What Are Focal Seizures?


The human brain operates by sending electrical signals through nerve cells called neurons. A seizure happens when there is an abrupt surge of disorganised electrical activity, resulting in various physical symptoms such as muscle contractions, visual disturbances, and loss of consciousness.1 

Seizures can impact the entire brain, but a focal onset seizure, also referred to as a partial seizure, occurs when the seizure originates in a specific region. 

There can be several causes for a focal seizure. Conditions like epilepsy, brain tumours, head trauma, or stroke-related damage can lead to recurring focal seizures. Infections, heatstroke, or low blood sugar levels can also act as triggers for seizures. 

Fortunately, seizures can be managed through treatment. Identifying and addressing the underlying cause can help decrease the frequency of focal seizures. With appropriate treatment, most individuals who experience seizures are capable of leading normal lives. This article will explore the causes, symptoms, and management options for focal seizures. 

Causes of focal seizures

Seizures can be caused by various conditions and circumstances, and sometimes the exact cause remains unknown. When a seizure occurs without a known cause, it is called an idiopathic seizure

Here are some of the potential causes of focal seizures:

  • Epilepsy
  • Liver or kidney failure
  • Very high blood pressure
  • Use of illegal drugs
  • Brain infections, such as meningitis
  • Brain and head injuries
  • Congenital brain defects, which are abnormalities in the brain that occur before birth
  • Stroke
  • Poisoning or venomous bites or stings
  • Heatstroke
  • Low blood sugar
  • Withdrawal from drugs or alcohol
  • Phenylketonuria, a genetic disorder that leads to brain damage and mental disability 

Signs and symptoms of focal seizures

When a focal seizure occurs, affecting only a specific part of the brain, the symptoms can vary depending on the area affected. For example, if the disturbance happens in the part of the brain responsible for vision, you may experience hallucinations or see bright lights. 

Other potential symptoms of focal seizures include:

  • Muscle contractions followed by relaxation
  • Contractions occurring on one side of the body
  • Unusual movements of the head or eyes
  • Numbness, tingling, or a sensation of something crawling on the skin
  • Abdominal pain
  • Rapid heart rate or pulse
  • Repetitive movements called automatisms, such as picking at clothes or skin, staring, lip smacking, and chewing or swallowing
  • Sweating
  • Nausea
  • Flushed face 
  • Dilated pupils, changes in vision, or hallucinations
  • Mood changes
  • Blackouts

Management and treatment for focal seizures

A focal seizure typically has a short duration, which means there isn't usually enough time to provide treatment while it is happening. However, a rare but dangerous type of seizure called status epilepticus can last longer and requires immediate emergency treatment. If the cause of the seizure is something other than epilepsy, such as an infection, it is important to treat the underlying cause appropriately.

If seizures continue to occur even after treating the underlying condition or if they are caused by conditions like idiopathic epilepsy, stroke, brain tumour, or other brain damage, it is necessary to use anti-epilepsy medication to prevent further seizures.

When someone is experiencing any type of seizure, it is helpful to keep other individuals and objects away until the seizure has ended. Involuntary muscle contractions during a seizure can accidentally cause harm to the person experiencing it. 


To diagnose a seizure, your doctor will rely on your description of the experience or the symptoms observed by others. However, identifying the underlying cause can be more challenging and of greater concern. 

Based on your symptoms and medical history, your doctor may perform various tests to determine the cause. These tests can include brain imaging scans, an EEG, blood tests, or a lumbar puncture to investigate the underlying factors contributing to your seizures.3


How can I prevent focal seizures

While it may not always be possible to prevent seizures, you can effectively manage them through medication. If you are prescribed medication for this purpose, it is important to follow your doctor's instructions and take the medication as prescribed without missing any doses. Additionally, maintaining a healthy lifestyle by getting sufficient sleep, eating a balanced diet, engaging in regular exercise, and finding ways to reduce stress can also contribute to seizure control. 

How common are focal seizures

The exact prevalence of focal seizures in the UK may vary depending on various factors such as age group, region, and population demographics. According to estimates from the Epilepsy Society in the UK, around 60% of people with epilepsy experience focal seizures. Epilepsy Action, another UK-based organisation, states that focal seizures are the most common type of seizure in adults with epilepsy.2

Who is at risk of focal seizures

There are several factors that can increase the risk of having  a focal seizure. Firstly, if you have a diagnosis of epilepsy, you are at a much higher risk to experience a focal seizure. Several brain conditions, such as brain tumours, can also increase the likelihood of developing a focal seizure. Other factors such as head injuries, or medical conditions such as liver or kidney failure can put you at risk as well. 

When should I see a doctor

If you are experiencing focal seizures or suspect that you may be having them, it is important to consult a doctor. Here are some situations in which you should consider seeking medical attention. 

  • First-time seizure: If you have never had a seizure before and experience a focal seizure, it is crucial to see a doctor for proper evaluation and diagnosis
  • Recurrent seizures: If you have experienced multiple focal seizures, it is important to seek medical attention for proper diagnosis and management
  • Seizure duration or intensity changes: If the duration or intensity of your focal seizures changes or if they become more frequent or severe, it is important to consult a doctor

Remember, a doctor is the best person to evaluate your specific situation and provide appropriate diagnosis and treatment options. They can help determine the cause of your focal seizures and develop an appropriate management plan tailored to your needs. 


Focal seizures occur when there is a sudden burst of chaotic electrical activity in a specific part of the brain. They can be caused by various factors, including epilepsy, brain conditions, head injuries, or certain medical conditions. The symptoms of focal seizures can vary depending on the affected area of the brain, such as muscle contractions, unusual movements, numbness, and changes in vision. Treatment involves addressing the underlying cause and, if necessary, using anti-epilepsy medication. It is important to seek medical attention if you experience focal seizures for proper diagnosis and management. 


  1. Beghi E. The epidemiology of epilepsy. Neuroepidemiology. 2019 Dec 18 [cited 2023 Jun 8];54(2):185–91. Available from: https://karger.com/ned/article/54/2/185/226881/The-Epidemiology-of-Epilepsy 
  2. Ioannou P, Foster DL, Sander JW, Dupont S, Gil‐Nagel A, Drogon O’Flaherty E, et al. The burden of epilepsy and unmet need in people with focal seizures. Brain Behav. 2022 Aug 26 [cited 2023 Jun 8];12(9):e2589. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9480957/ 
  3. Johannessen SI, Ben-Menachem E. Management of focal-onset seizures. Drugs. 2006 Sep 1 [cited 2023 Jun 8];66(13):1701–25. Available from: https://doi.org/10.2165/00003495-200666130-00004 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Athanasia Chiraki

Masters of Science - Clinical Neuroscience, University College London

Nancy is a Clinical Neuroscience postgraduate student studying at UCL. She has a Bachelor's degree in Psychology with Neuroscience from the University of Reading. She has experience in the mental health as well as hospitality sector, and her main interest is Neuroscientific Research and Artificial Intelligence. She is currently in the process of publishing her study on ADHD and deception.

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