A generalized seizure is a sudden change in consciousness, muscle control or behavior caused by abnormal activity on both sides of the brain. A generalized seizure is different from a partial (focal) seizure, which usually affects a small, localized area of the brain.
Seizures occur when the neurons in the brain suddenly increase activity, causing an electrical storm that can overwhelm the brain. This can result in various symptoms depending on the area of the brain affected. People who have a generalized seizure usually experience symptoms that affect their entire body, such as whole-body muscle contractions or a loss of consciousness.
The most identifiable and traumatic type of generalized seizure is the tonic-clonic seizure, also known as grand mal seizures or convulsions. Many tonic-clonic seizures are isolated events and, although distressing to witness, rarely cause neurological damage.
Generalized seizures may be caused by chronic underlying medical conditions that may require treatment (e.g., epilepsy). Many generalized seizures have no known cause, making them difficult to prevent. In cases where the underlying cause is unknown, seizures can sometimes be controlled with medication.
Generalized seizures can rarely be treated with brain surgery because the abnormal neuron activity occurs in the entire brain. However, people with recurrent generalized seizures that are poorly controlled by medication may be suitable for a type of treatment called vagus nerve stimulation.
There are certain things bystanders can do (and not do) to prevent additional harm to a person having a generalized seizure. For example, nothing should be placed in a person’s mouth during a seizure, and restraint should not be used. It is recommended that bystanders clear the area of furniture and objects that may cause injury to the person having a seizure. Also, the person having the seizure should be gently rolled onto his or her side to prevent choking on vomit or mucus.
About generalized seizures
A generalized seizure is a sudden change in consciousness, muscle control or behavior caused by abnormal activity in both sides of the brain. Generalized seizures are different from partial (focal) seizures, which usually occur in an isolated area in the brain. However, generalized seizures can sometimes begin with a partial seizure. This is called a partial onset seizure (or secondary generalized seizure). Some people may experience both partial and generalized seizures at different times. It is sometimes difficult to identify whether a seizure is partial or generalized.
Seizures are caused by a sudden increase in electrical activity in the brain. Neurons (nerve cells) produce electrochemical signals that instruct other parts of the body to perform certain actions, such as move and feel emotions or sensations.
A seizure occurs when some factor disturbs the pattern of electrochemical signals and causes the neurons to fire much faster than normal. This storm of electrical activity in the brain can result in the appearance of a seizure – changes in mood or behavior, hallucinations, involuntary muscle contractions or movement and loss of consciousness. During a generalized seizure, numerous symptoms may be experienced because the entire brain is affected.
After a generalized seizure, it may take minutes or hours to return to full consciousness. Many people report a feeling of confusion or extreme tiredness. This is called postictal syndrome. Children who have a seizure may fall into a deep sleep after the seizure ends. This is normal and enables the brain to recover after the stress of the seizure. These children should not be woken during this time.
Some people with recurrent generalized seizures may experience a vague change of consciousness that occurs minutes or hours before they have a seizure. This sensation is called an aura. The exact nature of the aura is often unique to each individual, although it may include noticing a strange taste in the mouth, twitching in one limb or an inexplicable feeling of fear or apprehension. Because most people experience the same progression of events during each seizure, auras can serve as a warning sign that a seizure is going to occur.
Other symptoms related to generalized seizures
Because generalized seizures involve abnormal brain activity throughout the whole brain, symptoms associated with these types of seizures are wide-ranging and may appear to be very severe. Unlike partial seizures, which may only involve one part of the body or one aspect of behavior, the symptoms of generalized seizures usually involve the entire body and often result in a loss of consciousness.
Some common symptoms related to generalized seizures include:
- Jerking or twitching muscles
- Sudden stiffening of muscles
- Disruption of involuntary bodily functions, such as breathing or bladder control
- Loss of muscle control throughout the entire body
- Loss of consciousness
- Salivation or foaming from the mouth
- Jaw clenching or tongue biting
Many people with recurring generalized seizures experience a combination of certain symptoms in addition to some symptoms of partial seizures (e.g., hallucinations).
Generalized seizures are often followed by symptoms of fatigue, drowsiness and confusion. Sleepiness may last for an hour or more, and a person may feel weak for up to two days following a generalized seizure. A person who has experienced a generalized seizure may have no memory of the event. In addition, some people may become agitated immediately following the seizure.
Immediate medical attention should be sought if a person has a seizure but no history of previous seizures, or if any of the following symptoms occur:
- Physical injury is sustained during the seizure
- Seizure lasts 5 minutes or longer
- Failure to regain normal state of mind within an hour after a seizure
Types and differences of generalized seizures
Generalized seizures involve both sides of the brain simultaneously and are often more severe than partial seizures. Types of generalized seizures include:
- Tonic-clonic seizures (grand mal seizures or convulsions). The most powerful type of seizure, tonic-clonic seizures are a combination of two types of seizures that often occur together: tonic seizures (in which muscles contract)and clonic seizures (spasms in which muscles periodically contract then partially relax). A person who experiences a tonic-clonic seizure may fall to the floor and become unconscious as muscles tense up (a tonic seizure), eyes roll back in the head and saliva production increases. Seconds after falling, the person’s entire body may begin to shake violently and rhythmically (a clonic seizure). Labored breathing and loss of bladder or bowel control may follow.
Typically, tonic-clonic seizures are not dangerous. However, people who witness this kind of seizure should seek medical care if the person’s seizure lasts for more than 5 minutes or if seizures follow in succession without the person waking. Tonic-clonic seizures are the type of seizure most people associate with the term seizure. They are also the most common type of single-episode seizure.
- Absence seizures (petit mal seizures). This kind of generalized seizure involves a momentary change in a person’s state of consciousness. This short-term “absence” of conscious activity may be so mild it is not noticed by others. People who experience this type of seizure may suddenly have a blank look on their face, appear to be staring off into space or drop something they were holding. Eyelids may droop or blink and muscles may twitch. Each episode lasts for just a few moments, making this type of seizure difficult to recognize and diagnose. Absence seizures most often occur during childhood and often resolve themselves as the child enters adolescence. Unexplained difficulties in school may indicate the occurrence of these types of seizures.
- Atonic seizures. This type of generalized seizure is sometimes called a drop attack because it involves a sudden loss of muscle function. During brief atonic seizures, a person may only experience a quick drop of the head. Longer atonic seizures may result in a person collapsing and falling to the floor. Atonic seizures can be particularly dangerous because of the risk of head injury during a fall.
- Myoclonic seizures. This involves the sudden and brief contraction and partial release of muscles of the body. It can affect muscles in just one part of the body or in the entire body. The movement experienced is similar to the jerking that can occur as people fall asleep. Myoclonic seizures tend to occur at the same time as other types of generalized seizures.
Potential causes of generalized seizures
Generalized seizures can be caused by anything that disrupts the normal functioning of the brain. Sometimes generalized seizures can begin as partial seizures. This may occur when a condition (e.g. head injury, brain tumor) that affects a specific portion of the brain causes increased neuron (nerve cell) activity to spread throughout the brain. Conditions that cause illness throughout the whole body (e.g. severe infections, immune system disorders, low blood-sugar level as a result of diabetes) can cause generalized seizures.
Other common causes of generalized seizures include:
- High fever (102 degrees Fahrenheit or 39 degrees Celsius)
- Medication interactions
- Drug or alcohol abuse and withdrawal
- Metabolic abnormalities
The majority of people who experience a generalized seizure never have another seizure. However, generalized seizures may recur when they are caused by chronic neurological conditions, such as epilepsy. Having more than one idiopathic seizure (a seizure with no known cause) may be an indication of this condition.
People who are taking seizure medications for epilepsy are most likely to have a seizure if they miss a dose of medication. Other triggers for people with epilepsy may include lack of sleep, alcohol use, illness or fever.
Generalized seizures may also be triggered by certain sensory information. A small proportion of people who have epilepsy characterized by generalized seizures are particularly sensitive to light. This is called photosensitivity. Television screens, computer games and strobe lights are common triggers of seizures in these people, although the amount of light stimulation needed to trigger a seizure may vary from person to person. Studies indicate that lights that flash between 5 and 30 times per second are most likely to trigger seizures in people who are photosensitive.
Treatment/prevention of generalized seizures
Treatment of generalized seizures may vary, depending on the cause of the seizure. In order to determine treatment options, a physician may conduct a series of tests to identify the cause of a patient’s seizures. These tests may include imaging tests such as magnetic resonance imaging (MRI) and computed axial tomography (CAT) scans. Additionally, a physician may recommend an electroencephalogram (EEG), which involves electrodes being placed on the scalp to measure brain activity. Blood tests may also be performed to identify metabolic disorders or infections that may be causing a patient’s seizures.
Generalized seizures that have an identifiable cause often involve treating the underlying cause (e.g., medications for metabolic disorders such as diabetes, treatment for alcohol or drug abuse). The effectiveness of treatment will depend on the cause of a patient’s seizures.
Like partial seizures, generalized seizures may be treated with anticonvulsant medications that help prevent nerve cells in the brain from firing in an abnormal manner. This may help control the seizures if the medication is taken as directed by a physician.
Generalized seizures can rarely be successfully treated with brain surgery because the abnormal neuron activity occurs in the entire brain. However, people with recurrent generalized seizures that are poorly controlled by medication may be suitable for a type of treatment called vagus nerve stimulation. The vagus nerve runs from the brain to the abdomen and controls many aspects of body functioning. People with generalized seizures can have a device similar to a pacemaker surgically implanted into their skin that stimulates the vagus nerve through a series of small electric shocks. These shocks may reduce seizures in people with epilepsy by up to 40 percent, according to the National Institute of Neurological Disorders and Stroke (NINDS).
Many generalized seizures have no known cause, making them difficult to prevent.
People with diabetes or other metabolic disorders may be able to prevent seizures by managing or treating their condition, such as by controlling their blood sugar level. Additionally, people who are taking medications should consult their physician before starting any new medications or taking over-the-counter drugs or supplements. This may reduce the risk of seizures being triggered by medication interactions.
Head injuries may increase the risk of experiencing a seizure, so people should protect their head by wearing appropriate gear when riding bicycles or motorcycles, or when playing contact sports. Binge drinking (consuming large amounts of alcohol in a short period of time) and illegal drug use should also be avoided.
What bystanders can do during a seizure
Witnessing a generalized seizure can be distressing. Often, people may do things that make the situation worse, or may not know what to do. Friends and family of a person who has seizures may be instructed by a physician on specific things to do during a seizure. In general, there are certain things bystanders can do (and not do) to prevent additional harm to the person having a generalized seizure.
What not to do:
- Do not place anything in the person’s mouth. This may increase the risk of choking.
- Do not restrain the person. Trying to hold a person down while they are having a seizure may cause more harm than good.
What to do:
- Clear the area. Move any furniture or objects out of the way that may cause harm to the person having a seizure. This includes objects on tables or stands that may be knocked over.
- If vomit or mucus are present, turn the person on their side. If the person begins vomiting, they should be gently rolled onto their side to prevent them from inhaling or choking on their own vomit. After the seizure is over, they may be gently rolled onto their side to keep their respiratory tract clear of mucus if they sleep for a short while after the attack.
- Mouth-to-mouth resuscitation is rarely required after a generalized seizure. In most cases, the person who has had a seizure returns to normal within minutes.
Questions for your doctor regarding seizures
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following generalized seizure-related questions:
- What type of generalized seizure did I have?
- Do you think my seizure was provoked? What could have caused it?
- If my seizure was unprovoked, do you think I have epilepsy?
- Will you need to speak to people who witnessed the seizure to confirm your diagnosis?
- What kind of treatment do you recommend for me? Are there risks involved?
- How will you identify any underlying medical conditions that may be related to my seizure?
- For how long will I require treatment?
- Is there a chance I could have another seizure?
- What should I do if I have another seizure?
- What can I do to reduce my risk of seizures?
- What should I do if my child or loved one has a seizure?