He Dravet's syndrome Is a type of infantile presentation epilepsy characterized by resistance to treatment and clinical evolution towards others Types of epileptic seizures and severe cognitive impairment (Sánchez-Carpinterio, Núñez, Aznárez and Narbona García, 2012).
At the etiologic level, Dravet's syndrome is a disease of genetic origin associated with more than 500 different mutations, however, approximately one 70% of those affected present a specific alteration in the SCN1A gene, located on chromosome 2 (Mingarro Castillo, Carmona de la Morena, Latre Martínez and Aras Portilla, 2014).
As for the clinical course, this disorder is characterized by the development of recurrent epileptic seizures during the first year of life. Usually, (Jiang, Shen, Yu, Jiang, Xu, Xu, Yu, Gao, 2016).
In addition, Dravet syndrome is considered one of the most serious types of epilepsy, since almost all affected children evolve towards a Severe or very severe neurological deterioration (Nieto-Barrera, Candao and Nieto-Jiménez, 2003).
The diagnosis of this type of pathology is similar to that of other epilepsies, based on the clinical examination, the characteristics of the convulsive episodes and The use of laboratory tests such as Electroencephalography .
In addition, a cure for Dravet's syndrome has not yet been identified; it is a type of epilepsy that is resistant to pharmacological treatment; Combination of different medical approaches may slow its progression (Mingarro Castillo et al., 2016).
Characteristics of Dravet's syndrome
Dravet syndrome, also called infantile severe myoclonic epilepsy (EMGI), is defined as a catastrophic and infrequent form of epilepsy Resistant to treatment that has a typical onset in the infantile stage (Dravet Syndrome Foundation, 2016).
As we all know, epilepsy is one of the most common conical course neurological disorders in the general population. Thus, this pathology is characterized By the recurrent presence of seizures (Epilepsy Foundation, 2016).
In epilepsy, habitual and functional patterns of brain electrical activity are altered, resulting in the development of spasms Loss of consciousness, behavioral disturbances or perception of strange sensations (National Institute of Neurological Disorders and Stroke, 2016).
Although there are a number of Types of epilepsies And types of crisis, Dravet's syndrome is classified within epilepsy Myoclonic, characterized by crisis or episodes of bilateral muscular shaking (Andalusian Epilepsy Association, 2016).
Specifically, this syndrome was initially identified by Charlotte Dravet in 1978 (Pérez y Moreno, 2015). In his clinical report Reference to the identification of several cases of severe epilepsy, resistant pharmacological treatment and with some clinical characteristics Shared with Lennox-Gastaut syndrome (Nieto-Barrera, Candado and Nieto-Jiménez, 2003).
In parallel to Dravet, other researchers, such as Scheffer and Bervic, describe a syndrome of epileptic character with a characterized genetic origin By the presence of febrile convulsions, in which Dravet syndrome is considered the most common phenotype (Pérez and Moreno, 2015).
However, it was not until 1985 when the International League of Epilepsy included it within"Epilepsies and indeterminate syndromes in relation to Location with presentation of generalized and focal crises"(Pérez and Moreno, 2015).
In addition, recent research indicates that Dravet's syndrome is a really serious and debilitating medical condition that, Life and significantly impairs the quality of life Of the affected person, in addition to that of his family (Dravet Syndrome Foundation, 2016).
In addition to the signs and symptoms characterized by convulsive episodes, this syndrome tends to evolve towards the presence of delays Significant in development, behavioral alterations, cognitive deficits, etc. In addition, it presents a high comorbidity with other types of conditions Such as sudden death (Dravet Syndrome Foundation, 2016).
About us
Epidemiological studies indicate that the syndrome of Dravet has an approximate incidence of 1 case per 20,000.40.0000 births. Without However, diagnostic protocols and new medical procedures can significantly increase this figure, since progressively Allow an earlier diagnosis (Dravet Syndrome UK, 2016).
In addition, its prevalence is estimated at around 7% of the types of epilepsies that appear during the early infantile stage, that is to say in children under three Years old (Mingarro Castillo et al., 2014).
As to its demographic distribution, Dravet syndrome similarly affects women and men, in addition a prevalence has not been identified Associated with specific geographic regions, and / or particular ethnic or racial groups (Mingarro Castillo et al., 2014).
On the other hand, if we refer to the data concerning its clinical course, between 3-7% of those affected present the first convulsive episodes Before the age of 7, while 7% usually develop during the 3 years (Pérez and Moreno, 2015).
In addition, in families affected by different epilepsy , Dravet's syndrome usually occurs in one of its members in more than 25% of the (Pérez and Moreno, 2015).
Signs and symptoms
As we have pointed out, the fundamental medical findings in Dravet's syndrome are seizures of epileptic character and febrile seizures:
to) Seizures
Convulsive episodes develop as a result of abnormal neuronal activity, whether at the generalized or focal level. They usually cause spasms Muscle and / or loss of consciousness, although there are different types. In the case of Dravet syndrome the most common are (National Institute of Neurological Disorders and Stroke, 2015):
- Tonic Crises : In this case, the episodes are characterized by the development of muscular tension, tending to the rigidity Generalized, especially in legs and arms.
- Myoclonic seizures : In this case, the episodes are characterized by the development of repetitive and uncontrolled muscular spasms, to Visual level, can be seen as shaking of the body.
- Tonic-clonic seizures : In this case, the episodes are characterized by a combination of the previous ones, in addition, they usually present of Parallels a temporary loss of consciousness.
B) Febrile seizures
Along with the crises described in the previous section, it is frequent to observe the development of episodes of high fever, that is, of abnormal increase of Body temperature, generally above 37 degrees.
Thus, different authors denominate this medical condition like febrile convulsive crisis, they can be part of an epileptic pathology or appear in the picture Other diseases that occur with high fever.
In addition to these cardinal symptoms, Dravet syndrome has a specific clinical course which we will describe below (Dravet Syndrome UK, 2016; López, Varela and Marca, 2013; Sánchez-Campiertero, Núñez, Aznárez and Narbona García, 2012):
The first signs and symptoms usually appear before the first year of life, that is, in the neonatal or lactation stage. Thus, seizures often Appear next to febrile episodes, are usually generalized tonic-clonic, and affect bilaterally or unilaterally the body.
In addition, the first crises usually have a prolonged duration, of even more than 5 minutes, reason why they usually require urgent medical intervention. On the other hand, in the early stages of the development of Dravet's syndrome neurological development is not usually initially affected.
As this pathology progresses, after several months since its presentation, crises usually become more frequent and intense, however, the Episodes of high fever have to disappear. In this case, the crises are usually myoclonic, although there may be some crises of absence, Characterized by the lack of response of the individual.
On the other hand, when the person reaches the stage between 2 and 4 years of age, prolonged epileptic seizures become a risk Severe for neurological integrity.
At this stage, it is already possible to identify important developmental delays, cognitive deficits and other symptoms, such as ataxia, sleep disorders or Behavioral changes.
Thus, the usual evolution of Dravet's syndrome is oriented towards epilepsy resistant to pharmacological treatment, with delay and stagnation Severe psychomotor development and the suffering of different cognitive deficits in a moderate to severe spectrum.
Usually, with the passage of time, a trend toward stabilization has been identified which allows the development of various capacities such as Language or functional gait.
Causes
Dravet syndrome is epilepsy of genetic origin, although it can be associated with a wide variety of genetic abnormalities, specifically more Of 500 specific mutations, most cases are associated with mutations in the SCN1A gene (National Organization For Rare Disorders, 2016).
At a specific level, this gene is located on chromosome 2 and is responsible for encoding an alpha 1 subunit of voltage-dependent sodium channels, In which its efficient functioning is fundamental for the correct transmission of nerve impulses between neurons (Mingarro Castillo et al. 2014).
Although the specific forms of the genetic mutation are not usually fully correlated with the specific clinical spectrum, it is more It is probable that the affected person presents a more severe symptomatology if it looks like a de novo mutation (random), that if his disease is the product of a Hereditary transmission (National Organization For Rare Disorders, 2016).
In addition, specific mutations in the SCN1A gene are also related to other epilepsy courses, including:
- Generalized epilepsy with febrile seizures.
- Severe infantile multifocal epilepsy.
- Sporadic infantile epileptic encephalopathy.
- Intractable tonic-clonic infantile crisis.
Diagnosis
In general, the different subtypes of epilepsy are diagnosed based on the clinical characteristics of seizure episodes: It is fundamental to know the moment of the initial presentation, the frequency, the duration and the form that the seizures take.
In addition, another important aspect is the physical and neurological examination, to identify other types of symptoms that accompany the crises, such as fever, Cognitive impairment , among others.
On the other hand, another basic measure is the electroencephalographic study, since it will offer us information about the organization of brain activity Of the person affected.
In addition, a genetic study is performed on Dravet syndrome to identify abnormalities compatible with genetic mutations and another type of Alterations.
Treatment
Dravet's syndrome is a type of drug-resistant epilepsy, ie, resistant to all classical or combination pharmacological approaches (Pérez and Moreno, 2015).
However, different approaches have been designed based on the combination of some drugs such as Valproate , Clobazam Or the sitirioentol, which are capable of Slow the progression of crises. However, they have important adverse effects (Pérez and Moreno, 2015).
In addition, other types of drugs are also used to decrease the intensity and duration of episodes, such as Clonazepam , Levetiracetam, Valproic and topiramate (Dravet Syndrome Foundation, 2016).
On the other hand, some approaches that have worsened clinical status have also been identified, these include: cabarmazepine, fosphenytoin, Lamotrigine, oxcarbazepine, phenytoin and vigabatrin (Dravet Syndrome Foundation, 2016).
References
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- DSF. (2016). What is Dravet Syndrome? Obtained from Dravet Syndrome.
- DSUK. (2016). What is Dravet Syndrome? Obtained from Dravet Syndrome UK.
- EP. (2016). Diagnosing Epilepsy . Obtained from Epilepsy Foundation.
- Jiang, P., Shen, J., Yu, Y., Jiang, L., Xu, J., Xu, L., et al. . . Gao, F. (2016). Dravet syndrome with favorable cognitive and behavioral development due to a Novel SCN1A frameshift mutation. Clinical Neurology and Neurosurgery , 144-146.
- López, I., Varela, X., & Marca, S. (2013). Epileptic Syndromes in Children and Adolescents. Rev. Med. Clin. Counts , 915-927.
- Mingarro Castillo, A., Carmona de la Morena, J., Latre Martínez, P., & Aras Portilla, L. (2014). Dravet's syndrome. Rev Clin Med Fam , 134-136.
- Nieto-Barrera, M., Candau, R., & Nieto-Jiménez, M. (2003). Severe myoclonic epilepsy in infancy (Dravet's syndrome). Nosologic location and Therapeutic aspects. Rev Neurol , 64-68.
- NIH. (2015). Febrile Seizures Fact Sheet . Retrieved from the National Institute of Neurological Disorders and Stroke.
- NIH. (2015). Epilepsies and crises . Retrieved from the National Institute of Neurological Disorders and Stroke.
- NORD. (2016). Dravet Syndrome Spectrum . Retrieved from the National Organization for Rare Disorders.
- Pérez, A., & Moreno, N. (2015). Dravet's syndrome. Salus , 27-31.
- Sánchez-Carpintero, R., Núñez, M., & Narbona García, J. (2012). Crisis with fever in the first year of life: epilepsy of the Dravet spectrum? An Pedatr (Barc) , 2018-223.