Focal or partial epilepsy: causes, symptoms and treatment

We know as "epilepsy" a group of disorders of the nervous system that is characterized by the predisposition to episodes of abnormal brain electrical activity leading to seizures and other symptoms. Sometimes other brain alterations associated with epilepsy also appear, such as delayed cognitive development.

In this article we will describe the causes, symptoms and treatment of partial or focal epilepsy, the most frequent subtype of this disease, which is defined by the alteration of electrical activity in limited regions of the brain.

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What is focal epilepsy?

The different types of epilepsy differ from each other by different clinical dimensions. One of the most relevant is the degree of generalization of the electrochemical dysfunction from a cerebral point of view; In this sense, the fundamental divergence is that between focal or partial epilepsy and generalized epilepsy.

We speak of partial epilepsy when there is a clear predominance of partial seizures. This means that episodes of dysfunction in brain activity, the cause of seizures, They begin in a specific area of ​​the brain, although it can later spread to all of this area. organ. When this phenomenon occurs, we speak of “secondary generalization”.

On the contrary, Generalized or “grand mal” seizures affect the entire brain, or a large part of it, from the moment they start. Generalized epilepsy is associated to a greater extent than focal epilepsy with the appearance of aura epileptic, a cluster of prodromes including disturbances in sensory perception or confusion psychological.

In the literature we can also find references to the involvement of one or both hemispheres when distinguishing between focal and generalized epilepsy. Loss of consciousness and epileptic aura are more characteristic of generalized seizures, although they can also occur in partial ones, especially if they affect a wide brain region.

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Symptoms of partial seizures

Focal epileptic seizures sometimes affect alertness, consciousness, and memory, and may also influence observable behavior. In these cases we are talking about focal or complex partial seizures, while if there are no alterations in memory and consciousness is maintained, they are considered simple focal seizures.

Another relevant difference is that the epileptic aura is more common in complex seizures than in simple ones. Symptoms and signs of focal epilepsy they can also vary greatly depending on which brain regions are affected.

The most common phenomena associated with partial seizures are the following:

• Sudden onset of intense emotions
• feeling nauseated
• Sensation of moving or falling to the ground, distorted perception of space
• Sensory disturbances and olfactory, auditory, tactile, gustatory, and visual hallucinations
• Dissociative phenomena: depersonalization and derealization
• abnormal muscle contractions
• Behavioral automatisms, for example walking or chewing
• Lateral eye movements, pupillary dilation
• Incrise of cardiac frecuency
• sweating
• Abdominal pain and discomfort
• Difficulty or inability to speak

Besides symptoms depend on which brain lobes are affected. If the crisis occurs in the frontal lobe, strange movements and difficulties to speak may appear; if in the storm, fear, automatisms and déjà vu; if in the parietal, tactile sensations and distortions in perception; and if they occur in the occipital, dysfunctions and sensations in the eyes.

As we have said previously, some partial seizures spread to the rest of the brain after starting in a specific region of the brain; it is this last aspect that gives them the consideration of focal points. The size of the brain area affected by the electrical alteration influences the degree of significance of the symptoms.

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Causes of this type of epilepsy

Partial epilepsy is the most common type of this disease.. It is especially common in the elderly (around 65 years of age or older), and the presence of cerebrovascular disorders or brain tumors is a highly relevant risk factor.

It is common for focal epilepsy, especially when it begins in adulthood, to appear as a consequence of different factors that damage the brain. Among these are ischemic strokes, head injuries, tumors and brain infections. In other cases the cause of focal epilepsy is unknown.

In children it is more common that the cause does not occur as a consequence of factors such as these, but that it is of a primary nature; in these cases we speak of “idiopathic epilepsy”. It is worth mentioning the existence of benign childhood focal epilepsy, which is characterized by the presence of focal seizures, by its relative mildness and by disappearing during adolescence.

Treatment of this alteration

Epilepsy, both focal and generalized, is generally managed by pharmacological treatment. The most common antiepileptic drugs include gabapentin, lamotrigine, topiramate, valproate, and oxcarbazepine. It can also be very useful to adopt a ketogenic diet (low in carbohydrates and high in protein).

In some severe cases of focal epilepsy it may be advisable to carry out a surgical intervention to prevent further risks or reduce interference in life. This type of surgery consists of remove the part of the brain with which epilepsy is associated so that episodes of dysregulation of brain electrical activity disappear.

However, the variability of the treatments is high; when their manifestation is particularly benign, epilepsy spectrum disorders may not have significant consequences or require any type of treatment.