Seizures Flashcards
ILAE for epilepsy
> 2 unprovoked seizures occurring >24 h apart
1 unprovoked seizure and a probability of further seizures similar to the recurrence risk after 2 unprovoked seizures (>60% over 10 years)
diagnosis of an epilepsy syndrome
Resolution of epilepsy
age-dependent epilepsy and is now > applicable age (e.g. benign Rolandic epilepsy)
OR
remained seizure-free for the last 10 years, with no anti-seizure medications for the last 5 years
Primary seizure
unprovoked, not linked to inciting event
secondary seizure
may be caused by: trauma illness intoxication/poison organ failure other metabolic disturbances cerebral tumours pregnancy supratherapeutic levels of some anti-convulsants
Generalized seizure
abnormal neuronal activity in both cerebral hemispheres causing alteration in LOC
Further classification
Tonic-clonic seizure
convulsions of stiffness and jerkiness
Tonic seizure
stiff
Clonic seizure
jerky
Absence seizure
starts in childhood
“Blanking out”
Atonic seizure
“Drop attacks”
suddenly falls, usually without LOC
Myoclonic seizure
jerking of whole body
Focal seizure
usually only involves 1 hemisphere
preseves consciousnes
may progress and cause altered sensorium
Simple focal seizure
with motor signs
with somatosensory/special sensory symptoms
with autonomic symptoms/signs
with psychic symptoms (disturbance of higher cerebral function)
Complex focal seizure
dyscognitive impaired consciousness clinical manifestations vary with site of origin and degree of spread - presence an nature of aura - automatisms - other motor activity
Usually lasts 1-2 minutes
Secondary generalized seizure
begins focally, with/without focal neurological symptoms
variable symmetry, intensity, duration of tonic and clonic phases
typically 1-2 min
postictal confusion, somnolence, with/without transient focal deficits
Convulsive seizure
uncontrolled, rhythmic motor movements
can affect part or all of body
Nonconvulsive seizure
don’t result in abnormal motor activity
patients may display confusion, altered mental status, abnormal behaviour, coma
Status epilepticus
> 30 minutes of persistent seizures or a series of recurrent seizures without intervening return to full consciousness
Time criterion shortened to 5 minutes –> duration of seizure activity related to outcome
Likelihood of achieving seizure cessation with typical treatments decreases with ictal duration
Common causes of status epilepticus in adults
AED noncompliance/withdrawal of AED: 25-26 alcohol 15-24 drug toxicity 2-10 infection 8 cerebral tumour 5-6 trauma 3-5 cerebrovascular disease/stroke 4-23 metabolic abnormality 4-13 hypoxia, cardiac arrest 4-12 idiopathic 4-5
West Syndrome
infantile spasms
cortical malformations
developmental delay –> mental retardation
abnormal EEG (Chaotic)
Lennox-Gastaut Syndrome
multitude of seizure types: focal, atonic, etc
significant mental delay and frequent seizures
Juvenile Myoclonic Epilepsy of Janz
starts in teens
myoclonic seizures early in the morning
lifelong
normal cognition
Infancy and childhood seizure etiology
prenatal/birth injury
inborn error of metabolism
congenital malformation
Adolescence and young adult seizure etiology
head trauma
drug intoxication/withdrawal
Childhood/adolescence seizure etiology
idiopathic/genetic
CNS infection
trauma
older adult seizure etiology
stroke
brain tumour
acute metabolic disturbances
neurodegenerative
Seizure precipitants
metabolic/electrolyte imbalance stimulants sedative/ethanol withdrawal sleep deprivation antiepileptic medication reduction/inadequate AED tx hormonal variations fever/systemic infection
Mechanism of seizure generation
abnormal increased electrical activity of initiating neurons activates adjacent neurons and propagates until thalamus and other subcortical structures are similarly stimulated
Excitation
Ionic: inward Na/Ca
NT: glutamate, aspartate
Glutamate
brain's major excitatory NT 2 groups of receptors Ionotropic Metabotropic Modulation by glycine, polyamine sites, Zinc, redox
Ionotropic glutamate receptors
Fast synaptic transmission
NMDA, AMPA, kainite
gated Ca and Na channels
Metabotropic glutamate receptors
Slow synaptic transmission
Regulation of second messengers (cAMP, inositol)
modulation of synaptic activity
Inhibition
Ionic: inward Cl, outward K
NT: GABA
GABAa: post synaptic specific recognition sites, linked to Cl
GABAb: presynaptic autoreceptors, mediated by K currents
Mechanism of generating hyperexcitable networks
excitatory axonal sprouting
loss of inhibitory neurons
losso f excitatory neurons which would normally be “driving” inhibitory neurons
EEG background abnormalities
significant asymmetries and/or degree of slowing inappropriate for clinical state or age
EEG interictal abnormalities
associated with seizures and epilepsy
spikes
sharp waves
spike-wave complexes
Phenytoin indication
iv/oral
focal seizures
secondarily generalized seizures
in hospitals as IV for status epilepticus
Phenytoin dose/MOA
once a day
block voltage-dependent sodium channels at high firing frequencies
Phenytoin SEs
gingival hypertrophy hirsutism coarsening of facial features cerebellar ataxia peripheral neuropathy teratogeneicity
Carbamazepine indication
no iv form
focal seizures
secondarily generalized seizures
Carbamazepine dose/MOA
started at low dose and built up slowly over days to weeks
Block NaV channels at high firing frequencies
Carbamazepine SEs
fewer side effects than phenytoin
Valproic acid indiations
absence seizures tonic-clonic (grandmal), myoclonic, atonic, tonic seizures focal seizures photosensitive seizures Lennox-Gastaut syndrome
Valproic acid MOA
block NaV
May enhance GABA transmission in specific circuits
Valproic acid SEs
in pregnancy may cause birth defects don't use in women of childbearing age weight gain menstrual irregularities transient hair loss tremors (rare)
Lamotrigine indication
Primary/genetic generalized epilepsy
lennox Gastaut Syndrome
Focal and secondarily generalized seizures
Good alternative to valproic acid
used extensively as a mood stabilizer by psychiatrists for bipolar, depression
Lamotrigine dose/MOA
started at low dose and built up over several weeks
block NaV at high firing frequencies
may interfere with pathologic glutamate release
Levetiracetam indications
monotherapy or as an add-on
partial seizures
seocnady generalized seizures
primary generalized seizures
Levetiracetam MOA
attaches to a specific binding site (saturable)
reduce CaV currents
Reverses inhibition of GABA and glycine-gated currents
Levetiracetam SEs
anxiety agitation mood swings depression suicidal ideation
Warning aura for seizures
epigastric fear deja vu olfactory gustatory auditory visual somatosensory autonomic motor vague usually nonspecific with aura: very focal seizure, usually no post-ictal phase
DDx of seizures
Syncope - neural/cardiogenic
Psychiatric: panic attacks, fugue state, pseudoseizures
Other neurologic conditions: migraine, paroxysmal movement disorders, sleep disorders, TIA, transient global amnesia, encephalopathy
Syncope definition
loss of consciousness and postural tone caused by cerebral hypoperfusion with spontaneous recovery
Neural: vasovagal, reflex-mediated, autonomic, valsalva, carotid sinus syndrome, reflex anoxic
Cardiogenic: arrhythmia,s cardiac structural abnormalities
Psychogenic non-epileptic seizures
"fake" stress suggestible, distractible occur in wakefulness in the presence ofa witness Asynchronous asymmetrical movements eyes closed consciousness retained/fluctuating Crying intractable to anti-epileptic medications no post-ictal confusion Belle indifference long duration
seizure management
ABCs roll on side, don't put anything in mouth vitals, iv access, O2 if needed thiamine bolus Glucose
Status eplepticus treatment
Lorazepam or midazolam
0-30 min: Phenytoin, cardiac/resp monitoring
30-60 min( refractory status): phenobarbitol OR valproic acid
>30-60 min: ICU-intube; midazolam bolus and infusion, then other infusions
Drug-resistant epilepsy
failure of adequate trials of 2 tolerated appropriately chosen and used antiepilpetic drug schedules to achieve sustained seizure freedom
Indications for epilepsy surgery
Drug-resistant focal epilepsy
- especially mesiotemporal sclerosis/lesional epilepsies
- curative goal
Drug resistant drop attacks and GTCs
e. g. Lennox Gastaut syndrome
- palliative goal
Seizure precautions
avoid:
- driving
- operating heavy machinery
- immersing in water
- being at heights
- using fire
- using power tools
- childcare
