treatment of epilepsy Flashcards
Epilepsy epidemiology
Bimodal age distribution: < 1y and > 60y
Mean age of onset = 11.1y
Mortality risk of epilepsy
Increased 2-3 fold Highest within first 12m in diagnosis Sudden Unexplained Death in Epilepsy (SUDEP) Status epilepticus Unintentional injuries Suicide
Characteristics of SUDEP
Peak at 20-40y
Mostly unwitnessed and sleep related
Risk factors: Presence and frequency of generalised tonic-clonic seizures; nocturnal seizures; lack of seizure freedom
Seizure definition
Transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
Epilepsy definition
Any of:
- At least 2 unprovoked seizures occurring > 24h apart
- One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10y
- Diagnosis of an epilepsy syndrome
Provoked seizures (Acute symptomatic seizure)
Events occurring in close temporal relationship with an acute CNS insult with varying intervals according to underlying condition
- metabolic
- toxic
- structural
- infectious
- inflammation
Pathophysiology
Hyperexcitability and hypersynchronisation
Can be traced back to instability in a single neuronal cell membrane or group of cells around it
Synchronised paroxysmal discharges occurring in a large population of neurons within the cortex
Causes of hyperexcitability
Voltage/ligand-gated K+, Na+, Ca2+ and Cl- ion channels
Abnormalities in intra/extracellular substances
Excessive excitatory neurotransmitters
Insufficient inhibitory neurotransmitters
Etiology of epilepsy
Genetics Structural Metabolic Immune Infectious Unknown
Classification of seizures
Based on mode of onset:
- Focal onset (begins in one hemisphere)
- Generalised onset (begins in both hemispheres)
Impairment of consciousness (with or without dyscognitive features)
Generalised tonic-clonic (grand-mal) seizures
Stiffening of limbs (tonic phase), then jerking of limbs and face (clonic phase)
Clonic phase lasts 1min
Incontinence with biting of tongue or inside of mouth
May have headache and appear lethargic, confused or sleepy after seizure
Full recovery takes several minutes to hours
Generalised clonic seizures
Clonic jerking that is asymmetrical and irregular
Most common in neonates, infants or young children
Generalised tonic seizures
Sudden loss of consciousness and rigid posture of entire body, lasting 10-20s
Occurs at all ages, associated with diffuse cerebral damage and learning disabilities
Characteristic and defining in Lennox-Gastaut syndrome
Generalised myoclonic seizures
Rapid, brief contractions of bodily muscles, usually on both sides concurrently
May involve just one arm or one foot
Generalised absence (petit mal) seizures
Basic lapse in awareness that begins and ends abruptly
Lasts only a few seconds, no warning, no after-effects
Often undetected
More common in children, 4-12y
Differences between generalised absence and complex partial seizures
Never preceded by auras
Lasts seconds
Begin frequently and end abruptly
Produce characteristic EEG pattern “3Hz spike waves”
Generalised atonic seizures
Classic drop attack, all postural tone suddenly lost
Short episode followed by immediate recovery
Occurs at any age, associated with diffuse cerebral damage and learning disabilities
Common in severe symptomatic epilepsies
Risk of seizure recurrence
Within the next 5y: ~30%, higher in the 1st 2y
Higher risk in the presence of:
- epileptic abnormalities on EEG
- prior brain insult
- structural abnormality in brain imaging
- nocturnal seizure
Risk of recurrent seizures after 2 unprovoked seizures at 4y ~70%
When is treatment not initiated?
First unprovoked seizure None of the following: - epileptic abnormalities on EEG - prior brain insult - structural abnormality in brain imaging - nocturnal seizure
Treatment goals
Absence of epileptic seizures
Absence of ASM-related side effects
Attainment of optimal QOL
2/3 can achieve seizure freedom
