Epilepsy Flashcards
What is the main inhibitory neurotransmitter in the transmitter? Respective receptors and associated ion currents?
GABAa - act on post-sypnatic receptors linked to Cl- channels (inward flow)
GABAb - act on pre-synaptic receptors mediated by outward K+ currents
Cellular mechanisms for generation of a seizure?
Too much excitation mediated by glutamate/aspartate and inward Na/Ca currents. Can happen with “sprouting” of excitatory axons.
Too little inhibition mediated by GABA and inward Cl- and outward K+ currents. Can happen with loss of feedback (interneurons) and feed-forward inhibitions.
Kindling Model
Repeated subconvulsive stimuli result ing electrical after-discharges.
Can eventually lead to stimulated-induced clinical and spontaneous seizures.
Football players?
Definition for epilepsy
1) At least two UNPROVOKED seizures occurring > 24 h apart OR
2) One UNPROVOKED seizure and probability of further seizures (at least 60%) over next 10 years OR
3) Diagnosis of epilepsy syndrome
What is the etiology of a majority of epilepsies?
UNKNOWN
What are common etiologies of seizures for the following age groups:
Children
Young Adults
Elderly
Children: febrile seizures, congenital cause, metabolic cause
Young adults: trauma, tumor
Elderly: stroke, tumor, degenerative conditions
Generalized Non-motor/Absence Seizure
Affected population
Symptoms/clinical features
Studies
School age children 3-12
Abrupt onset of BRIEF activity arrest and staring, unresponsive or delayed response
NO post-ictal state
EEG: 3-H spike-wave
Treatment: ethosuximide –> ONLY INDICATION FOR THIS MEDICATION
Generalized Motor/Myoclonic Seizure
Symptoms/clinical features
Studies
Brief, usually bilaterally synchronous, shock-like jerks of group of muscles lasting < 1 sec (think sleeping at night then sudden twitch)
EEG: generalized 4-6 Hz polyspike wave (one wave, many spikes-
Generalized Motor/Tonic-Atonic Seizure
Symptoms/clinical features
Studies
Tonic: Symmetric, tonic muscle contraction of extremities with tonic flexion of waist/neck lasting 2-20 seconds
Atonic: sudden loss of postural tone, usually with lost of consciousness
Generalized Tonic-Clonic/Primary Generalized
Symptoms/clinical features
Studies
Duration 30-120 seconds
Tonic: stiffening and falling, tongue biting, cyanosis, etc.
Clonic: rhythmic extremity jerking
Associated with loss of consciousness and post-ictal confusion
EEG: generalized polyspikes or poly-spike wave
Focal onset aware seizure (aka simple partial)
Clinical features vary according to location of seizure discharge–can be motor, autonomic (sweating, flushing), visual (ringing, hissing), etc.
Awareness preserved
Focal onset unaware seizure (aka complex partial)
Clinical manifestations vary but may include: aura, automatisms, other motor activity
IMPAIRED consciousness + post-ictal drowsiness/slowness
When to start anti-epileptic drugs (AED)?
Judgment call for only single unprovoked seizure –> look at risk factors like prior neurological insult, abnormal EEG, previous seizures, etc.
Most start AED after second unprovoked seizure.
What are the principles of initiating treatment?
Monotherapy PREFERRED when possible.
Start LOW dose then titrate up.
If seizures persist, consider alternative but if second drug must be aded may need to adjust dose of first drug.
If patient becomes seizure free, dose of initial drug may be reduced.
Define status epilepticus.
Treatment?
Common causes of SE?
If seizures > 5 min consider SE and treat with Lorazepam (maintain with phenytoin).
Epilepsy is cause of 1/3 cases.
In children, fever is common cause and in older adults stroke.
Note that not ALL SE are convulsive–can even cycle between convulsive and non-convulsive.
