Epilepsy Flashcards
What is the epidemiology of epilepsy?
Common
Normally presenting in childhood or teenage years
i) When presenting in adults – should be much more suspicious of organic cause/lesion/trauma
Much more prevalent in developing countries
After the first seizure, 70% will have a second within 12 months, usually the first 2 months
70% cases have no identifiable cause
70% of cases are well controlled with drug treatment
What is the aetiology of epilepsy and other seizures?
GEnetics - 30% of patients will have a 1st degree relative with epilepsy
TRauma/surgery/Mass lesions to the skull/ HYpoxia - most likely to cause epilepsy when it occurs in utero or early childhood
PYrexia – especially in children - can occasionally cause convulsions as an isolated incident
i) Known as febrile convulsion
ii) But can also increase the risk of having future seizures
DRugs - used to treat neurological and psychiatric disorders can often lower the seizure threshold i.e. TCAs, MAO-Is, amphetamines etc
Drug withdrawal – off anticonvulsants etc; Alcohol induced hypoglycaemia or withdrawal can be a cause
CNS INfections: Encephalitis; Meningitis
Hydrocephalus (can lower the seizure threshold)
VAscular abnormalities – especially in elderly or stroke patients as a result of infarction
MEtabolic disturbance: Hypoglycaemia/calcaemia/natraemia; Hypoxia; Uraemia
(Dr HyPy Tricked Me Into Getting -a- Vasectomy)
What is the pathophysiology behind a seizure?
Abnormal synchronised discharge of neurons: normal inhibitory mechanisms fail leading to mass simultaneous discharge
Individuals have a ‘seizure threshold’
i) Level of excitability at which cells will discharge uncontrollably
ii) In seizure patients, threshold is lower → neurons = hyperexcitable
Neurotransmitters involved
i) Glutamate = excitatory
ii) GABA = inhibitory
What are some triggers of seizures?
i) Sleep deprivation
ii) Alcohol intake + withdrawal
iii) Drug misuse
iv) Less common - Loud noises, Hot baths, Reading, Strange shapes, smells, sounds etc
v) Infection/metabolic disturbance
vi) Flickering lights i.e. on TV, games etc (cause primary generalised epilepsy only)
vii) Exhaustion - physical/mental
SAD LIFE
How do you classify all types of seizures?
Focal onset:
- Consciousness intact vs impaired
- Motor (e.g. myoclonic, spasms, atonic) vs non-motor onset (e.g. behaviour arrest, emotional)
- Focal to bilateral tonic-clonic (focal excitation spreads)
Generalised onset:
- Motor = tonic clonic vs other motor
- Non-motor = absence
Unknown onset:
- Motor = tonic clonic vs other motor
- Non-motor
- Unclassified (due to inadequate info about episode)
What is the post-ictal state?
What happens after the individual wakes after a seizure - may feel drowsy, confused, headache, myalgia, sore tongue, injury may have been sustained whilst falling/convulsing
How do you localise a seizure to the temporal lobe?
HEAD
Hallucinations (auditory/gustatory/olfactory - uncus)
Epigastric rising, Emotional states
Automatisms - complex motor movement with no recollection afterwards (lip smacking/grabbing/plucking)
Deja vu - hippocampus/Dysphasia post-ictal
How do you localise a seizure to the frontal lobe?
Jacksonian march – spreading focal motor seizure with retained awareness, spreading from face or thumb
Motor arrest
Subtle behavioural disturbances
Dysphasia
Post ictal Todd’s paralysis (weakness of limbs)
How do you localise a seizure to the parietal lobe?
Sensory disturbance – tingling, numbness Motor symptoms (due to precentral gyrus spread)
How do you localise a seizure to the occipital lobe?
Visual phenomena such as spots, lines, flashes
What are some other features of a simple partial seizure?
Isolated limb jerking/head turning (away from side of seizure)
Isolated parasthesia
What is generalised epilepsy?
Seizures arise in the brainstem or midbrain then spread simultaneously to both cortices
Absence seizures – petit mal
i) Childhood onset – can affect school performance so teachers educated to look out for attacks
ii) Patients are likely to develop tonic-clonic seizures later in life
Tonic-clonic seizures - grand mal
What happens during an absence seizure?
Patient unresponsive to stimuli but still conscious Patient stares, may go pale
May be some muscle jerking
After attack – normal function resumes quickly
Lasts <15s
May occur several in one day/short period of time
What happens during a tonic-clonic seizure?
Often aura before attack
Tonic phase – stiffening of limbs (tonic), epileptic cry (indistinguishable noises), tongue biting, incontinence, hypoxia/cyanosis – no breathing in this phase; lasts 10-60s
Clonic phase – convulsions/limb jerking, eye rolling, tachycardia, no breathing/random uncoordinated breaths; lasts seconds-minutes
What are some other types of seizures?
Myoclonic seizure - sudden jerk of limb, fae or trunk, patient may be suddenly thrown to the ground or have a violently disobedient limb
Atonic/akinetic seizure - sudden loss of muscle tone causing a fall, no loss of consciousness
Dissociative/non-epileptic seizures
i) Often a history of psychological trauma
ii) Those with epileptic seizures may also co-exhibit
iii) Usually involve - sinusoidal shaking/asynchronous limb movements (rather than repeat contractions), pelvic thrusting, waxing and waning in intensity, tip of tongue bitten (rather than side), eyes closed, some distractibility, prolonged seizures that could be mistaken for status.
What is status epilepticus?
Status = >30mins
When a seizure lasts >5mins OR multiple seizures in between consciousness is not recovered, lasting >5mins
Is a medical emergency
i) As brain cells swell due to electrolyte imbalance (as body cannot meet energy demands of rapidly discharging neurons) and cause herniation of the brain
ii) Also patient is likely not breathing → hypoxic
Management:
Buccal midazolam as first-line treatment in the community
Rectal diazepam if preferred, or if buccal midazolam is not available
Intravenous lorazepam if intravenous access is already established and resuscitation facilities are available (will be given this in hospital)
Need to call ambulance - admission if not controlled with these measures
How do you investigate seizures?
Diagnosis - must have 2 seizures in 2yrs w/no other cause to qualify for epilepsy, mostly clinical diagnosis
Neurological exam - mostly normal but may point to aetiology i.e. mass lesions
Bloods - hypoglycaemic, hypocalcaemia, CK serum levels raised after a tonic clonic; renal problems on U+E
EEG: Usually normal between fits
i) Characteristic wave patterns, usually with large amplitudes and sometimes rhythmic patterns may present during however:
Absence seizures - 3Hz spike and wave pattern
Tonic clonic seizures - tonic phase – 10-14Hz spike
ECG: Look for heart condition that may have caused a fall (common differential for seizure) i.e. AF
CT/MRI: Indicated for with
i) Late onset disease
ii) Partial seizures
iii) Associated with abnormal clinical signs
How do you differentiate a non-epileptic from an epileptic seizure?
i) EEG
ii) Serum muscle enzymes – raised in true tonic clonic seizures
iii) Serum prolactin
What medical treatments are there for epilepsy?
Pharmacological: only start after a minimum of 2 fits, only use one drug at a time, begin with a small dose and gradually increase until control achieved, toxic effects occur or maximum dose reached
Partial seizures ± secondary generalisation: carbamazepine (2nd:Sodium valproate)
Absence and tonic-clonic, myoclonic and atonic seizures: Sodium valproate
(2nd: lamotrigine)
Avoid carbamazepine in myotonic/atonic
How do you treat status epilepticus?
Benzodiazepines – diazepam
i) Useful acutely but not chronically
ii) Give IM, IV or rectal
iii) Paralyse and intubate after
Phenobarbital
i) Effective but can cause circulatory depression
Phenytoin
i) Given IV but can cause severe arrhythmia so be careful
What else is important in epilepsy?
Identify trigger factors if possible then can avoid pharmacological intervention
Driving:
Patient to inform DVLA
Patient cannot drive for X months when:
6m from 1st unprovoked seizure
6m from change in medication (if seizure free)
1yr seizure free with or without medication if Dx epilepsy
Drugs - are teratogenic, so contraceptives required for women
What are some surgical treatments for seizures?
Indicated for when
i) Mass lesions in brain
ii) Uncontrollable epilepsy
Procedures – removal of part of brain, will have an impact on other functions
i) Partial/total temporal lobectomy
ii) Corpus colossal section – to stop seizure spreading between hemispheres
iii) Hemispherectomy
iv) Selective amygdalo-hippocampectomy
v) Pre op - Wada test – injection of local anaesthetic into arteries of a part of the brain to simulate effects of removal of that part of the brain – can be useful to guide –ectomy decisions
