Epilepsy is a medical condition that produces seizures affecting a variety of mental and physical functions. It is also called a seizure disorder. When a person has two or more unprovoked seizures, they are considered to have epilepsy. Seizures happen when clusters of nerve cells in the brain signal abnormally, which may be briefly alter a person's consciousness, movements or actions.Epileptic seizures result from abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly 80% of epilepsy occurs in developing countries.Epilepsy becomes more common as people age. Onset of new cases occurs most frequently in infants and the elderly.As a consequence of brain surgery, epileptic seizures may occur in recovering patients.SYMPTOMS
Because epilepsy is caused by abnormal activity in brain cells, seizures can affect any process your brain coordinates. A seizure can produce:
-Temporary confusion
-A staring spell
-Uncontrollable jerking movements of the arms and legs
-Loss of consciousness or awareness
Symptoms vary depending on the type of seizure. In most cases, a person with epilepsy will tend to have the same type of seizure each time, so the symptoms will be similar from episode to episode.
Doctors generally classify seizures as either focal or generalized, based on how the abnormal brain activity begins.
Focal seizures
When seizures appear to result from abnormal activity in just one part of the brain, they're called focal or partial seizures. These seizures fall into two categories.
Simple focal seizures. These seizures don't result in loss of consciousness. They may alter emotions or change the way things look, smell, feel, taste or sound. They may also result in involuntary jerking of part of the body, such as an arm or leg, and spontaneous sensory symptoms such as tingling, vertigo and flashing lights.
Complex focal seizures. These seizures alter consciousness or awareness, causing you to lose awareness for a period of time. Complex focal seizures often result in staring and nonpurposeful movements — such as hand rubbing, chewing, swallowing or walking in circles.
Generalized seizures
Seizures that seem to involve all of the brain are called generalized seizures. Six types of generalized seizures exist.
Absence seizures (also called petit mal). These seizures are characterized by staring and subtle body movement, and can cause a brief loss of awareness.
Tonic seizures. These seizures cause stiffening of the muscles, generally those in your back, arms and legs and may cause you to fall to the ground.
Clonic seizures. These types of seizures are associated with rhythmic, jerking muscle contractions, usually affecting the arms, neck and face.
Myoclonic seizures. These seizures usually appear as sudden brief jerks or twitches of your arms and legs.
Atonic seizures. Also known as drop attacks, these seizures cause you to lose normal muscle tone and suddenly collapse or fall down.
Tonic-clonic seizures (also called grand mal). The most intense of all types of seizures, these are characterized by a loss of consciousness, body stiffening and shaking, and sometimes loss of bladder control or biting your tongue.
CAUSES
The diagnosis of epilepsy usually requires that the seizures occur spontaneously. Nevertheless, certain epilepsy syndromes require particular precipitants or triggers for seizures to occur. These are termed reflex epilepsy. For example, patients with primary reading epilepsy have seizures triggered by reading. Photosensitive epilepsy can be limited to seizures triggered by flashing lights. Other precipitants can trigger an epileptic seizure in patients who otherwise would be susceptible to spontaneous seizures. For example, children with childhood absence epilepsy may be susceptible to hyperventilation. In fact, flashing lights and hyperventilation are activating procedures used in clinical EEG to help trigger seizures to aid diagnosis. Finally, other precipitants can facilitate, rather than obligately trigger, seizures in susceptible individuals. Emotional stress, sleep deprivation, sleep itself, heat stress, alcohol and febrile illness are examples of precipitants cited by patients with epilepsy. Notably, the influence of various precipitants varies with the epilepsy syndrome. Likewise, the menstrual cycle in women with epilepsy can influence patterns of seizure recurrence. Catamenial epilepsy is the term denoting seizures linked to the menstrual cycle.
Different causes of epilepsy are common in certain age groups.
During the neonatal period and early infancy the most common causes include hypoxic ischemic encephalopathy, central nervous system (CNS) infections, trauma, congenital CNS abnormalities, and metabolic disorders.
During late infancy and early childhood, febrile seizures are fairly common. These may be caused by many different things, some thought to be things such as CNS infections and trauma.
During childhood, well-defined epilepsy syndromes are generally seen.
During adolescence and adulthood, the causes are more likely to be secondary to any CNS lesion. Further, idiopathic epilepsy is less common. Other causes associated with these age groups are stress, trauma, CNS infections, brain tumors, illicit drug use and alcohol withdrawal.
In older adults, cerebrovascular disease is a very common cause. Other causes are CNS tumors, head trauma, and other degenerative diseases that are common in the older age group, such as dementia.
When investigating the causes of seizures, it is important to understand physiological conditions that may predispose the individual to a seizure occurrence. Several clinical and experimental data have implicated the failure of blood–brain barrier (BBB) function in triggering chronic or acute seizures,some studies implicate the interactions between a common blood protein—albumin and astrocytes.[23] These findings suggest that acute seizures are a predictable consequence of disruption of the BBB by either artificial or inflammatory mechanisms. In addition, expression of drug resistance molecules and transporters at the BBB are a significant mechanism of resistance to commonly used anti-epileptic drugs.[24][25]
PATHOPHYSIOLOGY
Mutations in several genes have been linked to several types of epilepsy. Some genes that code for protein sub units of voltage-gated and ligand-gated ion channels have been associated with forms of generalized epilepsy and infantile seizure syndromes.One speculated mechanism for some forms of inherited epilepsy is mutations of the genes that code for sodium channel proteins; these defective sodium channels stay open for too long, thus making the neuron hyper-excitable. Glutamate, an excitatory neurotransmitter, may therefore be released from these neurons in large amounts, which — by binding with nearby glutamatergic neurons — triggers excessive calcium (Ca2+) release in these post-synaptic cells. Such excessive calcium release can be neurotoxic to the affected cell. The hippocampus, which contains a large volume of just such glutamatergic neurons (and NMDA receptors, which are permeable to Ca2+ entry after binding of both glutamate and glycine), is especially vulnerable to epileptic seizure, subsequent spread of excitation, and possible neuronal death. Another possible mechanism involves mutations leading to ineffective GABA (the brain's most common inhibitory neurotransmitter) action. Epilepsy-related mutations in some non-ion channel genes have also been identified.Much like the channelopathies in voltage-gated ion channels, several ligand-gated ion channels have been linked to some types of frontal and generalized epilepsies.
Acute brain insult such as stroke, infection, neurodegenerative disease, trauma, or a lesion on the brain can cause a normal brain to develop epilepsy over time; this process is called epileptogenesis. 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. It is important to note that these "kindled" animals do not experience spontaneous seizures. 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.The complexity of understanding what seizures are has led to considerable efforts to use computational models of epilepsy to interpret experimental and clinical data and to guide strategies for therapy.The physical, emotional, and social functioning of youths can be impacted by uncontrolled seizures.Some other noted consequences of repeated seizures are neuronal loss, gliosis, parenchymal microhemorrhages, excess of starch bodies, leptomeningeal thickening, subpial gliosis, perivascular gliosis and perivascular atroph
TESTS AND DIAGNOSIS
Your doctor may use a number of tests to diagnose epilepsy, from neurological exams to imaging techniques like MRI scans.
Neurological and behavioral exam. Your doctor may want to test your motor abilities, behavior and intellectual capacity to see how the seizures are affecting you.
Blood tests. Your doctor may take a blood sample to check for signs of infections, electrolyte imbalance, anemia or diabetes, which can be associated with seizures.
Your doctor may also suggest tests to detect abnormalities within the brain. These include:
Electroencephalogram (EEG). This is the most common test to help diagnose epilepsy. An EEG records the electrical activity of your brain via electrodes temporarily attached to your scalp with a paste-like substance. If you have epilepsy, it's common to have changes in your normal pattern of brain waves, even when you're not having a seizure. Your doctor may want to monitor you on video while conducting an EEG of you awake or asleep in hopes of recording the seizure to see what kind of seizures you're having. Sometimes your doctor will have to do something to provoke a seizure while you're being tested, such as asking you to sleep very little the night before.
Computerized tomography (CT). You might be given a CT scan if you go to an emergency room for an initial seizure, because it's generally a readily available test. CT machines use a type of X-ray equipment to obtain cross-sectional images of your brain and skull. CT scans can reveal abnormalities in the brain that might be causing your seizures, including tumors, bleeding and cysts.
Magnetic resonance imaging (MRI). An MRI provides much the same type of information as a CT scan, but in far greater detail. MRIs use radio waves and a strong magnetic field to produce detailed images of your brain. MRIs can reveal brain abnormalities that could be causing your seizures.
Functional MRI (fMRI). A functional MRI measures the changes in blood flow that occur when specific parts of your brain are working. Doctors generally use an fMRI before surgery to identify the exact locations of critical functions, like speech, so that surgeons can avoid injuring those places while operating.
Positron emission tomography (PET). PET scans use a small amount of low-dose radioactive material that's injected into a vein to help visualize active areas of the brain and detect abnormalities.
Single-photon emission computerized tomography (SPECT). This type of test is used primarily if you've had an MRI and EEG that didn't pinpoint the location in your brain where the seizures are originating. A SPECT test uses a small amount of low-dose radioactive material that's injected into a vein to create a detailed, 3-D map of the blood flow activity in your brain during seizures.
Neuropsychological tests. This group of tests includes IQ, memory and speech assessments, which help doctors pinpoint where the seizures are originating. This type of testing is routinely done before epilepsy surgery.
TREATMENT AND DRUGS
Medication
Most people with epilepsy can become seizure-free by using a single anti-epileptic drug. Others can decrease the frequency and intensity of their seizures. More than half the children with medication-controlled epilepsy can eventually stop medications and live a seizure-free life. Many adults also can discontinue medication after two or more years without seizures.Finding the right medication and dosage can be complex. Your doctor likely will first prescribe a single drug at a relatively low dosage and may increase the dosage gradually until your seizures are well controlled.
All anti-seizure medications have some side effects. Mild side effects include: Fatigue,Dizziness,Weight gain,Loss of bone density,Skin rashes,Loss of coordination,Speech problems.
More severe but rare side effects include:Depression,Suicidal thoughts and behaviors,Severe rash,Inflammation of certain organs, such as your pancreas or liver.
To achieve the best seizure control possible with medication:
-Take medications exactly as prescribed.
-Always call your doctor before switching to a generic version of your medication or taking other prescription medications, over-the-counter drugs or herbal remedies.
-Never stop taking your medication without talking to your doctor.
-Notify your doctor immediately if you notice new or increased feelings of depression, suicidal thoughts or unusual changes in your mood or behaviors.
At least half of all people newly diagnosed with epilepsy will become seizure-free with their first medication. If anti-epileptic medications don't provide satisfactory results, your doctor may suggest surgery or other therapies.
Surgery
Surgery is most commonly done when tests show that your seizures originate in a small, well-defined area of your brain that doesn't interfere with vital functions like speech, language or hearing. In these types of surgeries, your doctor removes the area of the brain that's causing the seizures.If your seizures originate in a part of your brain that can't be removed, your doctor may recommend a different sort of surgery in which surgeons make a series of cuts in your brain. These cuts are designed to prevent seizures from spreading to other parts of the brain.Although many people continue to need some medication to help prevent seizures after successful surgery, you may be able to take fewer drugs and reduce your dosages. In a small number of cases, surgery for epilepsy can cause complications such as permanently altering your cognitive abilities. Talk to your surgeon about his or her experience, success rates and complication rates with the procedure you're considering.
Therapies
Vagus nerve stimulation. This therapy involves a device called a vagus nerve stimulator that's implanted underneath the skin of your chest like a heart pacemaker. Wires from the stimulator are wrapped around the vagus nerve in your neck. The battery-powered device delivers short bursts of electrical energy to the brain through the vagus nerve. It's not clear how this inhibits seizures, but the device can reduce seizures by 20 to 40 percent and completely control seizures in about 5 percent of people. Most people still need to take anti-epileptic medication. Side effects of vagus nerve stimulation include hoarseness, throat pain, coughing, shortness of breath, tingling and muscle pain.
Ketogenic diet. Some children with epilepsy have been able to reduce their seizures by maintaining a strict diet that's high in fats and low in carbohydrates. This diet, called a ketogenic diet, causes the body to break down fats instead of carbohydrates for energy. Some children can go off the ketogenic diet after a few years and remain seizure-free. Consult a doctor if you or your child is considering a ketogenic diet. It's important to make sure that a child doesn't become malnourished when taking the diet. Side effects of a ketogenic diet may include dehydration, constipation, slowed growth because of nutritional deficiencies, and buildup of uric acid in the blood, which can cause kidney stones. These side effects are uncommon if use of the diet is properly and medically supervised.
COMPLICATIONS
Having a seizure at certain times can lead to circumstances that are dangerous to yourself or others.
Falling. If you fall during a seizure, you can injure your head or break a bone.
Drowning. If you have epilepsy, you're 13 times more likely to drown while swimming or bathing than is the rest of the population because of the possibility of having a seizure while in the water.
Car accidents. A seizure that causes either loss of awareness or control can be dangerous if you're driving a car or operating other equipment. Many states have driver's-licensing restrictions related to your ability to control seizures and impose a minimum amount of time that you've been seizure-free — ranging from three months to two years — before you're allowed to drive.
Pregnancy complications. Seizures during pregnancy pose dangers to both mother and baby, and certain anti-epileptic medications increase the risk of birth defects. If you have epilepsy and you're considering becoming pregnant, talk to your doctor as you plan your pregnancy. Most women with epilepsy can become pregnant and have a healthy baby. You'll need to be carefully monitored throughout pregnancy, and medications may need to be adjusted. It's very important that you work with your doctor to plan your pregnancy.
Emotional health issues. People with epilepsy are more prone to have psychological problems, especially depression, anxiety and, in extreme cases, suicide. This could be due to difficulties dealing with the condition itself as well as medication side effects.
Other life-threatening complications from epilepsy are uncommon, but do occur.
Status epilepticus. This condition occurs if you're in a state of continuous seizure activity lasting more than five minutes, or you have frequent recurrent seizures without regaining full consciousness in between them. People with status epilepticus have an increased risk of permanent brain damage and death.
Sudden unexplained death in epilepsy (SUDEP). People with poorly controlled epilepsy also have a small risk of sudden unexplained death. Overall, less than 1 in 1,000 people with epilepsy die of SUDEP, but it's more common among people whose seizures aren't controlled by treatment. The risk of SUDEP is particularly elevated when generalized tonic-clonic seizures are frequent, and the risk over a one-year period could be as high as approximately 1 in a hundred people.
