What are the 4 Types of Seizures?

Seizure Types & Triggers: Know the Signs, Act Early

A seizure is a brief outburst of spontaneous electrical activity in the brain, usually causing fleeting alterations in awareness, behaviour, sensations, or muscle control. Their presentation may completely vary across individuals.

You may observe a person stare blankly for a few seconds, have muscle twitches, or hit the ground with aggressive convulsions. Seizures can strike anyone at any age, and their cause varies from medical conditions and genetics to injury and infection.

Fortunately, a range of treatment options is available. However, before treatment, it is essential to know the particular type of seizure.

Keep reading for detailed insight!
 

Understanding the 4 Main Types of Seizures

Seizures are mainly classified according to where and how they start in the brain. The four main types are:

Focal Onset Aware Seizures

Also referred to as simple partial seizures, these seizures start in one particular part of the brain and don't affect consciousness. Individuals who experience them are awake and alert during the seizure and usually remember it afterwards. Its major symptoms may involve:

• A sense that something familiar is strange or vice versa
• Striking odours, tastes, or sensations
• Abruptly changing emotions, such as fear or anxiety
• Mild jerking or stiffness in a single area of the body
   

Focal onset aware seizures may be so subtle that they go unnoticed, or they may be mistaken for daydreaming. Even though they are short, they may serve as a warning that a more serious seizure is about to occur.

Such seizures may begin from scar tissue or abnormal parts of the brain, which can be due to trauma, stroke, infections such as meningitis, or congenital defects.

Focal Onset Impaired Awareness Seizures

Formerly known as complex partial seizures, these also begin in one region of the brain but bring about an alteration or loss of awareness. The individual becomes confused and dazed or exhibits repetitive movements called automatisms—such as lip-smacking, hand rubbing, or walking in a circle. This may last from 30 seconds to several minutes.

Some notable features of focal onset impaired awareness seizures are:

• Loss of consciousness or responsiveness
• Forgetfulness of the event after the seizure occurs
• Repetition of movement or behaviour
   

Seizures of this type typically involve the temporal or frontal lobes and often arise due to abnormalities such as cortical dysplasia or syndromes caused by genetic factors, as seen in tuberous sclerosis. Often, in a seizure, the person is not even aware that one has taken place, so the eyewitness account becomes crucial for diagnosis.

Generalised Onset Seizures

Generalised onset seizures involve both brain hemispheres at once and usually cause a total loss of awareness. These are the most dramatic forms of seizures and have several subforms, each with its own characteristics:

Absence Seizures (Petit Mal)

More frequent in children, these seizures appear as brief absences of attention, gazing into space, rapid blinking, or subtle facial movements. They are short-lived and occur quite often during the day.

Myoclonic Seizures

These result in abrupt, short jerks or twitches of the arms, head, or trunk. Tending to have a cluster pattern, particularly in the morning, they are a feature of juvenile myoclonic epilepsy.

Tonic and Atonic Seizures

Tonic seizures are characterised by abrupt muscle stiffness, typically in the trunk and limbs, which often causes the person to fall stiffly to the ground. Atonic seizures (or 'drop attacks') produce a sudden loss of muscle tone, causing the person to collapse limply. Both occur in severe epilepsy syndromes, such as Lennox-Gastaut syndrome, and can cause severe injury.

Tonic-Clonic Seizures (Grand Mal)

They start with stiffening of muscles (tonic phase), followed by rhythmic jerking (clonic phase), and are also commonly joined by loss of consciousness, loss of bladder control, and a post-seizure period of confusion. These may evolve from a focal seizure or occur as generalised seizures. The most common causes of generalised seizures are:

• Genetic predispositions
• Brain signalling imbalances
• External causes like sleep deprivation or alcohol
   

Since generalised onset seizures engage the entire brain, treatment typically involves antiepileptic drugs and, in complex cases, dietary treatment or neurostimulation.

Unknown-Onset Seizures

Sometimes, it is unclear where or how a seizure begins, particularly if the patient is alone at the time or the seizure occurs while they are sleeping. These are referred to as unknown onset seizures until additional testing (e.g., EEG or brain imaging) can determine whether they are focal or generalised. Some of its common manifestations include:

• A tonic-clonic seizure may be seen without an obvious onset.
• A seizure that happens all of a sudden
• Symptoms that don't easily fit focal or generalised patterns
   

Best Tips to Prevent Seizures

Here are some of the best tips to prevent various types of seizures from occurring:

• Take all antiepileptic medications exactly as prescribed to avoid withdrawal seizures or medication toxicity.
• Maintain a consistent sleep schedule, as lack of sleep is a known trigger for seizures.
• Avoid alcohol and recreational drugs, which can interact dangerously with seizure medications and trigger attacks.
• Eat balanced meals at regular intervals to prevent blood sugar fluctuations that may provoke seizures.
• Incorporate regular physical exercise to help manage stress, a common trigger for seizures.
• Manage fevers in children appropriately with paediatrician-recommended methods. While febrile seizures can be frightening, they are common and usually not dangerous.
• Limit exposure to flashing or flickering lights if you have photosensitive epilepsy.
• Work with a qualified neurologist to develop and adjust a tailored seizure management plan.
   

Seizures are multifaceted neurological occurrences with varied presentations and aetiologies. With a thorough understanding of the four types of seizures, patients and their carers will be able to notice the signs, receive a timely diagnosis, and access effective treatment. Additionally, people should follow preventive tips to minimise the risk of seizures.