Epilepsy and Seizure Disorders Flashcards
What is the definition of a seizure?
A transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. The common mechanism involves a fundamental disruption of the balance between inhibitory and excitatory neuronal activity and the development of recurrent excitatory circuits.
What is ictal semiology, interictal, and postictal?
Behaviors exhibited during a seizure are ictal semiology.
Interictal refers to the period between seizures.
Postictal refers to the period of time after a seizure occurs, as in postictal confusion or drowsiness.
What are generalized seizures?
seizures that arise in and rapidly engage bilaterally distributed networks
What are focal seizures?
Localized seizures involve more limited networks, typically within one hemisphere
What does the term simple partial seizure refer to?
Seizures not associated with impairment of consciousness or awareness, may include focal sensory or motor experiences or autonomic components
What does the term complex partial seizure refer to?
Seizures with alteration of consciousness or awareness
What does the term secondary generalized refer to?
Seizures evolving to a bilateral convulsive seizure
Define epilepsy?
Recurrent, unprovoked seizures. In most cases, seizures are a symptom of an underlying pathological condition or process affecting brain function
What epilepsies and electroclinical syndromes have an onset in the neonatal period?
Benign neonatal seizures
Benign familial neonatal epilepsy
Ohtahara syndrome
Early myoclonic encephalopathy
What epilepsies and electroclinical syndromes have an onset in infancy?
Febrile seizures Benign infantile epilepsy Benign familial infantile epilepsy West syndrome Dravet syndrome Myoclonic epilepsy of infancy Myoclonic encephalopathy in non-progressive disorders Epilepsy of infancy with migrating seizures
What epilepsies and electroclinical syndromes have an onset in childhood?
Febrile seizures, Febrile seizures plus
Early onset childhood occipital epilepsy
Epilepsy with myoclonic atonic seizures (astatic)
Childhood absence epilepsy (CAE)
Benign epilepsy with centrotemporal spikes
Late-onset childhood occipital epilepsy
Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE)
Epilepsy with myoclonic absences
Lennox Gastaut syndrome
Epileptic encephalopathy with continuous spike and wave during sleep
Landau Kleffner syndrome
What epilepsies and electroclinical syndromes have an onset in adolescence/adulthood?
Juvenile absence epilepsy
Juvenile myoclonic epilepsy (JME)
Epilepsy with generalized tonic-clonic seizures alone
Autosomal dominant epilepsy with auditory features (ADEAF)
Other familiar temporal lobe epilepsies
What epilepsies and electroclinical syndromes have a variable age of onset?
Familial focal epilepsy with variable foci
Progressive myoclonus epilepsies
Reflex epilepsy
What is the most common site of underlying pathology in adults and adolescents who have seizures with alteration of consciousness?
The temporal lobe, particularly the hippocampus. Adults often have hippocampal sclerosis characterized by neuronal loss in the hippocampal formation, mostly CA1 and CA3 subfields. The remaining neurons may become part of an epileptogenic network marked by synaptic reorganization.
What is the most common underlying pathology in childhood onset epilepsy?
The majority have idiopathic or cryptogenic epilepsy. Remaining are presumed intrauterine insult (7%), documented perinatal stoke (2%), or identified malformations of cortical development (MCD; 3%), neurocutaneous syndromes, chromosomal or genetic defect, and neurodegenerative conditions are also implicated.
What are known risk factors for seizure recurrence?
prolonged febrile convulsions that may induce neurological injury, neoplasm, disorders of neuroblast migration (cortical dysplasia, heterotopias, TBI)
What factors determine severity of cognitive impairment, and which is the most significant predictor?
Seizure frequency is most significant. Other variables include type of epilepsy risk factor (tumor, CNS infection, trauma), younger age of seizure onset, number of AEDs
Risk factors for Temporal Lobe Epilepsy (TLE)
Associated with hx of febrile seizures as an infant or toddler, especially prolonged seizures or recurrent episodes of febrile seizures; hippocampal sclerosis (HS) associated with perinatal complications, hyposix injury, CNS infections
Age of epilepsy onset in those with febrile seizure hx
Trimodal with peaks at age 5, 15, and 26, greatest frequency is in second decade of life
Behavior signs associated with TLE
Auras, often involving GI symptoms or psychic phenomena (deja vu), alteration of awareness, gradual clouding of consciousness, disorganized behaviors such as repetitive movements of hands, tongue, mouth, or lips; postictal confusion or fatigue is common for a few minutes to hours
How many cases of TLE with HS develop medically intractable seizures?
About one third
What are the risks of temporal lobectomy?
Problems with memory, language (naming), superior quadrantanopsia, longterm maintenance on AEDs
What are the benefits of temporal lobectomy?
Significant reduction of mood disturbance and increased quality of life, even with cognitive side effects (e.g., decline in material-specific learning)
Characteristics of childhood absence epilepsy (CAE)
Primary generalized epilepsy involving widespread neural networks at seizure onset; most common epilepsy syndrome of childhood (15%).
Age of onset between 3 - 8 years, peak occurrence around 6, with frequent remission during adolescence.
Children with CAE are otherwise neurologically normal, with normal brain imaging studies.
What behaviors characterize absence seizures?
Usually nondescript but involve a sudden alteration in consciousness, often described as “staring,” might involve subtle eyelid fluttering or lip movements, lasting 5-10 seconds
How is CAE treated?
Medications are usually very effective, especially ethosuximide (Zarontin) which is more effective than valproic acid and lamotrigine.
How many cases of CAE develop into juvenile myoclonic epilepsy?
About 15%
What is Landau-Kleffner syndrome (LKS)?
Pediatric condition involving abnormal EEG activity in the language-dominant perisylvian region. There’s normal language development prior to onset, until age 3 to 7 when progressive aphasias begins, followed by development of receptive language impairment, verbal auditory agnosia, expressive language deficits.
How does LKS affect intellectual and social function?
Many cases show regression of overall intellectual ability, deficits in attention, and some regression in sociability along with development of autistic behaviors
How does seizure treatment affect language deficits in LKS?
Treatment does not improve cognitive impairments, and disease course rarely shows spontaneous recovery of language.. Some patients improve with surgery in Wernicke’s area. Most require speech and language interventions such as learning sign language
What is Lennox-Gastaut syndrome?
Encephalopathic generalized epilepsy syndrome
-Patients present with multiple different seizure types (e.g., atypical absence, tonic, and atonic) and show regression of cognitive abilities, learning to severe cognitive impairment
Risk factors for Lennox-Gastaut
infantile spasms, MCD, neurocutaneous disorders, CNS infection, hypoxic-ischemic injury
EEG pattern of Lennox-Gastaut
Bursts of activity, especially during slow wave sleep, with background showing slow activity that may be disorganized or exhibit hypsarrhythmia pattern
What is Rasmussen syndrome?
Progressive unilateral encephalopathy with medically refractory seizures
- Typical onset between 3-14 years after normal premorbid cognitive and behavior development
- Seizure onset coincides with progressive cognitive decline in the side of seizure onset
- Eventual complete loss of function in the affected hemisphere, including hemiparesis
How is Rasmussen syndrome treated?
Aggressive surgical intervention such as modified functional hemispherectomy
In neuropsych assessment of epilepsy, how does IQ relate to seizures?
IQ serves as a general proxy for outcome, disease severity, and extent of underlying pathology
- Those with less severe epilepsy or more focal seizure onset are more likely to have normal IQ
- More severe epilepsy, or earlier onset, is associated with global cognitive impairments and low intelligence
Attention symptoms in epilepsy
30-40% of children with epilepsy have attention difficulties, predominately inattentive.
- Boys and girls are equally affected.
- Absence seizures tend to be more highly associated with attention problems.
What network is implicated in attention problems among children with absence seizures?
Anterior insula-frontal operculum and medial frontal cortex
What neuroanatomical differences have been identified in those with comorbid epilepsy and ADHD?
Increased gray matter volume especially in sensorimotor, supplementary motor, and prefrontal regions, as well as decreased brainstem volume
Processing speed symptoms in epilepsy and associated risk factors
Poor processing speed is often seen in epilepsy and can be associated with AEDs, decreased white matter, and frontal lobe epilepsy. Frequency of interictal epileptiform discharges and number of seizures may also affect processing speed.
How is language affected in epilepsy?
- Language deficits are common in epilepsy regardless of dominant hemisphere involvement
- Early seizure onset before or during critical language development can disrupt language networks
- More subtle language deficits are related to localized epilepsy involving dominant frontal or temporal lobes
- Progressive language impairment is less common but occurs in epilepsy syndromes Rasmussen or Landau-Kleffner
Describe language deficits in TLE
Deficits in word finding and semantic knowledge, confrontation naming
-Common in dominant hemisphere epilepsy as well as non-dominant, which may be related to prelexical object recognition and semantic association functions
What type of seizure activity is associated with visuospatial deficits?
-More common in primary generalized and generalized nonconvulsive epilepsy (e.g., CAE), and localization related epilepsy in the nondominant hemisphere.
What is the “crowding effect”
Visuospatial deficits in those with large, early onset epileptic lesions that provoke reorganization of language from left to right hemispheres or use bilateral support for language. It suggests there are preferential neural resources allocated for language development
Describe memory deficits in TLE
Material specific depending on side of seizure onset:
-Verbal memory impairment for dominant TLE
-Nonverbal/spatial memory impairment in nondominant TLE
Memory impairment is directly related to degree of hippocampal cell loss in those with TLE and HS
How are executive functions affected in epilepsy?
- More deficits associated with frontal-subcortical systems seizure involvement, often includes problems with planning, mental flexibility, impulse control, and motor coordination
- Dominant frontal lobe system epilepsy may impair word-list generation
- Nondominant frontal lobe epilepsy may impair nonverbal/figural fluency
How is emotion impacted in epilepsy?
Very high frequency of affective symptoms are found in those with epilepsy, especially anxiety and depression
What are refractory seizures?
Frequent seizures that don’t respond to AEDs
What is Rolandic epilepsy?
Childhood epilepsy with centrotemporal spikes, the most common form of partial epilepsy in childhood; begins between age 5-9, mostly in boys, and remits by puberty
- Seizures consist of unilateral paresthesias, movements of the face, and speech arrest
- May undergo secondary generalization during sleep
- Not associated with underlying structural lesions
- Inherited in autosomal dominant pattern
