Epilepsy

what is a seizure?

paroxysmal behavioural spell generally caused by an excessive disorderly discharge of cortical nerve cells

what is epilepsy?

syndrome of 2+ unprovoked/recurrent seizures on more than 1 occasion

What are epileptic syndromes characterised by?

behaviour during seizures, age of onset, cause and EEG characteristics

prolonged epilepsy remission

70% of cases well controlled with drugs

intractable epilepsy

30% of cases at least partially resistant to drug treatment

neurotransmitters in epilepsy

glutamate (excitatory) is increased and GABA (inhibitory) is decreased

focal epilepsy

seizures which begin from a single location in one hemisphere of the brain. Accounts for 80% of adult epilepsies

generalised seizures

Probably originate in deeper brain structure eg brainstem or thalamus, project to both hemispheres simultaneously

simple partial (focal) seizures

Symptomatology motor, sensory, vegetative or psychic. Consciousness may decrease but is preserved throughout the seizure

complex partial (focal) seizures

Initial subjective aura followed by impaired level of consciousness and abnormal behaviour (perioral and hand automatisms)

generalised seizures

absences, myoclonic, clonic, tonic or atonic

myoclonic seizure

sudden, brief muscle jerks that can affect any part of the body

clonic seizures

characterised by repeated jerking movements of arms and legs

tonic seizures

very short, muscles all become suddenly stiff - can cause a loss in balance and fall if it occurs when standing up

atonic seizures

cause all muscles to suddenly relax. Generally very brief

common seizure triggers

stress, lack of sleep, waking up, alcohol, medicines/drugs, periods and flashing lights

WGS epilepsy study

Took 1100 children’s genes to study them and identified 4 genes causing epilepsy: ARID18, CHD7, TCF4 and KAT68

epilepsy gene functions

GABA-A channels and NMDA receptors

What epilepsy drugs work by blocking sodium channels to reduce excitatory neurotransmitter release?

phenytoin, carbamazepine, felbamate and topiramate

How do barbiturates, benzodiazepines, valproate, gabapentin, tiagabine and topiramate work against epilepsy?

GABA potentiation to increase inhibitory action potentials

how do topiramate and felbamate work against epilepsy

glutamate receptor antagonists to reduce coupling

When does epilepsy start?

At any age but typically in childhood or people over 60

surgery for epilepsy

• elective surgery for people with drug resistant epilepsy

• removal of part of the brain which seizures start from - usually part of temporal or frontal lobes

vagus nerve stimulation

Used in drug resistant epilepsy where surgery not suitable. Device under the skin in left side of chest with electrode attached that connects to vagus nerve. Preprogrammed stimulation delivered from device

effects of VNS

• doesn’t work immediately

• 25-30% of people see seizures decrease by 50%+

• seizure control improves over time

• seizure meds taken alongside, dose etc might decrease though

diets used to help treat epilepsy

ketogenic diet, modified atkins diet and low glycemic index treatment

ketogenic diet

High fat, low carb diet which triggers shift from glucose metabolism to metabolism of fatty acids yielding ketone bodies. Not sure how it works but brain utilisation of ketones may suppress seizures