Focal seizures, also called partial seizures, occur in only one part of the brain.

They are a key symptom of epilepsy but can also occur due to other causes. There are two types of focal or partial seizures: simple and complex. This article looks at the types, causes, symptoms, and treatment of focal seizures.

The human brain contains neurons, or brain cells, that use electrical signals to communicate.

During a seizure, which is temporary, a person experiences an atypical surge of electrical activity in their brain. People can experience physical symptoms before, during, and after a seizure.

Unlike generalized seizures, focal seizures originate in only one part of the brain. In contrast, generalized seizures originate across the entire brain rather than one area.

All seizures occur due to atypical electrical discharge within the brain. However, there are types of seizures that differ according to how they affect the brain. Health experts classify seizures depending on where in the brain they start.

Generally, seizures fall into the following categories:

typeabsence, sometimes called “petit mal”tonic-clonic, sometimes called “grand mal” focal
brain impactzoning out or staring into spacemotor impact-like shaking
and muscle spasms and
sometimes loss of
consciousness
impact depends on
where the
seizure starts in the brain

Learn more about seizure types.

There are two types of focal seizures: simple focal seizures and complex focal seizures.

Simple focal seizure

Doctors also refer to simple focal seizures as focal aware seizures, which do not involve the loss of consciousness.

During a simple focal seizure, a person remains alert throughout the event and remembers it when it finishes. This seizure typically lasts less than 1–2 minutes.

Complex partial seizure

Doctors also refer to complex partial seizures as focal impaired awareness seizures.

When a person has a complex partial seizure, they lose consciousness and do not remember the seizure after it is over.

The seizure may last up to 10 minutes and can involve involuntary, repetitive movements known as automatisms, although most last around 1–2 minutes.

Secondary generalized seizure

Some focal seizures can start in one part of the brain and then move to another, essentially turning into generalized seizures, which can last around 5 minutes.

Seizures can have many different causes and triggers, some of which doctors still do not know.

Potential causes of focal seizures include:

  • epilepsy
  • meningitis
  • head injury
  • brain tumor
  • stroke
  • surgery
  • infection
  • substance withdrawal
  • medications
  • heatstroke
  • low blood sugar
  • endocrine disorders
  • metabolic disorders
  • genetic abnormalities

Potential triggers of focal seizures include:

Doctors also classify focal seizures into two additional types, depending on their cause. One type is an unprovoked seizure, which occurs without a known cause, and the other is an acute symptomatic seizure, which results from a triggering event or injury.

Because a focal seizure begins in one part of the brain, its symptoms can vary depending on the area it affects. Also, a person will usually have symptoms on only one side of their body.

However, if the focal seizure becomes a generalized seizure, they may begin to experience convulsions on both sides.

Symptoms that may occur during a focal seizure include:

  • muscle contractions
  • unexpected sensations
  • atypical head or eye movements
  • automatisms, such as skin picking or lip smacking
  • vision changes or auras

People who remember having a seizure often describe an aura at its onset.

An aura is a confusing feeling or the perception of an unexpected light or smell just before a seizure begins. Therefore, auras usually indicate the start of the atypical electrical activity in the brain prior to a seizure.

Following the aura, the individual may then have odd sensations, changes in motor abilities, or visual disturbances, usually on one side of the body.

However, bystanders may notice different symptoms in these individuals, such as staring, rapid eye blinking, or body stiffening, followed by confusion and tiredness after the event.

Doctors can diagnose a seizure according to a person’s account of the event. However, a bystander’s report can be more reliable than these reports, so clinicians prefer to hear both accounts if possible.

A healthcare professional will try to figure out whether the seizure was focal or generalized. They will also attempt to distinguish the seizure episode from other events that look similar to seizures.

Doctors will also take note of any potential triggers for a seizure. If they are unable to identify any, they will assess a person’s likelihood of another seizure.

If there are risk factors for another seizure, the doctor might decide if an individual would benefit from medication.

During the physical examination, they will look for signs that may indicate a condition that causes seizures, such as epilepsy, a brain infection, or other chronic syndromes, including neurofibromatosis or tuberous sclerosis.

Healthcare professionals may also order blood tests, imaging scans, and spinal taps. There are also options for neuroimaging, including EEGs or MRI scans.

Finally, they may recommend electroencephalography, a procedure that monitors brain activity.

Doctors prescribe medications to treat focal seizures and help prevent future occurrences. When possible, they will try to treat the underlying cause.

Medications

Doctors use antiepileptic medications to prevent seizures.

Several options are available for focal seizures. They come in two categories: broad-spectrum antiepileptic medications and narrow-spectrum antiepileptic medications.

Examples of broad-spectrum antiepileptic medications include:

  • lamotrigine (Lamictal)
  • levetiracetam (Keppra)
  • topiramate (Topamax)
  • valproate (Depakote)
  • zonisamide (Zonegran)

Examples of narrow-spectrum antiepileptic medications include:

  • carbamazepine (Tegretol)
  • oxcarbazepine (Oxtellar XR)
  • phenytoin (Dilantin, Phenytek)
  • lacosamide (Vimpat)

Ketogenic diet

Following a ketogenic diet, which limits carbs and focuses on high fat and certain proteins, may help reduce focal seizures in some people with epilepsy.

A doctor may recommend this treatment if at least two epilepsy medications have been ineffective. This dietary therapy is mainly for treating children, but healthcare professionals may recommend it for some adults.

Vagus nerve stimulation

Another therapy for epilepsy when medications are ineffective work is vagus nerve stimulation (VGS).

In this procedure, a technician attaches an electric stimulator to the left vagus nerve in the neck, which can help reduce electrical activity in the brain. In turn, this can reduce the intensity and severity of seizures.

However, this treatment can take as long as 2 years to be effective, so a person may wish to continue taking medications during this time.

Surgery

When other treatments are not providing beneficial outcomes, a person may need a surgical procedure to separate or remove the part of the brain causing the seizures.

An individual can discuss these options with their doctor. They should also mention whether they take any other medications or are pregnant, as these factors may influence the course of action that the doctor recommends.

While it is not always possible to prevent focal seizures, a person can reduce their occurrence if there is an identifiable cause or trigger. In this case, individuals can treat the underlying disease or do their best to avoid the trigger.

For example, they can monitor their blood sugar, get adequate sleep, avoid flashing lights, or reduce alcohol consumption.

The outlook for someone who has had a focal seizure depends on its underlying cause. However, effective treatments are available to help sustain a person’s quality of life.

Additionally, getting sufficient sleep, eating a nutritious diet, exercising regularly, and taking medication under guidance from a doctor can benefit those who experience seizures.

Here are some frequently asked questions and answers on focal seizures.

How common are focal seizures?

Focal seizures are the most common type of seizure that affects both adults and children. Approximately 36% of people who experience seizures have complex focal seizures involving a loss of consciousness.

What are continuous focal seizures?

It is possible to have continuous focal seizures. If a person with epilepsy experiences a focal seizure for 5 minutes or more or a series of seizures with short breaks in between, they are having a continuous focal seizure. Another way to experience continuous focal seizures is by having a rare condition called epilepsia partialis continua.

How are focal seizures in children different from those in adults?

Focal seizures due to epilepsy are very common in children. When epilepsy is the cause, children may experience additional symptoms to adults, including cognitive dysfunction, behavioral issues, hyperactivity, and even psychosis. As with adults, the specific symptoms will depend on the location of the seizure in the brain.

Focal seizures, or partial seizures, occur when there is a disruption of electrical impulses in one part of the brain.

A person may be aware they are having a seizure — health experts call this a simple focal seizure. In contrast, those who may be unaware are often experiencing a complex focal seizure.

Some focal seizures occur after a person encounters a trigger, but some may happen without a known cause. Treatment often involves antiepileptic medication, dietary changes, VNS, or surgery. The outlook depends on the underlying cause of the seizure.