Epilepsy is a common chronic neurological disorder that is characterized by recurrent unprovoked seizures. These seizures are transient signs and/or symptoms due to abnormal, excessive or synchronous neuronal activity in the brain. About 50 million people worldwide have epilepsy at any one time. Epilepsy is usually controlled, but not cured, with medication, although surgery may be considered in difficult cases. However, over 30% of people with epilepsy do not have seizure control even with the best available medications . Not all epilepsy syndromes are lifelong – some forms are confined to particular stages of childhood. Epilepsy should not be understood as a single disorder, but rather as a group of syndromes with vastly divergent symptoms but all involving episodic abnormal electrical activity in the brain.
In 1981, the International League Against Epilepsy (ILAE) proposed a classification scheme for individual seizures that remains in common use. This classification is based on observation (clinical and EEG) rather than the underlying pathophysiology or anatomy and is outlined later on in this article. In 1989, the ILAE proposed a classification scheme for epilepsies and epileptic syndromes. This can be broadly described as a two-axis scheme having the cause on one axis and the extent of localisation within the brain on the other. Since 1997, the ILAE have been working on a new scheme that has five axes: ictal phenomenon, seizure type, syndrome, etiology and impairment.
Long-term video-EEG monitoring for epilepsy is the gold standard for diagnosis, but it is not routinely employed owing to its high cost, low availability and inconvenience.
Convulsive or other seizure-like activity, non-epileptic in origin, can be observed in many other medical conditions. These non-epileptic seizures can be hard to differentiate and may lead to misdiagnosis.
Epilepsy covers conditions with different etiologies, natural histories and prognoses, each requiring different management strategies. A full medical diagnosis requires a definite categorization of seizure and syndrome types.
Beyond symptoms of the underlying diseases that can cause certain epilepsies, people with epilepsy are at risk for death from four main problems: status epilepticus (most often associated with anticonvulsant noncompliance), suicide associated with depression, trauma from seizures, and sudden unexpected death in epilepsy (SUDEP) Those at highest risk for epilepsy-related deaths usually have underlying neurological impairment or poorly controlled seizures; those with more benign epilepsy syndromes have little risk for epilepsy-related death.
Certain diseases also seem to occur in higher than expected rates in people with epilepsy, and the risk of these "comorbities" often varies with the epilepsy syndrome. These diseases include depression and anxiety disorders, migraine and other headaches, infertility and low sexual libido. Attention-deficit/hyperactivity disorder (ADHD) affects three to five times more children with epilepsy than children in the general population. Epilepsy is prevalent in autism.
There are many different epilepsy syndromes, each presenting with its own unique combination of seizure type, typical age of onset, EEG findings, treatment, and prognosis. The most widespread classification of the epilepsies divides epilepsy syndromes by location or distribution of seizures (as revealed by the appearance of the seizures and by EEG) and by cause. Syndromes are divided into localization-related epilepsies, generalized epilepsies, or epilepsies of unknown localization.
Localization-related epilepsies, sometimes termed partial or focal epilepsies, arise from an epileptic focus, a small portion of the brain that serves as the irritant driving the epileptic response. Generalized epilepsies, in contrast, arise from many independent foci (multifocal epilepsies) or from epileptic circuits that involve the whole brain. Epilepsies of unknown localization remain unclear whether they arise from a portion of the brain or from more widespread circuits.
Epilepsy syndromes are further divided by presumptive cause: idiopathic, symptomatic, and cryptogenic. Idiopathic epilepsies are generally thought to arise from genetic abnormalities that lead to alteration of basic neuronal regulation. Symptomatic epilepsies arise from the effects of an epileptic lesion, whether that lesion is focal, such as a tumor, or a defect in metabolism causing widespread injury to the brain. Cryptogenic epilepsies involve a presumptive lesion that is otherwise difficult or impossible to uncover during evaluation.
Some epileptic syndromes are difficult to fit within this classification scheme and fall in the unknown localization/etiology category. People who only have had a single seizure, or those with seizures that occur only after specific precipitants ("provoked seizures"), have "epilepsies" that fall into this category. Febrile convulsions are an example of seizures bound to a particular precipitant. Landau-Kleffner syndrome is another epilepsy which, because of its variety of EEG distributions, falls uneasily in clear categories. More confusingly, certain syndromes like West syndrome featuring seizures such as Infantile spasms can be classified as idiopathic, syndromic, or cryptogenic depending on cause and can arise from both focal or generalized epileptic lesions.
Below are some common seizure syndromes:
Objects should never be placed in a person's mouth by anybody - including paramedics - during a seizure as this could result in serious injury to either party. Despite common folklore, it is not possible for a person to swallow their own tongue during a seizure. However, it is possible that the person will bite their own tongue, especially if an object is placed in the mouth.
With other types of seizures such as simple partial seizures and complex partial seizures where the person is not convulsing but may be hallucinating, disoriented, distressed, or unconscious, the person should be reassured, gently guided away from danger, and sometimes it may be necessary to protect the person from self-injury, but physical force should be used only as a last resort as this could distress the person even more. In complex partial seizures where the person is unconscious, attempts to rouse the person should not be made as the seizure must take its full course. After a seizure, the person may pass into a deep sleep or otherwise they will be disoriented and often unaware that they have just had a seizure, as amnesia is common with complex partial seizures. The person should remain observed until they have completely recovered, as with a tonic-clonic seizure.
After a seizure, it is typical for a person to be exhausted and confused. Often the person is not immediately aware that they have just had a seizure. During this time one should stay with the person - reassuring and comforting them - until they appear to act as they normally would. Seldom during seizures do people lose bladder or bowel control. In some instances the person may vomit after coming to. People should not eat or drink until they have returned to their normal level of awareness, and they should not be allowed to wander about unsupervised. Many patients will sleep deeply for a few hours after a seizure - this is common for those having just experienced a more violent type of seizure such as a tonic-clonic. In about 50% of people with epilepsy, headaches may occur after a seizure. These headaches share many features with migraines, and respond to the same medications.
It is helpful if those present at the time of a seizure make note of how long and how severe the seizure was. It is also helpful to note any mannerisms displayed during the seizure. For example, the individual may twist the body to the right or left, may blink, might mumble nonsense words, or might pull at clothing. Any observed behaviors, when relayed to a neurologist, may be of help in diagnosing the type of seizure which occurred.
History and Availability- The first anticonvulsant was bromide, suggested in 1857 by Charles Locock who used it to treat women with "hysterical epilepsy" (probably catamenial epilepsy). Potassium bromide was also noted to cause impotence in men. Authorities concluded that potassium bromide would dampen sexual excitement thought to cause the seizures, which in fact it did (athough we know now that impotence is a side effect of bromide treatment, not a treatment of epilepsy). Barbiturate was first used in 1912 for both its sedative and antiepileptic properties. By the 1930s, the development of animal models in epilepsy research lead to the development of phenytoin by Tracy Putnam and H. Houston Merritt, which had the distinct advantage of treating epileptic seizures with less sedation. By the 1970s, an National Institutes of Health initiative, the Anticonvulsant Screening Program, headed by J. Kiffin Penry, served as a mechanism for drawing the interest and abilities of pharmaceutical companies in the development of new anticonvulsant medications.
Currently there are 19 medications approved by the Food and Drug Administration for the use of treatment of epileptic seizures in the US: carbamazepine (common US brand name Tegretol), clorazepate (Tranxene) clonazepam (Klonopin), ethosuximide (Zarontin), felbamate (Felbatol), fosphenytoin (Cerebyx), gabapentin (Neurontin), lamotrigine (Lamictal), levetiracetam (Keppra), oxcarbazepine (Trileptal), phenobarbital (Luminal), phenytoin (Dilantin), pregabalin (Lyrica), primidone (Mysoline), tiagabine (Gabitril), topiramate (Topamax), valproate semisodium (Depakote), valproic acid (Depakene), and zonisamide (Zonegran). Most of these appeared after 1990.
Other drugs are commonly used to abort an active seizure or interrupt a seizure flurry; these include diazepam (Valium, Diastat) and lorazepam (Ativan). Drugs used only in the treatment of refractory status epilepticus include paraldehyde (Paral), midazolam (Versed), and pentobarbital (Nembutal).
Some anticonvulsant medications do not have primary FDA-approved uses in epilepsy but are used in limited trials, remain in rare use in difficult cases, have limited "grandfather" status, are bound to particular severe epilepsies, or are under current investigation. These include acetazolamide (Diamox), progesterone, adrenocorticotropic hormone (ACTH, Acthar), various corticotropic steroid hormones (prednisone), or bromide.
Effectiveness - The definition of "effective" varies. FDA-approval usually requires that 50% of the patient treatment group had at least a 50% improvement in the rate of epileptic seizures. About 20% of patients with epilepsy continue to have breakthrough epileptic seizures despite best anticonvulsant treatment. .
Safety and Side Effects - 88% of patients with epilepsy, in a European survey, reported at least one anticonvulsant related side effect. Most side effects are mild and "dose-related" and can often be avoided or minimized by the use of the smallest effective amount. Some examples include mood changes, sleepiness, or unsteadiness in gait. Some anticonvulsant medications have "idiosyncratic" side-effects that can not be predicted by dose. Some examples include drug rashes, liver toxicity (hepatitis), or aplastic anemia. Safety includes the consideration of tetragenicity (the effects of medications on fetal development) when women with epilepsy become pregnant.
Principles of Anticonvulsant Use and Management - The goal for individual patients is, of course, no seizures and no side effects, and the job of the physician is to aid the patient to find the best balance between the two during the prescribing of anticonvulsants. Most patients can achieve this balance best with monotherapy, the use of a single anticonvulsant medication. Some patients, however, require polypharmacy; the use of two or more anticonvulsants.
Serum levels of AEDs can be checked to determine medication compliance, to assess the effects of new drug-drug interactions upon previous stable medication levels, or to help establish if particular symptoms such as instability or sleepiness can be considered a drug side-effect or are due to different causes. Children or impaired adults who may not be able to communicate side effects may benefit from routine screening of drug levels. Beyond baseline screening, however, trials of recurrent, routine blood or urine monitoring show no proven benefits and may lead to unnecessary medication adjustments in most older children and adults using routine anticonvulsants.
If a person's epilepsy cannot be brought under control after adequate trials of two or three (experts vary here) different drugs, that person's epilepsy is generally said to be medically refractory. A study of patients with previously untreated epilepsy demonstrated that 47% achieved control of seizures with the use of their first single drug. 14% became seizure free during treatment with a second or third drug. An additional 3% became seizure-free with the use of two drugs simultaneously. Other treatments, in addition to or instead of, anticonvulsant medications may be considered by those people with continuing seizures.
The evaluation for epilepsy surgery is designed to locate the "epileptic focus" (the location of the epileptic abnormality) and to determine if resective surgery will affect normal brain function. Physicians will also confirm the diagnosis of epilepsy to make sure that spells arise from epilepsy (as opposed to non-epileptic seizures). The evaluation typically includes neurological examination, routine EEG, Long-term video-EEG monitoring, neuropsychological evaluation, and neuroimaging such as MRI, Single photon emission computed tomography (SPECT), positron emission tomography (PET). Some epilepsy centers use intracarotid sodium amobarbital test (Wada test), functional MRI or Magnetoencephalography (MEG) as supplementary tests.
Certain lesions require Long-term video-EEG monitoring with the use of intracranial electrodes if noninvasive testing was inadequate to identify the epileptic focus or distinguish the surgical target from normal brain tissue and function. Brain mapping by the technique of cortical electrical stimulation or Electrocorticography are other procedures used in the process of invasive testing in some patients.
The most common surgeries are the resection of lesions like tumors or arteriovenous malformations which, in the process of treating the underlying lesion, often result in control of epileptic seizures caused by these lesions.
Other lesions are more subtle and feature epilepsy as the main or sole symptom. The most common form of intractable epilepsy in these disorders in adults is temporal lobe epilepsy with hippocampal sclerosis, and the most common type of epilepsy surgery is the anterior temporal lobectomy, or the removal of the front portion of the temporal lobe including the amygdala and hippocampus. Some neurosurgeons recommend selective amygdalahippocampectomy because of possible benefits in postoperative memory or language function. Surgery for temporal lobe epilepsy is effective, durable, and results in decreased health care costs. . Despite the efficacy of epilepsy surgery, some patients decide not to undergo surgery owing to fear or the uncertainty of having a brain operation.
Palliative surgery for epilepsy is intended to reduce the frequency or severity of seizures. Examples are callosotomy or commissurotomy to prevent seizures from generalizing (spreading to involve the entire brain), which results in a loss of consciousness. This procedure can therefore prevent injury due to the person falling to the ground after losing consciousness. It is performed only when the seizures cannot be controlled by other means. Multiple subpial transection can also be used to decrease the spread of seizures across the cortex especially when the epileptic focus is located near important functional areas of the cortex. Resective surgery can be considered palliative if it is undertaken with the expectation that it will reduce but not eliminate seizures.
Hemispherectomy involves removal or a functional disconnection of most or all of one half of the cerebrum. It is reserved for people suffering from the most catastrophic epilepsies, such as those due to Rasmussen syndrome. If the surgery is performed on very young patients (2-5 years old), the remaining hemisphere may acquire some rudimentary motor control of the ipsilateral body; in older patients, paralysis results on the side of the body opposite to the part of the brain that was removed. Because of these and other side effects it is usually reserved for patients who have exhausted other treatment options.
Now proven effective with infants, too: http://www.physorg.com/news140111291.html
A study conducted by Johns Hopkins reported that 50% of those patients starting the Ketogenic diet reported a decrease in seizures of 50% or more, with 29% of patients reporting a 90% reduction in symptoms; these patients had previously tried an average of six anticonvulsant drugs.
Vagus nerve stimulation (VNS) is a recently developed form of seizure control which uses an implanted electrical device, similar in size, shape and implant location to a heart pacemaker, which connects to the vagus nerve in the neck. Once in place the device can be set to emit electronic pulses, stimulating the vagus nerve at pre-set intervals and milliamp levels. Treatment studies have shown that approximately 50% of those treated in this fashion will show significant seizure frequency reduction.
The Responsive Neurostimulator System (RNS) is currently undergoing clinical study prior to FDA approval. This system relies upon a device implanted just under the scalp. The leads attached to the device are implanted either on the brain surface or in the brain area itself and are located close to the area where the seizures are believed to start. When a seizure begins, small amounts of electrical stimulation are delivered to suppress it. This system is different from the VNS system in that the RNS relies on direct brain stimulation and the RNS is a responsive system. The VNS pulses at predetermined intervals previously set by medical personnel. The RNS system is designed to respond to detected signs that a seizure is about to begin and can record events and allow customized response patterns which may provide a greater degree of seizure control.
A seizure response dog is a form of service dog that is trained to summon help or ensure personal safety when a seizure occurs. These are not suitable for everybody and not all dogs can be so trained. Rarely, a dog may develop the ability to sense a seizure before it occurs.
A number of systematic reviews by the Cochrane Collaboration into treatments for epilepsy looked at acupuncture, psychological interventions, vitamins and yoga and found there is no reliable evidence to support the use of these as treatments for epilepsy. Further studies are needed on the subject.
Epileptogenesis is the process by which a normal brain develops epilepsy after an insult. One interesting finding in animals is that repeated low-level electrical stimulation to some brain sites can lead to permanent increases in seizure susceptibility: in other words, a permanent decrease in seizure "threshold." This phenomenon, known as kindling (by analogy with the use of burning twigs to start a larger fire) was discovered by Dr. Graham Goddard in 1967. Chemical stimulation can also induce seizures; repeated exposures to some pesticides have been shown to induce seizures in both humans and animals. One mechanism proposed for this is called excitotoxicity. The roles of kindling and excitotoxicity, if any, in human epilepsy are currently hotly debated.
Other causes of epilepsy are brain lesions, where there is scar tissue or another abnormal mass of tissue in an area of the brain.
However, in most cultures, persons with epilepsy have been stigmatized, shunned, or even imprisoned; in the Salpêtrière, the birthplace of modern neurology, Jean-Martin Charcot found people with epilepsy side-by-side with the mentally retarded, those with chronic syphilis, and the criminally insane. In Tanzania to this day, as with other parts of Africa, epilepsy is associated with possession by evil spirits, witchcraft, or poisoning and is believed by many to be contagious. In ancient Rome, epilepsy was known as the Morbus Comitialis ('disease of the assembly hall') and was seen as a curse from the gods.
Stigma continues to this day, in both the public and private spheres, but polls suggest it is generally decreasing with time, at least in the developed world; Hippocrates remarked that epilepsy would cease to be considered divine the day it was understood.
In the U.S., people with epilepsy can drive if their seizures are controlled with treatment and they meet the licensing requirements in their state. How long they have to be free of seizures varies in different states, but it is most likely to be between three months and a year. The majority of the 50 states place the burden on patients to report their condition to appropriate licensing authorities so that their privileges can be revoked where appropriate. A minority of states place the burden of reporting on the patient's physician. After reporting is carried out, it is usually the driver's licensing agency that decides to revoke or restrict a driver's license.
In the UK, it is the responsibility of the patients to inform the Driver and Vehicle Licensing Agency (DVLA) if they have epilepsy. The DVLA rules are quite complex, but in summary, those continuing to have seizures or who are within 6 months of medication change may have their licence revoked. A doctor who becomes aware that a patient with uncontrolled epilepsy is continuing to drive has, after reminding the patient of their responsibility, a duty to break confidentiality and inform the DVLA. The doctor should advise the patient of the disclosure and the reasons why their failure to notify the agency obliged the doctor to act.
The Epilepsy Foundation's Jeanne A. Carpenter Epilepsy Legal Defense Fund is dedicated to advancing the rights of people with epilepsy by changing discriminatory practices, policies and laws and to ending epilepsy-related discrimination and injustice through education and increased access to legal services for individuals with epilepsy through a system of managed referrals and legal support to a nationwide network of attorneys committed to this cause.
Additionally, the Epilepsy Foundation is a vigorous advocate for people with epilepsy. In the United States, the Foundation has been active in Congress, the executive branch, and the courts, focusing attention on the needs of those with epilepsy. Priorities for the Foundation include: the availability of affordable quality health care, the search for the cure, and the protection of civil rights for people with epilepsy.