CC1: Role of Ion Channels in Epilepsy Flashcards Preview

Neuroscience > CC1: Role of Ion Channels in Epilepsy > Flashcards

Flashcards in CC1: Role of Ion Channels in Epilepsy Deck (18):

Define seizures

abnormal excessive & synchronous electrical discharges of brain neuronal network (neurons start to fire all at the same time)


Aura vs prodrome

prodrome: not really a seizure; feeling not well for days = PRE-ICTAL

aura: sense that seizure is going to happen; hard to describe symptoms before actual seizures (e.g. tingling of body, blurry vision, could be indescribable) = ICTAL = 1st part of seizures


Define pre-ictal, ictal, inter-ictal, post-ictal

pre-ictal: prodrome = not part of seizure;
ictal: aura = main manifestations of seizure
inter-ictal = periods btw seizures
post-ictal = after seizures


What is the ILAE Classification of seizures into which 2 groups?

1) Partial (focal) involving only 1 hemisphere
2) Generalized involving both hemispheres


Within generalized seizures involving both hemispheres, it can either be convulsive or non-convulsive. Which is more common?

Convulsive is more common. In non-convulsive, there are no convulsions, but pt is unconscious


In the group partial seizures in which only 1 hemisphere is involved, it can be either simple partial or complex partial. Explain symptoms that are found in these 2 groups.

Simple partial seizure: no loss of consciousness; there's shaking in one arm, tingling in one arm

Complex partial seizure: impaired consciousness; staring without understanding


Partial seizures can lead to secondary generalized seizures. How do secondary generalized seizures different from just generalized seizures?

The onset in which generalized seizures start off in both hemispheres while secondary starts off in one hemisphere.


Within generalized seizures, there are absence seizures. Absence seizures are most common in and characterized by?

Absence seizures are most common in children & are characterized by behavioral arrest in which patient is doing something, stops & stares at you. Within secs later, the pt will have no recollections of that happening.


Figure of 4 sign and epileptic cries are common symptoms. What describes figure of 4 sign?

rigid extension of one arm at the elbow, often with the fist clenched and flexed at the wrist, while the opposite extremity is flexed at the elbow.


Define epileptic syndrome

chronic seizures; predisposition to have seizures
complex of clinical features, signs & symptoms that together define a clinical d/o


Epileptic syndrome can be classified into 3 groups according to the ILAE.

1. idiopathic - probably genetic basis but not confirmed
2. symptomatic - known d/o
3. cryptogenic - not known


Majority of channelopathies that cause epilepsy are AD, de novo. Mutation in ion channels can either be gain of function or loss of function. Which is the MOST common Na+ epileptic channelopathy?

Severe Myoclonic Epilepsy of Infancy (SMEI)


Severe myoclonic epilepsy of infancy (SMEI) is the most common Na+ epileptic channelopathy. What are some of the symptoms and what is the pathophysiology?

1st yr of life = increase body temperature leading to seizures; progressively prolonged becoming cluster seizures

2nd yr of life = cognitive impairment, ataxia, psychomotor delay

Pathophys due to decrease Na+ channel density = loss of high freq action potentials leading to
1) loss of inhibitory function of GABAergic cortical interneurons --> seizures
2) loss of inhibitory function of Gabaergic purkinje cells -->ataxia


Generalized Epilepsy w/ Febrile Seizures Plus (GEFS+)

milder than SMEI
a milder form of Na+ channelopathy
-usu. no cognitive impairment
mutation = loss of function of inactivation
= gain of function of Na+ channels leading to persistent Na+ current


Febrile seizures

Of the 3 Na+ epileptic channelopathies, febrile seizures is the most mild.
-pt presents w/o previous neonatal seizures
-not meeting criteria for other acute symp seizures
-occurring in childhood after 1 month of age
-fever not associated w/ infection of CNS
-mutation is in Nav1.1 -missense mutation


List 2 K+ epileptic channelopathies

1) Benign familial neonatal convulsions (BFNC)
-normal development & behavior
-brief generalized & partial seizures
-resolves by age 6 weeks
-loss of function

2) Generalized Epilepsy & Paroxysmal Dyskinesia
-movement disorder with intact consciousness
-gain of function -large K+ influx


There are also Ca2+ and Cl2- epileptic channelopathies.

Ca2+ channelopathy: gain of function leading to excessive synchronous rhythmic burst firing leading to idiopathic generalized epilepsy

Cl2- channelopathy: idiopathic generalized epilepsy


Treatment for Epilepsy

**decrease hyperexcitability of neurons
-Na+ channel blockers
-increase GABA (GABA receptor agonists)
-surgery for non-channelopathies.