The Idiopathic epilepsy Primary epilepsy is a type of epilepsy of predominantly genetic origin in which seizures occur, but there are no neurological alterations or structural lesions in the brain .
The epilepsy Is a neurological disease that is distinguished by episodes of strong increases in neuronal excitation. These produce seizures, also known as epileptic seizures. During these attacks patients may suffer Convulsions , Confusion, and alterations in the state of consciousness.
Epilepsy is the most common neurological disease. In developed countries its prevalence is approximately 0.2%, while in developing countries its frequency is even higher (Arcos Burgos et al., 2000).
According to the World Health Organization, idiopathic epilepsy is the Type of epilepsy More common, affecting 60% of epileptic patients. The characteristic of this condition is that it does not have an identifiable cause, as opposed to secondary or symptomatic epilepsy.
However, in the infantile population it seems that it constitutes 30% of all infantile epilepsies, although the percentage varies according to the investigators.
Epilepsy syndromes that are part of idiopathic epilepsy are epilepsy of genetic inheritance in which several different genes participate, and which at present have not yet been defined in detail. Rare epilepsies involving only one gene are included, and epilepsy is the only or predominant feature.
As the exact cause is not yet known, idiopathic epilepsy can not be prevented. However, it appears that many cases are solved on their own. Thus, epileptic seizures manifest in childhood, but then disappear as they develop.
For treatment, antiepileptic drugs are usually chosen.
Types of idiopathic epilepsy
There are two major types of idiopathic epilepsy, generalized and focalized or partial epilepsy. The main difference between them is the type of seizure. In the generalized, the alterations in the cerebral electrical activity occupy the whole brain; While in the focal the altered activity is concentrated in a certain area (at least most of the time).
However, it should be noted that this distinction is physiologically relative. This is because some of the focal idiopathic epilepsies may have generalized physiological changes, but it is difficult to determine.
Generalized
Generalized idiopathic epilepsy is the one that occurs most frequently in the literature, since it seems to be the most common form of this type of epilepsy. According to Arcos Burgos et al. (2000), this type represents about 40% of all forms of epilepsy until the age of 40 years.
There is often a family history of associated epilepsy and it tends to appear during childhood or adolescence.
At electroencephalogram (A test that measures electrical impulses in the brain), these patients may have epileptic discharges that affect multiple areas of the brain.
Patients with this condition may develop different subtypes of generalized seizures. For example, Clonic tonic seizures Generalized (this can be subdivided into"great evil of chance"or"great evil of the awakening"), infantile absences, juvenile Juvenile myoclonic epilepsy.
Focused or partial
Also called benign focal epilepsy. The most common focal idiopathic epilepsy is benign partial epilepsy with centro-temporal points. It is also known as Rolandic epilepsy, because, when examining these patients through the electroencephalogram, paroxysms are associated with an area of the brain called Fissure of Roland .
On the other hand, there are a number of rare partial idiopathic syndromes and epilepsies that have genetic causes.
Causes
The exact mechanism by which this type of epilepsy is developed is not known with exactness, but everything seems to indicate that its causes are genetic.
This does not mean that idiopathic epilepsy inherits itself, but perhaps what is inherited is a predisposition or susceptibility to developing it. This predisposition can be inherited from one or both parents, and occurs by some genetic modification before the affected one is born.
This genetic tendency to experience epilepsy may be associated with the existence of a Low convulsive threshold . This threshold is part of our genetic makeup and can be passed from parent to child, and this is our individual level of resistance to epileptic seizures or electrical maladjustments of the brain.
Anyone has the potential to experience seizures, although there are individuals more likely than others. People with low seizure thresholds are more likely to start epileptic seizures than others with higher thresholds (Epilepsy Society, 2016).
However, it is important to note here that having seizures does not necessarily mean the existence of epilepsy.
Arcos Burgos et al. (2000) have identified some possible genetic components associated with the susceptibility to develop epilepsy. Thus, a possible genetic locus for Juvenile Myoclonic Epilepsy (a subtype of idiopathic epilepsy) would be 6p21.2 in the EJM1 gene, 8q24 for generalized idiopathic epilepsy; And in benign neonatal seizures, 20q13.2 in the EBN1 gene.
In a study of the University of Cologne in Germany they describe a relationship between idiopathic epilepsy and a deletion in a region of chromosome 15. This region seems to be related to a great variety of neurological conditions as autism , schizophrenia Y Mental retardation , With generalized idiopathic epilepsy being the most common. One of the genes implicated is the CHRNA7, which seems to participate in the regulation of neuronal synapses.
symptom
Idiopathic epilepsy, like many types of epilepsy, is associated with somewhat unusual electroencephalographic activity and the sudden onset of epileptic seizures. There are no motor sequelae or Cognitive abilities wave intelligence . In fact, many cases of idiopathic epilepsy refer spontaneously.
During crises, different Types of seizures In patients with idiopathic epilepsy:
- Myoclonic seizures: Are sudden, of very short duration and are characterized by jerks in the extremities.
- Crisis of absence: They are distinguished by loss of consciousness, fixed gaze and lack of response to stimuli.
- Tonic-clonic crisis (Or great evil): characterized by a sudden loss of consciousness, body stiffness (tonic phase) and then rhythmic shaking (clonic phase). The lips become bluish, there may be biting of the inside of the mouth and tongue and urinary incontinence.
However, the symptoms vary slightly depending on the exact syndrome we are talking about. In the following section they are described in more detail.
Related conditions and syndromes
There is a wide variety of epileptic conditions that belong to the category of idiopathic epilepsy. To better describe each, syndromes have been classified as generalized or partial.
Generalized idiopathic epilepsy syndromes
All usually have in common the absence of neuro-psychic alterations, frequent family history of febrile seizures and / or epilepsy. In addition to electroencephalography (EEG) with normal base activity, but with bilateral tip-wave complexes (Nieto Barrera, Fernández Mensaque and Nieto Jiménez, 2008).
Epilepsy with Absences (AE)
It is a condition that appears between 3 years and puberty. It stands out for daily crises that begin and end abruptly, in which there is a brief alteration of consciousness. The electroencephalogram reflects fast generalized tip-wave discharges.
Epilepsy with Absences Usually disappears spontaneously and in 80% of cases is treated effectively with antiepileptic drugs (Ureña Hornos et al., 2004).
It can also occur between 10 and 17 years, called epilepsy with juvenile absences. Nieto Barrera, Fernández Mensaque and Nieto Jiménez (2008) indicate that 11.5% of the cases have a family history of epilepsy. Crises arise more easily with whether the patient sleeps less than due or with hyperventilation.
Juvenile Myoclonic Epilepsy
Also called Janz's disease (JEM), it accounts for between 5 and 10% of all epilepsies. Its course is usually benign, without affecting mental capacities.
It is characterized by sudden jerks that may affect predominantly upper limbs, but also lower limbs. They do not usually affect the face. They often occur on awakening, although sleep deprivation and alcohol consumption are also facilitated.
It affects both sexes and appears between 8 and 26 years. As is repeated in families in 25% of cases, this condition seems to be associated with genetic factors. Specifically, it has been linked to a marker located on chromosome 6p.
Epilepsy of the Great Evil of Awakening (GMD)
It is also called"epilepsy with generalized tonic-clonic seizures", has a certain predominance in men and begins between the ages of 9 and 18. 15% of these patients have a clear family history of epilepsy.
Their crises last approximately 30 to 60 seconds. They begin with rigidity, then clonic jerks of all limbs, accompanied by irregular breathing, and guttural noises. The affected can bite the tongue or the inside of the mouth during this period, and even lose control of the sphincters.
Fortunately the attacks are not very common, being sleep deprivation, stress and alcohol risk factors.
Partial idiopathic epilepsy syndromes
These syndromes have in common that they are genetically determined, the absence of neurological and psychological alterations; And a good evolution. The symptoms, the frequencies of the seizures and abnormalities in the EEG are very variable.
Rolandic epilepsy or benign partial epilepsy with center-temporal tips
It is characterized to appear exclusively in the second childhood (between the 3 and 12 years), in the absence of cerebral injuries of any type. Crises partially affect the brain in 75% of cases, and often occur during sleep (at night, in the middle of the night and on awakening). These attacks primarily affect the bucco-facial motor region. However, these crises do not recur after 12 years.
Its main cause is a certain hereditary predisposition. Most of the parents and / or siblings of these children have presented epileptic seizures in infancy.
Epilepsy Versiva or Rotatoria Benigna
He appears between 8 and 17 years old in children with a family history of febrile seizures. Crises usually occur with rotation of the head and eyes to one side. It is also usually accompanied by a sudden turn of the whole body of at least 180 degrees, and there may be loss of consciousness or not. These patients usually respond well to antiepileptic drugs.
Focal Focal Epilepsy with Variable Focuses
Seizures usually appear during the day, and begin at about 12 years of age. They are usually partial (affecting specific areas of the brain) and the symptoms vary depending on the active zones of the brain.
Family Focal Epilepsy with Hearing Symptoms
The age of onset oscillates between the 4 and 50 years, but usually arises in the adolescence or early adultez. It is associated with a molecular marker on chromosome 10q22-24.
Its name is because its main manifestations are auditory symptoms. That is, the patient hears little noises, buzzing or ringing. In some people there are distortions such as volume changes, complex sounds (listening to specific voices or songs).
It is sometimes accompanied by ictal receptive aphasia, that is, a sudden inability to understand language. Interestingly, some attacks appear after hearing some sound, like a ringing phone. Its course is benign and responds well to medication (Ottman, 2007).
Epilepsy Autosomal Dominant Night Front
This type is more common in women, and appears for the first time at 12 years. It is linked to a mutation in 20q13.2 and crises are distinguished by feelings of choking, epigastric discomfort, fear, and repetitive and disorganized movements of the limbs at night.
Familial Epilepsy of the Temporal Lobe
It begins between 10 and 30 years and has an autosomal dominant inheritance. They are associated with certain sites on chromosomes 4q, 18q, 1q, and 12q.
The crises are accompanied by feelings of"deja vu", fear, visual, auditory, and / or olfactory hallucinations.
Treatment
As mentioned, many of the idiopathic epilepsy syndromes are benign. That is, they solve themselves at a certain age. However, under other conditions, the patient may need to take antiepileptic medication for life.
Adequate rest is important, limiting alcohol consumption and Treat stress ; Since these factors easily trigger epileptic seizures.
The most common in these cases is to use antiepileptic drugs, which are often very effective in controlling seizures.
For generalized epilepsy in all electrical activity of the brain, valproate is used. According to Nieto, Fernández and Nieto (2008); In women it tends to be replaced by lamotrigine.
On the other hand, if epilepsy is focal idiopathic, it is recommended to wait for the second or third crisis. To adapt the treatment to its frequency, schedule, characteristics, or repercussions. The most commonly used drugs are carbamazepine, oxcarbazepine, lamotrigine, as well as valproate.
References
- Arcos-Burgos, O. M., Palacios, L. G., Sánchez, J. L., & Jiménez, I. (2000). Genetic-molecular aspects of the susceptibility to develop idiopathic epilepsy. Rev Neurol, 30 (2), 0173.
- Causes of epilepsy . (March 2016). Obtained from Epilepsy Society.
- Díaz, A., Calle, P., Meza, M. and Trelles, L. (1999). Revolving epilepsy: Anatomopynamic correlation. Rev. Per. Neurol. 5 (3): 114-6.
- Rolandic epilepsy. (S.f.). Recovered on November 24, 2016, from APICE (Andalusian Epilepsy Association).
- Epilepsy Health Center . (S.f.). Retrieved on November 24, 2016, from WebMD.
- Falip, M., Santamarina, E., Rovira, R., Gratacós, M., Codina, M., & Padró, L. (2004). Generalized idiopathic epilepsy. Usefulness of semiology and electroencephalogram for classification. Rev Neurol, 39 (11), 1001-5.
- Helbig, I., Mefford, H.C., Sharp, A.J., Guipponi, M., Fichera, M., Franke, A., & Kron, K. L. (2009). 15q13. 3 microdeletions increase risk of idiopathic generalized epilepsy. Nature genetics, 41 (2), 160-162.
- Idiopathic Generalized Epilepsies . (S.f.). Retrieved on November 24, 2016, from Epilepsy Foundation.
- Ottman, R. (2015). Autosomal dominant partial epilepsy with auditory features. In: Pagon R.A., Adam M.P., Ardinger H.H., et al., Editors. GeneReviews. Seattle (WA): University of Washington.
- Ureña-Hornos, T., Rubio-Rubio, R., Gros-Esteban, D., Cabrerizo de Diago, R., Peña-Segura, J.L., & López-Pisón, J. (2004). Epilepsy with absences. Review of our 14 year experience. Rev. Neurol, 39, 1113-9.
- Shorvon, S. (s.f.). The Causes of Epilepsy: Idiopathic Epilepsy . Retrieved on November 24, 2016, from E-brain.