Chapter 24: Seizures Flashcards
What are causes of seizures? (6)***
- Infection
- Neoplasm
- Head Injury
- Heredity
- Toxic Effects
- Metabolic Disorder
(MINTHH)
What is the difference between epilepsy and seizures?
Epilepsy is a disease
Seizures are a symptom (abnormal discharge of cerebral neurons)
What is focal seizure?
What is a generalized seizure?
Seizure activity in a specific area in the brain .
Seizure activity all over the brain.
Focal seizures can become generalized.
What is the oldest and continual used seizure medication?
Phenobarbital
What is the principle mechanism of action of anti-seizure medication?
Targeting the voltage gated ion channels and excitatory synaptic functions.
Seizure medication will suppress the firing of abnormal or ectopic neurons.
What are the three main categories for the mechanism of action for antiepileptic medications.***
- Modification of ion conductance (Na+, K+, Ca2+)
- Enhancing inhibition (increasing GABA)
- Inhibiting excitation (decreasing Glutamate)
What are the two main categories of seizures.***
Focal onset
Generalized onset
What are the three sub-categories of focal onset seizures?***
- Focal Aware (simple partial)
- Focal Impaired Awareness (complex partial)
- Focal to bilateral tonic-clonic seizure (partial seizure secondarily generalized)– looks like generalized tonic-clonic
What are the five sub-categories of generalized onset seizures?***
- Generalized tonic-clonic (grand mal)
- Generalized absence (petite mal)- very similar to focal impaired awareness
- Myoclonic (one particular muscle group)
- Atonic/tonic (drop attack) - muscle tone or lack muscle tone
- Infantile Spasms (West’s Syndrome)- developmental disorder
Describe the focal aware seizure location.
Characteristics.
Seizure begins in a specific area of the brain.
Minimal spread of discharge.
Does not affect consciousness or awareness- may stare off into space.
Only way to know if it is a seizure is an EEG that may show abnormal discharge.
What does the EEG look like during a post ictal (post seizure) phase?
Decrease in all activity. Patient is tired and wants to sleep.
Describe complex focal seizures symptoms.
What lobe do complex focal seizures arise in?
May affect LOC, unresponsive.
Patient may show automatisms (lip smacking, swallowing, fumbling, scratching, walking about, repetitive motions).
Most complex focal seizures arise in temporal lobes
Describe a focal seizure secondarily generalized.
Begin as simple/complex focal seizure, but then spreads to the rest of the brain.
Looks like generalized tonic-clonic seizures.
What is the tonic phase?
What is the clonic phase?
Tonic (tone)- patient seizes up, increase muscle tone all over the body, clenching
Clonic (clonus)- rapid movement of all the muscle groups
Describe a generalized tonic clonic seizure (grand mal)
Person falls to the ground
Entire body stiffens (tonic)
Muscle Jerks/Spasm (clonic)
Tongue/Cheek hay be bitten
Urinary Incontinence
Post-ictal phase
What is it called when you have a sustained clonus phase for more than 30 minutes?
What are priorities need to be established (main considerations)?
Status Epilepticus
ABC (airway, breathing, circulation) and IV meds to treat seizure
Describe an absence seizure (petite mal).
This is a generalized seizure where patients will have symptoms that include:
Staring into space
Wake-up with no notice of seizure
Some automatism are possible.
What is a tonic seizure?
What is an atonic seizure?
What are the biggest issue with these two seizures?
Tonic seizure is a generalized seizure characterized by:
Sudden muscle contraction
Often causes falls
Form of drop attack
Atonic seizure is a generalized seizure characterized by:
Sudden loss of muscle tone
Patient falls without warning
Form of drop attack
Injury from fall that will cause pain or head trauma
What is the difference between a clonic and myoclonic seizure?
Both are generalized seizures, but the difference is clonic will involve the entire body shaking and jerking while the myoclonic only involves one muscle group.
What is Infantile Spasms (West Syndrome)
A development generalized seizure disorder that begins before the age of 6 months.
Repetitive muscle spasms that affects a child’s head, torso, and limbs.
If you’re curious, you can look up a video, but it’s upsetting.
What are drugs used in Focal Seizures and Generalized Tonic Clonic Seizures?
Phenytoin
Carbamazepine
Phenobarbital
Valproic Acid
Keppra
What is the oldest non-sedative anti-seizure drug?
What its mode of action?
What’s the more soluble prodrug called?
Phenytoin (Dilantin)
All modes of action: alters sodium, potassium, and calcium conductance.
It will enhance GABA.
Decreases Glutamate
Fosphenytoin
What is the clinical use of phenytoin (Dilantin)?
Why is it not recommended to give phenytoin IM?
What can be given IM instead?
One of the most effective drugs for partial and tonic-clonic seizures available.
Can cause local necrosis of tissues after repeated injections.
Fosphenytoin, because it is a prodrug (inactive)..
When phenytoin enters the body, 90% of it will be bound to _________.
If the patient has a low level of ________they might have a higher free level of phenytoin with a normal dose of phenytoin.
The main concern of this drug is the level of free floating phenytoin that can accumulate and cross the BBB. There can also be accumulation in the liver, muscle, fat leading to toxicity.
Serum proteins (Albumin)
Albumin
What is the therapeutic level for total phenytoin?
What is the therapeutic level for free phenytoin?
What are toxic doses of phenytoin?
What are lethal doses of phenytoin?
Total: 10-20 mcg/ml
Total: 1-2.5 mcg/ml (10% of total)
Toxic: 30-50 mcg/ml (total)
Lethal: >100 mcg/ml (total)
What other drugs besides phenytoin will compete for binding sites on albumin?
Carbamazepine
Sulfonamides
Valproic acids
What other drugs stated in lecture besides phenytoin will compete for binding sites on albumin?
Carbamazepine (seizure meds)
Sulfonamides (abx)
Valproic acids (seizure meds)
What should you be cautious with patients who are taking carbamazepine or valproic acid with phenytoin?
With carbamazepine, it will compete with phenytoin for binding sites on albumin which can lead to an increase in free floating phenytoin to cross the BBB.
Valproic acid is especially problematic because it kicks off phenytoin already bound to albumin.
What are toxicities with Phenytoin (Dilantin)?
- Nystagmus (rapid movement of eyes back and forth)
- Loss of extraocular pursuit of movement - can you follow my finger?
- Diplopia- double vision
- Ataxia- disordered movement, stumbling
- Sedation
- Rash/Lesions
(All these are dose related)
What are 3 long term toxicities with phenytoin?
What can you give to mitigate long term toxicities of phenytoin?
- Gingival hyperplasia - overgrowth of gum line
- Hirsutism (Coarsening of facial features)
- Megaloblastic anemia. (phenytoin blocks folate metabolism, no folate, no RBCs). If she needs it, give the lowest possible dose of phenytoin to a pregnant woman b/c it can have an effect on the developing fetus.
All three of these conditions are associated with decrease in folic acid (Vitamin B9). Give Vit B9 to mitigate long term toxicities.
What is the MOA of Carbamazepine (Tegretol) and indication of use?
Toxicity of Tegretol
MOA: This drug is a TCA, block Na+ Channel
Use:
***Drug of Choice for Focal Seizures
Generalized Tonic Clonic Seizures
TriGeminal Neuralgia
Bipolar, Depression, Anxiety
Toxicity: Diplopia, Ataxia, GI, drowsiness
What is a metabolic issue with Carbamazepine?
What happens to its half life?
Carbamazepine induces hepatic enzymes CYP3A4 that will affect the metabolism of the drug.
Initial Dose Half Life: 36 hours
Later Dose the Half Life will drop to 20 hours d/t to the increase of CYP3A4 (this will affect all antiseizure drugs)
What is the MOA of Lacosamide (Vimpat) and indication of use?
Toxicity of Vimpat?
MOA: Block Na+ channels, slow down excitation
Use: Widely used for focal seizures
Toxicity: Dizziness, Nausea, HA, Diplopia
What is the MOA of Phenobarbital and indication of use?
Toxicity of Phenobarbital?
MOA: Sedative/Hypnotic action Barbiturate (oldest and safest sedative), enhances GABA
Use:
***Drug of Choice for Infants
Focal Seizures
General Tonic Clonic
Toxicity: SEDATION, hepatic enzyme inducer
What is Phenobarbital not useful in?
Generalized Seizures: Absence, Atonic attacks, Infantile Spasms
Can actually worsen these symptoms
What is the MOA of Lamotrigine (Lamictal) and indication of use?
MOA: Ion Channel Blocker
Use: Focal Seizures
What are the MOA of the GABA analogs (Gabapentenin, pregabalin, vigabatrin) and indication of use?
MOA: Increase GABA to suppress rapid firing
Use: Adjunct use to neuralgia, infantile spasms
What is the MOA of Ethosuximide and indication of use?
Toxicity of Ethosuximide?
MOA: Ca2+ channel blocker
Use:
***Drug of Choice for Absence Seizures
Toxicity: GI, Lethargy, Hiccup, Euphoria
What is the MOA of Valproic Acid (Depakene) and indication of use?
Toxicity of Depakene?
Special consideration with phenytoin?
MOA: ALL (just like phenytoin)
Use: Broad Spectrum
Absence Seizures
Tonic-Clonic/ Clonic Seizures
Bipolar, Migraines
Toxicity: Hepato, GI, Sedation, Fine Tremors .
This drug will dislodge/displace phenytoin from albumin
Valproic Acid also inhibits metabolism of many drugs.
What is the MOA of Benzodiazepines and indication of use?
MOA: Increase GABA
Use: Status epilepticus, absence seizures
What are single seizure treatments?
Single seizures may not get medications, but it depends on recurrence.
Treatments:
Anti-epileptic drugs
Surgery
Vagus Nerve Stimulation - increase parasympathetic NS response
Ketogenic Diet (children)- high fat/protein meal, slower source of energy
What is the most common form of status epilepticus?
Generalized Tonic Clonic lasting more than 30 minutes
Life threatening emergency, constant movement of the skeletal muscles, burn through glucose quickly
Collapse of CV, respiratory, and metabolic system
What are pharmacological treatment for status epilepticus?
IV meds:
Diazepam/Lorazepam increase GABA
Fosphenytoin, longer acting
Phenobarbital, if unresponsive to above treatments
What is the only narcotic to stimulate seizure activity?
Demerol
Chronic phenytoin therapy makes patient resistant to __________.
Neuromuscular Blocking Agents
Chronic use of phenytoin decreases GABA receptors.
***If the patient has enough phenytoin on board, it can actually enhance NMB.
What anesthetics can cause seizuere?
Methohexital
Sevoflurane
