What is Epilepsy?

Epilepsy is a condition affecting the brain that predisposes a person to have recurrent seizures. A seizure refers to uncontrolled electrical activity in the brain that may produce convulsions, hallucinations, staring, twitching, and/or unresponsiveness. Seizures may be caused by genetic defects, head trauma, infections, brain tumors, or strokes. Metabolic disturbances can also cause seizures. In many cases, the cause of the seizures is unknown. Learn more about the different types of epilepsy

Epilepsy is usually diagnosed after a person has had at least two seizures that were not caused by some known medical condition, such as alcohol withdrawal or low blood sugar.

Types of Seizures

Seizures can have a wide variety of symptoms; some may be quite dramatic while others very subtle. After certain types of seizures, an individual may feel very confused. Some people may exhibit odd behavior, poor judgment, and aggression during this time.

Seizures can be characterized as:

Focal seizures

  • Simple partial seizures: These seizures occur while the individual is fully awake. They begin with abnormal electrical activity in one part of the brain. Sometimes these small seizures are called “auras” or “warnings.” Symptoms are determined by the location in the brain that is being affected. For example, a simple partial seizure from the back of the brain (occipital lobe) may cause a visual hallucination, while a seizure from the side of the brain (temporal lobe) may cause a feeling of déjà vu or strong emotion.

  • Complex partial seizures: A simple partial seizure can spread and become a complex partial seizure, impairing an individual’s level of awareness and alertness. An individual having complex partial seizures may not respond to questions and may exhibit repetitive movements of the limbs and odd behavior such as picking at clothes or chewing. Sometimes such a person is mistaken for being intoxicated or having a mental illness.

Generalized seizures
With generalized seizures, most or all of the brain is involved. Types of generalized seizures include:

  • Tonic, clonic, or tonic-clonic seizures: Seizures that begin as simple or complex partial seizures but then subsequently spread to the entire brain can manifest as tonic-clonic seizures. Also known as “grand mal” seizures, tonic-clonic seizures are the ones most often shown in movies and television. These seizures begin with loss of consciousness, falling, and a stiffening of the entire body. Sometimes the person lets out a loud cry. This part is called the tonic phase. It is usually followed by rhythmic body movements (clonic phase).

  • Absence seizures: These seizures usually begin in childhood and consist of a short period— usually less than 10 seconds—of staring, at times with eye blinking. During this time, the person cannot speak or understand what is being said to them. These seizures do not cause falls, and, when the seizure is over, the individual resumes usual function, often unaware that a seizure has occurred.

  • Myoclonic seizures:  Myoclonus refers to jerking movement of the body. Many people experience a few jerks while falling asleep. This is normal myoclonus and not seizure activity. Myoclonic seizures are a jerk or a series of jerks that occur while awake and may involve a single limb or both sides of the body at the same time. They often occur in the morning just after awakening. Sometimes individuals with myoclonic seizures blame themselves for being clumsy in the morning when in fact they are having seizures.  

  • Atonic seizures:  “Atonic” refers to a loss of posture. Individuals with sudden, brief head drops or falls which often result in bodily injuries may suffer from atonic seizures.

Seizure Mimics

Some events may look very much like seizures. These include syncope (commonly referred to as fainting), falls, migraines, transient ischemic attacks (or “mini strokes”), sleep disorders, movement disorders, memory problems, and psychogenic events. Unlike seizures, these disorders are not caused by abnormal electrical activity in the brain. The first step is to accurately diagnose and distinguish these events from seizures, as treatment may differ from that of seizures.

Contact Us

The Mount Sinai Epilepsy Center
1468 Madison Avenue
Annenberg 2nd floor
New York, New York 10029
Tel: 212-241-2627
Fax: 646-537-9690

Pediatric Epilepsy Monitoring Unit (EMU)
Kravis Children’s Hospital at Mount Sinai
1184 Fifth Avenue, Fourth Floor
New York, NY 10029
Tel: 212-241-2401
Fax: 212-241-3470

Epilepsy Surgery
1000 10th Avenue, Suite 10G
New York, NY 10019
Tel: 212-636-3666

Home Video EEG for Epilepsy

Lara Marcuse, MD; Madeline Fields, MD; and Ji Yeoun “Jenna” Yoo, MD, discuss how home video electroencephalography (EEG) can help optimize the diagnosis and management of epilepsy. Watch this video