Epilepsy encompases a wide variety of different seizures. Frequency and form of attacks vary greatly from person to person. With modern methods of treatment, however, many cases can be controlled. Because there are so many nuances in Epilepsy and so many different kinds of seizures, a specific classification system is being promoted by the International League Against Epilepsy. The International Classification of Epilepsy Seizures has been adopted by the medical community and is gradually replacing outdated seizure terminology including “grand mal” and “petit mal”.

The new classification scheme describes two major types of seizures: “focal” and “generalized”. It also divides each of these categories into subcategories including focal dyscognitive seizures, absence seizures, tonic-clonic seizures, and other types.

Focal Seizures

Focal seizures

Focal seizures with elementary symptomology were formely known as partial seizures. During this type of seizure the patient can experience a range of strange or unusual sensations including sudden, jerky movements of one body part, distortions in hearing or seeing, stomach discomfort, or a sudden sense of fear. Consciousness is not impaired. If another seizure type follows, these sensations may be referred to as an “aura”.

Focal dyscognitive seizures

Focal dyscognitive seizures (formerly complex-partial seizures) are characterized by a complicated motor act involving impaired consciousness. During the seizure the patient appears dazed and confused. Purposeless behaviours such as random walking, mumbling, head turning, or pulling at clothing may be observed. Usually, these so-called “automatisms” cannot be recalled by the patient. In children this seizure may consist of staring or lip-smacking, and therefore may be confused with the absence seizure described below.

Generalized Seizures

Absence (petit mal) seizures

Generalized absence seizures (formerly petit mal) are characterized by 5 to 15 second lapses in consciousness. During this time the patient appears to be staring into space and the eyes may roll upwards.

Absences are not preceded by an aura and activity can be resumed immediately afterwards. Typically, they occur in children and disappear by adolescence. They may, however, evolve into other seizure types, such as focal dyscogntive (complex-partial) or tonic-clonic. The occurrence of absence seizures in adulthood is rare.

Tonic-clonic (grand mal) seizures

The tonic-clonic (formerly grand mal) seizure is a generalized convulsion involving two phases. In the tonic phase, the individual loses consciousness and falls, and the body becomes rigid. In the clonic period the body extremities jerk and twitch. After the seizure, consciousness is regained slowly. If the tonic-clonic seizure begins locally (with a focal seizure) it may be preceded by an “aura”.

Other Types of Seizures

Dravet Syndrome is a genetic disorder of Chromosome 2 usually affecting a gene called SCN1A, causing epilepsy and other neurological and developmental problems. Dravet Syndrome accounts for 1% of the epilepsy population.

Tuberous Sclerosis Complex (TSC) is a genetic disorder that causes non-malignant tumors to form in many different organs, primary in the brain, eyes, heart, kidney, skin and lungs.

Malignant migrating partial seizures of infancy (MMPSI) is a severe form of Epilepsy that begins very early in life. Recurrent seizures begin before the age of 6 months but commonly start within a few weeks of birth. The seizures do not respond well to treatment. Although affected individuals may develop normally at first, progression stalls and skills decline when seizures begin; as a result, affected individuals have profound developmental delay.

Benign Rolandic Epilepsy is an epileptic syndrome occurring in young children that is age limited (you stop having seizures in the teen years). Salivation and twitching of the mouth or upper extremity on one side are typical manifestations. Seizures occur almost exclusively nocturnally.

Juvenile Myoclonic Epilepsy is characterized by onset in childhood or adolescence and is associated with extremity jerking or generalized tonic clonic seizures (‘grand mal’) within an hour or two of wakening from sleep. Seizures which may be due to sleep deprivation, alcohol intake or coffee tend to occur in the morning.

Special Categories of Seizures

Status seizures

Status Epilepticus is the term used to describe recurrent seizures without recovery of consciousness between attacks. This is a medical emergency and can be life threatening, or cause brain damage. Immediate action to get the necessary medical care should be taken.

Pseudo-seizures

Pseudo-seizures (or psychogenic seizures) are quite common and can occur in people who have, or do not have, Epilepsy. The attacks are triggered by a conscious or unconscious desire for more care and attention. The seizures start with rapid breathing, triggered by mental stress, anxiety, or pain. As the person breaths rapidly, they build up carbon dioxide in their body and change their chemistry. This can cause symptoms very much like a seizure: prickling in the face, hands, and feet, stiffening, trembling, etc. The appropriate treatment for pseudo-seizures is to calm the person and start them breathing at a normal rate. Treatment should also involve investigating the mental and emotional factors that led to the pseudo-seizure.

How do you distinguish epileptic seizures from pseudo-seizures?

Epileptic seizures and pseudo-seizures are distinguishable both by their nature and symptoms, but the diagnosis can be difficult. Epileptic seizures are caused by a change in how the brain cells send electrical signals to each other, while pseudo-seizures are triggered by a conscious or unconscious desire for more care and attention. Thus, measuring brain activity with an EEG and video telemetry is important for distinguishing epileptic and pseudo-seizures. Also, pseudo-seizures often lack the exhaustion, confusion, and nausea that is associated with epileptic seizures. Psychogenic seizures can occur in people who also experience epileptic seizures.

Chart of Seizure Classification

Below is a detailed chart of seizure classification, adapted from the International League Against Epilepsy (ILAE). This chart provides a comprehensive overview of the different types of seizures and their subcategories.

Download the Epilepsy Classification Chart

Acknowledgment
We acknowledge the valuable resources provided by the International League Against Epilepsy (ILAE) in helping to classify and understand epilepsy and its various types. The chart on this page has been adapted from the ILAE to provide a comprehensive overview of seizure classification.