What is epilepsy and what are its main types?

Epilepsy is a chronic brain disorder characterized by recurrent seizures caused by abnormal and excessive electrical activity in the brain. Normally, nerve cells send electrical and chemical signals to regulate thoughts, feelings, and movements. During an epileptic seizure, many nerve cells send signals simultaneously and faster than usual, which disrupts normal brain function and may cause abnormal involuntary movements, sensations, emotions, or behaviors, and may lead to loss of consciousness. Not all seizures cause convulsions, as symptoms vary significantly between different types of seizures [1].

Having a single seizure does not necessarily mean a person has epilepsy. Some seizures may occur due to other reasons such as high fever (febrile seizures in children), low/high blood sugar, head injuries, or certain illnesses. Epilepsy is usually diagnosed when seizures recur as a result of a brain disorder [1].

Main Types of Seizures

Seizures are generally divided into two main categories, focal seizures and generalized seizures, with numerous subtypes within each category [2]:

• Focal (Partial) Seizures: These seizures originate from only one part of the brain. The person may remain conscious during a focal seizure, but they may experience unusual motor, sensory, or psychological sensations, such as a sudden feeling of joy or anger, smelling non-existent odors, or seeing unreal things. In other types of focal seizures, there may be a change in consciousness, causing a dream-like experience or unusual repetitive behaviors such as blinking or repetitive mouth movements. These seizures usually last for a minute or two [2].
• Generalized Seizures: These seizures result from abnormal nerve activity that rapidly appears on both sides of the brain. They may cause loss of consciousness, falls, or severe muscle contractions. Types of generalized seizures include [2]:
  • Absence Seizures (Petit Mal): The person may appear to be staring into space, with or without slight muscle twitching.
  • Tonic Seizures: Cause stiffening of the body's muscles, often in the back, legs, and arms.
  • Clonic Seizures: Cause repeated jerking movements of muscles on both sides of the body.
  • Myoclonic Seizures: Cause jerks or twitches in the upper body, arms, or legs.
  • Atonic Seizures: Cause a sudden loss of normal muscle tone, which may lead the person to fall.
  • Tonic-Clonic Seizures (Grand Mal): Cause a combination of symptoms including body stiffening and repeated jerks in the arms and/or legs, as well as loss of consciousness.

Causes of Epilepsy

Epilepsy can have many potential causes, but in about half of the cases, no cause is identified. Epilepsy can arise as a result of problems with brain connections, an imbalance in nerve signaling, or a combination of these factors. Known causes include [2]:

• Genetic Factors: Genetic changes play a major role in some types of epilepsy. Some genes may affect a person's susceptibility to seizures and their response to anti-epileptic drugs [2]. For example, 15q13.3 microdeletion is associated with an increased risk of epilepsy [3].
• Brain Injuries: Such as traumatic head injuries, strokes, or brain tumors.
• Infections: Such as meningitis or viral encephalitis.
• Brain Development Problems: Including congenital brain malformations.
• Other Medical Conditions: Such as Alzheimer's disease, lack of oxygen to the brain, or certain cases of alcohol withdrawal.

Diagnosis and Treatment

To diagnose epilepsy, doctors may use a combination of tests, including an electroencephalogram (EEG) that measures electrical activity in the brain, and a computed tomography (CT) scan of the head [1]. The decision to start treatment depends on the doctor's assessment of several factors that affect the likelihood of future seizures [2].

Available treatment methods aim to control seizures and reduce their frequency and severity. Treatment options include anti-epileptic drugs, and in some cases, other treatments may be used, such as Vagus Nerve Stimulation [1]. It is worth noting that epilepsy varies in severity and impact from person to person and may be accompanied by a range of other health conditions [2].

When to Seek Emergency Help?

Most epileptic seizures last from 30 seconds to two minutes and do not cause permanent damage. However, a seizure should be considered a medical emergency if it lasts for more than 5 minutes, or if the person has multiple seizures without regaining consciousness between them [1]. In such cases, emergency care should be sought immediately. For more information about epilepsy, you can visit Epilepsy: A Comprehensive Guide to Causes, Seizure Types, and Treatment Options (Arabic).

Medical references

• Seizures
• Epilepsy and Seizures
• 15q13.3 microdeletion: MedlinePlus Genetics