Partial seizures, also known as focal seizures, are seizures that begin in a specific area on one side of the brain rather than affecting both sides at once. These episodes happen when unusual electrical activity affects a small part of the brain, leading to a wide range of symptoms depending on which brain region is involved.
What Are Partial Seizures?
When someone experiences a partial seizure, abnormal electrical signals fire off in a focused area of the brain. This is different from a generalized seizure, where both sides of the brain are affected from the very beginning. Think of partial seizures as a localized electrical storm in the brain, while generalized seizures are like storms affecting the entire brain at once.[1]
The brain is divided into two halves called hemispheres, which are the left and right sides of the brain. Partial seizures start in just one location within either the right or left hemisphere. As the seizure becomes more intense, the electrical activity can sometimes spread from one spot to another. In some cases, it can even cross from one hemisphere to the other, potentially turning into what doctors call a “focal to bilateral tonic-clonic seizure.”[4]
It is important to understand that having a seizure is not the same as having epilepsy. A seizure is a single event, while epilepsy is a condition where a person has two or more unprovoked seizures that happen more than 24 hours apart. Epilepsy can also be diagnosed after a single seizure if there is a high probability of future seizures, specifically 60 percent or higher over the next ten years.[2]
Types of Partial Seizures
Partial seizures are divided into two main categories based on whether they affect a person’s awareness. These are simple partial seizures and complex partial seizures. The key difference between them is whether the person remains aware during the episode.[3]
Simple partial seizures do not affect a person’s awareness or consciousness. During these seizures, the person stays alert and can often talk while the seizure is happening. They may also remember what occurred afterward. Simple partial seizures can affect different parts of the body or mind. They may be motor seizures that affect the muscles, sensory seizures that affect the senses, autonomic seizures that affect automatic body functions like heart rate or digestion, or psychic seizures that affect feelings or thoughts.[1]
Simple partial seizures are also known as auras. An aura is like a warning sign that can occur before a larger seizure develops, or it can be the only sign of a seizure if the electrical activity does not spread further. Auras occur while the person is still fully aware, and they can take many different forms including sensory symptoms, emotional changes, or automatic body responses.[4]
Complex partial seizures affect a person’s awareness and consciousness. During these episodes, people may appear to be daydreaming or staring blankly into space. They are not aware of their surroundings and may not respond to questions or directions. Complex partial seizures start in one area of the brain and then spread to another area. These seizures can last anywhere from 30 seconds to two minutes and are the most common type of epilepsy in adults.[11]
After a complex partial seizure ends, there is often a period called the post-ictal period, which is a recovery phase. During this time, the person may feel confused, tired, or disoriented. This recovery period also happens after generalized seizures but does not occur with simple partial seizures.[2]
Epidemiology
Partial seizures are actually the most common type of seizure. They make up more than half of all seizures that occur. One specific kind, called focal impaired awareness seizures, accounts for just over one-third of all seizures.[4]
Epilepsy itself affects about 3 percent of people during their lifetime. However, there is good news: about 70 percent of people with epilepsy eventually go into remission, meaning their seizures stop occurring.[14]
The temporal lobes of the brain are the most common location where partial seizures occur. This region is especially prone to this type of electrical activity.[2]
Anyone can have seizures under the right circumstances, but partial seizures happen more easily in certain groups of people. Those who have experienced head injuries, have birth abnormalities affecting the brain, had febrile seizures during childhood, have brain infections like encephalitis (which is inflammation of the brain), suffered strokes, have brain tumors, or other conditions affecting the brain are at higher risk.[4]
Causes
The cause of partial seizures is often unknown. In many cases, doctors cannot identify exactly why someone develops seizures. This makes diagnosis and treatment more challenging, as understanding the root cause could help guide better treatment approaches.[1]
Partial seizures happen when the brain’s electrical impulses discharge abnormally. This disrupts normal communication between neurons, which are the brain cells that send signals to each other. The seizures originate from the brain’s cerebral cortex or hippocampus region. The predisposition to have epileptic activity is determined by the underlying cause, whether it is known or unknown.[2]
Risk Factors
Certain diseases involving the blood vessels of the brain can raise the risk of partial seizures, especially in patients who are 65 years of age and older. As people age, changes in brain structure and blood flow can make seizures more likely to occur.[1]
Rapid breathing, also called hyperventilation, can trigger seizures in some people. Flickering lights are another common trigger that can set off seizure activity. These triggers vary from person to person, so it is important for each individual to identify what might cause their seizures.[11]
Seizures are more common in boys than girls, although the exact reasons for this difference are not completely understood.[11]
Symptoms
The symptoms of partial seizures vary greatly depending on which part of the brain is affected by the abnormal electrical activity. Some people may experience very subtle symptoms that are barely noticeable, while others may have more dramatic episodes.[3]
Common symptoms of partial seizures include muscle tightening, unusual head movements, and blank stares. The eyes may move from side to side involuntarily. People may experience numbness, tingling, or a sensation like ants crawling on their skin. Some individuals have hallucinations, which means they see, smell, or hear things that are not actually there.[1]
Other symptoms include pain or discomfort, nausea, sweating, a flushed face, and dilated pupils. The heart rate or pulse may become rapid. Vision changes can occur, and some people experience a feeling of déjà vu, which is the feeling that the current place and time have been experienced before. Mood or emotion changes are also common, and some people are unable to speak for a short while during or after the seizure.[1]
In complex partial seizures, additional symptoms appear because awareness is affected. People may have lip smacking movements, eyelid flutters, and chewing motions. They may rub their fingers together or make small movements with both hands. Some people experience unusual symptoms like repeating words or phrases, laughing, screaming, or crying during the seizure.[11]
Some partial seizures can involve automatic behaviors where the person picks at their clothing, smacks their lips, or seems to be daydreaming. They may stare blankly and be unable to respond to questions or directions for several minutes.[5]
Pathophysiology
The brain uses short bursts of electricity as signals to allow different areas to communicate with each other. These signals also travel from the brain to the rest of the body, controlling everything from movement to sensation. When part of the brain “overloads” with excessive electrical signals, a partial seizure occurs in that specific area.[6]
During a partial seizure, affected brain cells send abnormal signals to other neurons around them. The symptoms depend entirely on where in the brain the seizure happens. For example, if the electrical activity occurs in the part of the brain that controls arm movement, the person’s arm may jerk or twitch. If it happens in the sensory area, they might feel tingling or see flashing lights.[4]
When the surge of electrical activity moves from one location to another within the same hemisphere, or eventually crosses to the other hemisphere, the seizure can change from a simple partial seizure to a complex partial seizure, or even progress to affect both sides of the brain. This spread of electrical activity explains why some seizures start small and then grow larger.[4]
Over time, uncontrolled partial seizures can lead to changes in the brain. They can cause memory problems or issues with thinking ability. The ongoing abnormal electrical activity may also increase the risk for mood disorders like depression and anxiety. This is why controlling seizures is so important for long-term brain health.[4]
Prevention
While it is not always possible to prevent partial seizures entirely, certain lifestyle changes can help reduce the frequency of seizures and lower exposure to triggers. Avoiding specific triggers is an important prevention strategy. For people who are sensitive to flickering lights, avoiding strobe lights, certain video games, or rapidly flashing television images can help prevent seizures.[1]
Getting plenty of sleep is crucial for seizure prevention. Lack of sleep can lower the seizure threshold, making seizures more likely to occur. Establishing a regular sleep schedule and ensuring adequate rest each night can make a significant difference.[3]
Stress management is another important aspect of prevention. High stress levels can trigger seizures in some people. Finding healthy ways to manage stress, whether through relaxation techniques, exercise, or talking to a counselor, can help reduce seizure frequency.[7]
Regular exercise can be beneficial for people with partial seizures, as long as their seizures are under control. Walking and biking are great ways to stay active, though safety precautions should be taken. If someone chooses to bike, they should always wear a helmet to protect against head injuries if a seizure occurs. For some people, a stationary bike may be a safer choice than riding on the road.[16]
Nutrition also plays a role in seizure management. While not specifically a preventive measure for everyone, some people benefit from following a special diet. Taking any prescribed medications exactly as directed is perhaps the most important prevention strategy, as consistent medication levels in the blood help prevent breakthrough seizures.[7]
