Epilepsy

Question 1

Idiopathic epilepsy

Answer 1

For no apparent reason

Question 2

Symptomatic epilepsy

Answer 2

Following trauma, infection, stroke, tumour

Question 3

Cause

Answer 3

Due to abnormal discharges of groups of neurones in an epileptic focus. May become drug resistant if not treated early.

Question 4

Simple partial

Answer 4

Spread from primary focus. Initially afect only one hemisphere of the brain. Frontal and temporal lobe seizures are most common.Jacksonian- frontal lobe, trembeling of hand progessing up arm. Can be a warning sign for a clonic-tonic seizure.

Question 5

Complex Partial

Answer 5

Psychomotor involvement from the temporal lobe, mood changes or stereotyped repetative movements.

Question 6

Generalised

Answer 6

Tonic/clonic - most common type of generalised seizure. “grand mal”, body becomes rigid due to strong muscular contractions (tonic), gives way to clonic phase of shaking and convulsing.

Question 7

Petit mal

Answer 7

Absence of around 20 seconds, staring seizure, usually occurs in children and young adults, due to adnormal electtical activity in the brain.

Question 8

Status epilepticus

Answer 8

Continual tonic/clonic seizures, do not stop, needs immediate medical attention to stop the seizure.

Question 9

Surgical treatment

Answer 9

To remove lesions that are causing the epilepsy. Only used if medication does not work and only used in partial epilepsy.

Question 10

Vagal nerve stimulation

Answer 10

Electrical stimuation of the vagus nerve to reduce frequency and intensity of seizures. Used if seizures are difficult to control with medication.

Question 11

Anti-epileptic drugs

Answer 11

Can potentiate inhibitory neurotransmission
Can stabilise trigger cells in the epileptic focus
Can block excitatory neurotransmission

Question 12

Barbiturates

Answer 12

Good sedative:anti-convulsant activity.
Potentiates GABAa inhibition
Increases duration of Cl channel opening
Inducer of hepatic microsomal enzymes.
Low TI - respiratory depression
Addictive; withdrawl leads to anxiety, insomnia, delerium, convulsion, cv collapse, REM sleep, nightmares.
Potentiates ethanol
Acute or intermittent porphyria ( causing abdominal pain, can cause dementia)

Question 13

Hydantoins

Answer 13

Prodcues stabilisation of trigger focus and inhibits spread of exvitabilitu by blocking Na channels, stimulating Na/K pump.

Question 14

Benzodiazepines (1,4 and 1,5)

Answer 14

Highly lipophillic, orally absorbed, cross bbband placenta. High TI, few side effects, possible hangover feeling, flu like withdrawl.
Pyschological and physicak dependance.
Confusion and memory impairment in the elderly.
Potentiates GABA inhibition allosterically.
Produces muscle relaxation and motor incoordination.
Diazepam is drug of chouce for status epilepticus as it can be given intramuscularly of rectally.

Question 15

Drugs that increase GABA concentration

Answer 15

Valproic acid - inhibits GABA transaminase, can also block Na channels, few side effects, drug of choice in children.
Vigabatrin - inhibits GABA transaminase, can increase brain GABA 1000 fold. Used as adjunct to major drugs.

Question 16

Drugs that block Na channels

Answer 16

Carbamazepine - stabilises trigger cells by blocking Na channels, good for complex partial seizures, induces hepatic microsomal enzymes, size effects common (headache, bone marrow depression, agranulocytosis).
Lamotrigine - blocks Na and Ca channels, results in reduced glutamate release.

Question 17

Recently intoduced drugs

Answer 17

Zonisamide - blocks Na channels, blocks seizure formation.
GABApartin - blocks Ca channels
Felbamate - blocks NMDA receptors, Potentiates GABA
Topiramate - blocks glutamate receptors, reduces ap deoendant GABA release but inhibits the supressio of GABA release, enhances GABA receptor mediated currents
Levetiracetam - inhibits vesicular storage/ release at exvitatory synapse.