Epilepsy Flashcards
What is a seizure?
Sudden, abnormal, excessive, rapid, and repetitive discharges from cerebral neurons
Self-terminating but tends to recur
Clinically, intermittent stereotyped disturbance of
- Consciousness
- Behaviour
- Emotion
- Motor function/sensation
What is epilepsy?
Seizures recur, usually spontaneously
What is status epilepticus?
Seizure for >30 min
What is the difference between simple and complex partial seizures?
Simple - consciousness not impaired
Complex - consciousness impaired
- May start as simple partial seizure
What are the symptoms of partial seizures?
Motor
Somatosensory/special sensory
Autonomic
Psychological
Can partial seizures become generalised?
Yes, usually over years
= secondary generalisation
What are absence seizures often mistaken for, especially if they occur for only a few seconds?
Inattentiveness/distractedness
What are the common causes of seizures?
50% idiopathic Stroke Alcohol abuse Head injury Neurodegenerative
What prenatal, or perinatal, factors predispose you to epilepsy?
Intrauterine drug use
Perinatal trauma
Anoxia
Trauma and surgery
What are the metabolic causes of seizures?
Electrolyte disturbances > cause neuronal irritability
- Renal failure > uraemia
- Hepatic failure
- Acute hypoxia
What are the toxic causes of seizures?
Withdrawal of anti-epileptic drugs
Chronic alcohol abuse
CO/Pb/Hg poisoning
What are the triggers of seizures?
Sedative/ethanol withdrawal Sleep deprivation Anti-epileptic reduction/inadequacy Hormonal variations Stress Fever/systemic infection
What is the clinical assessment of presentation of first seizure?
Seizure/not? Focal onset? Evidence of interictal CNS dysfunction? Metabolic precipitant? Seizure and syndrome type?
What are the differential diagnoses of seizures?
Syncope Migraine Sepsis Hypoglycaemia Hypocalcaemia Hypomagnesaemia
What are the investigations of presentation of first seizure?
FBE - Anaemia - WCC UEC LFT ABG Glucose CMP ECG Brain imaging Lumbar puncture Blood/urine drug screen
What brain imaging is used to assess presentation of first seizure?
Mostly MRI, rather than CT
Rule out space-occupying lesion
What does an EEG show in epilepsy?
Background abnormalities - Significant asymmetries - Slowing inappropriate for clinical state/age Interictal abnormalities - Spikes - Sharp waves - Spike-wave complexes Ictal EEG most useful - Distinguish between seizure and pseudoseizure
What investigations can be used to distinguish between a seizure and a pseudoseizure?
Ictal EEG
Serum prolactin
What are the considerations when determining whether to treat or not treat after the first seizure?
Vast range of recurrence within 5 years Relapse rate may be reduced with treatment Abnormal findings > increased risk of recurrence - Imaging - Neurological exam - EEG - FHx Quality of life important factor
What are the mechanisms of action of the drugs used to treat epilepsy?
Blockers of repetitive activation of Na channel
Enhancers of slow inactivation of Na channel
GABA-A receptor enhancers
NMDA receptor blockers
AMPA receptor blockers
What medications are commonly used in the treatment of partial onset seizures?
Levetiracetam
Lamotigrine
Carbamezapine
- Less efficacious in generalised seizures
Valproate
- Better efficacy in generalised seizures than carbamezapine
What is the only specific treatment for absence seizures?
Ethosuximide
What medications are commonly used in the treatment of myoclonic seizures?
Benzodiaepines
Levetiracetam
What medications are commonly used in the treatment of tonic-clonic seizures?
Valproate
Lamotrigine
Levetiracetam
What are the advantages of monotherapy in the treatment of epilepsy?
Simplifies treatment
Reduces adverse effects
How are therapeutic and toxic ranges for medications in epilepsy defined?
Individual patients define their own ranges
What should be discussed with the patient when initiating and monitoring medications in epilepsy?
Likely and unlikely, but important adverse effects Likelihood of success Recording/reporting - Seizures - Side effects
What does the evaluation after seizure recurrence involve?
Progressive pathology?
Avoidable precipitant?
If on medications
- Problem with compliance/pharmacokinetic factors?
If not on medication, consider starting drug treatment
What is the management of status epilepticus?
IV anti-epileptic drugs; eg: phenytoin
If phenytoin not available, benzodiazepines can be given per rectal
Eventually, general anaesthesia with propafol/thiopentone should be commenced
