Epilepsy - what is it? - 2 November
Epilepsy is a common neurological (brain) disorder affecting 1% to 2% of the population.
Epilepsy is characterised by recurring, spontaneous, stereotyped seizures. Seizures are the result of bursts of electrical activity within the brain, caused by an imbalance in the chemicals responsible for the transmission of impulses. A person's behaviour will usually be different during a seizure.
What causes epilepsy?
Everyone has a genetically determined seizure threshold. Anyone can have a seizure if the trauma or disturbance is great enough to exceed the threshold. Factors such as fever, changes in blood chemistry, anxiety, sleep deprivation or alcohol may influence the onset of a seizure.
Many people develop epilepsy not knowing why. Where the cause is
known, it may be the result of:
- birth injuries
- severe head trauma
- infections, e.g. meningitis, encephalitis
- degenerative or vascular dementias
- hormonal changes
- genetically inherited conditions, e.g. tuberous sclerosis
Behaviour during a seizure can vary according to where in the brain the seizure arises. It may present as a convulsion, unusual body movement, a change in awareness, or simply a blank stare. The person may be unconscious or completely aware of what is happening.
Seizures are classified as:
- partial, affecting a small part of the brain
- generalised, affecting the whole brain
The disturbance in the brain begins in or involves a distinct
focal area. The function of this area of the brain
determines the behaviour during a seizure.
Simple partial seizures
Consciousness is not impaired. May present as:
- a tingling, numb sensation or twitching in arm, leg or face
- a distortion of light, smell, sound or space
- an unexplained fear or anxiety
Simple partial seizures may progress to involve the whole brain
and often serve as a warning of further
seizure activity (aura).
Complex partial seizures
- an altered state of consciousness characterised by a
change in awareness
- a blank stare
- semi purposeful inappropriate movements such as pulling at clothes, smacking lips, chewing or
wandering in a dazed state
- post seizure confusion is often prolonged
The whole brain is involved in this type of seizure resulting in a complete loss of consciousness.
Tonic clonic seizures
- body becomes rigid and person will fall if standing
- muscles relax and tighten rhythmically (convulse) causing the body and limbs to jerk
- breathing may be laboured and noisy (with blueness around the lips)
- may be incontinent
- consciousness regained slowly
- may be sleepy and confused
- brief interruption of consciousness
- blank stare
- may be fluttering of eyelids
- onset in childhood
- rapid recovery to normal functioning
- general stiffening of muscles without jerking
- may fall, usually backwards
- also known as drop attacks
- sudden loss of muscle tone
- falls, usually forward (slumping)
- injuries common, especially to face and head
- sudden brief jerking of limbs
- may involve both sides of the body
For more information, please visit: www.epilepsy.org.nz