Epilepsy and Seizure Flashcards
Most common site of pathology that causes seizure
The temporal lobe, in particular the hippocampus, is the most common site of pathology in adults and adolescents with seizures that include alteration of awareness, accounting for as many as two thirds of cases.
Hippocampal sclerosis
histopathologically defined pattern of cell loss along with astrogliosis in the hippocampal formation.
List-learning measures tend to be the most sensitive to hippocampal pathology.
Three main features for classifying seizures:
focal - have onset originating in networks limited within one cerebral hemisphere and may be discretely localized within the hemisphere, more widely distributed within the hemisphere, or originate in subcortical structures.
generalized
undetermined
What is a seizure?
a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
A diagnosis of epilepsy is made when:
there have been at least two unprovoked seizures, at least 24 hours apart
or after a single unprovoked seizure when the risk for another is known to be high (>60%) based on other medical factors (e.g., positive imaging findings), or an epilepsy syndrome has been diagnosed (e.g., childhood absence epilepsy).
New onset epilepsy in a previously healthy adult is uncommon, and often associated with…
primary CNS neoplasm, neurovascular event, trauma,
infection, or autoimmune disorders (may be associated with primarily temporal lobe pathology)
Neonatal seizures are frequently associated with…
hypoxic ischemic encephalopathy, 35–45%
What often contributes to childhood epilepsy?
malformations of cortical development (MCD) and low-grade brain tumors
Types of malformations of cortical development
- abnormal neuronal and glial proliferation or apoptosis (programmed cell death)
- abnormal neuronal migration
- abnormal cortical organization
Causes of increased mortality in epilepsy in the absence of other mortality risk factors include:
- SUDEP (sudden unexplained death in epilepsy)
- unintentional injury (e.g., falls, drowning)
- suicide
- complications associated with status epilepticus.
Seizure variables associated with severity of cognitive impairment include
- Seizure frequency
- type epilepsy risk factor (e.g., tumor, central nervous system [CNS] infection, trauma)
- younger age of seizure onset - number of antiepileptic drugs (AEDs).
Temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS)
- associated with a history of febrile seizures as an infant or toddler
- difficult to treat; as many as 1/3rd of patients with TLE develop medically intractable seizures.
Behavior associated with temporal lobe epilepsy (TLE)
Auras - GI symptoms (“butterflies” in the stomach) or psychic phenomena (e.g., déjà vu)
alteration of awareness and gradual alteration of awareness, but not necessarily with loss of consciousness
repetitive movements of the hands, tongue, mouth, or lips. Repetitive movements of the hand are typically ipsilateral to the side of seizure onset
Speech patterns during or immediately following a seizure in TLE are significant for lateralization
- absence of speech is not necessarily lateralizing, but the ability to continue speaking clearly is associated with non–language dominant temporal lobe onset
- aphasic or dysnomic speech typically following dominant TLE seizures.
Postictal confusion and/or fatigue is common, and the duration can vary from a few
minutes to a few hours
Secondary generalization to a tonic-clonic seizure occurs up to 50% of the time in TLE.
Resection surgery to address TLE increases risk of
decreased efficiency in learning and memory
word-finding deficits (if language dominant)
visual field defects
Childhood absence epilepsy
primary generalized epilepsy in that it involves widespread neural networks at seizure onset
most common epilepsy syndromes in childhood (15%)
self-limiting epilepsy syndrome - seizures typically do not
persist past adolescence
seizures can persist into adolescence and adulthood and, in approximately 15% of cases, can develop into juvenile myoclonic epilepsy.
Age of onset is typically between 3 and 8 years, with the peak occurring around 6 years.
high incidence of comorbid learning and/or attention disturbance.
involve frontal and subcortical networks involved in regulating attention.
CAE is associated with attention problems that adversely affect encoding and storage of new information, with relatively greater impact on visuospatial and nonverbal memory.
Behaviors of childhood absence epilepsy
alteration in awareness is apparent - described as “staring.”
possible minor motor automatisms, such as eyelid fluttering or lip movements,
Landau-Kleffner syndrome
progressive encephalopathy (sometimes referred to as acquired epileptic encephalopathy) that particularly affects language.
onset between the ages of three and seven years
Characterized by language and cognitive deficits:
- progressive aphasia begins with development of receptive language impairment and verbal auditory agnosia, followed by gradual development of expressive language deficits.
- progressive cognitive impairments: including regression of overall intellectual ability and deficits in attention
Typically, the course does not typically include spontaneous recovery of language
Lennox-Gastaut syndrome
referred to as “encephalopathic generalized epilepsy syndrome” due to the progressive and severe cognitive impairments/regression that are typically observed.
may present with multiple different seizure types
Risk factor: history of infantile spasms, MCD, neurocutaneous disorders (e.g., tuberous sclerosis [TS] complex), CNS infection (meningitis, encephalitis), and hypoxic-ischemic injury.
Rasmussen syndrome
characterized by a progressive unilateral encephalopathy and medically refractory seizures (drug resistant)
the most commonly reported presentation is in children between 3 and 14 years.
premorbid cognitive and behavior development is normal.
Once seizures begin, a progressive course generally results in loss of cognitive skills related to the side of seizure onset (e.g., language decline in dominant hemisphere; visuospatial decline in nondominant hemisphere). Ultimately, there is nearly complete loss of function in the affected hemisphere, including hemiparesis.
Electrophysiological findings in Landau-Kleffner syndrome implicate…
the language-dominant perisylvian region but can be bilateral and also include frontal lobe pathology.
Treatment of Rassmusen syndrome
aggressive surgical intervention (modified functional hemispherectomy) is often considered the best course.
Factors associated with normal IQ
less severe epilepsy & more focal seizure onset
risk factors for low IQ
age of seizure onset, with earlier onset associated with lower overall IQ
independent of other factors thought to be related to cognitive decline, such as seizure frequency or location of seizure onset.
localization of seizure onset may not have the expected influence on IQ; for example, verbal–nonverbal intellectual skill discrepancies have not been found to be a lateralizing sign in focal epilepsy syndromes.
Risk factors for IQ decline
seizure severity and treatment with multiple medications (which may also be a result of seizure severity)
