Module 14b Flashcards
Neurological disorder that produces brief disturbances in the normal electrical activity in the brain
Epilepsy
a sudden alteration of behaviour that is caused by CNS dysfunction
seizure
Seizure caused by primary CNS dysfunction. Due to depolarization and hypersynchronization of neurons.
Epileptic seizure
A seizure-like episode that is not the result of abnormal electrical activity in the brain
Non-epileptic seizure
A tendency for recurrent, spontaneous epileptic seizures
Epilepsy
A single, unremitting epileptic seizure of duration longer than 30 minutes OR frequent seizures without recovery of awareness in between.
Status epilepticus
Status epilepticus is an ________.
emergency
Seizures arising in one area of the brain.
Focal/Partial seizure
What are the two types of focal/partial seizures?
Simple partial seizure
Complex partial seizure
Involves no loss of consciousness.
Symptoms depend on where the seizure activity is arising from.
simple partial seizure
Loss of consciousness
Patients may appear to be awake, but are not aware of surroundings.
Symptoms depend on where the seizure is taking place.
Complex partial seizure
Seizures that have a bilateral, diffuse onset, seeming to arise from all areas of the brain at once.
Generalized seizure
What are the 5 types of generalized seizures?
Absence seizures Tonic/clonic seizures Myoclonic seizures Tonic seizures Atonic seizures
What is another name for absence seizures?
Petit-mal seizures
Involves loss of consciousness, behavioural arrest and staring
Absence seizures
Usually brief but may occur in clusters and can recur multiples times in a day.
Rarely associated with automatisms.
More common in childhood
Absence seizures
Tonic/clonic seizures involve these.
Abrupt loss of consciousness
Tonic period, lasting ~1 minute
Clonic period (involuntary muscle contractions), ~2-3 minutes
In the post-ictal phase of this seizure type, patients may be drowsy, confused and frequently complain of headaches
Tonic/clonic seizures
Used to be called grand-mal seizures
tonic/clonic seizures
Involve sudden, brief muscle contractions that can involve any muscle group
Myoclonic seizures
Sometimes associated with later development of generalized tonic-clonic seizures
Myoclonic seizures
Often involve sudden muscle stiffening and impaired consciousness
Tonic seizurs
Involve sudden loss of muscle tone
usually brief, around 15 seconds
Atonic seizures
Also called drop seizures, as their is a potential for falling injuries.
Atonic seizures
What generalized seizures have loss of consciousness?
Absence, tonic/clonic, tonic,
A seizure that begins in one area of the brain and then spreads throughout the brain
secondary generalized seizure
The preliminary focal phase of a secondary generalized seizure.
Aura
How do we localized focal seizures?
By the symptoms, as they often relate to specific brain areas
Describe where the focal seizure is likely localized:
Simple repetitive motor movements involving a localized muscle group associated with seizure activity.
Frontal lobe (primary motor cortex)
Describe where the focal seizure is likely localized:
Emotions such as anger, fear, euphoria and psychic symptoms such as deja vu, jamais vu or amnesia are assocaited with seizure activity
temporal lobe
Describe where the focal seizure is likely localized:
Localized paresthesias, such as numbness and “pins and needles” are associated with seizure activity
Parietal lobe (somatosensory cortex)
Describe where the focal seizure is likely localized:
Visual hallucinations, such as flashing or a repeated pattern in the environment, are associated with seizure activity
Occipital lobe
Describe where the focal seizure is likely localized:
Involuntary eye movement that can be seen in occipital lobe seizures
reflex nystagmus
Describe where the focal seizure is likely localized:
Simple partial seizures in the occipital lobe can be mistaken for what? Why?
Migraine headaches, as many of the symptoms are similar to common migraine auras
Describe where the focal seizure is likely localized:
More complex and widespread paresthesias are associated with seizure activity
Parietal lobe (somatosensory association cortex)
Describe where the focal seizure is likely localized:
Complex multi-sensory hallucinations and illusions which may be hard to distinguish from temporal lobe seizure activity.
Parietal lobe (higher order sensory association areas)
Describe where the focal seizure is likely localized:
Tonic posturing affecting the entire side of the body are associated with seizure activity
Frontal lobe ([contralateral] supplemental motor area + other higher level motor structures)
Describe where the focal seizure is likely localized:
Auditory hallucinations of buzzing or voices talking, and olfactory and gustatory hallucinations are associated with seizure activity
Temporal lobe
Describe where the focal seizure is likely localized:
More complex sensory phenomena, involving visual distortions, paresthesias (i.e. numbness) and autonomic disturbances associated with seizure activity
Temporal lobe
Epilepsy arising from an identified physical cause such as brain tumor, stroke, infection, or other injury
Symptomatic epilepsy
Epilepsy that does not have an identifiable cause; there is often a family history of seizures, and genetics likely play a role
Idiopathic epilepsy
Epilepsy that is likely to have an underlying cause that has not been identified.
Cryptogenic epilepsy
What are the three main classifications for the etiology of epilepsy?
Symptomatic epilepsy
Idiopathic epilepsy
Cryptogenic epilepsy
Describe the seizure threshold.
The seizure threshold is the balance between excitatory and inhibitory forces in the brain.
The difficulty in reaching this threshold will dictate the difficulty in generating a seizure
What are the four distinct mechanisms in which anti-epileptics work?
Blocking sodium channels
Blocking voltage-gated calcium channels
Glutamate antagonists
Potentiating the actions of GABA
How to sodium channel blockers work as an anti-epileptic?
Sodium channel blockers function to prolong the inactivation state (i.e. refractory period) of the voltage-gated sodium channels, preventing neurons from firing at high frequency
Most widely used AED (anti-epileptic drug) that blocks sodium channels.
Phenytoin
Phenytoin is useful in the treatment of what seizure types?
All but absence seizures
Describe the kinetics of phenytoin.
The liver has limited capacity to metabolize phenytoin, thus it shows non-linear kinetics –> a small increase in concentration may cause a large increase in plasma concentration
Phenytoin has a _______ therapeutic range and thus undergoes ________ ____ ________.
narrow
therapeutic drug monitoring
Adverse effects of phenytoin.
Sedation, gingival hyperplasia, skin rash
Phenytoin should not be used in pregnant women because it is a ________.
teratogen
How does blocking voltage-dependent calcium channels work as anti-epileptic treatment?
Inhibition of these calcium channels suppresses NT release, and thus action potential propagation
Describe how glutamate antagonists help with epilepsy treatment.
Glutamate is an excitatory NT and is thus a target for AEDs.
How does glutamate mediate its effects?
By binding to the NMDA receptor or AMPA receptor
Glutamate antagonists used to treat epilepsy block both the ______ and _______ receptors.
NMDA
AMPA
Describe the mechanism of action of drugs that potentiate the actions of GABA.
GABA is an inhibitor NT in the CNS
Binding of GABA to its receptors causes Cl- to rush into cells, hyperpolarizing them and making it more difficult to reach threshold
What are the traditional AEDs?
Newer AEDs?
Trad - phenytoin, valproic acid
Newer - lamotrigine
Why would newer AEDs be used instead of older ones if the effectiveness is similar?
Newer AEDs tend to have decreased sides and decreased propensity to induce hepatic drug metabolizing enzymes
