What are seizures?
A seizure is a brief and abnormal period of behavior caused by abnormal electrical activity in the brain.
Normal human activities, thoughts, perceptions, and emotions are produced by electrical impulses that stimulate nerve cells in the brain.
During a seizure, the usual electrical communication in the brain is disrupted by a chaotic and unregulated discharge.
The abnormal activity may be confined to one area of the brain, producing symptoms in only one small area of the body (partial or focal seizures), or the abnormal activity may spread throughout the brain causing loss of consciousness and an overall convulsion (such as grand mal).
A recurring seizure pattern is considered epilepsy.
As with symptoms in other parts of the body, seizures are a symptom of brain dysfunction and can be the result of a wide variety of neurological or medical problems. Seizures may be associated with high fever, head injury, central nervous system infections, brain tumor, stroke (cerebrovascular accident), ingestion of toxic substances, metabolic disturbances, certain drugs (cocaine), or alcohol (withdrawal or hereditary intolerance of alcohol).
In individuals who are prone to seizures (epileptics and certain diabetics), the seizures frequently occur during periods of stress, or when meals and sleep are missed. There may be an inherited tendency towards seizures. Seizures that appear to have no apparent cause (idiopathic epilepsy) account for up to 75% of the cases in adults. These seizures may actually be due to microscopic brain lesions that occurred during birth or other trauma, or may be caused by unexplained metabolic disturbances.
The symptoms of the seizure vary according to the type of brain dysfunction.
Approximately one person in two hundred suffers from epilepsy. Epilepsy seizures that began in childhood or adolescence, or in individuals who have a strong family history, often end by the time the individual reaches adulthood.
Epileptic seizures are generally classified into two main groups: generalized and partial seizures. The part of the brain from which it originates, and how widely and rapidly it fans out from its point of origin, determines the form a seizure takes.
- Generalized seizures arise from a wide area of the brain, affecting the whole body, and causing loss of consciousness.
- Partial seizures are usually caused by damage to a more limited area of the brain, and may not cause loss of consciousness. Although partial seizures begin in a limited area of the brain, the electrical disturbance can spread, affecting the whole brain, and may cause a generalized seizure.
Types of generalized seizures
The two main types of generalized seizure are grand mal and petit mal (absence).
- A grand mal seizure begins with loss of consciousness. The individual falls to the ground while the whole body stiffens, twitches, or jerks uncontrollably. There may be an initial cry, then breathing becomes very irregular during the seizure. Seizures usually last two to five minutes. Following the seizure, the muscles relax again. Bladder and bowel incontinence may occur. The individual may remain unconscious for a time after the seizure. Upon awakening, he may feel confused, disoriented, and have no recall of the seizure. Often the individual will have a headache, nausea, muscle soreness, and want to sleep. These effects usually wear off in several hours.
- Petit mal seizures, also known as absence seizures, mainly occur in children and adolescents. They are characterized by a momentary loss of consciousness, usually without abnormal movements. If movements are present, they are usually exaggerated eye movements, such as blinking. There is a loss of awareness that may last from a few seconds up to half a minute. To the casual observer, it may appear that the individual is simply daydreaming or inattentive. The seizure may be so brief that the individual is not even aware of it. Petit mal seizures can occur hundreds of times a day.
Types of Partial seizures
Partial seizures are divided into two categories: simple (consciousness retained) and complex (involves loss of consciousness).
- Simple partial seizures occur without warning and may last several minutes. Symptoms include abnormal twitching movements, tingling sensations, and may include hallucinations of smell, vision, or taste. Since the individual is aware throughout the seizure, he can recall the details. Jacksonian epilepsy is a simple partial seizure where the twitching occurs and spreads slowly from one part of the body to another. Although usually experienced on the same side of the body, the twitching can spread throughout the whole body.
- In complex partial seizures, the individual is usually aware of little, if anything, that happens during the seizure. Dazed and unresponsive, motions such as finger fumbling or lip smacking may occur. These automatic actions or behaviors (automatisms) may occasionally take a more bizarre form.
Both types of partial seizures can spread to involve the entire brain. When this happens, it is called "generalization," and the symptoms are similar to a grand mal seizure.
A myoclonic type of seizure consists of one or more spasmodic jerks, whereas a grand mal type seizure is tonic-clonic. This means that opposing muscle groups are contracting and then relaxing producing a series of jerking movements.
Status epilepticus is a special type of seizure in which motor, sensory, or psychic seizures follow one after the other with no intervening periods of consciousness. The grand mal form of status epilepticus may last for hours or days, and can be fatal.
Individuals who are prone to seizures can often sense a seizure is coming before it actually begins. Called an aura, this warning sensation can be in the form of a restless, irritable, or uncomfortable feeling, intense feelings of fear or familiarity (Deja vu), a tingling sensation, seeing lights, or a buzzing in the ears. Since individuals who experience the seizures often do not remember details. Information from someone who has observed the seizures is a valuable part of the history.
How is it diagnosed?
Physical exam: A complete neurological examination is performed.
Tests: An electroencephalogram (EEG) records the electrical impulses of the brain. (An EEG alone cannot always confirm or refute the diagnosis of seizures. The results must be weighed in light of other clinical findings. ) Often a CT scan of the brain is done to identify any abnormalities. Heart function tests (EKG or Holter monitor) are often used to rule out cardiac irregularities as the cause for loss of consciousness in an adult. Blood tests are used to identify other medical conditions associated with seizures. In addition, if the individual is on anticonvulsive medication, blood plasma levels are monitored in order to maintain therapeutic levels and to prevent side effects.
How are seizures treated?
Since seizures can be symptoms, treatment depends on the underlying condition. In general, opinion is divided on whether a single incidence of seizure should receive treatment.
Hospitalization may be required after grand mal seizures to stabilize the individual and for observation for recurring seizures.
Individuals with recurrent seizures are treated with anticonvulsant drugs. Since several are available, they can be used alone or in combinations. In almost all cases, anticonvulsant drugs lessen the frequency of seizures. Anticonvulsant medication may have unpleasant side effects, including drowsiness and impaired concentration. Depending on the cause of the seizure, if no seizures occur for two or three years, the medication dose may be reduced or stopped. If medication is ineffective and the seizures appear to be caused by a single area of brain damage (usually in the temporal lobe), surgery may be considered.
Tegretol (Carbamazepine), Depakote (Divalproex), Diamox (Acetazolamide), Topamax (Topiramate), Mysoline (Primidone), Trileptal (Oxcarbazepine), Klonopin (Clonazepam), Valium (Diazepam), Ativan (Lorazepam)
What might complicate it?
Temporal lobe epilepsy or seizures caused by severe brain damage are more difficult to control. In addition, some seizures may not respond to anticonvulsant medication.
Outcome depends on the underlying condition causing the seizures. In epilepsy, it is estimated that at least one-third of those suffering from epileptic seizures will eventually outgrow the condition. Another third find their seizures become less frequent while on anticonvulsant medication. The remaining third find their condition remains the same.
Grand mal and other motor seizures are unmistakable. Transient ischemic attacks may mimic some minor seizure disorders.
Neurologist, internist, neurosurgeon, and infectious disease specialist.
Last updated 21 December 2011