Elsa M. Raimondi

 Epilepsy is understood to be a clinical condition characterized by the presence of recurrent paroxysmal alterations which are called epileptic seizures. These epileptic seizures are transient clinical episodes that occur as a result of an abnormal, excessive, synchronous and spontaneous discharge of a group of neurons. Each seizure lasts from several seconds to a few minutes and manifests itself suddenly as a disturbance in behavior or as seizures or "jerks". The term seizure refers to generalized, jerky, involuntary movement attacks with loss of consciousness.

Pathophysiology

Abnormal, excessive, synchronous and repeated discharges of a specific group of neurons are responsible for the different types of epileptic seizures. Such discharges occur as a consequence of an imbalance between excitatory and inhibitory mechanisms in such a way that the former predominate over the latter and determine the initiation of physiological and neurochemical dysfunctions.

The intimate mechanism of such abnormalities has not been unraveled, but increased neuronal excitability could be produced by any of the following causes: 1) voltage-dependent ionic, sodium and calcium channel alteration; 2) abnormal regulation of the extracellular ionic content; 3) structural abnormalities of synaptic connections and / or postsynaptic receptors; 4) modifications in the levels of excitatory neurotransmitters (such as glutamate) and inhibitory (such as GABA). For the anomalous discharge to take place, in addition to hyperexcitability, there needs to be synchronization (simultaneity) between a sufficient number of neurons to generate and propagate the paroxysmal discharge. It has been mentioned that another characteristic of epilepsy is its ability to spontaneously discharge and in this sense, the mechanism that sets this capacity in motion remains unknown, although it is known that changes in the internal environment (for example, during menstruation) or external, such as intermittent beams of light, can modify the excitability of the abnormal neuronal group and trigger a seizure. Depending on where the neurons responsible for the discharges are located, the different clinical manifestations will take place. If the epileptogenic group is found in a limited focal zone of the motor cortex, the seizure presentation will be in the form of involuntary muscle jerks that may involve the upper limb and / or the half-face and / or the leg on the opposite side of the focus. . This is an example of a simple partial crisis. When it unloads a neuronal group located in the cortex of the temporal lobe, the seizures will have more complex manifestations that are related to memory and psychomotor activities. When the neuronal group that discharges, due to its connections, can cover both cerebral hemispheres, a generalized crisis can be had.

The abnormal discharges described so far can occur as a result of different causes: a) when no demonstrable or apparent structural cerebral alteration is found, it is referred to as idiopathic epilepsies and its origin is probably genetic. In general, this is responsible for generalized entry crises; b) When there are structural alterations, such as a focal lesion in the cerebral cortex (post-traumatic scar, etc.), partial seizures occur and are called symptomatic, acquired or secondary epilepsies. The spontaneous repetition of seizures is a necessary condition for labeling someone as epileptic: epilepsy is a chronic condition. On the other hand, if a seizure occurs in isolation as a result of an acute brain disorder or injury,

Symptoms and signs

It is important to recognize the type of seizure in order not to confuse them with other non-epileptic seizures and to be able to include them within a specific disease or pathology. There are 2 main groups of seizures: a) partial or focal seizures are those that originate in a group of neurons located in a specific area of ​​a brain hemisphere (epileptogenic focus); b) generalized ones that are due to a simultaneous activation of both cerebral hemispheres, possibly from the rostral reticular substance.

Partial seizures: they comprise 3 groups: simple partial, complex partial and secondarily generalized tonic-clonic. The difference between both types of partial seizures lies in the fact that in simple partial seizures, consciousness is not altered and, on the other hand, in complex ones there is a partial or total compromise of the level of consciousness. Either of these two types of crisis can lead to a secondary generalized crisis.

Simple partial seizures. They are characterized by presenting symptoms and signs corresponding to the discharge area and can be translated into motor, somatosensory, special senses, autonomic and psychic manifestations. In the case of motor seizures, the most common is that the patient has jerks limited to the facial muscles and distal parts of the limbs, particularly the upper limb and always on the opposite side to that of the epileptogenic focus. It may happen that the discharge spreads from its original place to contiguous areas and in such a way, the crisis will begin as facial jerks to continue successively with the movements in arm and leg, following what is called a "Jacksonian motor gait" (description given by Jackson). Sometimes, once the crisis is over, the patient is left with a transient (post ictal) weakness (paresis) that affects the muscular sectors involved and is known as Todd's palsy. Somatosensory crises consist of sensations of tingling, tingling, pricking, etc., on the opposite side to the focus. When primary areas of vision are involved, in the occipital lobe, the manifestations of the seizures will be in the form of flashes, or lights. If those affected are the secondary visual areas, in the temporo-parieto-occipital area, more complex visual hallucinations may occur, such as changes in the shape and size of objects. The superior temporal cortex can be the seat of crises that manifest as tinnitus or distortion of sounds. Somatosensory crises consist of sensations of tingling, tingling, pricking, etc., on the opposite side to the focus. When primary areas of vision are involved, in the occipital lobe, the manifestations of the seizures will be in the form of flashes, or lights. If those affected are the secondary visual areas, in the temporo-parieto-occipital area, more complex visual hallucinations may occur, such as changes in the shape and size of objects. The superior temporal cortex can be the seat of crises that manifest as tinnitus or distortion of sounds. Somatosensory crises consist of sensations of tingling, tingling, pricking, etc., on the opposite side to the focus. When primary areas of vision are involved, in the occipital lobe, the manifestations of the seizures will be in the form of flashes, or lights. If those affected are the secondary visual areas, in the temporo-parieto-occipital area, more complex visual hallucinations may occur, such as changes in the shape and size of objects. The superior temporal cortex can be the seat of crises that manifest as tinnitus or distortion of sounds. the manifestations of the crises will be in the form of flashes, or lights. If those affected are the secondary visual areas, in the temporo-parieto-occipital area, more complex visual hallucinations may occur, such as changes in the shape and size of objects. The superior temporal cortex can be the seat of crises that manifest as tinnitus or distortion of sounds. the manifestations of the crises will be in the form of flashes, or lights. If those affected are the secondary visual areas, in the temporo-parieto-occipital area, more complex visual hallucinations may occur, such as changes in the shape and size of objects. The superior temporal cortex can be the seat of crises that manifest as tinnitus or distortion of sounds.

Regarding autonomic crises, which mainly originate in the limbic lobe, they are expressed in the form of episodes of flushing, paleness, tachycardia, indefinite epigastric sensations, etc. Lastly, simple partial seizures with psychic symptoms are those that usually appear with feelings of strangeness about something or someone or, on the contrary, with a feeling of being known when in reality it is not (feelings of never seen or already seen) , or with affective disturbances such as anger or fear. For these crises to fall into the category of simple partials, there must be an indemnity of conscience, with full memory of the episode. If, on the other hand, the same type of symptomatology presents with partial or total alteration of consciousness, it will be in the presence of a complex partial crisis. The origin of the seizures, generally, is in the temporal lobe. The brevity, the abruptness of the episode and the stereotypy differentiate these epileptic seizures from disorders of a psychiatric lineage.

Complex Partial Seizures : the origin of the discharges is, generally, in the temporal lobe; it is followed in frequency by the frontal lobe. Typically, they manifest with altered level of consciousness; At the same time that the patient seems absent and staying in the position in which he was, automatic movements of the chewing or swallowing type begin to appear and to touch objects or parts of his body repeatedly. Each crisis lasts between 1 and 3 minutes. Sometimes the patient has a vague memory that something has happened to him.

Generalized Crisis: within this category are absences, generalized tonic-clonic seizures, myoclonic, atonic and tonic seizures. Absences are characterized by very brief episodes (10-15 seconds) of staring loss of consciousness, some rhythmic blinking, without falling, and possible repetition of many episodes during the day. These crises are observed in children and up to adolescence. Generalized tonic-clonic seizures, also called grand mal seizures, are the best known and most dramatic. Abruptly, the patient loses consciousness and posture, falling to the floor where he is at the same time that he begins to have bilateral and symmetrical muscle jerks, accompanied by tongue biting, dyspnea and cyanosis. There may be urinary incontinence. The episode lasts about 1 minute and is followed by a brief post-ictal coma, which is followed by a period of confusion and sleepiness that usually lasts no more than 30 minutes. The patient has amnesia from the seizure. Myoclonic seizures are abrupt, brief, symmetrical or not, arrhythmic muscular jerks and generally involve the upper limbs. They are very short and you do not lose consciousness. In atonic seizures there is a sudden loss of muscle tone lasting 2 to 3 seconds: if the legs are affected, the patient may fall to the ground. Consciousness is not affected. In tonic seizures there is a sustained and generalized muscle contraction, lasting several seconds and up to 1 minute. Consciousness is usually altered. the one that continues with a period of confusion and sleep that does not usually last more than 30 minutes. The patient has amnesia from the seizure. Myoclonic seizures are abrupt, brief, symmetrical or not, arrhythmic muscular jerks and generally involve the upper limbs. They are very short and you do not lose consciousness. In atonic seizures there is a sudden loss of muscle tone lasting 2 to 3 seconds: if the legs are affected, the patient may fall to the ground. Consciousness is not affected. In tonic seizures there is a sustained and generalized muscle contraction, lasting several seconds and up to 1 minute. Consciousness is usually altered. the one that continues with a period of confusion and sleep that does not usually last more than 30 minutes. The patient has amnesia from the seizure. Myoclonic seizures are abrupt, brief, symmetrical or not, arrhythmic muscular jerks and generally involve the upper limbs. They are very short and you do not lose consciousness. In atonic seizures there is a sudden loss of muscle tone lasting 2 to 3 seconds: if the legs are affected, the patient may fall to the ground. Consciousness is not affected. In tonic seizures there is a sustained and generalized muscle contraction, lasting several seconds and up to 1 minute. Consciousness is usually altered. arrhythmic and generally involving the upper limbs. They are very short and you do not lose consciousness. In atonic seizures there is a sudden loss of muscle tone lasting 2 to 3 seconds: if the legs are affected, the patient may fall to the ground. Consciousness is not affected. In tonic seizures there is a sustained and generalized muscle contraction, lasting several seconds and up to 1 minute. Consciousness is usually altered. arrhythmic and generally involving the upper limbs. They are very short and you do not lose consciousness. In atonic seizures there is a sudden loss of muscle tone lasting 2 to 3 seconds: if the legs are affected, the patient may fall to the ground. Consciousness is not affected. In tonic seizures there is a sustained and generalized muscle contraction, lasting several seconds and up to 1 minute. Consciousness is usually altered. of several seconds and up to 1 minute in duration. Consciousness is usually altered. of several seconds and up to 1 minute in duration. Consciousness is usually altered.

Status epilepticus : this is the name given to a clinical picture in which the patient has a continuous and lasting succession of seizures. It's a medical emergency

When a patient with idiopathic epilepsy is examined, outside of his seizures, he presents a normal neurological examination. When the epileptic is a carrier of symptomatic partial seizures, it is possible to find signs of different kinds, which indicate the existence of a focus

Study methodology

The evaluation of any patient who has had a seizure must be carried out exhaustively by means of a questioning directed to the same patient, to his relatives or to someone who has witnessed the episode. The semiological details of the seizure (s) should be collected in order to be able to determine whether such seizures are epileptic or not, and if they are, of what type (partial or generalized) and try to establish the etiology. For all this, the interrogation and the neurological physical examination is of primary and exclusive importance since no other means of study will be able to replace the clinical history and answer the questions raised. The medical history should record the presence of direct relatives with a history of seizures and the patient's habits, as well as any other pathology suffered in the past (meningitis, encephalitis, head trauma, etc.). Routine tests should be performed, which, depending on the age of the patient, should include levels of magnesium, calcium and phosphorus (children). An electroencephalogram (EEG) will be requested as a complement since it will be able to clarify some aspects (origin of the discharges or characteristics of the abnormal waves), but taking into account that even in the presence of epilepsy, the EEG may appear as normal (which does not invalidate diagnosis) and conversely, apparently abnormal EEGs may appear in healthy patients. In cases that require it, video electroencephalography can be used if the seizures are frequent and it has not been possible to typify them: in these cases, the seizures can be filmed and have the correlate of the EEG. If it is determined that the patient is a carrier of partial seizures, which the EEG corroborates, there is currently a consensus in requesting a Magnetic Resonance Imaging (MRI) of the brain since it allows the identification of most structural lesions of the brain. This method has made it possible for epilepsies that were considered idiopathic to finally be symptomatic. Computed tomography should be reserved for emergency situations or when the patient cannot be subjected to the action of magnetic fields.