Epilepsy Flashcards
How are ‘seizures’ and ‘epilepsy’ defined and how do they relate to one another?
Seizures are abnormal excessive neuronal activity in the brain. Caused by over expression of glutamate (excitatory neurotransmitter) or under expression of GABA (inhibitory neurotransmitter). Epilepsy is a condition that’s characterised by recurrent seizures.
Describe generalised seizures and partial seizures
Generalied seizures affects both sides of the brain from the start. They almost always impact on awareness so the terms ‘aware’ or ‘impaired awareness’ are not used for them
Partial/focal seizures originates in one side of the brain
If person remains alert and able to interact is called a focal onset aware seizure.
If person is not aware of surrounding its focal impared awareness seizure ( Complex partial seizure)
Diagnosis of epilepsy
- at least two unprovoked (or reflex) seizures occurring more than 24 hours apart
- one unprovoked seizure and a probability of further seizures (at least 60%)
- diagnosis of an epilepsy syndrome.
Define absence seizures and its symptoms
Absence seizures is a generalised seizure occur most often in children. It is characterized by a very brief loss of awareness, commonly manifested as a blank stare with or without subtle body movements such as eye blinking, lip smacking or chewing.
People with absence seizures may not be aware that something is wrong for years.
Kids who start having absence seizures in early years stand a good chance of outgrowing them without treatment.
Define tonic seizures and its symptoms
They are a form of generalised seizures and associated with sudden stiffening of muscles and may cause the person to fall, often backwards.
Define atonic seizures and its symptoms
also known as drop attacks, are characterized by a sudden loss of muscle tone (loss of muscle strength), which may cause the person to collapse or drop down.
Define Clonic seizures and its symptoms
Symptoms are rhythmic jerking muscle movements. Most commonly affected are the muscles of the neck, face, arms and legs. Clonic seizures are rare.
Define myoclonic seizures and its symptoms
Myoclonic seizures are brief jerks or twitches of a muscle or a group of muscles. There can be one or many twitches occurring within a couple of seconds.
Define Tonic-clonic seizures and its symptoms
Generalised convulsive seizures, which are combinations of muscle stiffening and jerking. It also involves sudden loss of consciousness and sometimes loss of bladder control.
A tonic-clonic seizure that lasts longer than 5min requires immediate medical treatment.
Define simple partial seizures and symptoms
Simple partial: depending on the affected brain area, patients may have unusual feelings, strange sensations or uncontrollable jerky movements, but remain conscious and aware of the surroundings.
Define complex partial seizures and symptoms
involves a loss or changes in consciousness, awareness and responsiveness.
How do the main symptoms for each seizure type relate to the causes and parts of the brain that are affected?
a seizure that begins in the occipital cortex may result in flashing lights.
a seizure that affects the motor cortex may result in rhythmic jerking movements of the face, arm, or leg on the side of the body opposite to the involved cortex (Jacksonian seizure).
a seizure that begins in the parietal cortex may cause distortion of spatial perception.
a seizure that begins in the dominant frontal lobe may cause sudden speech difficulties.
What are the main consequences of uncontrolled or poorly controlled seizures?
When seizures continue unchecked, complications can arise including (Therapeutic Guidelines, 2019):
central nervous system injury
noncardiogenic pulmonary oedema
rhabdomyolysis, acidosis and kidney failure
hyperthermia
aspiration risk
trauma (falls, shoulder dislocation etc)
increased risk of sudden unexpected death in epilepsy (SUDEP)
poor quality of life/uncertainty (unable to drive, employment affected etc)
Explain the seizure mechanism
Seizures are caused by brain alterations that resulted in an underactivity of GABA neurons and/or an over activity of glutamatergic neurons.
Describe the process of an action potential
Action potential:
When there is stimulus, the voltage gated sodium channels open
Positively charged sodium ions rush into cell → thus causing depolarisation
Depolarisation leads to opening of voltage gated calcium channels, thereby calcium ions enter the cell
Calciums triggers release of glutamate from vesicles
Neuron releases glutamate (excitatory neurotransmitter) into synaptic cleft.
triggers action potential from next neuron.
