Epilepsy Flashcards
Name the most important excitatory and inhibitory neurotransmitters in the brain and their associated receptors
Excitatory;
- Glutamate via NMDA receptor (Depolarise membrane via Na and Ca influx)
Inhibitory;
- GABA via GABAa receptor (Hyperpolarise membrane via Cl channels)
What are 2 causes of an imbalance of neurotransmitters, leading to seizures
- Loss of inhibitory signals via GABA
- Too many excitatory signals (NMDA/ Glutamate)
Not everyone who has a seizure has epilepsy
Who can diagnose epilepsy?
Specialists only, as it is very significantly life-changing
Describe the diagnostic criteria for Epilepsy
- At least 2 unprovoked/ reflex seizures occurring >24hrs apart
OR
- One unprovoked seizure and a probability of further seizures similar to the general recurrence risk after 2 unprovoked seizures (at least 60% over next 10 years)
Compare the types of Focal Onset seizures
Partial Mal seizure
Aware- Consciousness not impaired, Motor/ Somatosensory/ Psychic symptoms
Impaired awareness- Consciousness impaired, possibly confused
Compare the types of Generalised onset seizures
Grand Mal seizure
Tonic-clonic: Hypertonia followed by jerking/ shaking
Myoclonic: Muscles jerking
Absence (Petit Mal): Abrupt loss of awareness
Atonic: Loss of all muscle tone (often collapse)
Compare Generalised and Focal seizures in regards to parts of brain affected
Generalised;
- Originate and spread within both hemispheres
Focal;
- Originate within and limited to one hemisphere (so consciousness less likely to be impaired)
What’s a provoked seizure?
Due to another medical condition
Drug use + withdrawal, Alcohol withdrawal, Trauma, Metabolic disturbances etc
Describe the initial management of a seizure
Airway- Patent? Adjuncts needed?
Breathing- Sats, O2
Circulation- HR, BP
Disability- Consciousness, Glucose
Exposure- Recovery position?
Once a seizure begins, how long do you wait before giving seizure terminating drugs?
5 mins (most self terminate without drug use)
Define Status Epilepticus
A seizure lasting more than 5mins, or multiple seizures without a complete recovery between them
Describe the pharmacological treatment for Status Epilepticus
0-15 mins;
- Full dose Benzodiazepine
0-15 mins;
- 2nd Full dose Benzodiazepine
15-45 mins;
- 2nd line Anti-epileptic (Phenytoin, Levetiracetam- Monitoring for these, can cause low BP and Arrythmias)
- Consider IV Thiamine if they drank alcohol
45+ mins;
- Thiopentone, ONLY in presence of Anaesthetist and in suitable environment
When do Benzodiazepines work best?
List 3 ADRs
When membrane potential is positive (in seizures)
- Addiction
- CVS Collapse
- Airway issues
List 4 indications of Benzodiazepines
- Seizures
- Anxiolytic properties
- Sleep aids
- Alcohol withdrawal
List 3 Benzodiazepines used in treating Status Epilepticus
- Diazepam (rectal)
- Lorazepam (IV)
- Midazolam (Buccal/ Intranasal)
(Oral or IM preparations can work)
(NOT a guideline: Get fast acting Benzos into patient however possible)
List 2 investigations for Epilepsy
- EEG (Abnormal in many without Epilepsy, a single scan may show abnormalities in as few as 30% of epileptics)
- MRI (Generally not required, used to look for abnormalities that can explain epilepsy)
Name 6 AEDs (Anti-Epileptic Drugs)
- Benzodiazepines (for seizure termination)
- Phenytoin
- Carbamazepine
- Levetiracetam (safe in pregnancy)
- Lamotrigine
- Sodium Valproate (1st line for generalised seizures)
How does Carbamazepine/ Tegretol work?
(Used for epilepsy, Bipolar, chronic pain sometimes)
List 3 ADRs
- Na channel blocker
- Joint pain
- Suicidal thoughts
- Bone marrow failure
How does Phenytoin work?
List 3 ADRs
- Na channel blocker
- Bone marrow suppression
- Hypotension
- Arrhythmias
List 2 indications for Phenytoin and why we need to be careful when dosing it
- Status Epilepticus
- Adjunct in General seizures
- Exhibits Zero Order kinetics
How does Sodium Valproate (Epilim, Depakote) work?
List 3 ADRs
- Na channel blocker, Ca channel blocker, GABA Agonist
- Liver failure
- Pancreatitis
- Lethargy
How does Lamotrigine work?
List 2 indications
- Na channel blocker, Ca channel blocker
- Focal epilepsy
- When Valproate is contraindicated in generalised epilepsy
How does Levetiracetam (Keppra) work?
List 2 uses
- Binds to synaptic vesicle glycoprotein, stops the release of neurotransmitters into synapse
- Focal seizures
- Generalised seizures
List 6 general ADRs of AEDs
- Tiredness/ drowsiness
- N+V
- Mood changes + suicidal thoughts
- Increases risk of Osteoporosis
- Rashes, including Steven-Johnson Syndrome (especially Phenytoin and Carbamazepine)
- Anaemia, Thrombocytopenia, Marrow failure
List some DDIs of AEDs
Carbemezapine and Phenytoin;
- May decrease effectiveness of oral contraceptive pills
- May decreases effectiveness of some antibiotics
Valproate;
- Can increase [plasma] of other AEDs
- Ideally, patients on AEDs should not drink alcohol
List 2 AEDs that are CYP Inducers and 1 that is a CYP Inhibitor
Inducers;
- Phenytoin
- Carbamazepine
(Also Barbiturates- not prescribed anymore)
Inhibitors;
- Valproate
All AEDs carry a risk of congenital malformation.
Which has the highest risk?
Which 2 have the lowest risk?
Highest risk;
- Valproate
Lowest risk;
- Lamotrigine
- Levetiracetam
How does Carbamazepine influence its own metabolism?
Induces it’s own CYP enzyme overt time, increasing it’s own metabolism
