what is epilepsy

 What is epilepsy?


  
Illustration: Luis Parejo

Illustration: Luis Parejo
Updated Wednesday 03/05/2006 20:10 (CET)
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Epilepsy is caused by abnormalities in the electrical activity of the brain. This organ is unable to stop or inhibit electrical impulses between neurons. When an excessive discharge takes place there is a seizure or epileptic seizure.

The term epilepsy derives from the Greek 'epilambaneim', which means 'catch by surprise'. In the late nineteenth century, the English neurologist John Hugling Jackson, established the definition of epilepsy that remains in force today: "a sudden, rapid and excessive discharge of brain cells."

    CAUSES

    The location of the disorder varies according to the type of epilepsy, which can be focal or generalized. The causes of this disease are the most varied: it can be the result of congenital anomalies, vascular diseases such as cerebral infarction, infections, tumors, degenerative diseases or injuries. In many cases a specific cause is not discovered and they are called idiopathic epilepsies and other times they are only the fruit of an incorrect brain maturation and disappear when the development of the brain ends (in adulthood).

    Until a few years ago (and even today to a lesser extent) it was one of the diseases with the greatest social stigma, because of the spectacular attacks of a specific type of epilepsy, that of generalized seizures. Today the increase of the health culture in the general population has achieved to some extent that this disease is accepted and demystified.
    THE CRISIS

    In most cases, crises appear suddenly and unexpectedly. They are short, last a few seconds or at most a few minutes. The most striking include seizures and loss of consciousness, but there are many crises that are reduced to a momentary disconnection with the environment (the so-called absences) or slight rhythmic movements without loss of consciousness.

    The attacks are the result of a dysfunction of the brain's electrical activity. They begin when a group of neurons produces electrical impulses (discharges) of abnormal way, that propagate by the rest of the brain reaching the neurons that mobilize the muscles. They also start to discharge abnormally and that's when the uncontrolled movements typical of epileptic seizures occur.

    In addition to the causes listed above, any susceptible person may suffer an attack in isolation from drug intoxication or a sudden drop in glucose, but if repeated with some frequency is considered epilepsy.

    There are two main types of epileptic seizures: generalized, which affect the entire surface of the brain, and partial or focal seizures, where the discharge begins in a specific area that, sometimes, spreads through the rest of the cortex.
    DIAGNOSIS

    To make the diagnosis, the doctor first interrogates the patient who has supposedly suffered a crisis about risk factors such as family history, diseases he has suffered, toxic habits such as drug or alcohol consumption, history of fetal distress or after childbirth, history of head trauma etc.

    Subsequently, it is inquired about how the attack occurred and what behavior the person presented during the attack (if he had convulsions, if he urinated, if he bit his tongue ...). For this, the testimony of witnesses who have witnessed the crisis is of great help.

    The second part of the diagnosis has to do with the tests. It is mandatory in most cases in which it is suspected that a crisis may have occurred, a brain scan or an MRI (depending on the case) to rule out any intracerebral injury that may have caused the attack. An analytical test should also be carried out to rule out causative metabolic diseases and an electroencephalogram (EEG) that measures the brain's electrical activity to identify the abnormal electrical discharges that precipitated the crisis.
    WHO IS AFFECTED

    Although three quarters of epilepsy begins before age 18, this disease affects people of any age, race, sex, and social class. There are 50 million affected worldwide and in Spain it is estimated that around 400,000 people suffer from the disease and that 20,000 new cases appear every year.
    TREATMENT

    The main thing is to make sure that the patient has epilepsy before starting any antiepileptic treatment. Once the diagnosis is made, it is best to start the treatment as soon as possible.

    Attacks can be controlled with medication in 70% of cases. Between 20-30% do not respond to simple pharmacological treatment (with only one medEpilepsy surgery is a complex procedure that should only be performed in centers with adequate experience and resources.

    The main requirement for a surgical treatment is that the epilepsy is focal, that is to say, that the electrical discharges begin in a located place of the brain. In addition, the patient must present an unambiguous alteration visualizable in the magnetic resonance and this must be responsible for the abnormal discharges.

    The surgical procedure consists in the total or partial extirpation of the focal lesion or abnormal tissue of the brain responsible for the seizures. Logically to be a candidate for surgery, epilepsy must be uncontrollable with medication and, in addition, that the focus of brain tissue to be removed is accessible and not essential for the performance of an important function, such as speech or memory.
    STIMULATION OF THE VAGUE NERVE

    Another option is the implantation of an electrode to stimulate the vagus nerve. Vagus nerve stimulation is an effective procedure for the treatment of epilepsy resistant to drug treatment and may be indicated in patients with contraindication to conventional surgery described above or who do not want to undergo a surgical procedure in the brain.

    The mechanism of action of vagal stimulation is not yet fully understood but it is believed that as this nerve connects with many areas of the brain including the hippocampus, the amygdala, the thalamus and the cortex, which are often involved in epilepsy .

    Under the skin (at the level of the clavicle) a pulse generator is implanted which is a device similar to that of thecardiac pacemaker, from which wires start, ending in electrodes that are applied to the vagus nerve at the level of theneck