Epilepsy Flashcards
What are seizures? What is the pathophysiology of epilepsy?
intermittent, usually unprovoked and stereotyped episodes that result from abnormal electrical discharge of neurones of the cerebral cortex
a hyperexcitable state can result from
- increased excitatory synaptic neurotransmission
- decreased inhibitory neurotransmission
- an alteration in voltage-gated ion channels
- an alteration of intra or extra-cellular ion concentrations in favour ofmembrane depolarization.
What environmental factors cause epilepsy?
head injury
brain surgery
cerebral tumours
infarction.
inflammatory conditions of the brain
- encephalitis, chronic meningitis may present initially with seizures
drug overdose
alcohol withdrawal
metabolic disturbances
- hypoglycaemia, hypoxia, hypocalcaemia (can cause tetany) and hyponatraemia
it could also be idiopathic
- have no cause
What are drugs that can cause seizures?
antimicrobials
- chloroquine, mefloquine, isoniazid
cardiovascular
- lignocaine, procaine
antidepressants, antipsychotics or CNS drugs
- antimuscarinics, clozapine, lithium, TCA’s
endocrine
- desmopressin, insulin, oral contraceptives
anaesthetics
- propofol, ketamine
What are the types of generalised seizures?
generalised seizures
- tonic-clonic
- absence = sudden loss of awareness, motionless, unresponsive, blank stare
- myoclonic = jerks of a muscle group that may be single or repetitive, recovery is immediate
- atonic = sudden loss of muscle tone, drop to the ground due to limp muscles
- tonic = sudden increase in muscle tone, drop to the ground due to tense/stiff muscles
- clonic = repetitive jerks
- atypical absence = if other features occur such as jerks, spasms, automatism
What are the types of partial (focal) seizures?
simple partial
- consciousness preserved
- motor/sensory/somatosensory symptoms
= movements, tingling, flashing lights
- autonomic symptoms
= flushing, sweating
- psychic symptoms
= deja vu, structure hallucinations
complex partial
- impaired consciousness
= can be delayed or immediate
What is the difference between generalised and focal seizures?
generalised seizures
- seizure activity starts in both hemispheres of the brain simultaneously and consciousness is impaired from the outset
focal seizures
- seizure activity starts in a localised area of the cerebral cortex (usually the temporal or frontal lobes) and the clinical manifestations reflect the area affected. A tumour can also act as a focal point.
How can epilepsy be diagnosed?
CT or MRI
- can identify any structural abnormalities of the brain and can be useful in finding the focal point of seizures, especially when surgical treatment is being considered.
- should be performed in all patients other than children to exclude underlying lesion
EEG
- is a recording of the electrical activity of the brain. Up to 24 leads are placed on the scalp and can detect and amplify the signals from the surface of the brain.
- mainly useful in the classification and assessment of patients instead of diagnosis as some epileptic patients have normal EEGs
What are the driving regulations for patients with epilepsy?
patients who have had a first unprovoked epileptic seizure or a single isolated seizure must not drive for 6 months
patients with established seizure may drive a motor vehicle provided that
- they have had a seizure-free period of one year
- they are compliant to treatment and follow up
- they do not have a history of unproved seizures
What are the issues associated with valproate?
increased risk of teratogenicity associated
- increased risk of neural tube defects, minor congenital malformations, and developmental delay.
Valproate should not be used in female children, in females of childbearing potential, and pregnant females unless the conditions of the Pregnancy Prevention Programme are met or benefits outweigh the risks
if prescribed
- patients must be reviewed at least annually with PPP
- must be dispensed in whole packs with warning labels
Which anti-epileptics have increased teratogenicity risks? Which anti-epileptics has increased risk of cleft palate?
increased risk of teratogenicity
- phenytoin, primidone, phenobarbital, lamotrigine, and carbamazepine
increased risk of cleft palate if taken in the first trimester of pregnancy
- topiramate
What counselling should patients on anti-epileptic drugs be given?
contraception is required throughout treatment
- especially with drugs with increased teratogenicity (PPPLC)
if pregnant
- women should receive folic acid 5mg daily to counteract the risk of neural tube defects
dose of antiepileptics should be monitored carefully during pregnancy and after birth
- TDM
routine injection of vitamin K at birth effectively counteracts any antiepileptic-associated risk of neonatal haemorrhage
breast-feeding is acceptable with monotherapy antiepileptic drugs
- monitor infants for sedation, feeding, weight gain
How should anti-epileptic treatment be stopped?
abrupt withdrawal, particularly of the barbiturates and benzodiazepines, should be avoided, as this may precipitate severe rebound seizures.
reduction in dosage should be gradual and, in the case of barbiturates, withdrawal of the drug may take months.
in patients receiving several antiepileptic drugs, only one drug should be withdrawn at a time.
Why should patient mood be monitored while on anti-epileptics?
All anti-epileptic drugs are associated with a small increased risk of suicidal thoughts and behaviour
What is anti-epileptic hypersensitivity syndrome? What drugs cause this? What are the symptoms associated?
carbamazepine, lacosamide, lamotrigine, oxcarbazepine, phenobarbital, phenytoin, primidone, and rufinamide
symptoms usually start between 1 and 8 weeks of exposure
- fever, rash, and lymphadenopathy
- liver dysfunction, haematological, renal, and pulmonary abnormalities, vasculitis, and multi-organ failure
How should brand generic switching be handled? What are the categories?
Category 1
- Maintain on a specific manufacturer’s product
Category 2
- need for continued supply of a particular manufacturer’s product should be based on clinical judgement, seizure frequency, implications of breakthrough seizure, treatment history and consultation with the patient and/or carer
Category 3
- usually unnecessary to ensure that patients are maintained on a specific manufacturer’s product.
