The Types of seizures Are the generalized ones and the focal ones. Depending on the area of the brain that is affected will determine the presence of one type or another.
A seizure is based on an abnormal electrical shock to the brain that can lead to fainting, loss of consciousness and involuntary and uncontrolled (spasm) motor movements.
However, not all seizures are the same, as there are several types of seizures depending on the brain involvement that occurs.
Does having seizures involve having epilepsy?
Before we go into detail about the types of seizures and their characteristics, it is important to keep in mind that having a seizure does not mean that you have epilepsy.
In fact, the term seizure or convulsive seizure refers to sudden or sudden brain dysfunction that causes the person to collapse, have seizures, or present other abnormalities in behavior on a temporary basis.
Thus, from the medical point of view, convulsion is simply a transient symptom characterized by a neuronal activity in the brain that leads to peculiar physical findings such as contraction and repeated and trembling distension of one or several muscles of sudden.
Also, convulsive seizures can lead to alterations in the person's mental state and psychiatric disorders such as deja vu or Never vu .
Thus, it is now known that most seizures are caused by electric shocks occurring in brain Or by fainting, that is, by a reduction of cerebral blood supply.
Characteristics of seizures and epilepsy
The symptoms that occur in seizures may vary depending on the part of the brain involved.
As we will see later, depending on the region (major or minor) of the brain that is affected by neural electrical discharges, different types of crises may appear with certain symptoms and repercussions.
However, regardless of the crisis, seizure by itself does not imply the presence of epilepsy.
The epilepsy Is a disease characterized mainly by the recurrence of seizures in a chronic manner.
Thus, although the seizure is the main symptom of epilepsy, the fact of having a simple seizure does not demonstrate the presence of this disease.
What causes seizures?
In order to be able to talk about epilepsy, they must have recurrent seizures and the presence of neurological disorders that predispose the brain to such seizures.
Also, seizures may occur as a result of other medical conditions other than epilepsy.
Thus, low blood sugar concentrations, infections, head trauma, use of psychostimulants or pharmacological overdose poisonings can cause seizures.
In summary, any factor that causes a sudden lack of oxygen in the brain can cause a convulsive attack, but only those cases in which the crises occur repetitively and with a certain evolution will constitute the presence of epilepsy.
Finally, it is important to note that the convulsive crisis is usually associated with typical symptoms such as loss of consciousness, fainting or the presence of muscle spasms.
However, as we will see below, many seizures do not have to present these more prototypical symptoms.
In fact, a person can have seizures without practically realizing it, since they are often asymptomatic.
Thus, the defining event of the seizure is not the presence of its typical symptoms but the presence of abnormal electrical activity in the brain.
Types of seizures
Usually, there are two major types of seizures; however, we will see how different subtypes can be seen in each type of seizure.
Generalized crisis
These types of seizures are those that originate from an abnormal activity of neurons on both sides of the brain.
Thus, as the name implies, in generalized seizures, the whole brain is affected by abnormal electrical discharges.
By affecting the whole brain, it is considered that this type of seizures have a greater severity than those that are not generalized.
Likewise, the famous symptoms such as fainting, loss of consciousness or the presence of inflammation are usually prototypical of this type of seizures. muscle spasms .
When we talk about a generalized seizure, we are most likely to be doing about that type of convulsive seizure more popularly known.
Thus, if we associate the name of convulsion with the typical image of a person lying on the ground, unconscious and with sudden and repetitive muscle spasms, we are very probably referring to a generalized seizure crisis.
However, although this type of crisis is the one that produces muscle spasms more frequently, not all types of generalized seizures have them.
And it is that among generalized convulsions, we find different subtypes of crisis, each of them with certain characteristics.
Therefore, although all these seizures are characterized by being caused by the abnormal activity of nerve cells that starts on both sides of the brain, not all manifest themselves with the same symptoms.
In fact, among these types of seizures we can find"convulsive"crises, that is to say with the presence of involuntary and generalized motor movements, and"non-convulsive"crises, in which this type of muscular spasms does not occur.
To understand a little better how each of the subtypes of this type of seizures are, we briefly review their characteristics.
1- Crisis without seizure
This type of crisis is characterized by the absence of convulsion, ie when the person has this type of crisis does not manifest typical muscle spasms.
As we have said, this type of crisis belongs to generalized seizures, so it is characterized by the presence of abnormal activity in neurons on both sides of the brain.
Usually the condition of this type of crisis, although not involving the presence of muscular spasms and being visually less aggressive, is usually serious.
Thus, the person who suffers from it may appear to be looking into space or have slight tremors in their muscles.
However, they are considered as"little evil"seizures and the person who suffers from it keeps his gaze fixed for a few seconds and then returns to full function.
After suffering this crisis the individual does not remember what happened during the seizure.
However, the typical postictal period (after the seizure) does not usually occur, and we will see that they do appear in the vast majority of other types of seizures.
Myoclonic seizures
In this type of generalized crisis there are spasms or muscular contractions.
It is characterized mainly by the presence of rapid jerks of body muscles, especially those of the arms and legs, and loss of consciousness.
Myoclonic seizures may be caused by different pathologies.
A cause of myoclinic crisis classifies the seizure as benign or non-epileptic and produces very slight shakes, similar to those that people have when they fall asleep.
The other causes of this type of crisis are epileptic. Among them we can find one that is unique to infancy, benign myoclinic epilepsy.
It consists of a strange disorder, which is present in few cases and begins between 4 and two years of life.
The other two causes of myoclonic seizure is severe myoclonic epilepsy consisting of a disorder that causes chronic and progressive brain damage and Lennox-Gastaut syndrome , A severe neurological disorder that is associated with the absence of ear-waves in the EEG and Mental retardation .
3- Tonic crises
This type of seizures cause extreme stiffness of the muscles of the body, usually the back, legs and arms.
Like the rest are explained by abnormal electrical discharges in the brain and cause fainting and loss of consciousness in most cases.
4- Clonic crisis
Like the previous one there are muscular alterations but they are differentiated by the presence of repeated spasmodic movements in the muscles of both sides of the body instead of extreme muscular rigidity.
This type of crisis could be associated with the popularly known convulsion in which the person"convulses"through sudden muscle movements and constant spasms.
5- Tonic-clonic crisis
This type of crisis Present a mixture of symptoms of tonic seizures and clonic seizures.
Thus, the person may have rigidity in the body, repeated jerks in the limbs and total loss of consciousness.
This type of seizures are considered as the"grand mal"seizures and are interpreted as the most serious of all types of generalized seizures.
6- Atonic crisis
The last type of generalized crisis is characterized by a total loss of muscle tone.
In this way, the person affected by this type of seizure will fall or drop his head involuntarily and will collapse as he loses his muscle tone throughout the body.
Focal onset crisis
Unlike generalized seizures, such seizures are characterized by affecting only a particular region of the brain.
Thus, abnormal electrical discharges that characterize seizures, in this case, only affect a small part of the brain, so that the rest of neural structures are not affected by the seizure.
This type of crisis is considered less serious than the previous ones but much more prevalent in the society.
In fact, it is estimated that about 60% of people with epilepsy suffer from focal seizures rather than generalized seizures.
Likewise, such seizures do not usually affect the person's consciousness, so when an individual has a focal crisis, despite being able to slightly lose his state of consciousness, he will rarely faint or be totally unconscious.
Likewise, the typical muscular symptoms through fast and aggressive spasms and jerks in different regions of the body, are also not seen in focal onset crises.
Thus, focal seizures refer to such crises that may be virtually asymptomatic in some cases and are much less striking and shocking than generalized seizures.
Usually, although convulsions can be classified according to the region of the brain that affects them, they are subdivided into two main categories.
1- Simple focal crises
In this type of seizure, the person remains conscious and does not faint or lose consciousness at any time.
However, you may experience feelings, feelings or unusual or strange experiences.
Thus, in the presence of the crisis, ie an abnormal electrical activity in a specific region of the brain, the individual may have sudden and inexplicable feelings of joy, go to Or sadness.
Likewise, you may also have symptoms such as nausea or vomiting and have strange sensory experiences such as hearing, smelling, seeing or feeling things that are not real.
2- Complex focal crises
This type of seizure differs from the previous one mainly by the affectation of the conscience.
Thus, while in simple crises the person remains conscious, in this type of seizure the individual has a slight loss of consciousness.
Usually it is usual for the person suffering from a complex crisis to report a dream or strange experience, from which he can not remember anything clearly.
During the crisis the person may perform strange behaviors such as repetitive movements of the eyelids, motor tics, rare movements with the mouth or even alterations in gait, but will not present the musculare spasms typical of generalized seizures.
References
- Bleck TP. Seizures in the critical patient. In: Shoemaker WC. Critical Medicine. Madrid: Interamericana 2001.p. 1546-54.
- Married J. Convulsions and convulsive status. In: Married Flowers, Serrano A, editors. Emergency and treatment of severe child. Oxford: Oxford University Press. 2000. p. 321-5.
- Domínguez MA, Gutiérrez J. State of epilepsy. In: Gentleman A. Intensive Therapy. 2ed. City of Havana: ECIMED; 2003.p. 3687-3722.
- Navarro VR, Falcón A. Seizures in the severe patient. Neurology 1997; 25 (148): 2075-7.
- Navarro VR, López O, Ramírez CA, Becquer C. Convulsive State. Considerations about their classification and therapy. Rev Finlay 1992; 6 (3-4): 185-91.