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Types of Seizures

Tuesday 28 July 2020
Seizure Disorders

Table of Contents


I. What Are Seizures?

a. What Causes Seizures?

II. Generalized Seizures

a. Absence Seizures

b. Atonic Seizures

c. Clonic Seizures

d. Myoclonic Seizures

e. Tonic Seizures

f. Tonic-Clonic Seizures

III. Focal Seizures

a. Focal Seizures without Loss of Consciousness

b. Focal Seizures with Impaired Awareness


What Are Seizures?

A seizure is a sudden change in your behavior, movement, or feelings caused by unexpected and uncontrolled electrical activity in the brain. Many people think of seizures as convulsions, rapid shaking, and twitching of muscles and limbs. While some types of seizures may involve convulsing, other seizures may be mild and look as if someone is simply staring into space. Seizures are commonly associated with epilepsy, although a range of conditions can cause them.

Most seizures last between 30 and 120 seconds. If a seizure lasts for longer than five minutes, then medical assistance should be sought. [1] For people with epilepsy that have reoccurring seizures, anti-epileptic drugs (AEDs) such as Keppra (levetiracetam) and Dilantin (phenytoin) can help. These medications reduce electrical activity in the brain and reduce the frequency of seizures. Keep reading to learn more about the different types of seizures.

a. What Causes Seizures?

The nerves in the brain cells communicate with each other by sending electrical impulses. When there is a disruption to these impulses, seizures may occur.

The most common cause of seizures is epilepsy. However, several other factors can cause a seizure. Typically, epilepsy is not diagnosed until a person has had at least two seizures that were not caused by other factors. [2] Other common causes of seizures include:

  • Stroke
  • Brain tumor
  • Bleeding in the brain
  • High fever
  • Low blood sodium
  • Lack of sleep
  • Alcohol abuse, intoxication or withdrawal
  • Illegal or recreational drug use [1]

A plastic model of a brain

Generalized Seizures

Generalized seizures are seizures that affect all areas of the brain. There are six different types of generalized seizures that range from barely noticeable to severe convulsions. [3] Generalized seizures typically involve loss of consciousness.

a. Absence Seizures

Absence seizures are typically short and last for around 15 seconds or less. Common symptoms of absence seizures include stopping moving, staring into space, blinking, and lip-smacking. These seizures can be mistaken for daydreaming and are common in children. Previously known as ‘petit mal’ seizures, they can occur in clusters and usually resolve themselves. People that have absence seizures may not remember what has happened but should return to their usual state of alertness afterward. [4]

b. Atonic Seizures

Atonic seizures are also known as drop seizures or drop attacks. These seizures cause a sudden decrease in muscle tone resulting in a person’s body going limp or collapsing. Atonic seizures can occur suddenly without warning. This prevents people from being able to protect themselves and may cause other injuries. People may lose consciousness during the fall, although they may regain alertness when landing on the floor. [5]

Atonic seizures typically occur during childhood. Many children that suffer from atonic seizures will also have myoclonic or tonic seizures and sometimes may have Lennox-Gastaut syndrome. Lennox-Gastaut syndrome is a condition that causes epilepsy in young children, particularly those with learning problems.

A man lies face down on the floor unconscious

c. Clonic Seizures

Clonic seizures cause rapid jerking and relaxing of muscles. Muscle spasms will gradually slow down and finally, stop as the seizure ends. Clonic seizures can affect any muscle group but often occurs in the arms, neck, and face. People often have a deep sigh at the end of these seizures before normal breathing resumes. [4]

d. Myoclonic Seizures

Myoclonic seizures can cause quick and spontaneous twitching or jerking in the arms and legs. Myoclonic muscle contractions can be confined to individual muscles or muscle groups. These seizures can last less than half a second. These seizures are similar to sudden jerks that people experience as they are falling asleep. Seizures can vary from mild tremors to severe twitches that cause the body to fall. [6]

e. Tonic Seizures

Tonic seizures cause muscle stiffness in the arms, legs, and back. Stiffening muscles can cause the back to arch, and contracting muscles in the chest may make breathing difficult. Breathing difficulties may cause the face and lips to turn blue and the person may make gargling noises. People suffering tonic seizures may also lose consciousness and their eyes may roll to the back of their heads. Tonic seizures usually last for under a minute. [4]

f. Tonic-Clonic Seizures

Tonic-clonic seizures were previously called ‘grand-mal’ seizures. Symptoms of these seizures include stiffening of muscles, shaking, loss of consciousness, biting of the tongue, and loss of bladder or bowel control.

Focal Seizures

Whereas generalized seizures involve the whole brain, focal or partial seizures only affect part of the brain. Focal seizures and their symptoms may also be the result of other neurological disorders such as migraines or narcolepsy. [1]

A woman clutching her head in pain

a. Focal Seizures without Loss of Consciousness

These seizures may also be called simple partial seizures. As the name suggests, the person having the seizure does not lose consciousness. Symptoms of these seizures can include limb twitching or tingling, dizziness, or changes to the senses. [7]

Focal seizures occur on one side of the brain so not all seizures will cause the same symptoms. Symptoms depend on the location of the malfunctioning electrical signals that occur. These seizures may affect motor, sensory, psychic, or autonomic skills. [8]

b. Focal Seizures with Impaired Awareness

These seizures are also known as complex partial seizures and result in loss of consciousness. As well as losing consciousness, people suffering these seizures may be unresponsive, stare blankly, or perform repetitive motions. [7]

The content in this article is intended for informational purposes only. This website does not provide medical advice. In all circumstances, you should always seek the advice of your physician and/or other qualified health professionals(s) for drug, medical condition, or treatment advice. The content provided on this website is not a substitute for professional medical advice, diagnosis or treatment.