Seizure (patient information)
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What is a seizure?
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement (tonic-clonic seizure) or as mild as a brief loss of awareness. It can manifest as an alteration in mental state, tonic or clonic movements, convulsions, and various other psychic symptoms (such as déjà vu or jamais vu). The medical syndrome of recurrent, unprovoked seizures is termed epilepsy, but seizures can occur in people who do not have epilepsy.
About 4% of people will have an unprovoked seizure by the age of 80 and yet the chance of experiencing a second seizure is between 30% and 50%. Treatment may reduce the chance of a second one by as much as half. Most single episode seizures are managed by primary care physicians (emergency or general practitioners), whereas investigation and management of ongoing epilepsy is usually by neurologists. Difficult-to-manage epilepsy may require consultation with an epileptologist, a neurologist with an interest in epilepsy.
Non-epileptic seizures are paroxysmal events that mimic an epileptic seizure but do not involve abnormal, rhythmic discharges of cortical neurons. They are caused by either physiological or psychological conditions. The latter is discussed more fully in psychogenic non-epileptic seizures.
Medically, when used on its own, the term seizure implies an epileptic seizure. The lay use of this word can also include sudden attacks of illness, loss of control, spasm or stroke. Where the physician is uncertain as to the diagnosis, the medical term paroxysmal event and the lay terms spells, funny turns or attacks may be used.
Types of seizure
There are many types of seizures. These can be classified into two broad groups:
- Primary generalized seizures—seizures begin with widespread involvement of both sides of the brain. Generalized seizures are divided according to the effect on the body, but all involve loss of consciousness. These include absence, myoclonic, clonic, tonic, tonic–clonic, and atonic seizures.
- Absence: In absence seizures, the person may appear to be staring into space with or without jerking or twitching movements of the eye muscles[citation needed]. These periods last for seconds, or even tens of seconds. Those experiencing absence seizures sometimes move from one location to another without any purpose.
- Myoclonic: Myoclonus is brief, involuntary twitching of a muscle or a group of muscles. The most common time for people to encounter them is while falling asleep (hypnic jerk), but myoclonic jerks are also a sign of a number of neurological disorders. Hiccups are also a kind of myoclonic jerk specifically affecting the diaphragm. Also when a spasm is caused by another person it is known as a "provoked spasm". Shuddering attacks with babies also fall in this category. In almost all instances in which myoclonus is caused by Central Nervous System (CNS) disease it is preceded by other symptoms.
- Clonus is a series of involuntary muscular contractions due to sudden stretching of the muscle. Clonus is a sign of certain neurological conditions, and is particularly associated with upper motor neuron lesions such as in stroke, multiple sclerosis, spinal cord damage and hepatic encephalopathy. Unlike the small, spontaneous twitching known as fasciculations (usually caused by lower motor neuron pathology), clonus causes large motions that are usually initiated by a reflex.
- Tonic-clonic: Tonic–clonic seizures (formerly known as grand mal seizures or gran mal seizures) are a type of generalized seizure that affects the entire brain. Tonic–clonic seizures are the seizure type most commonly associated with epilepsy and seizures in general. There are two phases of a seizure, tonic and clonic, and is often preceded by an aura: The person may feel a sense of strong déjà vu, lightheadedness and/or dizziness, unusual (and possibly inappropriate) emotions, intense feelings of discomfort or foreboding, altered vision and hearing (which may or may not include hallucinations), and sometimes other symptoms. In the tonic phase, the person will quickly lose consciousness, and the skeletal muscles will suddenly tense, often causing the extremities to be pulled towards the body or rigidly pushed away from it, which will cause the person to fall if standing. The tonic phase is usually the shortest part of the seizure, usually lasting only a few seconds. Lastly, the clonic part of the seizure is the part most people are familiar with: The person's muscles will start to contract and relax rapidly, causing convulsions. These may range from exaggerated twitches of the limbs to violent shaking or vibrating of the stiffened extremities. The person may roll and stretch as the seizure spreads. The eyes typically roll back or close and the tongue often suffers bruising sustained by strong jaw contractions. Incontinence is seen in some cases.
- Tonic seizures (also called drop seizures, akinetic seizures or drop attacks), are a minor type of seizure. They consist of a brief lapse in muscle tone that are caused by temporary alterations in brain function. The seizures are brief - usually less than fifteen seconds.
- Partial seizures—seizures begin with involvement of a smaller, localized area of the brain. With some partial seizures, the disturbance can still spread within seconds or minutes to involve widespread areas of the brain (secondary generalized seizure). Partial seizures are further divided on the extent to which consciousness is affected (simple partial seizures means consciousness unaffected, and complex partial seizures means consciousness is affected).
Signs and Symptoms
Seizures can cause involuntary changes in body movement or function, sensation, awareness, or behavior. Seizures are often associated with a sudden and involuntary contraction of a group of muscles and loss of consciousness. However, a seizure can also be as subtle as a fleeting numbness of a part of the body, a brief or long term loss of memory, visual changes, sensing/discharging of an unpleasant odor, a strange epigastric sensation, or a sensation of fear and total state of confusion. A seizure can last from a few seconds to status epilepticus, a continuous seizure that will not stop without intervention. Therefore seizures are typically classified as motor, sensory, autonomic, emotional or cognitive. After a seizure, while the brain is recovering, there can be a transient loss of memory; usually the short term memory.
In some cases, the full onset of a seizure event is preceded by some of the sensations described above. These sensations can serve as a warning to the sufferer that a generalized tonic–clonic seizure is about to occur. These "warning sensations" are cumulatively called an aura. Also, it is commonly believed among healthcare providers that many seizures, especially those in children, are preceded by tachycardia that frequently persists throughout the seizure. This early increase in heart rate may supplement an aura as a physiological warning sign of an imminent seizure.
Some patients are able to tell when a seizure is about to happen. Some symptoms experienced by the person before a seizure may include dizziness, lightheadedness, tightening of the chest, and some experience things in slow-motion just prior to the seizure. Symptoms experienced by a person during a seizure depend on where in the brain the disturbance in electrical activity occurs. Partial and frontal seizures and focal epileptic discharges tend to happen more during sleep than during wakefulness. In contrast, psychogenic nonepileptic seizures are rare between midnight and 6 a m. and never occurred during sleep. Generalized epilepsy but not focal epilepsy is higher in the morning probably reflecting a diurnal variation in cortical excitability. A person having a tonic–clonic seizure may cry out, lose consciousness and fall to the ground, and convulse, often violently. A person having a complex partial seizure may appear confused or dazed and will not be able to respond to questions or direction. Some people have seizures that are not noticeable to others. Sometimes, the only clue that a person is having an absence seizure is rapid blinking, extreme confusion for a few seconds or sometimes into hours.
Causes
Unprovoked seizures are often associated with epilepsy and related seizure disorders.
Causes of provoked seizures include:
- sleep deprivation
- cavernoma or cavernous malformation is a treatable medical condition that can cause seizures, headaches, and brain hemorrhages. An MRI can quickly confirm or reject this as a cause.
- arteriovenous malformation (AVM) is a treatable medical condition that can cause seizures, headaches, and brain hemorrhages. An MRI can quickly confirm or reject this as a cause.
- head injury may cause non-epileptic post-traumatic seizures or post-traumatic epilepsy, in which the seizures chronically recur.
- intoxication with drugs
- drug toxicity, for example aminophylline or local anaesthetics
- normal doses of certain drugs that lower the seizure threshold, such as tricyclic antidepressants
- infection, such as encephalitis or meningitis
- fever leading to febrile convulsions (but see above)
- metabolic disturbances, such as hypoglycaemia, hyponatremia or hypoxia
- withdrawal from drugs (anticonvulsants, antidepressants, and sedatives such as alcohol, barbiturates, and benzodiazepines,)
- space-occupying lesions in the brain (abscesses, tumors)
- seizures during (or shortly after) pregnancy can be a sign of eclampsia.
- seizures in a person with hydrocephalus may indicate severe shunt failure.
- binaural beat brainwave entrainment may trigger seizures in both epileptics and non-epileptics
- haemorrhagic stroke can occasionally present with seizures, embolic strokes generally do not (though epilepsy is a common later complication); cerebral venous sinus thrombosis, a rare type of stroke, is more likely to be accompanied by seizures than other types of stroke
- multiple sclerosis sufferers may rarely experience seizures
Some medications produce an increased risk of seizures and electroconvulsive therapy (ECT) deliberately sets out to induce a seizure for the treatment of major depression. Many seizures have unknown causes.
Seizures which are provoked are not associated with epilepsy, and people who experience such seizures are normally not diagnosed with epilepsy. However, the seizures described above resemble those of epilepsy both outwardly, and on EEG testing.
Seizures can occur after a subject witnesses a traumatic event. This type of seizure is known as a psychogenic non-epileptic seizure and is related to posttraumatic stress disorder.
Mild seizures can be induced through a combination of quickly standing, hyperventilation and applying pressure to the sternum.
Diagnosis
Only about 25 percent of people who have a seizure or develop status epilepticus have epilepsy. It is important to distinguish primary epileptic seizures from secondary causes. Blood tests, lumbar puncture or toxicology screening can be helpful in specific circumstances suggestive of an underlying cause like alcohol or benzodiazepine withdrawal, meningitis or drug overdose, but there is insufficient evidence to support their routine use in the work-up of an adult with an apparently unprovoked first seizure. A 2007 evidence-based review from the American Academy of Neurology and the American Epilepsy Society recommends an electroencephalogram (EEG, brain wave activity) and brain imaging with CT scan or MRI scan in the work-up. MRI is more sensitive in a first apparently unprovoked seizure.
Differentiating an epileptic seizure from other conditions such as syncope can be difficult. A reliable description of a witnessed seizure is the most important factor in determining whether a seizure has occurred.
Management
The first aid for a seizure depends on the type of seizure occurring. Generalized seizures will cause the person to fall, which may result in injury. A tonic–clonic seizure results in violent movements that cannot and should not be suppressed. The person should never be restrained, nor should there be any attempt to put something in the mouth. Potentially sharp or dangerous objects should also be moved from the vicinity, so that the individual is not hurt. After the seizure if the person is not fully conscious and alert, they should be placed in the recovery position. Bystanders should remain calm and avoid crowding the person.
It is not necessary to call an ambulance if the person is known to have epilepsy, if the seizure is shorter than five minutes and is typical for them, if it is not immediately followed by another seizure, and if the person is uninjured. Otherwise, or if in any doubt, medical assistance should be sought.
A seizure longer than five minutes is a medical emergency. Relatives and other caregivers of those known to have epilepsy often carry medicine such as rectal diazepam or buccal midazolam in order to rapidly end the seizure.
Safety
A sudden fall can lead to broken bones and other injuries. Children who are affected by frequent drop seizures may wear helmets to protect the head during a fall.
The unusual behavior resulting from the chaotic brain activity of a seizure can be misinterpreted as an aggressive act. This may invoke a hostile response or police involvement, where there was no intention to cause harm or trouble.
A seizure response dog can be trained to summon help or ensure personal safety when a seizure occurs. These are not suitable for everybody. Rarely, a dog may develop the ability to sense a seizure before it occurs.
Where to find medical care for a seizure
Directions to Hospitals Treating seizure