Seizure

Jai Ganesh · 2024-10-28 16:17:39

Seizure

Gist

A seizure is a burst of uncontrolled electrical activity between brain cells (also called neurons or nerve cells) that causes temporary abnormalities in muscle tone or movements (stiffness, twitching or limpness), behaviors, sensations or states of awareness. Seizures are not all alike.

A seizure is a sudden, uncontrolled burst of electrical activity in the brain. It can cause changes in behavior, movements, feelings and levels of consciousness.

Anything that interrupts the normal connections between nerve cells in the brain can cause a seizure. This includes a high fever, high or low blood sugar, alcohol or drug withdrawal, or a brain concussion. But when a person has 2 or more seizures with no known cause, this is diagnosed as epilepsy.

Summary

Seizure is sudden, uncontrolled electrical activity in the brain. Seizures produce a wide range of symptoms, including changes in behaviour, shaking or sudden movements, and changes in consciousness. Often the cause of a seizure is unknown.

Characteristics

About 25 to 30 percent of seizures are provoked seizures (also known as acute symptomatic seizures), being triggered by underlying conditions, such as fever or stroke, or by exposure to flashing lights or moving objects. Unprovoked seizures occur in the absence of any clear cause; in some cases, they happen days after a possible cause, such as a head injury or alcohol withdrawal. Seizures can be a onetime event—some 10 percent of people worldwide experience a single seizure in their lifetime—or a recurring event. Recurrent seizures typically are a sign of epilepsy, a chronic neurological disorder caused by an absence or excess of signaling of neurons in the brain; epilepsy affects more than 50 million people worldwide.

The duration of a seizure varies, some lasting 30 seconds and others lasting two minutes. A seizure that is more than five minutes in duration or having more than one seizure that occurs over that same amount of time, with no return to consciousness between episodes, is known as status epilepticus. Status epilepticus can result in brain damage or death.

Types of seizures
Seizures are categorized into two broad types: focal (partial) or generalized. Both types of seizures may be preceded by a prodrome, or an early warning symptom, in which the individual experiences an altered emotion or sensation. A prodrome may include an aura, with distortions in vision (e.g., seeing bright lights), hearing strange sounds, changes in taste or smell, feeling strange sensations on the skin, or experiencing a sense of déjà vu or unexplained emotions, such as fear or joy. The person may also sweat, drool, become pale, or experience a change in heart rate. Difficulty speaking or involuntary twitching may also occur.

Focal seizures

Focal seizures—which can be caused by prior injury to the brain, such as from stroke, meningitis, or physical trauma—begin in the left or right hemisphere and remain in that area; thus, symptoms occur in a specific part or on one side of the body. Focal seizures may be characterized as simple partial seizures when the electrical discharges do not spread and the affected person experiences only an aura. This is in contrast to a complex partial seizure, wherein the electrical discharges spread, resulting in a loss of or altered consciousness. Affected individuals may feel like they are dreaming and may stare into space and perform repetitive movements, such as walking in circles or rubbing their hands. Afterward they may not know that the seizure occurred.

Generalized seizures

Generalized seizures occur when electrical discharges of a focal seizure spread to both hemispheres of the brain. Generalized seizures may also have generalized onset, meaning that they begin on both sides of the brain simultaneously. There are several different types of generalized seizures.

* Absence seizures (or petit mal seizures) are brief, lasting about 5–10 seconds, and may happen dozens or hundreds of times per day; they often occur in children.
* Atonic seizures (also known as drop attacks) last about 15 seconds and involve a loss of muscle control, causing the affected individual to collapse.
* Clonic seizures involve repetitive or rhythmic jerking movements, particularly of the neck, face, and arms, on both sides of the body.
* Myoclonic seizures are characterized by sudden brief jerks or twitching movements and occur especially in the morning.
* Tonic seizures cause muscle stiffening in the arms, legs, and back and sometimes cause the individual to lose consciousness and fall.
* Tonic-clonic seizures (or grand mal seizures) are often seen in epilepsy but can also be caused by other conditions (e.g., brain injury, infection, congenital or development abnormalities, or drug or alcohol withdrawal). Tonic-clonic seizures may be several minutes in duration and involve a tonic phase, which lasts 10–30 seconds and frequently is characterized by screaming and an abrupt loss of consciousness, and a clonic phase, which lasts 30–60 seconds or longer and is characterized by convulsions.
* Tonic-atonic seizures involve a tonic episode followed by an atonic episode.

Causes

Seizures may be caused by genetic disorders or congenital abnormalities, such as abnormalities of blood vessels in the brain. Acquired conditions and injuries associated with seizures include stroke, severe concussion, traumatic brain injury, degenerative brain diseases (e.g., Alzheimer disease or frontotemporal dementia), infection, and lack of sleep. Flashing lights, moving patterns, and certain medications also can trigger a seizure in some persons. Some seizures are related to drug use, including alcohol intoxication and alcohol withdrawal. High fever can cause febrile seizures; this is especially common in children between six months and five years of age.

Diagnosis and treatment

Seizure disorders may be diagnosed based on medical history, symptoms, and various tests, including electroencephalogram (EEG), computed tomography (CT), magnetic resonance imaging (MRI), spinal tap, and blood testing. Treatment varies widely and is based on treating the underlying cause. If the cause cannot be identified or treated, antiepileptic drugs may be prescribed. Some patients also benefit from a ketogenic diet (a low-carbohydrate, high-protein diet). Surgery may be undertaken in cases in which scarred brain tissue is suspected of triggering seizures. Vagus nerve stimulation, in which an implanted device sends mild electrical pulses to the brain via the vagus nerve to stabilize electrical activity in the brain, may be used to prevent or reduce the frequency of seizures.

Details

A seizure is a sudden change in behavior, movement, and/or consciousness due to abnormal electrical activity in the brain. Seizures can look different in different people. It can be uncontrolled shaking of the whole body (tonic-clonic seizures) or a person spacing out for a few seconds (absence seizures). Most seizures last less than two minutes. They are then followed by confusion/drowsiness before the person returns to normal. If a seizure lasts longer than 5 minutes, it is a medical emergency (status epilepticus) and needs immediate treatment.

Seizures can be classified as provoked or unprovoked. Provoked seizures have a cause that can be fixed, such as low blood sugar, alcohol withdrawal, high fever, recent stroke, and recent head trauma. Unprovoked seizures have no clear cause or fixable cause. Examples include past strokes, brain tumors, brain vessel malformations, and genetic disorders. Sometimes, no cause is found, and this is called idiopathic. After a first unprovoked seizure, the chance of experiencing a second one is about 40% within 2 years. People with repeated unprovoked seizures are diagnosed with epilepsy.

Doctors assess a seizure by first ruling out other conditions that look similar to seizures, such as fainting and strokes. This includes taking a detailed history and ordering blood tests. They may also order an electroencephalogram (EEG) and brain imaging (CT and/or MRI). If this is a person's first seizure and it's provoked, treatment of the cause is usually enough to treat the seizure. If the seizure is unprovoked, brain imaging is abnormal, and/or EEG is abnormal, it is recommended to start anti-seizure medications.

Signs and symptoms

A seizure can last from a few seconds to 5 minutes. Once it reaches and passes 5 minutes, it is known as status epilepticus. Accidental urination (urinary incontinence), stool leaking (fecal incontinence), tongue biting, and turning blue due to inability to breathe commonly are seen in seizures.

A period of confusion typically follows the seizure that lasts from seconds to hours before a person returns to normal. This period is called a postictal period. Other symptoms during this period include drowsiness, headache, difficulty speaking, psychosis, and weakness.

Observable signs and symptoms of seizures vary depending on the type. Seizures can be classified into generalized seizures and focal seizures, depending on what part of the brain is involved.

Focal seizures

Focal seizures affect a specific area of the brain, not both sides. It may turn into a generalized seizure if the seizure spreads through the brain. Consciousness may or may not be impaired. The signs and symptoms of these seizures depends on the location of the brain that is affected. Focal seizures usually consist of motor symptoms or sensory symptoms.

Sensory symptoms: Auras are subjective sensations that occur before focal seizures. Auras include changes in vision, hearing, or smell (example is smelling rubber). Feelings of deja-vu or abdominal discomfort are also examples of auras. A person who experiences focal weakness of a limb may also have just experienced a focal seizure. This is known as Todd’s Paralysis.

Motor symptoms: Head turning and eyes moving to one side, with contraction of limbs on one side is a common presentation. Automatisms are also an indicator that a seizure is focal. These are repetitive movements. It can be lip smacking, chewing, swallowing, eyelid fluttering, feet shuffling, or picking movements. Jacksonian March is also a motor presentation of a focal seizure, with contractions spreading from one muscle to the next on one side of the body.

Generalized seizures

Generalized seizures affect both sides of the brain and typically involve both sides of the body. They all involve a loss of consciousness and usually happen without warning. There are six main types of generalized seizures: tonic-clonic, tonic, clonic, myoclonic, absence, and atonic seizures.

* Tonic-clonic seizures, also known as Grand Mal seizures, present with continuous stiffening of the body for 10-20 seconds followed by rhythmic jerking. It may be accompanied by an increased in blood pressure, increase in heart rate, urinary incontinence. The person may turn blue if breathing is impaired. Shoulder dislocation and tongue biting are also possible.

* Tonic seizures produce constant contractions of the muscles. The body stiffens for a prolonged period of time. The muscles most commonly affected are the neck, shoulders, hips, and trunk.

* Clonic seizures involve jerking of the muscles rhythmically.

* Myoclonic seizures involve short contractions of muscles in either a few areas of the body or through the whole body. They are not typically rhythmic.

* Absence seizures last 10-15 seconds usually. It is characterized by a sudden, brief episode where a person is unaware of what is happening and does not respond. The person stops in the middle of activity. The person often does not fall over. They may return to normal right after the seizure ends, with no postictal state. The person is usually unaware of what just happened.

* Atonic seizures involve the loss of muscle activity causing a person to drop abruptly with their muscles limp. This is called a drop attack.

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Seizure

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