What is epilepsy
A tendency to recurrent, usually spontaneous, epileptic siezures
What is an epileptic seizure
a sudden, synchronous discharge of cerebral neurone causing symptoms or signs that are apparent either to the patient or an observer
What are the two main variations of seizures?
Partial/focal= caused by electrical discharge restriced to a limited part of the cortex of one cerebral hemisphere.
Generalised- simultaneous involvement of both hemispheres, always associated with loss of consciousness or awareness
How can partial/focal seizures be further subdivided?
Simple= without loss of awareness e.g. one limb jerking (Jacksonian seizure) Complex= loss of awareness e.g. temporal lobe seizure
Why do some people get an ‘aura’ before a generalized seizure?
They have a partial seizure which spreads due to failure of inhibitory mechanisms and then go on to have a secondnary generalized seizure.
The patient may remember the partial seizure but not the generalized one, resulting in an ‘aura’
How can generalized seizures be subdivided?
- Typical absence seizures (petit mal)
- Generalised tonic-clonic seizures (GTCS, grand mal)
- Myoclonic, tonic and atonic seizures
Describe the events of an absence seizure.
Usually begins in childhood.
Loss of awareness and a vacant expression for less than 10 seconds before returning to normal with no recollection of the seizure.
No motor manifestations except slight fluttering of the eyelids.
Never due to acquired lesiosn eg tumours.
Children with this condition may go on to have grand mal seizures.
These seizures are sometimes confused as temporal lobs seizures.
What are the phases of a grand mal seizure
Prodrome- often no warning or can have aura
Tonic-clonic phase- initial tonic stiffening followed by clonic phase with synchronous jerking of limbs, reducing in frequency over about 2 mins until the convulsions stop.Eyes may remain open, may bite tongue, may be incontinent of urine/faeces
Post-ictal pahse- a period of flaccid unresponsiveness followed by gradual return of awareness with confusion and drowsiness- usually lasts around 15 mins to an hour. Head ache common.
What are myoclonic, tonic and atonic seizures
Myoclonic- momentary brief contractions of a muscle or muscle groups eg hand twitching. Common in primary generalized epilepsies.
Tonic- just have tonic phase and no clonic phase
Atonic- a sudden collapse with loss of muscle tone and consiousness
Describe the mechanism of a simple partial seizure?
An example would be a focal MOTOR seizure know as a Jacksonian seizure which originates in the motor cortex.
What are the features of a complex partial seizure
- usually arise in temporal or frontal lobe
- preceding aura can include nausea and a variety of psychihc phenomena or hallucinations such as deja vu, jamais vu, olfactory hallucinations, visuall halluncination or misperceptions (micropsia or macropsia), fer
- follow a period of complete or partial loss of awareness for about 1-2 mins
- this stage can be accompanied by speech arrest or automatisms such as lip smackin, or even more complex motor behabrous like walking in a circle or undressing
- attacks can be followed by a post ictal phase of confusion
- can go on to have secondary generalized seizure
When does epilepsy tend to present
Children and teenagers- genetic, perinatal, congenital
Young adults- trauma, drugs, alchohol
Older age( over 60)- CVD or neoplasm
When does generalized epilepsy usually present
What abnormalities are present on EEG in generalized epilepsy
What are the main types of epilepsy syndromes
Primary generalized epilepsies (Childhood, absence epilepsy, Juvenile myoclonic epilepsy, monogenic disorders)
Symptomatic and localization relates epilsepsy (LRE)
When do PGE usually present
What is childhood absence epilepsy
absence seizures in childhood- typically resolves spontaneously at 18yrs
What is juvenile myoclonic epilepsy
Myoclonic jerks start in teenage years, followed by GTCS, one third also have absences.
Seizures often occur in the morning
What can trigger a seizure in JME
sleep deprivation, alchohol, strobe lights - risk factors
What is the treatment of PGE usually
What is the downside of sodium valproate
can uses lamotrigine as alternative
What is focal onset epilepsy (LRE)
epilepsy due to an underlying structural cause
onset can occur at any age
How is LRE treated
Carbamazepine or lamotrigine first line
What is a frequent cause of LRE
childhood febrile convulsions is the main risk factor
How common is ‘drug resistant epilepsy’
about one third of pts
What other things can cause an increased risk of epilepsy
trauma cerebral palsy brain surgery tumours vascular disorders- CVD, arteriovenous malformations, cavernous haemangiomas Alzheimer's encephalitis TB meningitis alchohol and drugs metabolic problems- hypocalcaemia, hypoglycaemia, hyponatraemia, acute hypoxia, uraemia, porphryia