What Causes Seizures? Understanding the Triggers and Risk Factors

A seizure is characterized by a sudden, uncontrolled electrical disturbance in the brain. This disruption can manifest in a variety of ways, affecting movement, behavior, feelings, and consciousness levels. While epilepsy, defined by two or more unprovoked seizures occurring at least 24 hours apart, is a well-known condition associated with seizures, it is crucial to understand that not all seizures are caused by epilepsy.

Seizures present diversely, with symptoms varying significantly depending on the type and location of the brain’s electrical activity. These episodes can range from subtle and barely noticeable to dramatic and debilitating, impacting daily life to varying degrees. Seizures are classified based on their origin in the brain and how they spread. The majority of seizures are brief, typically lasting from 30 seconds to two minutes. However, a seizure exceeding five minutes is considered a medical emergency requiring immediate attention.

While seizures can be triggered by identifiable events such as stroke, head injuries, or infections like meningitis, often, the underlying cause remains elusive. Effective management of seizures is often achieved through medication, although these can come with side effects. Therefore, a collaborative approach with healthcare professionals is essential to balance seizure control with minimizing medication-related adverse effects.

Symptoms of Seizures: Recognizing the Signs

Seizure symptoms are incredibly varied and depend heavily on the type of seizure experienced. They can range from mild, almost imperceptible changes to dramatic and obvious events. Common seizure symptoms may include:

Transient Confusion: A period of disorientation or difficulty thinking clearly immediately following a seizure.
Staring Spells: An episode of unresponsiveness characterized by a fixed gaze, often mistaken for daydreaming, particularly common in absence seizures.
Involuntary Jerking Movements (Convulsions): Uncontrollable, rhythmic muscle contractions, typically affecting the arms and legs, a hallmark of tonic-clonic seizures.
Loss of Consciousness or Awareness: Ranging from brief lapses in awareness to complete unresponsiveness, depending on the seizure type.
Emotional and Cognitive Changes: These can include sudden feelings of fear or anxiety, the unsettling sensation of déjà vu (a feeling of familiarity with a new situation), or alterations in thinking patterns.

Seizures are broadly categorized into two main types: focal seizures and generalized seizures. This classification is based on where the seizure originates in the brain. When the origin is unknown, seizures are classified as having an unknown onset.

Focal Seizures: Originating in One Brain Area

Focal seizures, also known as partial seizures, begin with abnormal electrical activity in a localized area of the brain. These seizures can occur with or without loss of consciousness.

Focal Seizures with Impaired Awareness (Complex Partial Seizures): These seizures involve a change or loss of consciousness or awareness. Individuals may appear awake but are not fully responsive to their environment, often described as feeling like being in a dream. During these seizures, a person may stare blankly, not respond to questions or instructions, and exhibit repetitive behaviors such as hand rubbing, lip smacking, repeating words or phrases, or walking in circles. Post-seizure amnesia is common, with individuals often having no memory of the event.
Focal Seizures Without Impaired Awareness (Simple Partial Seizures): These seizures do not cause a loss of consciousness. Instead, they may manifest as altered emotions, or changes in sensory perception, affecting sight, smell, taste, sound, or touch. Individuals may experience sudden and intense emotions like anger, joy, or sadness, nausea, or unusual and difficult-to-describe sensations. Other symptoms can include speech difficulties, localized muscle jerking (e.g., in an arm or leg), and sensory disturbances like tingling, dizziness, or seeing flashing lights.

It’s important to note that the symptoms of focal seizures can sometimes mimic other neurological or psychiatric conditions, such as migraines, mental health disorders, or narcolepsy, a sleep disorder.

Generalized Seizures: Affecting the Entire Brain

Generalized seizures are characterized by widespread electrical disturbances affecting both sides of the brain from the onset. Different types of generalized seizures include:

Absence Seizures (Petit Mal Seizures): Primarily seen in children, absence seizures are characterized by brief staring spells, sometimes accompanied by subtle body movements like eye blinking or lip smacking. These seizures are very short, typically lasting only 5 to 10 seconds, but can occur frequently throughout the day, sometimes hundreds of times. They cause a brief lapse in awareness, which can easily be missed or mistaken for inattentiveness.
Tonic Seizures: Tonic seizures cause muscle stiffness. They often affect the muscles of the back, arms, and legs, leading to falls and potential injury. Loss of consciousness may occur during tonic seizures.
Atonic Seizures (Drop Seizures): Atonic seizures result in a sudden loss of muscle tone, most commonly affecting the legs, causing the individual to collapse or fall. These are also known as “drop attacks” due to the sudden and uncontrolled falls they cause.
Clonic Seizures: Clonic seizures are characterized by repetitive, jerking muscle movements. These movements typically affect the neck, face, and arms on both sides of the body.
Myoclonic Seizures: Myoclonic seizures involve brief, shock-like jerks or twitches of muscles or muscle groups. They often affect the arms and legs. Consciousness is usually not lost in myoclonic seizures.
Tonic-Clonic Seizures (Grand Mal Seizures): The most recognizable type of seizure, tonic-clonic seizures involve a distinct sequence of events. They begin with a tonic phase (muscle stiffening), followed by a clonic phase (jerking movements). Loss of consciousness is common, and individuals may experience loss of bladder control (urination) or bite their tongue. Tonic-clonic seizures can last for several minutes and may sometimes start as focal seizures that then spread to involve the entire brain.

Stages of a Seizure: Prodrome, Ictal, and Postictal

Seizures can be divided into three phases:

Prodrome (Pre-ictal Phase): This is the period preceding a seizure, serving as an early warning. Individuals may experience vague sensations or behavioral changes hours or even days before a seizure. An aura, considered the earliest symptom of a seizure, can occur during the prodrome. Auras are diverse and can include feelings of déjà vu or jamais vu (a sense of unfamiliarity with a familiar situation), unusual sensations, fear, panic, pleasant feelings, olfactory (smells), auditory (sounds), gustatory (tastes), visual (blurred vision), or cognitive (racing thoughts) disturbances. Headache, numbness, tingling, nausea, or dizziness may also occur. While many experience a prodrome or aura, some individuals do not have any warning signs.
Ictal Phase: This phase encompasses the seizure itself, from the first symptom (including the aura) to the termination of seizure activity. Symptoms during the ictal phase are determined by the type of seizure.
Postictal Phase: This is the recovery period immediately following a seizure. It can last from minutes to hours, with recovery time varying depending on the seizure type and affected brain areas. Common postictal symptoms include slow responsiveness, memory difficulties, speech and writing problems, sleepiness, confusion, dizziness, sadness, fear, anxiety, frustration, nausea, headache, and weakness. Individuals may also experience thirst or the urge to urinate.

When to Seek Immediate Medical Attention for a Seizure

It is crucial to seek emergency medical help if you or someone you witness experiencing a seizure exhibits any of the following:

Seizure lasting longer than five minutes: This is status epilepticus, a medical emergency.
Breathing cessation after seizure: Respiratory distress following a seizure requires immediate intervention.
Rapidly recurring seizures: Multiple seizures in close succession without regaining consciousness between them are dangerous.
High fever: Seizures accompanied by fever may indicate a serious underlying infection.
Heat exhaustion/Overheating: Seizures in the context of hyperthermia are concerning.
Pregnancy: Seizures during pregnancy require prompt medical evaluation due to risks to both mother and baby.
Diabetes: Seizures in individuals with diabetes can be related to blood sugar imbalances.
Seizure-related injury: Any injury sustained during a seizure necessitates medical assessment.
Seizure in water: Drowning is a significant risk if a seizure occurs while swimming or bathing.

Furthermore, it is essential to consult a healthcare professional after experiencing a seizure for the first time to determine the cause and appropriate management.

What Causes Seizures? Identifying the Underlying Factors

Seizures arise from disruptions in the normal communication between nerve cells (neurons) in the brain. Neurons communicate via electrical impulses, and anything that interferes with these pathways can trigger a seizure. In some cases, genetic mutations can predispose individuals to seizures.

Epilepsy stands as a primary cause of recurrent seizures. However, it is important to reiterate that seizures can occur in individuals without epilepsy, triggered by various factors, including:

High Fever (Febrile Seizures): Elevated body temperature, particularly in infants and young children, can provoke febrile seizures.
Brain Infections: Infections of the brain, such as meningitis (inflammation of the membranes surrounding the brain and spinal cord) and encephalitis (inflammation of the brain itself), can disrupt brain function and lead to seizures.
Serious Systemic Illnesses: Severe illnesses, including infections like COVID-19, can sometimes trigger seizures due to metabolic imbalances or inflammation affecting the brain.
Sleep Deprivation: Insufficient sleep can lower the seizure threshold, making seizures more likely in susceptible individuals.
Electrolyte Imbalances (e.g., Low Blood Sodium – Hyponatremia): Abnormalities in blood electrolyte levels, such as low sodium, can disrupt neuronal function and trigger seizures. Certain medications, particularly diuretics (“water pills”), can contribute to hyponatremia.
Certain Medications: Some medications, including certain antidepressants, pain relievers, and smoking cessation drugs, can increase the risk of seizures as a side effect.
Acute Brain Injury: Recent head trauma, causing bleeding or swelling in the brain, or stroke (disruption of blood flow to the brain), can lead to seizures.
Illicit Drug Use: Stimulant drugs like amphetamines and cocaine can disrupt brain activity and induce seizures.
Alcohol Misuse: Both alcohol withdrawal and excessive alcohol consumption can trigger seizures. Alcohol withdrawal seizures are a serious complication of alcohol dependence.

Risk Factors for Seizures: Who is More Susceptible?

Several factors can increase an individual’s likelihood of experiencing seizures:

History of Head or Brain Injuries: Prior head trauma significantly elevates seizure risk.
Cognitive Impairment/Neurodegenerative Conditions: Conditions like dementia and Alzheimer’s disease increase seizure susceptibility.
Stroke: Stroke is a major risk factor, as it can damage brain tissue and disrupt electrical activity.
Alzheimer’s Disease: As mentioned above, Alzheimer’s disease and other dementias increase seizure risk.
Brain Tumors: Tumors in the brain can directly disrupt normal brain function and trigger seizures.
Substance Misuse (Alcohol or Illicit Drugs): Chronic alcohol or drug abuse increases the risk of seizures, both during use and withdrawal.
Family History of Seizures or Epilepsy: Genetic predisposition plays a role, and having a family history of seizures or epilepsy increases individual risk.

Potential Complications of Seizures: Understanding the Dangers

Seizures can lead to various complications that pose risks to both the individual experiencing the seizure and potentially others:

Falls and Injuries: Loss of consciousness and muscle control during a seizure can result in falls, leading to head injuries, fractures, and other trauma.
Drowning: Seizures occurring during swimming or bathing carry a high risk of drowning due to loss of consciousness and inability to self-rescue.
Motor Vehicle Accidents: Seizures causing loss of awareness or control while driving can have catastrophic consequences, leading to car accidents and injuries.
Pregnancy Complications: Seizures during pregnancy pose risks to both the pregnant individual and the developing fetus. Certain antiseizure medications can also increase the risk of birth defects. Careful management of seizures and medication adjustments are crucial for pregnant individuals with epilepsy.
Mental Health Disorders: Individuals with seizures have a higher prevalence of depression, anxiety, and other mental health conditions. This can be attributed to the challenges of living with seizures, medication side effects, and the underlying neurological condition.
Sudden Unexpected Death in Epilepsy (SUDEP): While rare, SUDEP is a serious complication where a person with epilepsy dies unexpectedly without a clear cause of death. Poorly controlled seizures and other factors are believed to contribute to SUDEP risk, but the exact mechanisms are still under investigation. Effective seizure management is vital in minimizing SUDEP risk.

Prevention of Seizures: Minimizing Triggers

For individuals with a history of seizures, particularly those with epilepsy, avoiding known seizure triggers is crucial for prevention:

Prioritize Adequate Sleep: Maintaining a regular and sufficient sleep schedule is essential.
Avoid Alcohol and Illicit Drugs: Substance use is a significant seizure trigger.
Stress Management: Chronic stress can exacerbate seizures. Stress-reduction techniques may be beneficial.
Limit Exposure to Flashing Lights: For individuals with photosensitive epilepsy, flashing lights can trigger seizures.

By understanding the diverse causes of seizures, recognizing the symptoms, and being aware of risk factors and prevention strategies, individuals and healthcare providers can work together to effectively manage seizures and improve the quality of life for those affected.