; adolescent onset is rare.
What is the usual age at onset for Dravet syndrome?
1-20 months.
What types of seizures may occur in Lennox-Gastaut syndrome?
Tonic seizures; may also have generalized tonic-clonic, myoclonic, atonic, atypical absence, or focal seizures.
What type of seizures are associated with Dravet syndrome?
Often prolonged, hemiconvulsive, or generalized tonic-clonic seizures with fever.
What does the interictal EEG show for Lennox-Gastaut syndrome?
Slow background with high-amplitude, generalized slow (<2.5 Hz) spike and wave; generalized paroxysmal fast activity in sleep.
What does the interictal EEG show for Dravet syndrome?
Usually normal at onset.
What are common comorbidities associated with Lennox-Gastaut syndrome?
Intellectual disability (often moderate to severe), behavior problems.
What is the prognosis for Dravet syndrome?
Drug-resistant and lifelong.
What is the prognosis for patients with Lennox-Gastaut syndrome?
Drug-resistant and lifelong.
What is the usual age at onset for self-limited neonatal epilepsy?
First month of life, most in the first week.
What is the usual age at onset for Rasmussen syndrome?
Usually childhood.
What type of seizures are associated with self-limited neonatal epilepsy?
Focal clonic or tonic seizures which may evolve to bilateral tonic-clonic.
What type of seizures are characteristic of Rasmussen syndrome?
Focal/hemispheric seizures that increase in severity and frequency.
What is the prognosis for self-limited neonatal epilepsy?
Epilepsy remits by 6 months with normal development.
What does the interictal EEG show for Rasmussen syndrome?
Hemispheric background slowing and interictal discharge.
At what age does self-limited infantile epilepsy typically onset?
3-20 months.
What are common comorbidities associated with Rasmussen syndrome?
Progressive hemispheric dysfunction; acquired hemiparesis, visual field deficit, and possible language deficits.
What seizure types are seen in self-limited infantile epilepsy?
Focal impaired awareness or focal clonic seizures, which may evolve to bilateral tonic-clonic.
What is the prognosis for patients with Rasmussen syndrome?
Drug-resistant; often seizures resolve after hemispherotomy.
What is the common EEG finding in self-limited infantile epilepsy?
Usually normal.
What is the usual age at onset for developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep?
Late preschool or school age.
What is the prognosis for self-limited infantile epilepsy?
Most remit by early preschool years with normal development.
What types of seizures may occur in developmental and/or epileptic encephalopathy?
Focal motor, which may evolve to bilateral tonic-clonic seizures.
What age range is associated with self-limited epilepsy with autonomic seizures (Panayiotopoulos syndrome)?
2-9 years.
What does the EEG show for developmental and/or epileptic encephalopathy?
Significant activation of spike discharges in sleep, with near continuous slow spike and wave in slow sleep.
What type of seizures are characteristic of Panayiotopoulos syndrome?
Focal autonomic seizures (often retching or vomiting) with or without impaired awareness.
What is the prognosis for patients with developmental and/or epileptic encephalopathy?
Continuous spike and wave in sleep typically resolves by adolescence; however, seizures may persist depending on etiology.
What is the common EEG finding in self-limited epilepsy with autonomic seizures?
High-amplitude focal or multifocal discharges that increase in sleep.
What is the usual age for progressive myoclonus epilepsies?
Any age.
What is characteristic of seizures in progressive myoclonus epilepsies?
Progressive worsening of myoclonic seizures with time; often emergence of other seizure types.
What is the prognosis for self-limited epilepsy with autonomic seizures?
Remission by later childhood.
What does the EEG show for progressive myoclonus epilepsies?
Progressive background slowing and/or increased epileptiform discharges.
What age range is associated with self-limited epilepsy with centrotemporal spikes?
3-12 years.
What is the prognosis for patients with progressive myoclonus epilepsies?
Progressive decline with time; myoclonus is drug-resistant.
What type of seizures are seen in self-limited epilepsy with centrotemporal spikes?
Focal seizures with dysarthria, sialorrhea, and unilateral tonic or clonic movement of the lower face.
What is the common EEG finding in self-limited epilepsy with centrotemporal spikes?
High-amplitude centrotemporal discharges that increase in sleep; normal background.
What is the prognosis for self-limited epilepsy with centrotemporal spikes?
Remission by early adolescence.
What age range is associated with sleep-related hypermotor epilepsy?
Childhood and adolescence.
What type of seizures are characteristic of sleep-related hypermotor epilepsy?
Focal motor seizures with hyperkinetic or asymmetric tonic or dystonic features, occurring predominantly in sleep.
What is the common EEG finding in sleep-related hypermotor epilepsy?
Often normal but frontal discharges may be seen mostly in sleep.
What is the prognosis for sleep-related hypermotor epilepsy?
Often drug-responsive; surgery may be an option if drug-resistant.
What age range is associated with mesial temporal lobe epilepsy with hippocampal sclerosis?
2 years through adulthood.
What type of seizures are seen in mesial temporal lobe epilepsy with hippocampal sclerosis?
Focal aware or impaired awareness seizures with features referable to mesial temporal lobe.
What is the common EEG finding in mesial temporal lobe epilepsy with hippocampal sclerosis?
Often focal slowing or discharges in frontotemporal leads.
What is the usual age at onset for Childhood Absence Epilepsy?
3-10 years.
What comorbidities are associated with mesial temporal lobe epilepsy with hippocampal sclerosis?
Memory problems and depression.
What type of seizures are associated with Childhood Absence Epilepsy?
Typical absence seizures occurring multiple times per day.
What is the prognosis for mesial temporal lobe epilepsy with hippocampal sclerosis?
High incidence of drug resistance but may become seizure-free after resective surgery or thermoablation.
What is the interictal EEG finding for Childhood Absence Epilepsy?
Generalized 3-Hz spike-and-wave discharge.
What are common comorbidities associated with Childhood Absence Epilepsy?
Learning problems and attention deficit hyperactivity disorder (ADHD).
What is the prognosis for Childhood Absence Epilepsy?
Two-thirds remit typically by later childhood or adolescence; may evolve to juvenile myoclonic epilepsy if it does not remit.
What is the usual age at onset for Juvenile Absence Epilepsy?
8-19 years.
What percentage of Juvenile Absence Epilepsy patients will develop generalized tonic-clonic seizures?
Approximately 80%.
What is the prognosis for Juvenile Absence Epilepsy?
Often controlled with antiseizure medications, but remission is rare.
What is the usual age at onset for Juvenile Myoclonic Epilepsy?
Adolescence to young adulthood.
What types of seizures are associated with Juvenile Myoclonic Epilepsy?
Myoclonic seizures; most also have generalized tonic-clonic seizures.
What is the interictal EEG finding for Juvenile Myoclonic Epilepsy?
Generalized polyspike-and-wave discharge, often activated with photic stimulation.
What are common comorbidities associated with Juvenile Myoclonic Epilepsy?
ADHD, depression, anxiety.
What is the prognosis for Juvenile Myoclonic Epilepsy?
Often controlled with antiseizure medications, but remission is rare.
What is the usual age at onset for Epilepsy with Generalized Tonic-Clonic Seizures Alone?
Adolescence to young adulthood.
What is the interictal EEG finding for Epilepsy with Generalized Tonic-Clonic Seizures Alone?
3-Hz generalized spike and wave or polyspike and wave.
What are common comorbidities associated with Epilepsy with Generalized Tonic-Clonic Seizures Alone?
ADHD, depression, anxiety.
What is the prognosis for Epilepsy with Generalized Tonic-Clonic Seizures Alone?
Often controlled with antiseizure medications, but remission is rare.
What is the usual age at onset for Epilepsy with Eyelid Myoclonia?
2-14 years.
What types of seizures are associated with Epilepsy with Eyelid Myoclonia?
Eyelid myoclonia; many patients also have typical absence and generalized tonic-clonic seizures.
What is the interictal EEG finding for Epilepsy with Eyelid Myoclonia?
3- to 6-Hz generalized polyspike or polyspike-and-slow-wave.
What are common comorbidities associated with Epilepsy with Eyelid Myoclonia?
Mild cognitive delay, ADHD, anxiety, depression.
What is the prognosis for Epilepsy with Eyelid Myoclonia?
Eyelid myoclonia is often drug-resistant; remission is possible but rare.
What is the usual age at onset for Myoclonic Absence Epilepsy?
2-12 years.
What types of seizures are associated with Myoclonic Absence Epilepsy?
Myoclonic absence seizures; generalized tonic-clonic seizures may be seen in some cases.
What is the interictal EEG finding for Myoclonic Absence Epilepsy?
3-Hz generalized spike and wave time-locked with myoclonic jerks.
What are common comorbidities associated with Myoclonic Absence Epilepsy?
Mild cognitive delay, ADHD, anxiety, depression.
What is the prognosis for Myoclonic Absence Epilepsy?
Remits in approximately 40% of cases.
