Altered Neurotransmission - Seizures

Aura

A sensory, motor, or psychic warning sign before a seizure, usually focal

Ictal

The period during which the seizure is actively is actively occurring

Post-ictal

The recovery phase following a seizure, characterized by confusion, fatigue, or altered consicousness

Myoclonus

Sudden involuntary muscle jerks that is a type of seizure or symptom

Seizure Threshold

The balance point of neuronal excitability at which a seizure is triggered, lowering this will increase seizure risk

Automatism

Involuntary and repetitive movements seen during focal impaired awareness seizures

Seizures

Result from abnormal, excessive, and synchronous neuronal activity in the brain

Provoked seizures

Metabolic, infections, trauma: overall reversible

Unprovoked seizures

No cause, genetics: chronic

Neuronal hyperexcitability

Imbalance

First step of seizure initiation

Seizures arise from neuronal cell bodies located in the gray matter of the brain

Paroxysmal depolarization shift

first initiation step of seizure

Neuron synchronization

Partial depolarization of a neuron occurs when a large group of surrounding neurons is repeatedly activated

Spark step of a seizure

Na and Ca influx, paroxysmal depolarization shift (single neuron fires abnormally)

Spread step of a seizure

Increased extracellular K and glutamate, nearby neurons partially depolarize then begin firing together (synchronization)

Storm step of a seizure

Decreased Gaba, repolarization, and inhibition. Increased Ca and glutamate. Network becomes self-sustaining, ongoing seizure activity (failure of inhibition)

Focal seizures

Partial seizures that start on 1 side (hemisphere) of the brain. May or may not lose consciousness

Generalized seizures

Involves both sides of the brain (both hemispheres). Usually causes loss of consciousness

Focal aware seizures (Simple partial)

Remain conscious and experience motor symptoms (jerking), sensory changes, autonomic signs, or psychic symptoms

Focal impaired awareness seizures (complex partial seizures)

Consciousness is impaired, automatisms, confusion, and behavior arrest occurs.

Tonic-clonic seizures (as seen on TV)

characterized by muscle stiffening and jerking movements, may cause loss of consciousness and postictal confusion

Absence seizures

Brief episodes of staring and unresponsiveness in children