PHAR
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- What is epilepsy?
- Epilepsy is a brief disorder of brain function associated with sudden abnormal discharge of nerves
- Describe the classification of epilepsy.
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Partial:
- simple
- complex (reduced consciousness)
- secondarily generalised
Generalised: loss of consciouness
- Absence
- Tonic-clonic
- Tonic or Clonic or Atonic; Myoclonic
Status epilepticus: continuous succession of fits - What are the symptoms of Partial Seizures?
-
Motor: e.g. "Jacksonian march"
Sensory: e.g. hallucinations of smell, taste, hearing
Psychic: e.g. "deja vu", automatism
Sensory/psychic symptoms common in temporal lobe epilepsy - What are the symptoms of Tonic-clonic (grand mal) seizures?
-
Mood change +/- aura
- Tonic muscle spasm, loss of consciousness
- Clonic stage:jerking, salivation, +/- incontinence
- Confusion/headache - What are symptoms of generalised seizures?
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Absence (petit-mal): starts in childhood, transient loss of consciousness but not posture (~10sec)
Myoclonic: jerking of limbs
Atonic: loss of posture - List the mechanisms of action of anticonvulsants
-
Potentiate GABA; benzodiaszepines, barbiturates, gabapentin (?)
- GABA analogue: tiagabine
- Reduce GABA breakdown; vigabatrin, balproate (?)
- Block Na+ channels; carbamazepine, phenytoin, topiramate - How do anticonvulsants work?
-
Dose-related CNS depression (all anticonvulsants)
Cortical (sedation):
e.g. benzodiazepines & barbiturates
Cerebellar (ataxia, nystagmus, diplopia):
e.g. phenytoin - Describe the uses of different anticonvulsants.
-
Valproate - most types (often used for generalised)
Carbamazepine, phenytoin - most types, except absence (carbamazepine often used for partial epilepsies)
Clonazepam - myoclonic, absence
Ethosuximide - absence
Vigabatrine, lamotrigine, gabapentin, topiramate, tiagabine, levetiracetam - "add on" therapy - Carbamazepine
-
- Also used for trigeminal neualgia
- Liver enzyme induction
- Marrow depression, jaundice, gastrointestinal upset, rashes, hypersensitivity
- need to monitor blood - Phenytoin
-
- Narrow safety margin, cerebellar effects
- Phenytoin metabolism can become saturated with zero order kinetics
- Liver enzyme induction: drug interactions; folate, Vit D & neonatal Vit K deficiency
- Rashes, marrow depression, lymphadenopathy
- Costmetic effects: gum enlargement, acne, hairiness, coarse features