Seizure Physiology Flashcards
A seizure is…
A transient occurrence of signs +/- symptoms due to abnormal excessive or synchronous neuronal activity in the brain
Epilepsy is…
Disorder of the brain characterized by an enduring predisposition to generate epileptic seizures
Epilepsy diagnosis is expanded to include patients…
With only 1 unprovoked seizure, but at significant risk of seizure recurrence
EEG, brain injury, structural brain abnormalities, nocturnal seizures
An unprovoked seizure is one that occurs…
In the absence of an acute brain event (stroke. head trauma, infection)
Etiology of seizures is…
Variable causes - largely unknown
Genetics
Structural lesions in the brain
Metabolic disorders
Infectious
Immune
Anything that disturbs normal functioning of cerebral cortex can cause seizures
Synchronous hyperexcitability may be due to…
Increased excitatory and decreased inhibitory synaptic neurotransmission
Alteration of voltage-gated ion channels
Alteration of intra/extracellular ion concentrations
Hypersynchrony (recruitment of neighbouring neurons into an abnormal firing mode)
Many of the ASMs target 1+ of these possible causes
Seizures have profound impact on patient’s lives, such as…
Stigma
Fear of seizures
Injuries/hospitalizations
Lost productivity
Development of anxiety + MDD
Increase in mortality
Seizures can manifest in many ways, which generally reflect…
The electrical discharges in various locations in the brain - different functions can be impacted
Ex: sensory, motor, autonomic, emotions, consciousness, memory, cognition
Not just convulsions!
Accurate seizure classification is critical, for…
Selecting the most appropriate ASM - not all ASM’s treat all seizure types, and some drugs can lead to seizure worsening when used for the incorrect seizure type
A seizure is classified as focal…
When it originates within networks limited to one hemisphere
Can progress to generalized
A seizure is classified as generalized…
When it originates at some point within, and rapidly engaging, bilaterally distributed networks
A seizure is classified as unknown when…
Seizures are unwitnessed and difficult to classify - or occur while the patient is asleep
Focal seizures can present as…
Aware (simple partial)
Impaired awareness (complex partial)
Can include motor onset (atonic, clonic, tonic, automatisms) and nonmotor onset (cognitive, emotional, sensory)
Generalized onset seizures can present as…
Tonic-clonic (bilateral sharp tonic contractions, periods of rigidity + clonic mvmts)
Myoclonic (brief bilateral shock-like muscle contractions)
Absence (sudden onset of loss of consciousness, no motor activity, blank stare)
Epilepsy syndromes refers to…
Clusters of features that may occur together
Includes seizure type, EEG and imaging findings, age-dependent features, specific comorbidities, triggers, and prognosis
