IC6- Seizures and Epilepsy I Flashcards
Define seizure
Transient occurence of SSx due to abormal excessive or synchronus neuronal activity in the brain
Define epilepsy
Disease of the brain defined by any of the following conditions:
1. AT LEAST 2 unprovoked seizures occurring > 24 h apart
2. One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
3. Diagnosis of an epilepsy syndrome
Define acute symptomatic seizures
Seizures that result from some immediately recognizable stimulus or cause, i.e. that occur in the presence or close timely association (about a week) with an acute brain insult (metabolic, toxic, structural, infectious, hypoxic, etc.)
Define remote symptomatic seizures
Seizures that occur longer than 1 week following a disorder that is known to increase the risk of developing epilepsy
Define unprovoked seizures
- Seizures occurring in the absence of a potentially responsible clinical condition
OR - Beyond the interval estimated for the occurrence of acute symptomatic seizures
What are the metabolic etiologies of acute symptomatic seizures? (4)
- Hyponatremia
- Hypocalcemia
- Hypomagnesemia
- Hypoglycaemia
What is the etiology of acute symptomatic seizures from toxic substances/ drugs? (4)
- Illicit drugs (e.g. cocaine, amphetamines)
- Drugs (e.g. Tricyclic antidepressants, carbapenems, baclofen)
- ETOH (withdrawal & intoxication)
- Benzodiazepine withdrawal
What are the structural etiologies of acute symptomatic seizures? (2)
- Stroke
- Traumatic Brain Injury
What are the infection/ inflammation etiologies of acute symptomatic seizures? (2)
- CNS infection
- Febrile illness
Define non-epileptic events
Abnormal paroxysmal psychic, sensory and/or motor manifestations which resemble (at least in part) to epileptic seizures but are not related to abnormal epileptiform discharges
What are the 2 types of non-epileptic events?
- Psychogenic non-epileptic seizures (PNES)
- Physiological non-epileptic events
Elaborate more on Psychogenic non-epileptic seizures (PNES)
- Partial alteration of level of consciousness with a partial preservation of awareness
- Caused by stressful psychological experiences or emotional trauma
- Involuntary
Elaborate more on physiological non-epileptic events. Give some examples
- Symptoms of a paroxysmal systemic disorder (e.g. convulsive syncope, hypoglycemia, movement disorders, migraine aura, non-ictal dysautonomia, intoxications, transient ischemic attacks, balance disorder, sleep disorders, panic attacks)
Which factors make a pt more susceptible to ‘drug-induced seizures’
- Previous seizures
- Structural or functional brain abnormalities
- Concurrent drug use
Name some common drugs which are known to lower the seizure threshold (IMPT!) (4)
- High dose β-lactams
- Opioids (analgesics) (eg. tramadol)
- Immunosuppressants (cyclosporine)
- Stimulants (dextroamphetamine, methylphenidate)
- Buproprion (antidepressant/ smoking cessation)
What are the 2 components of the pathophysiology of a seizure?
Hyperexcitability and Hypersynchronization
In the pathophysiology of seizures, what contributes to the hyperexcitability (enhanced predisposition of a neuron to depolarize)? (4)
- Voltage- or ligand-gated K+, Na+, Ca2+, and Cl– ion channels
– Abnormalities in intra- & extracellular substances (e.g., Na+, K+, O2, glucose, etc) - Excessive excitatory neurotransmitters (e.g. glutamine, acetylcholine, histamine, cytokines, etc)
- Insufficient inhibitory neurotransmitters (e.g.GABA, dopamine)
In the pathophysiology of seizures, what contributes to the hypersynchronization?
Hippocampal sclerosis:
- Intrinsic reorganization of local circuits- hippocampus, the neocortex and the thalamus
- Contribute to synchronization and promote generation of epileptiform activity
What is the etiology of epilepsy? (5)
- Structural
- Eg. Hippocampal sclerosis, brain tumours, vascular malformations, glial scarring (including stroke and traumatic brain injury) - Genetic/presumed genetic
- Eg. Dravet syndrome with SCN1A mutations - Neurodegenerative
- Eg. Alzheimer’s disease - Metabolic
- Eg. Inborn errors of metabolism, mitochondrial disorders - Infectious
- Eg. Bacterial menigitis, encephalitis, neurocysticercosis
State the ILAE Classification of epilepsy.
What are the different types of onset of seizures? What do they mean?
- Mode of onset:
1. Focal onset: seizures begin only in ONE hemisphere
2. Generalized onset: seizures begin in BOTH hemispheres
3. Secondarily generalised: being in one hemisphere, then SPREAD to the other - Impairment of consciousness (with/ without dyscognitive features)
Which 3 key features help classisfying epilepsy according to ILAE?
- Where seizures begin in the brain
- Level of awareness during the seizure
- Other features of the seizure
What are the phases of a seizure? (4)
- Prodromal
- Early ictal (aura)
- Ictal
- Postictal
What are the 2 types of focal onset seizures?
- Simple partial seizures: focal onset seizures WITHOUT dyscognitive features
- Complex partial seizures: focal onset seizures WITH dyscognitive features
What is the clinical presentation of focal onset/ simple partial onset of epilapsy (without dyscongnitive feaures) in terms of motor symptoms? (2)
- Clonic movements (eg, twitching or jerking) of the arm, shoulder, face, or leg
- Speech arrest (involves muscles of articulation- dysarthria)