Epilepsy Flashcards
How is epilepsy defined?
It is defined by recurrent unprovoked (= spontaneously occurring) seizures
What is an epileptic seizure?
paroxysmal change in behaviour due to synchronised rhythmic firing of populations of CNS neurons
How often does epilepsy occur in the population?
1% of the general population has epilepsy
5% of the general population has a risk of one seizure in the lifetime
When is the probablity of an epileptic seizure the highest?
U-shaped distibution: childhood-adolescence (0-20) + older age (60-80)
When can a person be diagnosed with epilepsy?
- 2 unprovoked seizures, > 24 hours apart
- 1 unprovoked seizure & causative CNS disease and pathological EEG alterations
What is a focal seizure?
Does it originate in one hemisphere or in both?
initial symptoms/signs (clinical and EEG) indicate origination of seizure activity within an area of one hemisphere
Clinical data: partial onset; seizures during sleep; focal slowing or hyperexcitability; structural lesion
What is a generalised seizure?
Does it originate in one hemisphere or in both?
initial symptoms/signs indicate origination of seizure activity simultaneously in both hemispheres
Clinical data: generalized seizures; 30 minutes after awakening; positve family history; generalized hyperexcitability; negative MRI
What types of focal seizures are there?
- focal aware => preserved concioussness, aware of having a seizure
- focal impaired awareness => impaired concioussness, staring (additional symptoms of focal aware, automatic behaviors like lip smacking, fumbling, wandering)
- focal to bilateral tonic-clonic (secondary) => loss of concioussness, falling on the ground
What types of generalised seizures are there?
- Absence seizures → absent staring, non-motor, can occur in clusters
- Tonic seizures → stiff muscles of the back, arms, and legs
- Atonic seizures → “drop seizures”, loss of muscle control
- Clonic seizures → repeated jerking; the neck, face, and arms
- Myoclonic seizures → brief jerks and twitching; upper body, arms, and legs
- Tonic-clonic seizures → the most dramatic, stiffness and shaking, loss of consciousness
Where are focal aware seizures localized?
- temporal lobe (65%):
-lateral (10%) — auditory symptoms
-mesial (90%) — psychic or autonomic symptoms (deja vu, fear (amygdala)) - frontal lobe (25%) - tonic (rigility/stiff) / clonic (jerking) movements
- occipital lobe (5%) - visual symptoms
- parietal lobe (5%) - paraesthesia (tickling), vertigo
sum to 100%, no multiple localizations — very rare + a difficult case: seizure and abnormality — are there causation relations?
What is an epileptic syndrome in focal epilepsy?
ILAE: epileptic syndrome is “a characteristic cluster of clinical and EEG features, often supported by specific etiological findings (structural, genetic, metabolic, immune, and infectious).”
history/clinical data
* partial or partial onset seizures
* seizures during sleep
EEG
* focal slowing or hyperexcitability
cMRI
* structural lesion
What is an epileptic syndrome in generalised epilepsy?
history/clinical data
* generalised seizures
* 30 min after awakening
* positive family history
EEG
* generalised hyperexcitability
cMRI
* not helpful, always negative
What can be the etiology of epilepsy?
Structural vs. genetic epilepsy
Structural
1. Hippocampal sclerosis
2. Malformations of cortical development
3. Vascular malformations
4. Prenatal injuries and developmental abnormalities (oxygen deficiency, ASD, malnutrition)
4. Postnatally acquired CNS lesions
-infectious/inflammatory causes (HIV, viral encephalitis, parasitic infections)
-neoplasia
-cerebro-vascular accidents
-traumatic brain injury
-neurodegeneration
Genetic
1. ion channel mutation (Na+, K+, Cl–channels)
2. receptor mutation (GABA-receptor, acetyl-cholin-receptor)
3. ion transporter mutation (Na+-K+-ATPase)
What are the main differnces bertween syncope and tonic-clonic seizure?
syncope vs. tonic-clonic seizure
duration: < 30s vs. 1-2min
reorientation: <30s vs. 4-45 min
trigger: 50% vs. almost never
tongue biting: rare vs. frequent
Mind: convulsions (even though arrhythmic vs. rhythmic), falls and eyes open can be charasteristical of both
What are the features of psychogenic non-epileptic seizures?
- duration: > 10 min
- motor convulsions fluctuating
- put on, deflectable
- tip of the tongue biting
- never out of sleep
- injuries rare
- ictal EEG unchanged
- eyes closed
What is myoclonus?
Myoclonus is a type of muscle twitching or jerking that is caused by sudden, brief, and irregular muscle contractions. e.g. hyperventilation-induced myoclonus as a result of breathing too rapidly and deeply => decrease in carbon dioxide levels in the blood
What is PNES?
Psychogenic non-epileptic seizure:
* resemble epileptic seizures but are not the result of abnormal electrical discharges in the brain
* the spike and spike pattern is not seen on EEG
* psychosomatic – physical manifestation of psychological distress
What does the risk of reoccurence of an epileptical seizure depend on?
Risk for seizure reoccurence
* if you have one seizure (5%) -> 30-40% of the second seizure
* if you have two seizures (diagnosis) -> 60% of reoccurence
Can epilepsy be modified or treated? How does it influence treatment options?
The chronic disorder epilepsy cannot be modified or treated. Treatment options are antiseizure medication (ASM) and secondary prophylaxis (preventing syptoms occurence)
What is the treatment goal in chronic epilepsy
maintenance of normal life style = complete seizure freedom + no or minimal substance adverse effects
What are the targets of treatment?
Na+ and Ca2+ channels, GABA system, glutamate receptors (AMPA & NMDA)
How successful is treatment with antiepileptic drugs?
60%: good prognosis, seizure-free with 1. or 2. monotherapy, no relevant adverse effects, commonly seizure-free with AED termination
30%: pharmacoresistant with polytherapy
10%: seizure-free with polytherapy
When is epilepsy surgery recommended? How successful it can be?
- pharmacoresistance
- identification of one epileptic focus with EEG
- suitable MRI lesion
- resection possible without persistent neurological/neuropsychological deficits
- not younger than 17 years
58% of patients are seizure-free after 1 year follow up
What are less invasive treatment options? Are they effective?
Laser treatment – MRI-guided borehole. Same 58% of patients seizure free
priniciple: thermal therapy
