Seizures Flashcards
What is needed for neurons to maintain resting potential, depolarise, and depolarise
Ionic gradient
What maintains ionic gradient in neurones
Ionic channels and pumps
Inhib and excitatory NT
Glutamate excite
GABA inhib
Seizure cellular level
cortical neurons begin to fire in a hypersynchronous manner. This increased rate and sustained network of firing has a characteristic pattern and is called a paroxysmal depolarizing shift. It results in a spreading wave of electrical activity
How does refractory period of neurones change during a seizure
May reduce
Neuronal changes during seizure
Hypersynchronous firing
Sustained incr firing rate
Paroxysmal depolarising shift
Decr refractory period
Loss of surrounding neuronal inhibition
NT imbalance
Initial trigger of seizures
High frequency action potential generation with concurrent hyper polarisation
(Likely mediated by astrocytedps through calcium signalling)
Which cell type is involved in the initial trigger of a seizure via hyper polarisation
Astrocyte
Seizure definition
Transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Epilepsy
Conceptually, epilepsy exists after at least one unprovoked seizure, when there is high risk for another.
Epilepsy is considered to be a disease of the brain defined by any of the following conditions:
1. At least two unprovoked seizures occurring >24 h apart
2. One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
3. Diagnosis of an epilepsy syndrome
Resolved epilepsy
– had an age-dependent epilepsy syndrome but are now past the applicable age
– or who have remained seizure-free for the last 10 years and off antiseizure medicines for at least the last 5 years
How long does a person have to be seizure free and off meds for resolved epilepsy
10 yrs
Off meds 5 yrs
Generalised seizure
Rapid bilateral onset
Always LOC
Convulsive or non convulsive
Generalised seizure subtypes
Tonic clonic
Atonic
Absence
Myoclonic
What parts of the brain are involved in generalised seizure
Originate within brain and quickly engage bilateral networks
Can include cortical and subcortical structures
Focal seizure
Onset within 1 hemisphere
Aura, motor, or autonomic sx
Retained or altered consciousness (stare blankly, grunting, automatisms)
Often progresses to bilateral convulsive in adults
What does a focal seizure often progress to in adults
Bilateral convulsive seizure
Focal seizure parts of brain involved
Originate in networks limited to 1 hemisphere
May be discretely localised or more widely distributed
What is an unknown seizure
Insufficient evidence to characterise as focal, generalised, or both
What type of seizure is a generalised onset non motor presentation
Absence
Which type of seizure may have retained awareness
Focal
Sx of cognitive seizure
Impaired language
Other cognitive impairment
Positive features - deja vu, hallucination, perception distortion
Sx of emotional seizure
Anxiety
Fear
Joy
Simple partial and complex partial seizure
Simple - focal that doesn’t effect consciousness
Complex - focal that affects consciousness
Secondary generalised seizure
Focal that progresses to generalised
What can bring on an absence seizure in kids
Hyperventilation
What type of seizure may have aura
Focal
Causes of epilepsy
Genetics - channelipathy, GLUT1 deficiency
Structural-metabolic issues - neurocutaneous disorder, childhood epilepsy, cortical dysplasia
Acquired Causes of seizures
Trauma
Stroke
Tumour
Infection
Autoimmune
Causes of provoked seizures
Fever
Drugs/toxins
Metabolic
Catamenial
Reflex epilepsies
Cryptogenic seizure
Probably has underlying cause but normal imaging
Symptomatic seizure
Secondary to known or presumed brain disorder
Are epilepsy syndromes more common in kids or adults
Kids
Epilepsy syndromes
Benign Rolandic epilepsy
Infantile spasms / west syndrome
Juvenile Myoclonic
Progressive Myoclonic
Rasmussen
Lennox gastaut
Dravets
Landau klefgner
Epilepsy imitators
Vasovagal syncope
Reflex anoxic seizure
Breath holding attack
Hyperventilation syncope
Neurological syncope
Orthostatic intolerance
Long QT
Cardiac syncope
Innattention
Tantrums
Panic attack
Dissociative state
Hallucinations
Non epileptic seizure
Hypnogogic jerks
Sleep related rhythmic movement disorder
Status epilepticus
Seizure lasting 30+ mins, or cluster or seizures without intervening recover for 30+ mins
Consequences of prolonged seizures
Mesial temporal sclerosis
Death
Febrile convulsions
Seizures associated with raised temperature in a child (usually 6months to 6 years)
Typically short generalised seizures with rapid recovery
Febrile convulsions usual age
6mo-6yrs
Febrile convulsion tx
Gently cool
Rarely - benzo is not terminating
NOT AED
Can antipyretics prevent febrile convulsions
No
Eclampsia
Acute life threatening condition associated with pregnancy
Eclampsia presentation
Confusion, headaches, tremor, twitching
Progresses to generalised tonic clonic and comz
Eclampsia risk factors
Often already has pre eclampsia
May have HELLP syndrome
Primitravida
Young
Eclampsia tx
Oxygen
Magnesium sulphate
BP max - hydralazine, labetalol
Deliver baby
Impact seizure recommendation
Generally benign
CT within 1 hr
5 types of post traumatic seizure
Immediate - within 24hrs
Early - within 7 days
Late - after 7 days
Recurrent - post traumatic epilepsy, focal or fpgeneralised
Hypoxic-ischaemic - usually myoclonic or focal w alt consciousness, if status usually fatal
Post traumatic epilepsy
One or more unprovoked seizures occurring 7 days after TBI with no other cause
Contusion to which lobes if most linked to post traumatic epilepsy
Frontal > parietal > temporal
Post traumatic epilepsy prophylaxis
Steroids
Seizure tx ladder
Oxygen
Benzos
Phenytoin
Levetiracetam
Phanobarbitone/thiopentone
General anaesthesia- propofol, fentanyl
Neuro monitoring in ICU
Consider - glusoces, thiamine, rectal paraldehyde
Seizure prophylaxis
AED
Post head injury - phenytoin, levetiracetam (keppra)
What AED type should be avoided in absence seizures
Carbamazepine
