Seizures Flashcards
Define seizure
Paroxysmal event characterized by a sudden, transient alteration in brain function. Due to an abnormal, excessive hypersynchronious discharge of CNS neurons
They can have various forms of activity
Define epilepsy
2 unprovoked seizures w/ or w/o convulsions separated by at least 24 hours
Epidemiology of Seizures
New onset occurs in <1yo and >55yo
largest population is ages 15-64
Etiology of Seizures
most are idiopathic
causes can include vascular abnormalities, malformations, trauma, stroke
Tumors, infections, neurodeg diseases are rare causes
The two major groups of seizures are…
partial
generalized
Define Partial Seizure
partial originates in a local area of the brain
unilateral
Define Generalized seizure
involve both hemispheres of the brain
may be primary or secondary generalization of a partial seizure
The two types of partial seizures are…
Simple partial
complex partial
Define simple partial seizure
no impairment of consciousness
May have motor, sensory, autonomic, or psych symptoms
Define complex partial seizure
impairment of consciousness, involves some form of autonomic behavior
Absense Seizures
Also known as petite Mal- sudden, brief impairment of consciousness without loss of postural control. blank stare abrupt, quick seen primarily in childhood
Tonic Clonic seizures
Also known as grand Mal- sudden loss of consciousness loss of postural control tonic clonic phase postical state can last several hours
Status Epilepticus
Life threatening
Any seizure lasting longer than 5 minutes
Can be one long seizure or two consecutive with no pause in between
Most common cause is abrupt cessation of AED
Diagnostics of seizures
Neuro exam is usually normal
neuroimaging as part of initial dx should be done
EEG- may be normal between seizures-may use sleep deprivation, photic stimulation, hyperventilation, or prolonged monitoring to instigate a seizure
MRI is preferred, is more sensitive than CT
Criteria of Surgical intervention in seizure management:
Most common is temporal lobectomy Done when seizure focus is localized and is not near a critical part of the brain # criteria must be met: Definite dx of epilepsy failure of drug therapy localization of seizure focus
Vagal Nerve Stimulator
can be used in all types of seizures
placed in chest, tunneled to vagus nerve in the left neck
current stimulates every 5 minutes
usually used in pt that don’t respond to drug therapy and are not surgical candidates
Risk Factors for repeated seizures:
Abnormal EEg
CNS lesion
PArtial seizures
Positive FH
If no RF are present, there is a 101-5 percent risk of a repeated seizure
If one or more RF are present the risk is 100 percent
Michaelis-Menten Metabolism
-When the maximum capacity of hepatic enzymes to metabolize the drug is reached within normal dose range
non-linear behavior
-Small changes in doses can result in disproportionately large changes in serum concentration >toxicity
-if too large a dose increase is made, or a breakthrough seizure activity if too large a reduction in dose is made.
Clinical significance of MM metabolism and serum levels:
non-linear behavior- too large of a dose > serum toxicity
seum concentration <7mcg- increase 100mg/day
seum concentration 7-12mcg- increase 50mg/day
seum concentration >12mcg increase no more than 30mg
Protein Binding
phenytoin and valproate are highly protein bound
normal phenytoin is 88-92% bound, 8-12% unbound
the unbound oration is able to leave the blood and produce :
clinical effect on the CNS
dose related SE in the CNS
distribute to other peripheral sites and be metabolized
