What is a Seizure?

A seizure is a disruption of ordinary brain activity. It can take on many forms including personality, mood, memory, sensations, movement and consciousness. Any of these functions may be temporarily disturbed in the course of a seizure.

There are two main types of seizures: partial and generalized.


Partial Seizures

Simple Partial Seizures

  • Consciousness is not impaired. The seizure may be confined to rhythmical twitching of one limb or part of a limb, or to unusual tastes or sensations such as pins and needles in a specific part of the body. Simple partial seizures sometimes develop into other sorts of seizures and so they may be referred to as a "warning" or "aura."

Complex Partial Seizures

  • Consciousness is affected, so the person may have limited or no memory of the seizure. The seizure can be described as changes in awareness as well as automatic movements such as fiddling with clothes or objects, mumbling or making chewing movements, or wandering about and general confusion. Sometimes the person will respond if spoken to. Complex partial seizures most often involve the temporal lobes of the brain, but can also affect the frontal, parietal and occipital lobes.

    Both of these partial seizure types may spread to involve the whole of the brain. This is called Secondarily Generalized Seizures. If the seizure spreads rapidly, the person may not be aware of the partial seizure onset.

Generalized Seizures

With these types of seizures the whole brain is involved and consciousness is lost. They often occur with no warning and the person will have no memory of the event.

Tonic-clonic convulsive seizures (grand mal)

  • In the first part of the seizure the person becomes rigid and may fall. The muscles then relax and tighten rhythmically, causing the person to convulse. At the start of the seizure the person may bite their tongue or cry out. Breathing may become labored and they may become incontinent. After the seizure the person may feel tired, confused, have a headache and may need to rest to recover fully.

Tonic seizures

  • This type of seizure involves general stiffening of the muscles without rhythmic jerking.

Atonic seizures

  • This type of seizure is more commonly referred to as "drop attacks." These involve a sudden loss of muscle tone, causing the person to fall. Again, there is risk of injury, but rapid recovery.

Myoclonic seizures

  • This type of seizure involves brief and abrupt jerking of one or more limbs. These often happen within a short time of waking up, either on their own or with other forms of generalized seizures.

Absence seizures

  • These seizures occur more commonly in children. They are sometimes referred to as "petit mal" seizures. The person experiences a brief interruption of consciousness and becomes unresponsive. They may appear "blank" or to be "staring," usually without any other features, except perhaps for a fluttering of the eyelids. Absence seizures typically last only a few seconds and they may go unnoticed because of how subtle they appear.
There are other types of seizure patterns to be familiar with. Most common patterns seen in neuro ICU settings are: status epilepticus, periodic lateralized epileptiform discharges (PLEDS), generalized periodic epileptiform discharges
(G-PEDS), alpha coma, burst suppression and electrical cerebral inactivity (ECI).