Seizures lecture Flashcards
What is our normal neurobiology?
Electrical activity: non-synchronous
Neurons: can maintain resting potential, depolarise and repolarise
Ion channels/pumps: maintain gradient and have adequate energy to work
Neurotransmitters: balance between inhibitory (GABA) and excitatory (glutamate)
Neurobiology in seizures?
Cortical neurons are hypersynchronous
Develop paroxysmal depolarising shift: leading to increased firing rate and sustained NETWORK of firing
Spreading wave of electrical activity
Refractory period reduced
Loss of surrounding neuronal inhibition
Neurotransmitter imbalance may be found
Summary of neurobiology in seizures
Initial trigger = high frequency action potential and hyperpolarisation
Often seen in astrocytes with calcium signalling
Leading to a NETWORK ISSUE (‘epileptic aggregate’)
Clinical definition of seizure
Transient occurrence of signs/symptoms associated with abnormal excessive/synchronous neuronal activity in the brain
ILAE 2014 epilepsy definition
- at least 2 unprovoked seizures more than 24 hours apart
- 1 unprovoked seizure with probability of further seizure is more than 60% occurring in the next 10 years
- diagnosis of epilepsy syndrome
Day to day epilepsy definition
At least one unprovoked seizure with high risk of another
Resolved epilepsy
- age-dependent epilepsy syndrome - now past applicable age
2. seizure free for 10 years and off anti-seizure meds for 5 years
How are seizures classified?
1/ generalised
2/ focal
3/ unknown
What is a generalised seizure?
rapid onset
bilateral
loss of consciousness
convulsive/non convulsive (brainz monitoring if LOC and non-convulsive)
Examples of generalised seizure
Tonic/clonic Absence (typical/atypical/with myoclonic changes) Clonic Tonic Atonic Myoclonic
What is a focal seizure?
onset in 1 hemisphere often involves: aura/MOTOR/autonomic sx awareness: retained/altered often progresses to both hemispheres: BILATERAL CONVULSIVE SEIZURE
What is an irritative lesion? Where would they look?
Epilepsy/minor stroke
look AWAY from focus
What is a destructive lesion? Where would they look?
Massive MCA infarct
look TOWARDS the focus
How are absence seizures caused? (most of time)
hyperventilating (decreased calcium ions)
What are the causes of a seizure?
PROVOKED: fever toxin/drug/withdrawal metabolic catamenial reflex epilepsys
ACQUIRED: trauma stroke tumour infection autoimmune
What are the causes of epilepsy?
GENETIC
abnormal syndromes
channelopathies
GLUT1 deficiency
STRUCTURAL/METABOLIC
tuberous sclerosis (neurocutaneous disorder)
epilepsy syndrome
structural development disorders
What is a febrile convulsion?
Short generalised seizure with increase in temperature in children (6months - 6 years)
Rapid recovery
Treat:
gently cool
refer if first
refer if no source of infection found
What is reflex anoxic seizure?
Noxious stimuli -> reflex cardiac standstill and seizure in children (under 2)
cyanosis
pallor
tonic clonic
downbent nystagmus
BENIGN
short latency from stimuli (differentiate between vasovagal)
What is eclampsia?
life threatening condition in pregnancy
confusion, headache, tremour -> gen tonic clonic
primips
young women
What conditions predispose to eclampsia?
pre-eclampsia (proteinuria, hypertension)
HELLP
How do you treat eclampsia?
oxygen magnesium sulphate (4g IV) manage BP with labetalol or hydralazine deliver baba treat complications
Management of post traumatic seizure?
CT within 1 hour
hypoxic - ischaemia: myoclonic or focal and altered GCS
Definition of post traumatic epilepsy
One or more unprovoked seizure 7 days after TBI with no other cause
Predictions of PTE
skull fracture
severity of injury
haemorrhage
contusion FL>PL>TL
Emergency management of seizure in trauma
Help
ABC (adjuncts?)
COMA
C-spine
Oxygen
Monitoring
Access (IV)
Med ladder in emergency management of seizure
Oxygen Benzos (max 2x dose) Phenytoin Phenobarbitone/thiopentone GA (propofol/thiopentinol) ITU for neuromonitoring
What is the dose of lorazepam?
2-4 mg IV bolus
0.1mg/kg
What is the dose of diazepam?
5-10mg PR
0.25mg/kg IV or 0.5mg/kg PR
What is the dose of midazolam?
1-2mg bolus iv
0.5mg/kg buccal
What is the dose of phenytoin?
1g IV slow over 30 mins
ECG monitoring (cause arrhythmias)
18mg/kg IV
What is the dose of phenobarbitone/thiopentone?
4mg/kg
What else do you need to think about giving in seizure?
glucose (0.5mg/kg IV)
thiamine
recatal paraldehyde (children)
DVLA post seizure
Prophylaxis of seizure post head trauma?
phenytoin
levetiracetam
(topiramate)
What should you avoid giving in absence seizures?
carbamazapine
What can you do whilst wait for CT head in TBI?
- optimal neuroprotection
- bleeding status (meds/clotting)
- prepare for theatre
How can you optimise neuroprotection?
loosen c-spine immobilisation hyperosmotic fluids (mannitol/HTS) head up tilt 30 degs sedation? control CO2 (normal to low) control O2 (avoid hypoxia and hyperoxia) glucose and temp control ensure have BP
What is an ICP bolt?
intracranial device
screwed into brain with small port into part of brain with limited function
directly measures ICP -> continual assessment
(CPP=MAP-ICP)
What are the indications for ICP bolt?
- GCS <8 and abnorm CT
- GCS <8, norm CT but 2 of:
- age >40
- BP <90
- abnorm posturing
What is an external ventricular drain?
temporary diversion of CSF due to:
- obstruction of csf flow
- failure of csf absorption (sah)
- overproduction of csf (rare)
intraventricular meds
often seen in diffuse injuries to avoid surgery and decrease icp
pros of EVD?
monitor ICP
decrease ICP
cons of EVD?
operative risk
risk of infection
difficult if ventricles displaced or small
if decompress ventricles could lead to expansion of haematoma
not difinitive
When can you do burr holes?
frontal
suboccipital
parietal
temporal bones
What are the pros of burr holes?
buys time - temporarily relieves pressure
what are the cons of burr holes?
unlikely benefit to acute bleed (sticky wont come out)
operative risk
delay definitive treatment
indications for surgery in EDH
> 30cm3 (regardless of GCS)
GCS <9 and anisocoria (unequal pupils)
indications for conservative management of EDH
vol <30cm3 thickness <15mm midline shift <5mm GCS >8 No focal neuro deficit
indications for surgery in acute SDH
thickness >10mm and MLS >5mm regardless of GCS if thickness if <10mm and MLS <5mm but: - GCS drops by 2 - pupils fixed and dilated or anisocoria - ICP more than 20
What is status epilepticus?
Seizure lasting 30 mins or more
or
cluster of shorter seizures without intervening and recovery continues for 30 mins or more
what can prolonged seizures cause?
mesial temporal sclerosis (temporal lobe seizures) - CA1 and subiculum
seizures beget seizures (kindling)
- seizures induce more seizures?
risk of death
