[Cris Alarcon. NIH]
I was 50-years-old when I was hospitalized for my first major seizure in December of 2015. I had been very healthy up to that time, or so I thought! After being diagnosed with epilepsy I started on a journey to understand who this stranger is in my head. This is a multi-part story starting with
"What are the epilepsies?"
"What are the different kinds of seizures?"
The epilepsies are chronic neurological disorders in which clusters of nerve cells, or neurons, in the brain sometimes signal abnormally and cause seizures.
What are the different kinds of epilepsy?
Just as there are many different kinds of seizures, there are many different kinds of epilepsy. Hundreds of different epilepsy syndromes – disorders characterized by a specific set of symptoms that include epilepsy as a prominent symptom – have been identified. Some of these syndromes appear to be either hereditary or caused by de novomutations. For other syndromes, the cause is unknown. Epilepsy syndromes are frequently described by their symptoms or by where in the brain they originate.
Absence epilepsy is characterized by repeated seizures that cause momentary lapses of consciousness. These seizures almost always begin in childhood or adolescence and tend to run in families, suggesting that they may be at least partially due to genetic factors. Individuals may show purposeless movements during their seizures, such as a jerking arm or rapidly blinking eyes, while others may have no noticeable symptoms except for brief times when they appear to be staring off into space. Immediately after a seizure, the person can resume whatever he or she was doing. However, these seizures may occur so frequently (in some cases up to 100 or more a day) that the person cannot concentrate in school or other situations. Childhood absence epilepsy usually stops when the child reaches puberty. Although most children with childhood absence epilepsy have a good prognosis, there may be long-lasting negative consequences and some children will continue to have absence seizures into adulthood and/or go on to develop other seizure types.
Frontal lobe epilepsy is a common epilepsy syndrome that features brief focal seizures that may occur in clusters. It can affect the part of the brain that controls movement and involves seizures that can cause muscle weakness or abnormal, uncontrolled movement such as twisting, waving the arms or legs, eye deviation to one side, or grimacing, and are usually associates with some loss of awareness. Seizures usually occur when the person is asleep but also may occur while awake.
Temporal lobe epilepsy, or TLE, is the most common epilepsy syndrome with focal seizures. These seizures are often associated with auras of nausea, emotions (such as déjà vu or fear), or unusual smell or taste. The seizure itself is a brief period of impaired consciousness which may appear as a staring spell, dream-like state, or repeated automatisms. TLE often begins in childhood or teenage years. Research has shown that repeated temporal lobe seizures are often associated with shrinkage and scarring (sclerosis) of the hippocampus. The hippocampus is important for memory and learning. It is not clear whether localized asymptomatic seizure activity over years causes the hippocampal sclerosis.
Neocortical epilepsy is characterized by seizures that originate from the brain's cortex, or outer layer. The seizures can be either focal or generalized. Symptoms may include unusual sensations, visual hallucinations, emotional changes, muscle contractions, convulsions, and a variety of other symptoms, depending on where in the brain the seizures originate.
There are many other types of epilepsy that begin in infancy or childhood. For example, infantile spasms are clusters of seizures that usually begin before the age of 6 months. During these seizures the infant may drop their head, jerk an arm, bend at the waist and/or cry out. Children with Lennox-Gastaut syndrome have several different types of seizures, including atonic seizures, which cause sudden falls and are also called drop attacks. Seizure onset is usually before age four years. This severe form of epilepsy can be very difficult to treat effectively. Rasmussen's encephalitis is a progressive form of epilepsy in which half the brain shows chronic inflammation. Some childhood epilepsy syndromes, such as childhood absence epilepsy, tend to go into remission or stop entirely during adolescence, whereas other syndromes such as juvenile myoclonic epilepsy (which features jerk-like motions upon waking) and Lennox-Gastaut syndrome are usually present for life once they develop. Children with Dravet syndrome have seizures that start before age one and later in infancy develop into other seizure types.
Hypothalamic hamartoma is a rare form of epilepsy that first occurs during childhood and is associated with malformations of the hypothalamus at the base of the brain. People with hypothalamic hamartoma have seizures that resemble laughing or crying. Such seizures frequently go unrecognized and are difficult to diagnose.
When are seizures not epilepsy?
While any seizure is cause for concern, having a seizure does not by itself mean a person has epilepsy. First seizures, febrile seizures, nonepileptic events, and eclampsia (a life-threatening condition that can occur in pregnant women) are examples of conditions involving seizures that may not be associated with epilepsy. Regardless of the type of seizure, it’s important to inform your doctor when one occurs.
First Seizures
Many people have a single seizure at some point in their lives, and it can be provoked or unprovoked, meaning that they can occur with or without any obvious triggering factor. Unless the person has suffered brain damage or there is a family history of epilepsy or other neurological abnormalities, the majority of single seizures usually are not followed by additional seizures. Medical disorders which can provoke a seizure include low blood sugar, very high blood sugar in diabetics, disturbances in salt levels in the blood (sodium, calcium, magnesium), eclampsia during or after pregnancy, impaired function of the kidneys, or impaired function of the liver. Sleep deprivation, missing meals, or stress may serve as seizure triggers in susceptible people.
Many people with a first seizure will never have a second seizure, and physicians often counsel against starting antiseizure drugs at this point. In some cases where additional epilepsy risk factors are present, drug treatment after the first seizure may help prevent future seizures. Evidence suggests that it may be beneficial to begin antiseizure medication once a person has had a second unprovoked seizure, as the chance of future seizures increases significantly after this occurs . A person with a pre-existing brain problem, for example, a prior stroke or traumatic brain injury, will have a higher risk of experiencing a second seizure. In general, the decision to start antiseizure medication is based on the doctor’s assessment of many factors that influence how likely it is that another seizure will occur in that person.
In one study that followed individuals for an average of 8 years, 33 percent of people had a second seizure within 4 years after an initial seizure. People who did not have a second seizure within that time remained seizure-free for the rest of the study. For people who did have a second seizure, the risk of a third seizure was about 73 percent by the end of 4 years. Among those with a third unprovoked seizure, the risk of a fourth was 76 percent.
Febrile Seizures
Not infrequently a child will have a seizure during the course of an illness with a high fever. These seizures are called febrile seizures. Antiseizure medications following a febrile seizure are generally not warranted unless certain other conditions are present: a family history of epilepsy, signs of nervous system impairment prior to the seizure, or a relatively prolonged or complicated seizure. The risk of subsequent non-febrile seizures is low unless one of these factors is present.
Results from a study funded by the National Institute of Neurological Disorders and Stroke (NINDS) suggested that certain findings using diagnostic imaging of the hippocampus may help identify which children with prolonged febrile seizures are subsequently at increased risk of developing epilepsy.
Researchers also have identified several different genes that influence the risks associated with febrile seizures in certain families. Studying these genes may lead to new understandings of how febrile seizures occur and perhaps point to ways of preventing them.
Nonepileptic Events
An estimated 5 to 20 percent of people diagnosed with epilepsy actually have non-epileptic seizures (NES), which outwardly resemble epileptic seizures, but are not associated with seizure-like electrical discharge in the brain. Non-epileptic events may be referred to as psychogenic non-epileptic seizures or PNES, which do not respond to antiseizure drugs. Instead, PNES are often treated by cognitive behavioral therapy to decrease stress and improve self-awareness.
A history of traumatic events is among the known risk factors for PNES. People with PNES should be evaluated for underlying psychiatric illness and treated appropriately. Two studies together showed a reduction in seizures and fewer coexisting symptoms following treatment with cognitive behavioral therapy. Some people with epilepsy have psychogenic seizures in addition to their epileptic seizures.
Other nonepileptic events may be caused by narcolepsy (sudden attacks of sleep), Tourette syndrome (repetitive involuntary movements called tics), cardiac arrhythmia (irregular heart beat), and other medical conditions with symptoms that resemble seizures. Because symptoms of these disorders can look very much like epileptic seizures, they are often mistaken for epilepsy.
NIH
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Next: Are there special risks associated with epilepsy?
