Complex Partial Seizures: Causes, Treatment, And Impact On The Brain

Seizures are relatively common. 10%¹ of the general population will have at least one seizure during their lifetime. Seizures are generally self-limiting and last approximately 2–3 minutes. As they don’t last long, they do not directly damage the brain but are dangerous in some situations, like driving. 

Keep reading to learn more about complex partial seizures and their impact on the brain. 

Have you considered clinical trials for Epilepsy?

We make it easy for you to participate in a clinical trial for Epilepsy, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What are seizures?

Seizures occur when there is abnormal electrical activity in the brain. During the seizure, the brain has increased electrical activity. Afterward, there is a temporary period of reduced brain activity which is the brain’s way of recovering before returning to normal.

What are the symptoms of complex partial seizures?

If you break the name down, you’ll understand what complex partial seizures are. ‘Complex’ refers to the impaired consciousness that occurs, so you might feel confused or black out completely. ‘Partial’ means seizures begin in one part of the brain.

Complex partial seizures are also known as “focal-impaired awareness seizures” and “focal-onset-impaired awareness seizures.” They are the most common type of seizure. Approximately 36%² of seizures after the first year from the onset are complex partial seizures.

What do complex partial seizures affect?

The brain has four lobes, and your symptoms largely depend on which area the seizure affects. Although the brain is a complex system of neural connections, each lobe has primary functions. They are:

  • Frontal lobe: Executive function, motor function

  • Parietal lobe: Integration of sensory information

  • Temporal lobe: Memory, hearing, smell, language, and emotion

  • Occipital lobe: Processing visual information 

Because complex partial seizures typically only affect one area, the symptoms will be specific. The most common area of the brain affected is the temporal lobe. As such, people with complex partial seizures typically report the following symptoms:

  • Aura before the seizure

  • Feeling funny

  • Strange smells

  • Non-directed movements are restricted to one body part, such as lip smacking, chewing, and fumbling of the fingers and thumbs. This is “automatism.”

  • Loss of consciousness

  • Unable to recall the seizure afterward

Language features can also be present if the seizure occurs in your dominant hemisphere, which is usually the left hemisphere. In most people, complex partial seizures have a slow progression. This is associated with oral and motor automatism and more noticeable post-event confusion.

Complex partial seizures can also occur in other parts of the brain. Only 10–30% of these seizures originate from another part of the brain. The next most affected area is the frontal lobe. These seizures are very short, recurrent, and often occur at night. 

Seizures can also affect the parietal and occipital lobes, but this is much less common.

As the location of the seizure varies, complex partial seizures can cause many symptoms, including:

  • Jerking or stiffening of the limbs

  • Dizziness

  • Language difficulties: Being unable to speak or understand speech

  • Vision difficulties: Temporary blindness, blurred vision, hallucinations, or rapid eye movement

  • Nausea and vomiting

  • Confusion

What causes complex partial seizures?

Complex partial seizures can occur for no reason, but structural or physiological abnormalities may cause them. Several studies estimate that doctors cannot find the specific cause in about 50%³ of seizure cases.

Generally speaking, the most common causes of seizures are stroke, idiopathic (i.e., no known reason), and infection. There are different causes by age group:

  • Children: Congenital abnormalities, fevers, infection

  • Adolescents and young adults: Trauma

  • Middle-aged adults: Trauma, tumors, strokes

  • Older adults and elderly: Strokes, degenerative disorders


A stroke occurs when blood flow is interrupted in one area of the brain. The cause may be a blood clot in the vasculature or a ruptured blood vessel. This creates damaged tissue that’s more vulnerable to seizures. A seizure can occur immediately after a stroke or later on. 

One study⁴ investigated the prevalence between stroke and epilepsy and reported that 11.5% had an epileptic seizure due to the stroke. 


Idiopathic means doctors are unable to find a specific cause. Despite having no clear cause, these seizures can reoccur. 

One study⁵ in Neurology India took 76 people with a history of one seizure and investigated their recurrence risk. They found that 28% of participants had more seizures in the future. The median duration between the first and second seizures was approximately ten months. 

Those on anti-epileptic medication were at significantly less risk of recurrence than those who weren’t.


An infection in your central nervous system can make you more vulnerable to seizures. Our brain goes through a series of changes to combat the infection, such as increasing immune cells. 

How are complex partial seizures diagnosed?

Epilepsy is a clinical diagnosis based on history and examination findings. A detailed medical history is essential for diagnosing complex partial seizures accurately and choosing the right treatment. Make sure your health professional knows the events leading up to the seizure, the seizure itself, and what happened afterward. 

Because complex partial seizures are often hard to remember, take someone who saw the seizure to your doctor's appointment. They will be able to answer any questions that you can’t. 

After the consultation, your doctor can order several tests to confirm the diagnosis and investigate potential causes. They include:

Electroencephalography (EEG)

An EEG allows physicians to see how the brain works by measuring its electrical activity. Doctors have safely used EEGs in clinical practice for many decades. 

While there are no inherent risks of having an EEG, outside factors such as flashing lights can increase the likelihood of seizure in people with photosensitivity. It takes approximately 45 minutes to two hours to record a sufficient amount of data.

The technician places electrodes in various positions on your head and scalp. During recording, the electrodes detect subtle changes in electrical activity from your brain. The physician will interpret these results to see whether there is any abnormal activity and where it is coming from.

Your results may be regular despite having a seizure, as your brain returns to normal after a seizure. 50%⁶ of EEG results will be normal in people with seizures, so it is not necessary for diagnosis.

Blood test

Blood tests will rule out factors such as infection and metabolic causes.


Your doctor may consider neuroimaging if clues in your history suggest the cause could be structural. For instance, imaging such as a head CT or MRI can look for any physical damage if you fell over before the seizure. 

What is the treatment for complex partial seizures?

Preventing further seizures is the main goal of treatment, and doctors often use anti-epileptic medications. They modulate various chemicals (e.g., sodium, gamma-aminobutyric acid, and glutamate) in the brain, ultimately making it less excitable. Approximately 70%⁷ of patients can control seizures with medication. 

Research hasn’t found a benefit to starting medication after one unprovoked seizure. Therefore, these medicines are typically reserved for people with two or more seizures. Your doctor can prescribe various drugs, and the type will depend on your medical history, preference, and any side effects. 

The most common medications for complex partial seizures are carbamazepine, phenytoin, valproic acid, and oxcarbazepine. These drugs have different side effects; however, the most common side effects amongst anti-epileptic medications include:

  • Sedation

  • Fatigue

  • Dizziness

  • Confusion

  • Headaches

Research has linked other factors to improved health outcomes in complex partial seizures, such as staying away from potential triggers. Some evidence⁸ suggests that ketogenic diets are beneficial in reducing seizure activity. Surgery is an option for severe cases. 

What are the long-term consequences of seizures?

The long-term consequences of seizures are largely unknown. Brief seizures are generally safe, although longer duration or reoccurrence will have negative effects. 

Scientists don’t completely understand the exact effect on the brain, but losing consciousness in some situations can cause harm in the form of falls and burns. People with epilepsy have a higher mortality rate⁹ than the general population.

It is worth mentioning the psychological toll on people who have complex partial seizures. Because these seizures are unpredictable, people can often be anxious to socialize because they do not want to have a seizure in public. 

Governments prohibit driving if you’ve had a seizure recently. In the US, the required seizure-free duration differs between states. This can impact your independence and leave you feeling frustrated. 

Do complex partial seizures cause brain damage?

These seizures generally do not cause brain damage. However, if they are severe and last longer than five minutes, they are renamed “status epilepticus,” a medical emergency. This condition can cause brain damage depending on the duration of the seizure. 

Reported effects include cognitive impairment, increased risk of further epileptic effects, and psychiatric conditions.

The lowdown

Complex partial seizures are one of the most common types of seizures. There are numerous causes of complex partial seizures, including infection and stroke. 

A health professional will diagnose you using various tests, including blood tests and neuroimaging, and treat you accordingly.

Have you considered clinical trials for Epilepsy?

We make it easy for you to participate in a clinical trial for Epilepsy, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Discover which clinical trials you are eligible for

Do you want to know if there are any Epilepsy clinical trials you might be eligible for?
Have you taken medication for Epilepsy?
Have you been diagnosed with Epilepsy?

Editor’s picks