Epilepsy Flashcards
Define a seizure
Transient occurrence of signs or symptoms due to abnormal electrical activity in the brain, leading to a disturbance of consciousness, behaviour, emotion, motor function or sensation
Most important excitatory neurotransmitter Via which receptor? How does it work?
Glutamate via NMDA R
Cation channel (Na/ Ca in, K out)
Depolarises membrane
More likely to fire AP
Most important inhibitory neurotransmitter Via which receptor? How does this work?
GABA via GABAa R
CL- channel
Hyperpolarises membrane
Less likely to fire AP
Pathology of seizures
Normal brain - inhibitory and excitatory sides are in balance
A seizure: manifestation of abnormal XS excitation & synchronisation of a group of neurones within brain
Caused by: loss of inhibitory (GABA mediated) signals OR too strong excitatory (NMDA/ glutamate) signals
- genetic variation (brain chemistry/ R structure)
- exogenous activation receptors (drugs)
- acquired changes brain chemistry (drug withdrawal, metabolic changes (decreased Na/ glucose)
- damage any of these networks (strokes/ tumours)
Symptoms and signs of seizure
- Often an aura prior e.g. headache/ funny sensations/ de ja vu
- Generalised seizures - loss of consciousness often, changes in muscle tone, tongue biting
May also: - For tonic-clonic seizures - initial hypertonic phase, followed rapid clonus (shaking/ jerking)
OR - For atonic seizures - lose all muscle tone (don’t fit)
- Post- ictal period minutes- hours (reduced consciousness)
Define epilepsy
Tendency toward recurrent seizures unprovoked by a systemic or neurological insult
Criteria, one of:
- 2+ unprovoked (or reflex) seizures occurring more than 24hrs apart
- 1 unprovoked/ reflex seizure & a probability of further seizures similar to general recurrence risk after 2 unprovoked (_>60% over next 10yrs)
- diagnosis of an epilepsy syndrome
- made by a specialist in an epilepsy or first fit clinic
What is a reflex seizure? List some types
Seizure brought on by a particular stimulus: Photogenic Concentrating Eating Hot water immersion Reading Orgasm Movement
Classification of seizure types
Focal onset - one side of brain affected (can eventually spread to both sides) - aware or impaired awareness - motor or nonmotor onset
Generalised onset (bilateral spread rapidly) - impaired awareness or LOC - motor (tonic-clonic, other motor) or nonmotor (absence - odd behaviour/ vacant e.g. typical/ atypical/ myoclonus/ eyelid myoclonic)
Unknown onset - motor (tonic-clonic/ other motor) or nonmotor - unclassified
What is a generalised seizure?
Originate at some point within -> rapidly engage bilaterally
CN include cortical & subcortical structures but not necessarily the entire cortex
Old term= grand mal
Old term for absence seizure = petit mal
What is a focal seizure?
Originates within networks limited to one hemisphere, may be discretely localised or more widely distributed (can eventually become bilateral)
Old term = partial seizure
What is a provoked seizure?
Seizure as a result of another medical condition, e.g.:
- drug use/ withdrawal
- alcohol withdrawal
- head trauma & IC bleeding
- metabolic disturbances (hyponatraemia/ hypoglycaemic)
- CNS infections
- febrile seizures infants
- uncontrolled hypertension
Unlikely need ongoing AED treatment if cause treated
Differentials for seizures
- syncopal-episodes e.g. vasovagal syncope
- cardiac issues e.g. reflex anoxic seizures, arrhythmias
- movement disorders e.g. parkinsons, huntingtons
- TIAs
- migraines
- non-epileptic attack disorders (old term= pseudo- seizures)
Initial management of a seizure
A-E assessment:
- Airway
- breathing (O2 sats)
- circulation (high HR, BP normally high, can go low drugs)
- disability (consciousness level)
- Execute recovery position
Start a timer
Get help
What is status epilepticus?
A seizure lasting _>5mins or multiple seizures without complete recovery _>5mins
Medical emergency
How to treat status epilepticus
Wait and if needed move on to next step
- Wait 5 minutes
- Benzodiazepine (full dose, give gradually)
- Benzodiazepines again
- phenytoin (or Levetriacetam) loading dose
- Call intensive care/ anaesthetics
- Thiopentone/ general anaesthesia