Seizures

There are many types of seizures, divided into two primary categories: generalized and focal. Seizures are categorized based on the area of the brain in which the surge of abnormal activity occurs.

Generalized seizures

Generalized seizures occur throughout the entire brain, involving both sides (hemispheres). They are broken down into the following subtypes:

• Tonic-clonic seizures. Formally known as “grand mal seizures,” this type of seizure tends to be severe, causing body shakes, abrupt stiffening of the arms and legs, loss of bladder control, biting of the tongue, and unconsciousness. They can last between one to three minutes.
• Tonic seizures. These seizures generally cause stiffening of the back, leg, and arm muscles. Usually lasting 10 to 30 seconds, you may lose consciousness and collapse to the ground.
• Clonic seizures. Clonic seizures manifest as jerky, repeated muscle movements. The rhythmic twitches typically occur in the face, neck, and both arms, lasting 30 to 60 seconds.
• Absence seizures. Previously known as “petit mal seizures,” absence seizures may only last for a moment but can occur dozens to hundreds of times a day. These mini-seizures may be associated with lip-smacking and blinking. They are more prevalent in children and are often misinterpreted as daydreaming or “spacing out.”
• Atonic seizures. Atonic seizures (or drop seizures) cause an abrupt drop of the head or a collapse due to sudden muscle control loss. These seizures can lead to severe injuries, including head injuries due to an abrupt collapse caused by loss of muscle tone.
• Myoclonic seizures. These seizures involve quick jerks or twitches of the legs and arms, with no loss of consciousness.

Focal seizures

Focal seizures usually occur in a small brain area on only one side (hemisphere). Previously referred to as partial seizures, they are generally categorized into two types:

• Focal seizures with preserved awareness (previously called simple partial seizures). During these seizures, the person does not lose consciousness but may experience a feeling of déjà vu, muscle tightening, numbness, tingling, nausea, hallucinations (smells, sounds), or severe panic. Sometimes the person may have intact awareness but an inability to communicate.
• Focal seizures with impaired awareness (previously called complex partial seizures). These seizures are similar to focal seizures with preserved awareness but involve some form of loss of awareness or disorientation and an inability to communicate, which can last for a few minutes. People experiencing this kind of seizure may develop a blank stare and repetitive moments such as blinking, lip smacking, finger movements, grunting, or shouting and typically have memory loss during the episode.

Epilepsy is a condition that involves having recurring seizures, or a single seizure, followed by tests revealing an increased risk of recurrence. An epileptic seizure can happen in any area of the brain, with temporal lobe seizures being the most common.

A breakthrough seizure occurs when a person with epilepsy has had seizure freedom (no seizures) for a while and then experiences another seizure.