The brain has millions of nerve cells (or neurones) which control the way we think, move and feel. The nerve cells do this by passing electrical signals to each other. If these signals are disrupted, or too many signals are sent at once, this causes
a seizure (sometimes called a 'fit' or 'attack'). A seizure is an abnormal paroxysmal discharge of cerebral neurons which manifest as changes in motor, sensory, behavioral or autonomic function.
This electrical discharge from a group of nerve cells in the brain typically is:
The seizure may lead to:
- Involuntary body movements
A seizure is a sign of an underlying disorder; there are two types:
- Idiopathic (self-originating; without known cause (most epileptics))
- Symptomatic (known medical or traumatic cause)
A seizure may have several aetiologies:
- CNS: epilepsy, head injury, stroke, brain tumour, hypoxic insult.
- Metabolic: hypoglycaemia, hyponatremia.
- Toxicological: poisons, abuse or withdrawal from alcohol, medications or other drugs.
- Infectious: fever (especially in children younger than 5 years old), meningitis, malaria, encephalitis.
- Environmental: stress, fatigue, medical non-compliance.
There are three main phases to a seizure:
- Aura phase; patients report this is similar to a premonition to a seizure occurring. It is a sensation a patient
may get that precipitates the seizure and can present as alterations in various senses or feelings, such as:
- Ictal phase; general or partial, presenting as:
- Focal seizure: Abnormal movement of isolated body part/s with altered conscious state
- Generalised seizure: Affects both sides of the brain, therefore causing loss of consciousness in these patients.
- Post-Ictal phase;
- Abnormal breathing
Approx 33% of people have focal seizures which affects only one portion of the brain. Often subtle and unusual, focal seizures can be mistaken for intoxication and daydreaming
- Aware Seizures: When a person is awake and aware during a seizure. This used to be called a simple partial seizure.
- Impaired Awareness: When a person is confused or their awareness is affected in some way during a focal seizure. This used to be called a complex partial seizure.
Tonic-clonic, absent or atonic seizure (an altered conscious state with a vacant stare).
- Tonic: All the muscles stiffen and back arches. Air being forced past the vocal cords causes a cry or groan. The person loses consciousness and falls to the floor. The tongue or cheek may be bitten, so bloody saliva may come from
the mouth. The person may turn a bit blue in the face.
- Clonic: The arms and usually the legs begin to jerk rapidly and rhythmically, bending and relaxing at the elbows, hips, and knees. After a few minutes, the jerking slows and stops. Bladder or bowel control sometimes is lost as the
body relax. Consciousness returns slowly, and the person may be drowsy, confused, agitated, or depressed
- Altered conscious state
- Rigid muscles
- Generalised shaking – continuous or repeated
- Clenched jaw
- Head and mouth trauma
Side-effects (common and uncommon):
- Secondary trauma (tongue biting, falls)
- Brain damage
The process of having a seizure is exhausting as your muscles
uncontrollably contract and relax multiple times and your brain is in
over drive. The end to a seizure represents a transition from the seizure back to the individual’s normal state, typically characterized by a deep sleep with gradual
recovery. It may last from seconds to minutes to hours,
depending on several factors including which part(s) of the brain were affected by the seizure and whether the individual was on anti-seizure medication. If a person has a complex partial seizure or a convulsion, their level of awareness gradually
improves during the post-ictal period, much like a person waking up from anesthesia. Encouraging the patient to relax and providing reassurance is the most
important part of caring for a post-ictal patient.
Convulsive status epilepticus is defined as any seizure activity that meets any of these three critiera;
- A persistent tonic/clonic seizure lasting greater that 5 minutes
- a generalised tonic‐clonic convulsion lasting more than 30 minutes
- Repeated tonic‐clonic convulsions over a 30 minute period without recovery of consciousness between each convulsion
A status epilepticus can occur in both partial and non–convulsive seizures and may lead to:
- Direct neuronal damage
- Secondary neuronal injury
- Respiratory arrest
- Previous seizures
- Type of seizure
- Any preceding injury e.g. head trauma
- Medical conditions, drugs or alcohol