Flashcards in Epilepsy Deck (16):
Describe a partial seizure
Partial seizure involves one hemisphere, can cause motor disturbance, behavioural change, unpleasant smell
- Simple: retain awareness
- Complex: lose awareness, lip smacking
Describe generalised seizures and the different types
A generalised seizure involves both hemispheres
- Tonic Clonic (grand mal): loss of consciousness, stiffness, limb-jerking, loss of bladder control, followed by postictal period
- Atonic: sudden loss of tone
- Myoclonic: muscle jerking
- Absence seizure: unresponsive, 'day dreaming', jerking of body, rapid blinking
Possible causes of epilepsy
Primary - no identifiable cause
Secondary - due to brain injury and hypoxia, tumours, alcohol/drugs
Investigations of epilepsy
CT scan to rule out any structural abnormalities
Management of epilepsy
VG-sodium channel blockers eg. Carbamazepine/Phenytoin/Lamotrigine
GABA enhancers eg. Sodium valproate
Sodium valproate = first line for primary generalised seizures
Carbamazepine = first line for partial seizures
Lamotrigine = used in women of child bearing age
Mechanism of action of sodium valproate
Acts to increase the amount of GABA by stimulating synthesising enzymes and inhibiting inactivation enzymes.
Increased GABA leads to increased Cl ion channels opening -> hyperpolarisation, increases threshold for AP generation
ADRs and DDIs of sodium valproate
ADRs: CNS effects eg ataxia, tremor, sedation, teratogensis
DDIs: action inhibited by antidepressants/antagonised by antipsychotics.
Highly protein bound, so displaced by aspirin etc
Mechanism of action of carbamazepine
Blocks Voltage gated sodium channels. Binds to internal side, and blocks when channels are in inactivated state (voltage dependent).
Prolong the inactivation state and set the firing rate back to normal, then detach from binding site
ADRs and DDIs of carbamazepine
ADRs: drowsiness, dizziness, ataxia, motor disturbances, GI disturbance, BP variation, hyponatraemia, teratogenesis
DDIs: acts as a CYP450 inducer, so reduces levels of phenytoin, warfarin,corticosteroids, oral contraceptives
Anti depressants interfere with action.
Complications of epilepsy
Physical injury (falls)
What is status epilepticus
Prolonged seizures (>30mins), without a recovery period of consciousness.
High mortality rate, high risk of brain damage, so medical emergency
Treatment of status epilepticus
Give Benzodiazepines or IV Phenytoin
Mechanism of action of benzodiazepines
Act to enhance GABA mediated inhibition by binding at a distinct receptor site on the GABA receptor ion channel and enhancing the binding of GABA.
ADRs of benzodiazepines
Sedation, confusion, impaired coordination, aggression, resp and CNS depression.
Build tolerance with chronic use, can get dependence
Pathophysiology of epilepsy
= Excessive neuronal activity in the brain
Episodic discharge of abnormal, high frequency electrical activity leading to recurrent seizures
Hypersynchronisation of neurones leads to loss of homeostatic control