CC 1: Epilepsy Flashcards
What is the main function of ion channels?
Allows for selective permeability
What is the definition of a seizure?
Abnormal excessive and synchronous electrical discharges of brain neuronal network that are characterized by clinical signs/ syptoms
What is Aura?
Part of the ictal (part of the seizure), it is short in length/ time and hard to describe.
It is adistinctive feeling or some other warning sign when a seizure is coming—different from person to person.
What is a prodrome?
This is a pre-ictal phase.
This is the time before the seizure. It can last from minutes to days and make people
act and feel differently.
What is the ictal phase?
It is the seizure period
What is the interical phase?
this is the time between seizures
What is the post ictal phase?
altered state of consciousness after a seizure
What are the two main types of seizures?
Partial (focal) and generalized
Which type of seizure includes both hemispheres?
A generalized seizure
What are the two types of generalized seizures?
Convulsive and non-convulsive
What are the two types of partial seizures?
Simple partial and complex partial
What is the definition of a simple partial seizure?
No impaired consiousness
What is the definition of a complex partial seizure?
Impaired consiousness
What is a secondary generalized seizure?
A seizure that started out as partial and then became generalized
What is epilepsy?
A disease of the brain characterized by enduring predisposition to generate epileptic seizures.
It is a complex of clinical features, signs and symptoms that together define a distinctive, recognizable clinical disorder.
What is the most likely cause of an idiopathic epileptic condition?
Genetic cause
What is the most likely cause of a crytogenic epileptic condition?
Unknown cause
What is the most likely cause of a symptomatic epileptic condition?
Known CNS cause
What is the definition of an epileptic channelopathy?
Lowered seizure threshold based on a mutation causing changes in the current carried by the channel. Can either be a gain of function/ enhanced or loss of function/ reduced
True or False:
Autosomal recessive and de novo mutations
False. Rarely autosomal recessive….they are usually autosomal dominent.
In Na channelopathies, what subunit is usually effected?
Alpha subunit
Where are the following channels usually found:
Na 1.1 channels?
Na 1.3 channels?
Na 1.2 channels?
Na 1.6 channels?
Na 1.1 and Na 1.3 are found in cell bodies of neurons
Na 1.2 are found in unmyelinated azons and dendrites
Na 1.6 channels are found in myelinated axons and dendrites
When does Severe Myoclonic Epilepsy of Infancy (SMEI) usually occur?
During the 1st year of life
What is the typical presentation of SMEI?
Febrile seizures that occur in progressively longer clusters. Eventually an epileptic status occurs. Psychomotor delays occur and there is eventually ataxia and cognitive impairment
What is the pathological cause of SMEI?
Reduced Na channel density
In SMEI, what does the reduction of Na channel densitiy lead to?
It leads to a loss of high frequency AP which leads to loss of inhibitory function of GABA in interneurons and Purkinje cells.
This eventually leads to seiure and ataxia
What is the treatment for SMEI?
Drugs to reduce the uptake of GABA and increase the response of post synaptic GABA receptors.
Examples: Tiagabine and Benzodiazepines
What is Generalized Epilepsy with Febrile Seizures + (GEFS+)?
This is a condition similar to SMEI, but it is milders. There is usually no cognitive impairment.
This is usually a familial condition.
What is the pathology of GEFS+?
It is a mutation that leads to a loss of function of fast inactivation, which leads to a gain of functionof Na channels because they are open longer (a persistent Na current)
What is the treatment for GEFS+?
Antiepileptic medications
How are febrile seizures defined?
1- Seizures occuring in childhood after 1 month of age
2- associated with febrile illness but NOT cause by an infection of the CNS
3- No history of neonatal seizures or unprovoked seizures
4- The seizure fit no other criteria
What type of channelopathy causes febrile seizures?
A mutation in the NA 1.1 channel. This reduces the peak Na current.
What channels are effected in K channelopathies?
Usually K 7.2 and K 7.3
What are M currents?
Close to resting potential and is regulated by M receptors and other G coupled receptors
Where are K 7.2 and K 7.3 channels typically found?
in cells with M currents
What would a missense mutation cause in a K+ channel? What disease would this cause?
impaired influx of K+
decreased M current
Benign familial Neonatal Convulsion
How long does Benign Familial Neonatal Conculsion usually last?
6 weeks
What is two pore forming mutation K channelopathies?
Generalized Epilepsy
Paroxysmal Dyskinensia
What does a pore forming mutation do?
larger K+ influx (gain of function)
What is the most common type of Ca channel to have a channelopathy?
T-type Ca channels
Where are T type channels located mainly?
In thalamic cells
What are the three subtypes of T type Ca cahnnels?
Ca 3.1, Ca 3.2, Ca 3.3
What type of mutation is commonly associated with Ca channelopathies?
Gain of function mutation that leads to excessive synchronous rhythmic burst
What is a major clinical Ca channelopathy?
Idiopathic Generalized Epilepsy
What is a major clinical Chloride channelopathy?
Idiopathic Generalized Epilepsy
Why is the Chloride gradient so important
Maintenance of the Chloride gradient is needed for GABAergic synapse hyperpolarization
What do antiepileptic drungs do?
Decrease the hyperexcitability of neurons . They are generally Na channel blockers and increase the inhibitory function of neurons
Are antiepileptic drugs the only treatment for epilepsy?
No, there is also Epilepsy syrgery if there is a failure to respond to 2 medications
