Week 5 - Seizures Flashcards
Explain the pathophysiology of the different seizure types:
Seizure activity is the result of abnormal/uncontrolled neuronal depolarisation.
Increased release of excitatory neurotransmitters or decreased availability of GABA is associated with seizure activity.
Changes in membrane potential stimulated by hypoxia, hyperthermia, hypoglycaemia, hyponatraemia, brain injury and some drugs.
What is the treatment for seizures?
Benzodiazepines: anxiolytic, muscle relaxant, anticonvulsant, hypnotic, memory impairment.
Enhance GABA transmission, increasing frequency of openings of GABA channels, increased opening time and receptor affinity for GABA.
What are some seizure triggers?
Alcohol Diet - caffeine, Low BSL Infection - high temp Lack of sleep Menstruation Stress Photosensitivity
What are Partial seizures?
Begin focally in a unilateral cortical site and affect part of body controlled by part of brain.
Mainly caused by stroke, tumour or head injury.
What is the difference between Simple and Complex partial seizures?
- Simple: no alteration in LOC - involve involuntary limb movement (stiffening), deja vu, unpleasant smell/taste, stomach sensations, memory of event
- Complex: altered LOC, starts in temporal/frontal lobe, appears confused, no recollection of incident, can be mistaken for drug/alc/psych
What are Generalised seizures?
Involve both cerebral hemispheres (subcortical structures) and brain stem
Many types including absence, atonic, tonic-clonic
What is an Absence seizure?
Awareness and responsiveness are impaired, pt simply stare and eyes may roll back.
Start suddenly and cannot be interrupted, generally lasting <10secs but can occur frequently throughout the day.
What is an Atonic seizure?
Drop attack
Affect muscle tone and pt collapses to the ground but usually remains conscious, pt tends to recover quite quickly.
What is a Myoclonic seizure?
Brief shock-like jerks of a muscle group lasting a couple of seconds, but sometimes many will occur in short timeframe
What is a Tonic seizure?
Muscle tone greatly increased, as body and limbs make sudden stiffening movements.
Often occur in clusters during sleep and tend to last <20secs, patient tends to remain conscious
What is a Tonic-Clonic seizure?
Body stiffens and falls to the ground (tonic), limbs begin to jerk in strong, symmetrical movements (clonic).
Patient may dribble, facial cyanosis, incontinence.
Generally last 1 to 3 minutes. Pt will be extremely drowsy afterwards.
What is a secondary Generalised seizure?
Seizure activity spreads from focal point (partial) across to both sides of brain and pt has no recall of event. Generally lasts 1-3mins.
What are the phases of generalised seizures?
- Pre-ictal: period just before seizure, may involve aura, restlessness, nervousness and wandering.
- Ictal: seizure period
- Post-ictal: period after seizure - disorientation, confusion, salivation, unresponsiveness
What is Status Epilepticus?
> 5mins of seizure activity or multiple seizures without full recovery of consciousness between seizures.
Neurological emergency, which if untreated may lead to hypoxia, hyperthermia, cerebral damage and death.
Occurs most commonly in patients with no history of epilepsy.
What are Psychogenic seizures?
Events resembling an epileptic seizure, but without the characteristic electrical discharges associated with epilepsy. They are of psychological origin, and are one type of non-epileptic seizure mimics.
