seizure/epilepsy Flashcards
what is a seizure
transient occurrence of S&s +/- symptoms due to abnormal excessive/synchronous neuronal activity in brain
what is epilepsy
disease of brain defined by any of
- at least 2 unprovoked seizures happening > 24h apart
- one unprovoked seizure and probability of further seizures similar to general recurrence risk after 2 unprovoked seizures occurring over the next 10 years
- diagnosis of epilepsy syndrome
what is acute symptomatic seizure
- immediately recognisable stimulus
- occur in presence/closely timely association with acute brain insult
what is remote symptomatic seizure
- absence of potentially responsible clinical condition
- occur 1 wk after disorder that incrase risk of developing epilepsy
what is unprovoked seizure
no direct stimulus or acute seizure that last longer than normal
what are non-epileptic events
- abnormal paroxysmal psychic, sensory, motor manifestations which resemble epileptic seizures but not abnormal epileptiform discharges
- types
1) psychogenic non-epileptic seizures (PNES)
- partial alteration in level of consciousness with partial preservation of awareness
- caused by stressful psychological experiences or emotional trauma
2) physiological non-epileptic event
- symptoms of paroxysmal systemic disorder
- examples: convulsive syncope, hypoglycemia, migraine order, intoxication, panic attack
risk for recurrent seizure
1) lower risk: single seizure normal EEG, normal brain scan
2) higher risk: previous seizure, epileptiform EEG, abnormal brain scan
pathophysiology of seizure
- synchronised paroxysmal discharges occuring in large population of neurons within cortex starting from defined regions (foci)
- unbalanced excitatory & inhibitory receptor/ion channel function which favour depolarisation = dysregulated discharge
- split into 2 components
1) hyperexcitability
2) hyper synchronisation
pathophysiology of seizure - hyperexcitability
- enhanced predisposition of neurons to depolarise
- causes
1) voltage gated K+, Na+, Ca2+, Cl- channels
2) abnormalities in intra/extracellular substances
3) excess excitatory neurotransmitters (e.g. glutamate bind to NMDA receptor -> open Ca2+ ion channel)
4) insufficient inhibitory neurotransmitters (GABA bind to GABA receptor = open Cl- ion channel)
pathophysiology of seizure - hyper synchronisation
hippocampal sclerosis
- intrinsic reorganisation of local circuits (hippocampus, neocortex, thalamus)
- contribute to synchronisation and promote generation of epileptiform activity
aetiology of acute seizure
1) metabolic
- low Na, Ca, Mg, FBG
2) toxic substances/drugs
- alcohol, drugs, benzodiazepine withdrawal
3) structural
- stroke, traumatic brain injury
4) seizure triggers
- hyperventilation, photo stimulation, physical/emotional stress, sleep deprivation, sensory stimuli, infection, hormonal change, drugs
classifications of seizures based on mode of onset
1) focal onset: 1 hemisphere
2) generalised onset: both hemisphere
3) secondary generalised: start with 1 hemisphere then spread to other
tldr phases of seizure onset
1) prodromal
2) early ictal (aura)
3) ictal
4) postictal
prodromal for seizure onset
- before seizure
- subjective feeling/sensation
- symptoms: confusion, anxiety, irritability, headache, tremor, mood disturbances
early ictal (Aura) for seizure onset
- not everyone w epilepsy experience aura
- common symptoms
** bitter acidic taste, dejavu, dizzy, hallucination, psych problems, numbness, ringing/buzzing sound, vision problems
ictal for seizure onset
symptoms
- stiffening, chewing, confusion, difficulty breathing, drooling, twitching in one direction, inability to move/speak, pupil dilation
postictal for seizure onset
- recovery period after seizure
- duration depends on seizure type, severity and regions of brain affected
- common symptoms: arm/leg weakness, body sore, confusion, malaise, memory loss, HTN, headache, nausea, thirst
clinical presentation of focal onset
1) motor symptoms
- clonic movement (twitch/jerk) of arm, shoulder, face, leg
- speech arrest
2) sensory
- numbness/tingling
- visual disturbances (flashing lights)
- rising epigastric sensation
3) autonomic symptoms
- sweating, salivating, pallor, BP, HR
4) psychic (somatosensory) symptoms
- flashback
- visual, auditory, gustatory, olfactory hallucination
- affective symptoms: fear, depression, anger, irritability
types of generalised seizures
1) tonic clonic (GTC, grand mal)
2) clonic
3) tonic
4) myoclonic
5) absence (pepti mal)
6) atonic
7) partial seizure
tonic clonic (GTC, grand mal) clinical presentation
1) tonic phase
- stiffening of limbs
- decrease/lack of breathing
- cyanosis of nails/lips/face that returns during clonic phase
2) clonic phase
- last 1 min
- occur after brain hyperpolarised and insensitive to stimuli
- possible symptoms
** incontinence
** biting of tongue/inside mouth
** noisy/laboured breathing
3) after
- headache, lethargic, confused, sleepy
clonic clinical presentation
- clonic jerking (asymmetrical, irregular)
- most frequent in young
tonic clinical presentation
- sudden loss of consciousness & rigid posture of entire body (10 - 20s)
- characteristic of Lennox-Gaustat syndrome
myoclonic clinical presentation
rapid, brief contraction of bodily muscles (bilateral but can be unilateral)
absence (petit mal) clinical presentation
- abrupt lapse in awareness, triggered by physical exertion, less erratic
- mistaken as persistent staring
- more common in children
- only few seconds, no sfter effect
- not preceded by aura
- characteristic EEG pattern: 3Hz spike waves
partial seizure clinical presentation
- simple: consciousness not impaired
- complex: consciousness impaired
components of seizure diagnosis
1) history taking
2) neurologic examination
3) concomitant medical conditions
history taking for seizure diagnosis
- onset, duration, symptoms
neurologic examination for seizure diagnosis
1) scalp EEG
- epileptic discharges: generalised all regions affected, partial only some regions affected
- limitations
** normal EEG X exclude possibility of epilepsy
** normal person can have abnormal EEG
** Expensive, labour intensive
2) MRI w gadolinium
- indication: adult w first seizure, pt w focal neurologic deficit, suggestion of focal onset
3) biochemical/toxicology
- rule out electrolyte abnormality
- CK raised after GTC
tldr nonpharmaco for seizure treatment
1) ketogenic diet
2) vagus nerve stimulator (VNS)
3) responsive neurostimulator system (RNS)
4) epilepsy surgery
5) seizure diary
ketogenic diet for seizure treatment
1) indication
- X tolerate or X respond to ASM treatment
2) low carbohydrates, high fat diet
- induce ketosis, prevent seizures
3) limitations
- challenging to adhere long term
vagus nerve stimulator for seizure trearment
- indication: intractable focal seizure, X respond well to ASM
- stimulator send electrical stimulus
responsive neurostimulator system (RNS) for seizure treatment
- indication: pt w focal seizures who have
1) undergone testing that localised ≤ 2 epileptogenic foci -> 2 foci causing seizure
2) not responsive to ≥ 2 ASM
3) frequent and disabling symptoms - continuously monitor electrical activity in brain -> deliver brief pulses of electrical stimulation when it detects epileptiform activity that can lead to a seizure
epilepsy surgery
indication
- last line for focal seizure
- early therapy for epileptic syndrome