CPT25 - Epilepsy Flashcards
1
Q
Epileptic Seizures
Definitions
Aetiology
Pathophysiology
Differential Diagnoses
A
- ) Definitions
- seizure: episodes of abnormal electrical activity
- epilepsy: >2 unprovoked seizures >24hrs apart
- status epilepticus: seizure lasting > 5mins or > 3 seizures in one hour (w/o complete recovery) - ) Aetiology
- genetic: differences in brain chemistry
- drugs: exogenous activation of receptors
- metabolic: acquired changes in brain chemistry
- neuronal damage: e.g. from strokes or tumours - ) Pathophysiology - ↑↑excitation and synchronisation of a group of neurones within the brain due to:
- ↑excitatory (glutamate) or ↓inhibitory (GABA) signals - ) Differential Diagnoses - from epilepsy
- syncopal episodes, TIAs, migraines
- movement disorders e.g. Parkinsons, Huntingtons
- cardiac e.g. arrhythmia, reflex anoxic seizures
- non-epileptic attack disorders
2
Q
Other types of seizures
Focal/Partial
Reflex
Provoked
A
- ) Focal/Partial - begins in one hemisphere, (often temporal lobes), can be local or widely distributed
- patient can be aware (most common) or not aware
- affects hearing, speech, memory and emotions
- presentations: hallucinations, memory flashbacks, déjà vu, doing strange things on autopilot
- Mx: 1°carbamazepine/lamotrigine, 2°sodium valproate or levetiracetam - ) Reflex Seizure - brought on by a particular stimulus:
- light, music, eating, movement, reading, thinking, hot water immersion, orgasm
- can be generalised or focal - ) Provoked - the result of other medical conditions
- drug/alcohol use or withdrawal
- head trauma/intracranial bleeding, CNS infections
- metabolic e.g. hyponatraemia, hypoglycaemia
- febrile seizures in infants, uncontrolled hypertension
3
Q
Management/Diagnosis of a Seizure/Epilepsy
Initial Management x4
Pharmacological Treamtent
Investigations x2
Imaging
A
- ) Initial Management - ABCDE
- expect high HR, you want to prevent hypertension
- get them into the recovery position if possible
- start a timer, no drugs for first 5 minutes
2.) Pharmacological Treatment - benzodiazepines
- ) Investigations - EEG, routine blood tests
- electroencephalogram (EEG): shows typical patterns, relies on capturing an episode
- you can have an abnormal EEG w/out epilepsy
- routine blood tests
- ECG to exclude problems in the heart - ) Imaging - MRI
- can detect vascular or structural abnormalities
- not required when confident of epilepsy
4
Q
4 features of using benzodiazepines to manage status epilepticus
Examples x3
Mechanism
Usage x4
Side Effects x3
A
1.) Examples - lorazepam (IV), diazepam (rectal), midazolam (buccal or intranasal)
- ) Mechanism - GABAa agonists
- ↑Cl- conductance –> hyperpolarisation
- works best when membrane is postive (seizures) - ) Usage - for status epilepticus (full loading dose given twice or more)
- anxiolytics, sleep aids, alcohol withdrawal - ) Side Effects
- addiction, cardiovascular collapse, airway issues
5
Q
5 other anti-epileptic drugs (AEDs)
Carbamazepine Phenytoin Sodium Valporate Lamotrigine Levetiracetam
A
- ) Sodium Valproate - GABAa agonist/NaC blocker
- first-line for most forms apart from focal seizures
- teratogenic: need pregnancy prevention programme
- other side effects: hepatitis, hair loss, tremor, PCOS, neural tube defects, linked to weight gain - ) Carbamazepine - blocks NaC when inactivated
- first-line for focal seizures
- CYP450 inducer: ↓efficacy of COCP and some Abx
- other side effects: SJS, agranulocytosis, aplastic anaemia - ) Phenytoin - NaC blocker, exhibits zero-order kinetics
- CYP450 inducer: ↓efficacy of COCP and some Abx
- other side effects: vitD deficiency –> osteomalacia, folate deficiency –> megaloblastic anaemia - ) Lamotrigine - NaC blocker, also affects Ca channels
- effective in focal epilepsy or when sodium valproate is contraindicated
- side effects: SJS (skin rash), leukopenia - ) Levetiracetam - synaptic vesicle glycoprotein binder which ↓neurotransmitters release into the synapse
- can be used for focal and generalised seizures
- has fewer side effects and is safe in pregnancy
6
Q
4 features of the other anti-epileptic drugs (AEDs)
Mechanisms x3
Side Effects x6
Drug-Drug Interactions
Pregnancy Usage
A
- ) Mechanisms - sodium channel blockers (most)
- GABAa agonists, synaptic vesicle glycoprotein binder - ) Side Effects - tired/drowsiness, N/V, osteoporosis
- mood changes and suicidal thoughts
- blood disorders: ↓RBCs, ↓platelets, marrow failure
- rashes, inc SJS (esp carbamazepine and phenytoin)
3) Drug-Drug Interaction - CYP inducers or inhibitors
- inducers: carbamezapine, phenytoin
- inhibitors: sodium valporate
- careful with warfarin and shouldn’t drink alcohol
- ) Pregnancy - teratogenic (greatest risk w/ valproate)
- levetiracetam and lamotrigine are the safest
7
Q
Generalised (Grand-Mal) Seizures
Definition Tonic-Clonic Absence/Petit Mal Myoclonic Atonic
A
1.) Definition - seizure originates in both hemispheres
- ) Tonic-Clonic - most typical seizures
- LOC w/ episodes of muscle tensing (tonic) followed by muscle jerking (clonic), often associated with:
- involuntary movements: tongue biting, incontinence, groaning and irregular breathing
- prolonged post-ictal period: where the person is confused, drowsy, and feels irritable or depressed
- Mx: 1°sodium valproate, 2°lamotrigine or carbamazepine
3.) Absence - typically happens in children
- lose awareness of surroundings, stares into space, is non-responsive, but then abruptly returns to normal.
- typically only lasts 10-20 seconds, most patients stop having absence seizures as they get older
Mx: 1°sodium valproate or ethosuximide
- ) Myoclonic - muscle jerking
- sudden brief muscle contractions w/o LOC
- often in children as juvenile myoclonic epilepsy.
- Mx: 1°sodium valproate, 2°lamotrigine/levetiracetam/topiramate - ) Atonic - known as “drop attacks”
- brief lapses in muscle tone, usually lasting < 3 mins
- often begin in childhood, may indicate Lennox-Gastaut syndrome
- Mx: 1°sodium valproate, 2° lamotrigine
