Types of Seizures Common in Dup15q syndrome

Types of Seizures

There are many different types of seizures and the videos below have several examples. These videos show children with dup15q syndrome having active seizures and may be upsetting to some viewers

These videos should not be used as a diagnostic tool. If you believe your child has had a seizure, please consult your neurologist.


Tonic-clonic seizures combine the characteristics of tonic and clonic seizures.  The tonic phase comes first: All the muscles stiffen and air being forced past the vocal cords may cause a cry or groan. The person loses consciousness and may fall to the floor. Next, the arms and legs begin to jerk rapidly and rhythmically, bending and relaxing at the elbows, hips, and knees. After a few minutes, the jerking slows and stops. Consciousness returns slowly, and the person may be drowsy, confused, agitated, or depressed. These seizures generally last 1 to 3 minutes. Tonic-clonic seizures were formally referred to as grand mal seizures.


Muscle “tone” is the muscle’s normal tension. Atonic means “without tone” so in an atonic seizure, muscles suddenly lose strength. The eyelids may droop, the head may nod, and the person may drop things, and may fall to the ground. These seizures are also called drop seizures. The person usually remains conscious. These seizures typically last less than 15 seconds.


Myoclonic seizures are brief, shock-like jerks of a muscle or a group of muscles. “Myo” means muscle and “clonus” means rapidly alternating contraction and relaxation—jerking or twitching—of a muscle. Usually, they don’t last more than a second or two. There can be just one, but sometimes many will occur within a short time. Myoclonic seizures usually cause abnormal movements on both sides of the body at the same time.


In a tonic seizure, muscle tone is greatly increased and the body, arms, or legs make sudden stiffening movements. During the seizure, the person usually remains conscious. Tonic seizures most often occur during sleep and usually involve all or most of the brain, affecting both sides of the body. If the person is standing when the seizure starts, he or she may fall. These seizures usually last less than 20 seconds.


An absence seizure is characterized by a lapse of awareness or staring into space. A simple absence seizure generally lasts less than 10 seconds. Because they happen so quickly, it’s very easy to miss them, or to confuse them with daydreaming or not paying attention. During a complex absence seizure, a person will make some kind of movement in addition to staring into space. Movements may include blinking, chewing, or hand gestures. A complex absence seizure can last up to 20 seconds.  Absence seizures were formally referred to as petit mal seizures.

Simple Partial

When people have simple partial seizures, they are fully awake, alert, and able to interact throughout the seizure. There are several types of simple partial seizures.  In motor seizures, there is a change in muscle activity. For example, a person may have abnormal movements such as jerking of a finger or stiffening of part of the body. In sensory seizures, people may smell or taste things that aren’t there; hear a clicking, ringing, or a person’s voice when there is no actual sound; or feel a sensation of “pins and needles” or numbness. They may have visual hallucinations or may experience illusions—distortions of true sensations. For instance, they may believe that a parked car is moving farther away, or that a person’s voice is muffled when it’s actually clear.  Autonomic seizures cause changes in the part of the nervous system that automatically controls bodily functions. These common seizures may include strange or unpleasant sensations in the stomach, chest, or head; changes in the heart rate or breathing; sweating; or goosebumps.  Psychic seizures change how people think, feel, or experience things. They may have problems with memory, garbled speech, an inability to find the right word, or trouble understanding spoken or written language. Or, they may suddenly feel emotions like fear, depression, or happiness with no outside reason.  Simple partial seizures are typically brief, lasting less than 2 minutes.

​Complex Partial

Complex partial seizures may start with a simple partial seizure as described above.  Then, the person loses awareness and stares blankly. Most people perform a repetitive action during the seizure, such as moving their mouth or picking at the air, or their clothing. Less often, people may repeat words or phrases, laugh, scream, or cry.  Some display gross motor actions like bicycling movements of the legs or pelvic thrusting. Complex partial seizures usually last between 30 seconds and 2 minutes. Afterward, the person may be tired or confused for about 15 minutes and may not return to normal function for hours.

Infantile Spasms

Infantile spasms are brief tonic seizures that begin presenting in children during the first 2 years of life. Some seizures are characterized by brief head nods, whereas others consist of violent flexion of the trunk, arms, and legs. Infantile spasms frequently occur in clusters, and the intensity and frequency of the spasms in each cluster may increase to a peak before progressively decreasing. The seizures are very brief, so casual observers may miss single seizures. The number of seizures per cluster varies considerably, with some clusters consisting of as many as 150 seizures. The number of clusters per day also varies, with some patients having as many as 60 clusters per day. Crying or irritability during or after a flurry of spasms is commonly observed. Learn More About Infantile Spasms. 

We are proud to be a partner of the Infantile Spasms Action Network.  Visit the ISAN website for more information. https://infantilespasms.org/

West Syndrome

Due to the complex seizure combinations that occur in patients with Dup15q Syndrome, West Syndrome is also a common seizure diagnosis. For more information, use the links below. West Syndrome is characterized by a specific type of seizure (infantile spasms) seen in infancy and childhood. This syndrome leads to developmental regression and causes a specific pattern, known as hypsarrhythmia (chaotic brain waves), on electroencephalography (EEG) testing. Infantile spasms usually begin in the first year of life, typically between 4-8 months. About West Syndrome

Lennox-Gastaut Syndrome (LGS)

Due to the complex seizure combinations that occur in patients with Dup15q Syndrome, Lennox-Gastaut Syndrome is commonly a seizure diagnosis. Lennox-Gastaut syndrome (LGS) is a type of epilepsy with multiple different types of seizures, particularly tonic (stiffening) and atonic (drop) seizures. Visit Lennox-Gastaut Syndrome Foundation for more information. https://www.lgsfoundation.org/

Developmental  Epileptic Encephalopathy (DEE)

Some individuals with dup15q syndrome may also be considered to have a Developmental Epileptic Encephalopathy. Developmental and Epileptic Encephalopathy (DEE) refers to a group of severe epilepsies that are characterized both by seizures, which are often drug-resistant, as well as encephalopathy, which is a term used to describe significant developmental delay or even loss of developmental skills. Neurodevelopmental impairment is common, affecting cognition, communication, attention, behavior, and sleep. The underlying etiology of the syndrome can be a cause of the neurodevelopmental impairment, while seizures themselves can also have an adverse impact. DEE-P Connections

Download the information sheet below that can prepare you to recognize and respond to seizures.

Seizure Recognition

Much of the information above is the intellectual property of the Epilepsy Foundation.  Copyright ©1996-2014 Epilepsy Foundation of America, Inc. Landover, MD. All rights reserved.  For more information about epilepsy and types of seizures, see www.epilepsy.com.

Epilepsy Care Standards Update

The American Academy of Neurology (AAN) has standardized quality measures with the overarching goal to improve the delivery of care for patients with epilepsy for providers, practices, and systems. These standards are reviewed and updated periodically and the latest updates that have been updated were just released.  To find out what the standards are and the updated included visit: http://n.neurology.org/lookup/doi/10.1212/WNL.0000000000006425