Overview

A concussion is a mild traumatic brain injury that affects brain function.¹ Some individuals may experience a seizure following a concussion, while others may develop what is known as post-traumatic epilepsy and experience multiple seizures.² This article discusses the relationship between concussions and seizures, the risk factors of seizures, management and prevention.

What are concussions?

A concussion is a mild traumatic brain injury that causes sudden, but often short-lived, loss of mental function.¹ They can be caused by direct trauma to the head, such as a fall, blow or accident, or can occur due to rapid acceleration-deceleration of the head, which is the forceful movement where the head is quickly propelled forward or backwards then abruptly stopped.^2,3 

What is epilepsy?

Epilepsy is a condition that affects the brain and causes recurring episodes known as seizures.⁴ Epileptic seizures are described as bursts of electrical activity in the brain that temporarily affects how it works.⁵. The symptoms of seizures can vary widely, so there is no set list of symptoms; some individuals lose awareness, whereas others don’t. Moreover, some individuals experience convulsions, which can consist of involuntary twitching of their arms and legs.⁴ There are multiple types of epileptic seizures, which are often classified based on their onset and the associated symptoms.⁴

Understanding the risk of seizures following a concussion is crucial for effective management and prevention strategies. Seizures can impact a person’s quality of life and sometimes require long-term treatment.⁶ Recognising and addressing this risk can promote better outcomes, reduce complications, and improve overall patient care. 

Concussion

Symptoms and management

Similarly to epilepsy, there is a wide range of symptoms that manifest as a result of concussions.^3,7 The symptoms can affect memory, judgement, speech, muscle coordination and balance.^3,7 Individuals who suffer a concussion often report a period of amnesia where they cannot remember the events leading up to the concussion and the period immediately after.³ Common symptoms include disorientation, headaches, dizziness, vision disturbances, and sensitivity to light, among many others.⁷ Historically, concussions were treated simply with rest. However, there are now newer approaches, such as therapy, that aim to target specific symptoms. It is advised to limit physical activity during recovery, and a thorough medical examination is often necessary before returning to sports, which poses the risk of further head injury.⁷ 

Risks of seizures after a concussion

Early seizures

Traumatic brain injury (TBI) is a well-recognised cause of seizures and epilepsy.⁸ The type and severity of trauma that a person experiences can affect the resulting damage. TBIS can cause brain contusion (bruising of the brain) and brain haemorrhage (bleeding of the brain). A person with TBI needs immediate medical attention.⁹ It is more than often not possible to reverse the damage caused to brain tissue by trauma, but immediate attention can help to prevent further injury.⁹ 

Approximately 1 in 10 people who suffer a TBI will experience an early seizure following the incident; 50% of the early seizures occur during the first 24 hours following the TBI, and 25% of early seizures occur during the first hour following the TBI.² The majority of early seizures following a TBI are classified as generalised tonic-clonic seizures, which means the seizures have a generalised onset, affecting both sides of the brain.¹⁰ People who experience early seizures after a TBI are at a higher risk for developing post-traumatic epilepsy (PTE) than those who do not experience any seizures.²

Late seizures

Late seizures are those which occur more than a week after a TBI. The most common reason for the delay in this type of seizure is more serious injury to brain cells, which changes the chemical environment around them.¹¹ Late seizures are more likely to lead to the development of PTE than early seizures.¹¹ 

Post-traumatic epilepsy (PTE)

A person who suffers from PTE is at higher risk for recurrent seizures due to brain injury.¹² It is believed that around 1 in 50 people who suffer from a TBI will develop PTE⁸. There are a range of seizures that someone with PTE will experience, ranging from mild seizures that are easier to manage to more severe seizures that are more resistant to treatment.⁸ 

The pathogenesis of seizures following a TBI entails structural, metabolic and inflammatory changes in the brain.¹³ The structural changes that TBI can elicit are neuronal death, axon damage and disruption of the blood-brain barrier.¹³ Disruption of the blood-brain barrier enables the infiltration of peripheral inflammatory cells and molecules into the brain, contributing to neuroinflammation and hyperexcitability.¹³ 

The metabolic changes resulting from TBI include an imbalance in neurotransmitters, which can lead to excessive glutamate release and excitotoxicity.¹⁴ It can also cause mitochondrial dysfunction and oxidative stress, which can contribute to neuronal hyperexcitability and cell death.¹⁴ 

TBI also induces inflammatory changes in the brain, triggering an inflammatory response that releases pro-inflammatory cytokines, such as interleukin-1-beta, interleukin-6 and tumour necrosis factor-alpha.¹⁵ These pro-inflammatory cytokines can contribute to disrupting the blood-brain barrier, which promotes neuronal hyperexcitability and contributes to the development of epilepsy.¹⁵ It has been identified that toll-like receptors (TLRs), in particular TLR3, play a key role in mediating the inflammatory response and susceptibility to seizures.¹⁶ 

It is likely a combination of structural, metabolic and inflammatory changes that create a hyperexcitable state in the brain, which lowers the seizure threshold and increases the chance of seizures post-TBI.¹⁶ Although everyone who suffers from a TBI is at risk of suffering seizures, certain individuals face a higher risk of this. 

High-risk individuals 

There are risk factors for both early and late seizures. Younger age (especially less than 5 years of age), individuals who experience bleeding internally in the brain or between the brain and its outer covering, swelling of a large area of the brain, or those who lose consciousness for more than 30 minutes are more likely to experience early seizures.¹⁷ On the other hand, Individuals who suffer from TBI who are over the age of 65, who previously have a history of long-term alcohol abuse, who experience a depressed skull fracture or who have metal fragments lodged in their brain are more likely to develop late seizures.^17,18 

How to screen for the risk of seizures?

We need to consider the patient’s clinical history, whether they have suffered from previous injuries or any neurological disorders, pre-existing conditions and age. A key factor to consider is the severity of the disease, necessitating the investigation for any haemorrhages. Tools such as the Glasgow Coma Scale will determine the level of consciousness and injury severity.¹⁹ Imaging, such as CT scans or MRIs, will often be used to identify any structural damage to the brain, which is associated with a higher risk of post-traumatic seizures.²⁰ EEGs may be used to measure any abnormal electrical signalling in the brain, which will be particularly useful in identifying patients at high risk of an early seizure.²⁰ Moreover, blood work can be conducted to identify any metabolic imbalances or toxic substances that can potentially contribute to the risk of a seizure.²¹ Overall, continuous monitoring is essential, particularly during the first-week post-injury, as late seizures are a key predictor of later epilepsy. 

Management and prevention of post-traumatic seizures

Preventative measures focus on reducing the risk of a concussion, which is mainly through implementing safety practices, such as wearing protective gear during high-risk activities. If seizures occur, management involves administering proper treatment to help control and prevent future seizures. Treatment involves the use of antiepileptic drugs, of which there are many types. Phenytoin is a commonly used drug for early seizures following TBI and has been shown as effective in reducing seizures during the first week post-TBI.²³ Alongside medication, lifestyle and dietary changes are recommended for a speedy recovery. Ketogenic diets are believed to be useful in managing seizures, especially in people who do not respond well to medication.²³ Although the exact mechanism is not fully understood, it is believed that the ketogenic diet alters the gut microbiome composition and function in a way that confers protection against seizures.²³ 

Summary

Research indicates that there is a correlation between experiencing a TBI and experiencing seizures following this. This has been shown to pose the risk of developing epilepsy, especially when the individual experiences late seizures. More research is required to understand this link and, more importantly, the exact mechanism behind epilepsy and seizures so that better treatment options can become available. There is currently no cure for seizures, only treatment that can be administered for management.