11A. Types of epilepsy (and epileptic seizures)

Epileptic seizures

Definition and epidemiology

Epileptic seizures are single transient events caused by excessive or synchronous neuronal activity in the brain. There are many different types.

Etiology

  • Provoked seizures (topic 1B)
  • Symptomatic seizures (topic 1B)
  • Epilepsy

Epilepsy is the least frequent cause of epileptic seizures.

Classification

Epileptic seizures are classified according to whether they originate from a circumscribed region of the brain, like a lobe or hemisphere, or from the entire brain.

  • Partial or focal seizures – those which originate from a circumscribed brain region
    • Simple partial seizure (focal seizure with awareness)
    • Complex partial seizure (focal seizure without awareness)
  • Generalised seizures – those which originate from the entire brain
    • Absence seizure
    • Myoclonic seizure
    • Generalised tonic-clonic seizures (grand mal)

Simple partial seizure (focal seizure with awareness)

Simple partial seizures are the only type in which the consciousness of the patient is preserved. As a partial seizure, they originate from a circumscribed part of the brain.

The exact features depend on the part of the brain involved. If the occipital cortex is involved, the patient may see flashing lights. If the motor cortex is involved, the patients may have jerking of a contralateral body part. If the frontal lobe is involved, the patient may have problems with speech.

There is no post-ictal tenebrosity.

Complex partial seizure (focal seizure without awareness)

Complex partial seizures originate from a circumscribed part of the brain and cause impaired consciousness. They may be preceded by simple partial seizures.

Patients appear awake but are unresponsive. They may stare into space or perform automatisms, like chewing, lip smacking, grimacing, etc.

There is post-ictal tenebrosity afterward, where the patient is tired, confused, and don’t remember the incidence.

Absence seizures

Absence seizure is a type of generalised seizure. The consciousness is impaired. They mostly occur in children and adolescents, not frequent in adults.

The patient suddenly becomes unresponsive and stares blankly in the middle of an activity. The unresponsiveness lasts for only a few seconds, and they can occur hundreds of times a day. The patient is usually unaware of the interruption.

There is no post-ictal tenebrosity.

Myoclonic seizure

Myoclonic seizure is a type of generalised seizure. The consciousness may be impaired but not always. It usually occurs in epilepsy syndromes.

The patient experiences sudden, brief muscle contractions (myoclonus) which can affect a single body part, multiple body parts, or the entire body.

There is no post-ictal tenebrosity.

Generalised tonic-clonic seizure (grand mal)

This is the most famous type of seizure, and the most important. The consciousness is impaired. Any type of seizure can progress into this type.

As the name suggests, there are two phases. In the tonic phase there is generalised tonic muscle contraction, which usually causes extension of the limbs. The patient may form a “cry” as air is expelled out of their lungs. Due to tonic contraction of the respiratory muscles, there is apnoea which can lead to cyanosis.

The tonic phase is followed by a clonic phase with rhythmic muscle twitching.

During either of the phases, the patient may bite the lateral aspect of their tongue and have bladder incontinence.

There is post-ictal tenebrosity afterward, where the patient is tired, confused, and don’t remember the incidence. The patient usually also has muscle pain due to the clonus.

Epilepsy

Definition

The term epilepsy is used to describe a person who has an underlying predisposition to epileptic seizures, so that they have recurrent epileptic seizures without provocation. This can be due to an epilepsy syndrome, or due to the damaging effects of a stroke, tumour, trauma, etc.

Epilepsy syndromes are chronic conditions with typical clinical features, typical age of onset, typical types of seizures, and typical etiology. Some epilepsy syndromes include:

  • Temporal lobe epilepsy
  • Juvenile myoclonic epilepsy
  • West syndrome

Evaluation

Video-EEG is essential for the evaluation, as well as neuroimaging. Video-EEG refers to the use of video monitoring simultaneously as EEG. It may also be helpful to introduce provoking factors like sleep deprivation.

Treatment

70% of epileptic patients become seizure-free on chronic drug treatment. The type of drug depends on the type of epileptic seizure the patient has.

Focal or partial epilepsy is treated with focal antiepileptic drugs, like carbamazepine, oxcarbamazepine, and phenytoin.

Generalised epilepsy is treated with broad-spectrum antiepileptic drugs, like valproate, lamotrigine, levetiracetam.

If drug treatment is ineffective and the epilepsy is related to a specific location, we can perform epilepsy surgery. Most patients become seizure-free after surgery.

The last option for epilepsy is neuromodulation, either deep brain stimulation or vagus nerve stimulation.


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