Neurology - epilepsy Flashcards
What is epilepsy?
Epilepsy is defined by any of the following:
- At least two unprovoked seizures occurring more than 24 hours apart.
- One unprovoked seizure and a probability of further seizures similar to the general recurrence risk after two unprovoked seizures, occurring over the next 10 years.
- Diagnosis of an epilepsy syndrome.
Types of seizures
Generalised tonic-clonic
Focal seizures
Absence seizures aka petit mal
Atonic seizures
What causes epilepsy?
No one specific cause
Some people are born with it and it may be caused by events in neonatal or birth period
Some people develop it in later life as a result of head injury, infection, brain tumour or a stroke
However in many cases the cause of the epilepsy is unknown
Other causes of seizures
Alcohol withdrawal seizures
Psychogenic non-epileptic seizures (previously called pseudoseizures)
Hypoglycaemia Electrolyte abnormalities eg. low Na Meningitis, encephalitis Drug abuse Brain tumour Head trauma
Febrile convulsions (usually children)
What is a seizure in lay terms?
Burst of signalling between the cells of the brain which interferes with the brain’s normal function and produces the
May be precipitated by warning signs (aura) - e.g. a sensation of warmth or a sound (different for different people)
What is the presentation of a generalised tonic-clonic seizure?
Loss of consciousness
Tonic (muscle tensing)
Clonic (muscle jerking)
Typically the tonic phase comes first
May have associated tongue biting, incontinence, groaning and irregular breathing.
Post-ictal period of confusion, drowsiness, irritability, depressed mood
Management of tonic-clonic seizures
First line - sodium valproate
Second line - lamotrigine or carbamazepine
What is the presentation of focal seizures?
They can present in various ways depending on where they start
May progress to generalised seizure
Presentations include:
- Hallucinations
- Memory flashbacks
- Deja-vu
- Doing strange things on autopilot
- Jerking of only one part of the body e.g. arm/hand
They can be simple or complex focal seizures:
- Simple - remain awake and aware
- Complex - not able to respond to others, not aware and wont remember the seizure
Treatment of focal seizures
First line: carbamazepine or lamotrigine
Second line: sodium valproate or levetiracetam
Absence seizures presentation and treatment
Typically occur in children and most stop having them as they get older
Patient becomes blank, stares into space and abruptly returns to normal -usually 10-20s later.
Unaware of surroundings and wont respond during the episode
First line: sodium valproate or ethosuximide
Atonic seizures presentation and management
Also known as drop attacks
These are brief lapses in muscle tone
Don’t usually last more than 3m
Typically begin in childhood
May be indicative of Lennox-Gastaut syndrome
Management is:
First line: sodium valproate
Second line: lamotrigine
Myoclonic seizures
Myoclonic seizures present as sudden brief muscle contractions, like a sudden “jump”.
The patient usually remains awake during the episode.
They occur in various forms of epilepsy but typically happen in children as part of juvenile myoclonic epilepsy.
Management is:
First line: sodium valproate
Other options: lamotrigine, levetiracetam or topiramate
Sodium valproate mechanism of action and side effects
First line option for most forms of epilepsy (except focal seizures)
It increases concentrations of GABA in the brain
Side effects:
- Teratogenic
- Liver damage and hepatitis
- Hair loss
- Tremor
It must be avoided in girls or women unless there are no suitable alternatives and strict criteria are met to ensure they do not get pregnant.
Carbamazepine side effects and mechanism of action
Side effects:
- Agranulocytosis
- Aplastic anaemia
- Induces the P450 system so there are many drug interactions
One major hypothesis is that carbamazepine inhibits sodium channel firing, treating seizure activity.
Phenytoin side effects
Folate and vitamin D deficiency
Megaloblastic anaemia (folate deficiency)
Osteomalacia (vitamin D deficiency)
