FOCAL ONSET SEIZURES (partial seizures)


What is a Focal Onset Seizure (partial seizure)?

The human brain is divided into two hemispheres, a right hemisphere and a left hemisphere. A focal seizure (previously referred to as a partial seizure) is a seizure which begins in one hemisphere of the brain. Focal onset seizures can be divided into different categories depending on the type of symptoms a person experiences.  

One of the ways we describe or classify focal seizures is to consider a person’s level of awareness. If a person has focal aware seizures (previously referred to as a simple partial seizures) this means that there is no loss of awareness of their surroundings during the seizure. If a person has a change in their level of awareness then the name used to describe this is a focal impaired awareness seizure (previously referred to as a complex partial seizure).  

Sometimes it is difficult to know for certain if a person has impaired awareness and in these cases a focal seizure can be described by the motor symptoms which the person may or may not experiences during a seizure. The type of symptoms the person experiences would help to then classify a seizure as MOTOR vs NON-MOTOR.  

Motor seizures cause a change in muscle activity. For example a person may have abnormal body movements such as jerking of a finger or stiffening of one part of the body. The movements may spread from one area and involve one side of the body or sometimes extend to involve muscles on both sides of the body. Sometimes motor seizures present with weakness. This can affect specific muscles or affect speech. Other symptoms of motor seizures include coordinated actions, for example automatic repetitive hand movements, referred to as automatisms.  

Non motor seizures can cause changes in any one of the senses. People with non motor seizures may smell or taste things that aren’t there; they may hear clicking, ringing or a person’s voice when there is no actual sound; they may experience a sensation of pins and needles, numbness or pain; they may have a sensation of spinning or floating in space; they may have visual hallucinations and describe the symptom of seeing things that are not there, for example a spot of light, a scene with people. They may experience illusions – distortions of true sensations. For example, they may believe that a parked car is moving farther away, or that a person’s voice is muffled when it is actually clear.

Other types of non motor focal onset seizures include:

Autonomic seizures

These 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 goose bumps.

Emotional/Cognitive seizures:

  • These 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.
  • They may suddenly feel emotions like fear, depression, or happiness with no outside reason.
  • Some may feel as though they are outside their body or may have feelings of déja vu ("I've been through this before") or jamais vu ("This is new to me"— even though the setting is really familiar). 

Who is at risk for FOCAL ONSET AWARE (simple partial) seizures?

Anybody can get them. They may be more likely in people who have had a head injury, brain infection, stroke, or brain tumor but most of the time the cause is unknown. 

What is it like to have a FOCAL ONSET AWARE (simple partial) seizure?

When people have focal onset aware seizures, they are fully awake, alert and able to interact throughout the seizure. Overall, these seizures are brief lasting less than 2 minutes 

Medical disorders such as, stomach disorders or a pinched nerve can cause some similar symptoms. Hallucinations can accompany psychiatric illness or the use of certain drugs. And some symptoms (such as déja vu) are experienced by almost everyone at some time. Whether the symptoms represent simple partial seizures depends on how often they occur and whether they are associated with other episodic changes or other seizure types. 

What happens after a FOCAL ONSET AWARE seizure (simple partial seizure)?

When a focal onset aware seizure ends, the person more often than not simply continues doing whatever they were doing before it started. If the focal onset aware seizure is an aura (a warning) a stronger seizure with loss of consciousness, a focal impaired awareness seizure may follow. No first aid is needed for a focal onset aware seizure. 

If someone has FOCAL ONSET AWARE seizure (simple partial seizure), how often will they occur?

It depends. Some people may have just one seizure and others may have several. 

How can I tell if someone is having a FOCAL ONSET AWARE seizure (simple partial seizure)?

Because the person is fully alert and able to interact, someone may not be able to tell when a person is having a focal onset aware seizure unless the person tells them. 

How are FOCAL ONSET AWARE seizures (simple partial seizures) diagnosed?

A complete medical history and physical examination can help to rule out other possible causes of the symptoms and assess the likelihood of epilepsy. Although EEGs are also helpful they may not always show an abnormality during a focal aware seizure. 

How are FOCAL ONSET AWARE seizures (simple partial seizures) treated?

There are several medicines, a device (Vagus nerve stimulator), surgery and diet that can help prevent further focal onset aware seizures from occurring. 

What should I do if I think my child, loved one, or myself may have FOCAL ONSET AWARE seizures (simple partial seizures)?

If you think that you, your child or loved one may have focal onset aware seizures, it is important to let your doctor know right away. Seek help to get an accurate diagnosis and treatment plan.