WK THREE - Seizures

Seizure

Transient occurrence of symptoms and/or signs due to abnormal excessive or synchronous neuronal activity in the brain.

Normal Cell Depolarisation Pathway

• positive ions pass through channels in the cell into the neuron

• influx of + cells (Na) raises the resting membrane potential and so the threshold potential is reached = depolarisation

• potassium leaves the cell = repolarisation

Excitatory and inhibitory neurotransmitters

The balance between excitatory neurotransmitters (allowing positive ions to enter the cell) & inhibitory neurotransmitters (allowing negative ions to enter the cell) determines whether a neuron will depolarize or not.

Seizure pathophysiology

Increased release of excitatory neurotransmitters or decreased availability of GABA is associated with seizure activity.

Excitatory Neurotransmitters

• acetylcholine

• noradrebaline

• dopamine

• serotonin

Seizure causes

• Structural: acquired (e.g. stroke, trauma, tumor), or genetic (e.g. malformations of cortical development)

• Genetic: underlying genes are not yet known • Infectious: e.g. meningitis, encephalitis, TB, malaria, etc

• Metabolic: hypo/hyperglycaemia, hypoxia

• Systemic diseases: eclampsia, febrile convulsions

• Secondary to medications / drugs / alcohol

• Unknown

Seizure differentials

• Syncope

• Stroke

• TBI

• Migraine with aura

• Movement disorder

• Overdose

• Hypoglycaemia etc

• Sleep disorder

Seizure triggers

• Alcohol ‐ Reduces the effect of medication

• Diet - Caffeine, Low BSL

• Infection/Illness ‐ High temp

• Lack of sleep

• Menstruation

• Smells / sounds / flickering lights

• Missed normal medication

• Other drugs

• Stress

Seizure types

- Focal aware seizure

- Focal impaired awareness seizure

- Generalised absence seizure

- Generalised atonic seizure

- Generalised myoclonic seizure

- Generalised tonic seizure

- Generalised tonic-clonic seizure

- UNKNOWN

Focal Seizure

• small region of the brain & limited to one hemisphere (60%)

• presents sutble or unusually - intoxicated, daydreaming

Focal Aware Seizure

• no alteration in CS & brief

• fully aware, cant talk/respond

• involuntary limb movement, aura, etc..

Focal Imapired Aware Seizure

• associated with LOC

• confused/dazed

• strange mannerisms

• lasts for several minutes

• mistaken for drugs/alcohol use

• aura?

Generalised Seizure

• both hemispheres from the onset

• awareness is ALWAYS affected

3 Seizure Phases

• preictal - aura, restlessness, wandering

• ictal - seziure period

• postictal - disorientation, confusion, salivation, unresponsiveness..

Abscence Seziure

• lapse in awareness and responsiveness - looks like staring or daydreaming

• cannot be interrupted, lasts <10s

• can occur many times in a day

Atonic Seizure

• brief seizures that cause sudden loss in muscle tone

• ‘drop attacks’

Myoclonic Seizure

• muscle jerking seizures characterized by quick, involuntary muscle jerks, typically occurring in clusters. They may affect one or more muscle groups.

TONIC

• stiffening of muscles, typically resulting in a sudden loss of consciousness or posture. Tonic seizures can last from a few seconds to a minute and often occur during sleep.

CLONIC

• jerking phase, symmetrical, rhythmic movements

• may dribble, cyanose, lose control of bladder..

Status epilepticus

> 5 minutes of seizure activity or multiple seizures (greater than or equal to 2 of any duration) without full recovery of consciousness between seizures. Happens most commonly in patients with NO diagnosis.

Why do we intervene with a seziure after 5 minutes?

• unlikely to cease on its own after 5 minutes, and so anticonvulsants are required

Epilepsy

Epilepsy is a condition encompassing a broad range of seizure disorders and is diagnosed in patients suffering recurrent seizures.

Epilepsy Risks

• underlying brain disease

• seizures in dangerous positions

• prolonged seizures

• sudden and unexplained seizures

• cardiac arrest during seziure

• suicide

Psuedoseizure

Can look exactly like normal seizures, however this is not associated with uncontrolled neuronal depolarisation. Altered conscious state cannot be taken as evidence, if in doubt, treat as normal seizure.

Febrile convulsions

Seizures associated with fever in the absence of CNS infection or acute electrolyte imbalance in a young child (between 6 months and 6 years). Peak age = 18‐24 months.

SIMPLE VS COMPLEX Febrile Convulsions

SIMPLE: <15 minutes no more than once in 24hrs

COMPLEX: >15mins or more than once in 24hrs

Febrile convulsion Managment

• reassurance for parents

• manage as per normal seziure if occuring on arrival

Eclampsia

A seizure hat arises do to pre-eclampsia. Usually last <90 seconds and are self limiting. Treated as normal seizure.

Benzodiazepine effects

o Anxiolytic

o Muscle relaxant

o Anticonvulsant

o Hypnotic

o Memory impairment

Benzodiazepine MOA

• enhances GABA transmitssion

• increases gaba channel openings & time open

Benzodiazepine Adverse Effects

• related to CNS depression

• dependance with prolonged use

• additve effects with other CNS depressants

Adult seizure initial management

- manage airway and ventilation

- if airway patent, deliver high-flow oxygen

- midazolam 10mg IM (<60kg/elderly/frail = 5mg IM)

Paediatric seizure initial management

- manage airway and ventilation

- if airway patent, deliver high-flow oxygen

- midazolam IM (adolescent 12-15yrs = 5mg, medium child 5-11yrs = 2.5-5mg, small child 1-4yrs = 2.5mg, small & large infant <12 months = 1mg, newborn = 0.5mg)

- continue to monitor

How is a seizure diagnosed IN HOSPITAL

• EEG!

• MRI

• blood tests

Seziure Community Management

• anti epileptic drugs

• medical weed?

• strict driving requirements!