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

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

What is focal epilepsy?

The different types of epilepsy differ from each other in different clinical dimensions. One of the most relevant is the degree of generalization of electrochemical dysfunction from a brain 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 the episodes of brain activity dysfunction, which causes the seizures, begin in a particular area of the brain, although it can later extend to the entire brain. When this phenomenon occurs we speak of “secondary generalization”.

In contrast, generalised or “grand mal” epileptic seizures affect the whole brain , or a large part of it, from the moment they start. Generalised epilepsy is associated to a greater extent than focal epilepsy with the appearance of the epileptic aura, a set of prodromes which include alterations in sensory perception or psychological confusion.

In the literature we can also find references to the involvement of one or both hemispheres in 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 seizures, especially if they affect a wide brain region.

Symptoms of partial seizures

Sometimes focal epileptic seizures affect the level of alertness, awareness and memory, and may also influence observable behaviour. In these cases we speak of partial or complex focal seizures , while if there are no alterations in the memory and consciousness is maintained they are considered simple focal seizures.

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

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

  • Sudden onset of intense emotions
  • Feeling of nausea
  • Sensation of moving or falling to the ground, distorted perception of space
  • Sensory disturbances and olfactory, auditory, tactile, taste and visual hallucinations
  • Dissociative phenomena: depersonalization and de-realization
  • Abnormal muscle contractions
  • Behavioral automatisms, e.g. walking or chewing
  • Lateral eye movements, pupil dilation
  • Increased heart rate
  • Sweating
  • Abdominal pain and discomfort
  • Difficulty or inability to speak

In addition the symptoms depend on the affected brain lobes . If the crisis occurs in the frontal lobe, strange movements and difficulties in speaking may appear; if in the temporal lobe, fear, automatism and déjà vu; if in the parietal lobe, tactile sensations and distortions in perception; and if they occur in the occipital, dysfunctions and sensations in the eyes.

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

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 tumours is a very relevant risk factor.

It is common for focal epilepsy, especially when it begins in adulthood, to appear as a result of various factors that damage the brain. These include ischemic strokes, head injuries , tumours and brain infections. In other cases the cause of focal epilepsy is unknown.

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

Treatment of this disorder

Epilepsy, both focal and generalized, is usually managed by drug treatment. Common antiepileptic drugs include gabapentin, lamotrigine, topiramate, valproate, and oxcarbazepine. The adoption of a ketogenic (low carbohydrate, high protein) diet may also be helpful.

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In some severe cases of focal epilepsy, surgery may be recommended to prevent further risk or decrease interference with life. This type of surgery consists of removing the part of the brain with which the epilepsy is associated so that episodes of dysregulation of the brain’s electrical activity disappear.

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