epilepsy Flashcards
What is epilepsy?
Epilepsy is a chronic noncommunicable disease of the brain characterised by recurrent epileptic seizures
What are the epileptic seizures like?
pileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical activity in the brain
What causes epilepsy?
The cause of epilepsy remains unknown in approximately 50% of all cases globally. Generally speaking, the causes can be divided as follows:
- Structural
- Genetic
- Infectious
- Metabolic
- Immune
- Unknown
What are structural causes of epilepsy?
Brain damage from prenatal or perinatal causes
Congenital abnormalities or genetic conditions with associated brain malformations
Severe head injury
Stroke
What percentage of epilepsy is preventable?
25%
reducing head injuries, preventing infection and using drugs to lower severe fevers in children
How would you categorise seizures in epilepsy?
Seizure types are divided into two main categories:
- Partial (focal) seizures
- Generalised seizures
Partial seizures can spread and cause secondary generalisation
What are partial seizures in epilepsy?
Caused by electrical discharge restricted to a limited part of the cortex of one cerebral hemisphere.
Partial seizures are further sub-divided according to whether or not there is loss of awareness
What are simple partial seizures in epilepsy?
A partial seizure WITHOUT loss of awareness
Originates in motor cortex
Typically results in jerking which spreads to one half of the body
What are complex partial seizures in epilepsy?
A partial seizure WITH loss of awareness
Usually originates in temporal lobe, but can arise in frontal lobe
Can lead to deja vu, hallucinations or fear
There follows a period of complete or partial loss of awareness of surroundings, lasting for 1–2 minutes on average. This is accompanied with involuntary motor movement
What are generalised seizures in epilepsy?
Simultaneous involvement of both hemispheres, always associated with loss of consciousness or awareness
What is a typical absence seizure in epilepsy?
Generalised seizure with conscious loss
There is loss of awareness and a vacant expression for <10 seconds before returning abruptly to normal and continuing as though nothing had happened. No motor symptoms
Due to primary generalised epilepsy, NEVER due to acquired lesions
What is a generalised tonic-clonic seizure in epilepsy?
An initial tonic stiffening is followed by the clonic phase with synchronous jerking of the limbs, reducing in frequency over about 2 minutes until the convulsion stops
This is often followed by a period of flaccid unresponsiveness and confusion and drowsiness asting 15 minutes to an hour or longer. Headache is common after a GTCS.
What are myoclonic, tonic and atonic seizures in epilepsy?
Myoclonic seizures or ‘jerks’ take the form of momentary brief contractions of a muscle or muscle groups, e.g. causing a sudden involuntary twitch of a finger or hand.
Tonic seizures consist of stiffening of the body, not followed by jerking.
Atonic seizure. A sudden collapse with loss of muscle tone and consciousness.
How would you diagnose epilepsy?
- Extensive patient history, including drug and alcohol use
- Serum calcium
- ECG
- EEG
- Brain MRI
What would you see on an EEG in epilepsy?
- Focal cortical spikes or generalised spike and wave activity are abnormal
- Epileptic activity is continuous
What is the recurrence rate of epileptic seizures after a first episode?
Some 70–80% of people will have a second seizure, the risk
being highest in the first 6 months after the initial seizure
How would you manage epilepsy?
A prolonged seizure may be treated with rectal diazepam, lorazepam or buccal midazolam
- Anitepileptic Drugs (AEDs)
- Surgery
What is status epileptics and how would you treat it?
Status epilepticus means a medical emergency of a seizure lasting for over 30 minutes.
Status epilepticus has a mortality of 10–15%. The longer the duration of status, the greater the risk of permanent cerebral damage. Rhabdomyolysis may lead to acute kidney injury in convulsive status epilepticus.
What do you know about antiepileptic drugs and their use in epilepsy?
First line: sodium valproate, levetiracetam, lamotrigine
Aim for mono therapy - 70% of patients will have good
seizure control with a single AED.
There are interactions between AEDs (and with other medications), e.g. between sodium valproate and lamotrigine. New generation AEDs have fewer interactions.
How does sodium valproate work?
Salproate sodium is converted into its active form, valproate ion, in blood. Although the mechanism of action remains to be elucidated, valproate sodium increases concentrations of gamma-aminobutyric acid (GABA) in the brain, probably due to inhibition of the enzymes responsible for the catabolism of GABA.
Would you ever consider stopping antiepileptic drugs in an epilepsy patient?
Withdrawal of AEDs should be considered after a seizure-free period of at least 2–3 years. There is a 50% seizure recurrence rate after withdrawal so careful discussion and explanation are essential.
When would you consider surgery in epilepsy?
Uncontrolled seizures caused by hippocampal sclerosis
Temporal lobectomy will result in seizure freedom in 50–70%
Would you continue antiepileptic drugs during pregnancy?
The overall risk of birth defects in babies of
mothers who take one AED is around 7%, as compared with
3% in women without epilepsy
The risk to the fetus of uncontrolled seizures
is greater than the risks of continuing AED treatment
Breastfeeding is okay
How do antiepileptic drugs influence contraception?
AEDs inducing hepatic enzymes (e.g. car-
bamazepine, phenytoin and phenobarbital) reduce efficacy
of oral contraceptives
A combined contraceptive pill containing a higher dose of oestrogen or the progesterone-only
pill provides greater contraceptive security
What are the main three types of epilepsy?
- Primary generalised
- Symptomatic and localisation-related epilepsy (LRE)
- Hippocampal sclerosis
What is the prognosis for Childhood absence epilepsy?
Spontaneous remission by age 18 is usual
