Module 14b Flashcards by Dallas Toon

Neurological disorder that produces brief disturbances in the normal electrical activity in the brain

Epilepsy

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a sudden alteration of behaviour that is caused by CNS dysfunction

seizure

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Seizure caused by primary CNS dysfunction. Due to depolarization and hypersynchronization of neurons.

Epileptic seizure

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A seizure-like episode that is not the result of abnormal electrical activity in the brain

Non-epileptic seizure

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A tendency for recurrent, spontaneous epileptic seizures

Epilepsy

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A single, unremitting epileptic seizure of duration longer than 30 minutes OR frequent seizures without recovery of awareness in between.

Status epilepticus

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Status epilepticus is an ________.

emergency

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Seizures arising in one area of the brain.

Focal/Partial seizure

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What are the two types of focal/partial seizures?

Simple partial seizure

Complex partial seizure

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Involves no loss of consciousness.

Symptoms depend on where the seizure activity is arising from.

simple partial seizure

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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

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Seizures that have a bilateral, diffuse onset, seeming to arise from all areas of the brain at once.

Generalized seizure

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What are the 5 types of generalized seizures?

Absence seizures
Tonic/clonic seizures
Myoclonic seizures
Tonic seizures
Atonic seizures

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What is another name for absence seizures?

Petit-mal seizures

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Involves loss of consciousness, behavioural arrest and staring

Absence seizures

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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

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Tonic/clonic seizures involve these.

Abrupt loss of consciousness
Tonic period, lasting ~1 minute
Clonic period (involuntary muscle contractions), ~2-3 minutes

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In the post-ictal phase of this seizure type, patients may be drowsy, confused and frequently complain of headaches

Tonic/clonic seizures

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Used to be called grand-mal seizures

tonic/clonic seizures

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Involve sudden, brief muscle contractions that can involve any muscle group

Myoclonic seizures

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Sometimes associated with later development of generalized tonic-clonic seizures

Myoclonic seizures

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Often involve sudden muscle stiffening and impaired consciousness

Tonic seizurs

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Involve sudden loss of muscle tone

usually brief, around 15 seconds

Atonic seizures

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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