Patho of seizures Flashcards
Where/ how do neurotransmitters work?
Work at synaptic cleft, where they either inhibit or excite the neurons
Whether a neuron is inhibitory or excitatory is dependent on?
On the receptor they bind to
3 key points about receptors
1) they’re proteins
2) match size & shape of neurotransmitter
3) named according to transmitter they bind with
Action of transmitters:
Ex. of inhibitory transmitters Hint: 3
1) dopamine
2) serotonin
3) GABA
Action of transmitters:
Ex. of excitatory transmitters Hint: 2
1) ACh (Acetylcholine)
2) norepinephrine
Where is Acetylcholine (ACh) found in the body?
CNS, PNS, & ANS
Is ACh excitatory or inhibitory?
Can be either → depends on neurons secreting it
- PNS → excitatory at neuromuscular junctions
- ANS → inhibitory & slows HR
Serotonin (5-hydroxytrptamine) is derive from?
tryptophan
Where is serotonin primarily found?
GI tract, PLTs, Brainstem
Serotonin contributes to
feeling of well being & mood regulation
Where is dopamine located?
mainly in substantia nigra of midbrain/ basal ganglia region
List 6 functions of dopamine
1) behavior & cognition
2) voluntary motor movement
3) motivation punishment & reward
4) attention
5) working memory
6) learning
List some examples of neuropsychiatric & voluntary motor movement disorders that dopamine is involved in
1) social phobia, ADHD, drug & alcohol dependence
2) Parkinson’s disease
3) Tourette’s syndrome
What is the chief inhibitory transmitter in the CNS?
GABA → gamma amino butyric acid
What kind of effect does GABA have on the brain?
relaxing, anti-anxiety, & anticonvulsant effect
What kind of effect does GABA have on the muscles?
Inhibitory effect → decrease muscle spasms & improved tone
What is norepinephrine?
An excitatory neurotransmitter in the brain & stress hormone within endocrine system
Norepinephrine plays a role in what response?
Fight or flight response
What is glutamate & what is it involved in?
1) major mediator of excitatory signal
2) Involved in cognition, memory, & learning
What neurotransmitter plays several roles in both normal & abnormal brain activity?
Glutamate
Action potentials are also known as ____ ____ ____
Neuron conduct impulses
Action potentials are abrupt changes in what?
Membrane potential which permit nerve signals to be transmitted from the cell body down the axon
Action potentials stimulate ____, _____, & _____ ions to move across axon membrane (Hint: electrolytes)
Sodium, potassium, & calcium
What are the 3 phases of neuron conduction (action potentials)?
1) depolarization of the neuron = positively charged ion
2) repolarization of neuron = return of neuron to a negative value
3) resting period
What can lead to seizures?
Impulses that do not maintain a systematic order (excitatory, inhibitory, & rest phase become irregular & chaotic)
Neurons are usually in a ____ charged state
negatively
Define seizures
A single episode of abnormal electrical d/c from cortical neurons (too much OR too little) that results in abrupt & temporary altered state
Define epilepsy
A group of syndromes characterized by unprovoked, recurrent seizures
Define status epilepticus
Continuous seizure activity for more than 5 min or 2 or more sequential seizures that occur w/o full recovery of consciousness btwn attacks
List 10 common causes of seizures
1) trauma
2) ETOH withdrawal
3) illicit drug use
4) brain tumor
5) congenital malformations
6) stroke
7) metabolic disorders
8) Alzheimer’s disease
9) Neurodegenerative disease
10) idiopathic
List 2 examples of metabolic disorders that can cause seizures
1) uremia
2) electrolyte imbalances
List 4 things that can trigger seizures (Hint: think environmental factors)
1) flashing lights
2) stress
3) certain drugs
4) metabolic changes
List 5 common causes of epilepsy
1) genetic causes
2) head trauma
3) medical disorders
4) prenatal injury
5) developmental disorders
Epilepsy may occur in genes coding for what 3 different things
1) ion channels
2) neuronal receptors
3) transcription factors
List 3 medical disorders that can cause epilepsy
1) dementia
2) meningitis
3) encephalitis
List 2 developmental disorders that can cause epilepsy
1) autism
2) down syndrome
Who can have a seizure?
ANYONE
For an actual seizure to occur what 3 things have to be occurring?
1) excitable neurons
2) increase in glutaminergic activity
3) reduction in activity of normal inhibitory GABA projection
Pathophysiology of seizures (Hint: 3)
1) messages from body are carried by neurons of the brain through discharges of electrochemical energy
2) impulses occur in bursts
3) during periods of unwanted discharges, parts of the body may act erratically
What are the 2 classifications of seizures?
1) focal or partial
2) generalized
List 2 types of focal/ partial seizures
1) simple partial
2) complex partial
List 4 types of generalized seizures
1) Absence (Petit-mal)
2) Tonic-clonic (Grand mal)
3) Atonic/ akinetic (drop attacks)
4) status epilepticus
Where do focal seizures occur in the brain?
Start & remain in ONE hemisphere
Pathophysiology of focal seizures
High frequency bursts of action potentials & hypersynchronization
What can happen to a patient’s awareness when experiencing a focal seizure?
Awareness may be maintained or lost
What is an aura? & what type of seizures can they be associated with?
Warning sensation before a seizure occurs
- can occur with focal seizures
Focal seizures may have ___, ___, ____ Sx, & ____
Motor, sensory, autonomic Sx, & automatisms
Autonomic Sx of focal seizures
Due to stimulation of ANS (i.e. pallor, sweating, pupillary dilation, epigastric sensation)
What are automatisms seen in focal seizures?
Coordinated involuntary movements occurring during state of impaired consciousness either during or after seizure
-Patient is unaware; often associated w/ temporal lobe seizures
Focal seizure when pt retains awareness is when? Hint: 2
1) Person is aware, & can experience body movements, like a jerk
2) May experience an aura
Focal seizure with awareness is similar to what other type of seizure?
Partial seizures
Focal seizure with altered/impaired consciousness is when?
Seizure may spread to the other hemisphere, causing loss of awareness
Where do partial seizures usually begin?
In one hemisphere (typically temporal or frontal lobe)
Partial seizures can be characterized as ___ or ___
simple or complex
Pathophysiology of generalized seizures Hint: 3
1) starts in 1 hemisphere & spreads w/ involvement of both hemispheres
2) may have motor &/or nonmotor Sx
3) impairment of consciousness
How are tonic-clonic (grand mal) seizures characterized?
Begin with rigid violent contractions (tonic) followed by repetitive (clonic) activity of all extremities
Body stiffness & relaxation
List 4 things seen in tonic-clonic seizures that help identify them
Muscle stiffness, dilation of pupils, altered respirations
usually lasts < 1 min
How are absence seizures characterized?
Short episodes of staring & loss of consciousness ~ 10 sec
How are myoclonic seizures characterized?
B/L jerking of muscles w/ no loss of consciousness
How are atonic seizures characterized?
Sudden loss of muscle tone; “drop to ground”
Status epilepticus is identified by what 2 things?
1) continuous seizure activity for > 5 min
2) 2 or more sequential seizures that occur w/o full recovery of consciousness between attacks
What seizure classification is considered a neurological emergency?
Status epilepticus
Which type of seizure requires immediate intervention? & why?
Status epilepticus
→ b/c extreme energy expenditure & potential lack of O2 during prolonged seizures
How do we Dx seizures? Hint: 3
1) H&P
2) neurological exam
3) diagnostic procedures (chemistries; toxicology screens; CT; MRI; EEG)
What are the 3 phases of seizures?
1) Pre-ictal
2) Ictal
3) Post-ictal
Define pre-ictal phase
May be started by a trigger &/or preceded by an aura
Define ictal phases
Actual seizure
Increases in metabolic demand
Define post-ictal phase
Post seizure
Has decreased responsiveness; feels fatigued
