What is epilepsy, what are its types and symptoms? What causes seizures?

The success of treatment and prognosis of the disease are individual and take into account many factors, from the age of the patient to the type of seizure to adherence to specific regimens.

Epilepsy is a disease that imposes many limitations on the patient, significantly impairs quality of life, limits employment and ultimately can be life-threatening.

Epilepsy is a brain disease characterised as a predisposition to epileptic seizures with cognitive, psychological and social consequences.

A diagnosis of epilepsy requires at least one properly documented epileptic seizure.

Epilepsy is manifested by repeated, unprovoked seizures (i.e. during normal daily and life routines).

For a diagnosis of epilepsy, it is sufficient to have experienced only one seizure if further investigations such as electroencephalography (EEG) and magnetic resonance imaging (MRI) of the brain indicate a high risk of recurrence. The probability of recurrence must be at least 60 %.

An epileptic seizure is a transient condition caused by characteristic epileptic activity in the brain. This epileptic activity is caused by abnormal synchronisation, excessive excitation or insufficient inhibition of nerve cells in the brain.

A small group of cells may be involved, but a larger number of neurons may be affected.

Clinical symptoms depend on the area affected by the abnormal activity.

Seizures are either a manifestation of epilepsy or other acute brain damage (haemorrhage, ischaemia, trauma, infection, metabolic disease, intoxication, withdrawal symptoms, etc.).

Seizures are then referred to as acute or symptomatic episodes.

The disease ranks third among all neurological diseases, surpassed by cerebrovascular disease and dementia. About 50-80 new cases are diagnosed per 100 000 inhabitants each year. Approximately 50 million people suffer from it worldwide.

Epilepsy is most often diagnosed in the first year of a child's life. It has a second peak in incidence in old age, especially in people over 75.

The basis of epileptic seizure is hyperexcitability of the cerebral cortex. This phenomenon may reflect functional pathological changes or anatomical structural disorders. Genetic and external factors are involved.

The basic division of seizures is into unprovoked (idiopathic) and provoked (symptomatic).

Idiopathic seizures are most often caused by genetic factors and account for 30% of all seizures.

60% of seizures are caused by structural changes and 30% of seizures are of unknown aetiology. This means that their cause remains undetected.

Genetic causes of epilepsy

There are about 240 genetic mutations that can cause epilepsy.

For example, progressive myoclonic epilepsy is a manifestation of several genetic diseases, especially metabolic or neurocutaneous diseases.

Epilepsy is also a manifestation of genetic diseases such as tuberous sclerosis, neurofibromatosis type 1, Struge-Weber syndrome, Down syndrome, Fragmented X chromosome syndrome, Prader-Willi syndrome and many others.

Another large group of developmental disorders manifested by epilepsy are congenital malformations of the brain. So-called cortical dysplasias lead to small to large changes in the cerebral cortex.

These can be abnormalities of gyrification (brain gyri), for example, smooth brain surface, tiny gyri, or, on the contrary, too large and bulky gyri.

There is also what is called heterotopia. This is where the grey matter of the cerebral cortex is in unusual places, for example, in the depths of the white matter. Large malformations or dysplasia associated with tumours may be present.

Acquired causes

Underlying symptomatic epilepsies are disorders across the neurological spectrum.

Acute causes are distinguished, such as:

• metabolic disorders such as hypoglycaemia (low blood sugar).
• intoxication, e.g. alcohol poisoning
• use of drugs that can provoke seizures
• strokes
• head trauma
• neuroinfection

Chronic acquired epileptogenic causes:

• Hippocampal sclerosis (cell changes and reorganization with loss of neurons)
• cerebral palsy (CP)
• post-traumatic epilepsy, as a consequence of head trauma
• brain tumours
• vascular abnormalities in the brain
• post-inflammatory changes; brain abscess, viral herpetic encephalitis,
• autoimmune diseases such as autoimmune encephalitis, sclerosis multiplex, systemic lupus erythematosus
• post-vaccination epilepsy
• reflex epilepsy, triggered by a single constant provoking factor, e.g. flash of light, startling loud noises, etc.

The main manifestation of epilepsy is epileptic seizures.

The most basic division of seizures is into focal and generalized.

Such a division of seizures is essential for determining the targeted therapy. There are several types of antiepileptic drugs and some are effective only for one type of seizure, for example, focal seizures, while generalized seizures may be exacerbated.

The most recent seizure classification is from 2017 and was developed by the International League Against Epilepsy.

Focal seizures

These seizures have a focal clinical picture. There is also a circumscribed local activity on EEG scanning corresponding to the relevant brain centre that controls the part of the body where the seizure is manifesting.

At the same time, loss of consciousness with subsequent memory loss is not present.

Focal seizures can spread and turn into a generalised seizure.

They are further divided into motor seizures and seizures without motor manifestations.

Motor focal seizures have purely motor manifestations. They may be confined to a small part of the body or spread to multiple areas.

For example, they are manifested by so-called automatisms, which are cyclical repetitions of a certain movement or even the same words. Hyperkinetic seizures are manifested by agitation with repetition of distinctive movements, e.g. cycling.

Seizures without motor manifestations are autonomic. This means that the disorder occurs at the level of the autonomic nervous system.

They are manifested by:

• Vomiting
• piloerection (erection of hairs)
• redness
• dilation of the pupils (mydriasis)
• urination

Another type is cognitive seizures:

• behavioral seizures
• speech impairment
• memory impairment
• perceptual disturbance (dream states, disorientation to person and place)
• emotional seizures, such as mood changes, anxiety states

Sensory seizures:

• changes in sensitivity of body parts
• flashes before the eyes
• sound sensations
• perception of patterns
• disturbance of spatial perception

Generalized seizures

These are characterised by abnormal activity in both cerebral hemispheres. They are characterised by altered consciousness accompanied by motor symptoms and memory impairment.

Movement symptoms are bilateral and synchronous. EEG pathological curves are recorded from both cerebral hemispheres.

1. Myoclonic seizures

These are multiple, brief, violent contractions of single muscles or muscle groups of the limbs, trunk, face. The limbs are affected symmetrically. They involve dropping objects from the hands or falling to the ground.

2. Clonic seizures

These are repetitive twitches of the limbs with progressive strength and frequency.

3. Tonic seizures

These are manifested by a firm and violent contraction. This contraction fixes the limbs in a rigid and unnatural position.

4. Generalised tonic-clonic seizures

The most prominent feature is a disturbance of consciousness with a fall, tonic spasm of the face, limbs, respiratory muscles including the diaphragm, causing a sudden cry.

The patient turns blue, bites his tongue. Bloody saliva may come out of the mouth, he wets himself.

After the clonic spasm has passed, there is muscle relaxation, confusion, memory loss and disorientation for several tens of minutes.

5. Atonic seizures

These are characterised by a sudden drop of the head and a buckling of the legs followed by a fall. They are short seizures lasting about 4 seconds. They occur in so-called Doose syndrome, which affects children aged 7 months to 6 years.

6. Absence

These are very brief, sudden disturbances of consciousness with interruption of ongoing activity. They most often present only with staring, freezing, change in facial expression, blinking or twitching of the facial muscles.

The patient is not unconscious, but is not responsive or reactive. After the seizure, he or she continues smoothly with previous activity.

Sometimes the seizures are so subtle that they go unnoticed by others. However, they can be very numerous, disrupt concentration and may mimic a child's learning disability or other cognitive disorder.

Diagnosis is based on a thorough history, a detailed description of the seizure and a set of investigative methods.

A family history of seizures, the presence of psychiatric disorders, maternal illness during pregnancy, complicated childbirth with convulsions, suffocation, febrile convulsions in childhood, frequent collapses, history of nervous system infections and head injuries may point to the diagnosis.

Of the investigative methods, the following are of key importance:

• structural imaging, e.g. MRI
• electroencephalography and video-electroencephalography
• laboratory blood tests

Magnetic resonance imaging of the brain has greater sensitivity and specificity than brain CT. MRI can show various brain abnormalities, malformations, vascular anomalies and other pathologies that can only be registered on MRI images.

Electroencephalography (EEG) is the most important examination in the diagnosis of epilepsy.

It is a functional examination of brain activity.

It is performed using 16 electrodes attached to the surface of the head.

The examination lasts 20-30 minutes. During the examination, the patient performs various activating activities that can provoke hyperactivity of the cerebral cortex. Hyperventilation, photostimulation (flashing light), sleep deprivation (the patient is examined after a sleepless night) are mainly used.

This examination is of the highest diagnostic value when performed as soon as possible after the seizure. The aim is to determine more precisely what type of seizure it is. The diagnosis is confirmed by the detection of epileptiform waves.

If the waves are slow and regional, the seizure may be due to structural lesions of the brain. If the waves are generalized from both hemispheres, this is indicative of encephalopathy and metabolic origin of the seizures.

Video EEG monitoring

It is particularly useful in patients for whom no available medical therapy is working (i.e. they are pharmacoresistant).

It is performed as a conventional EEG examination with simultaneous filming of the patient and their seizures.

Chronic epilepsy medications are discontinued prior to the examination. Recordings vary in length, sometimes requiring up to 24 hours of monitoring.

The aim is to distinguish epileptic seizures from non-epileptic ones, e.g. psychogenic ones.

The second goal is to refine seizure classification if seizures are inconsistent. A third reason for performing video EEG may be for preoperative evaluation of a patient with pharmacoresistant epilepsy who is preparing for an epilepto-neurosurgical therapeutic intervention.

Laboratory tests

Laboratory tests should include glycaemia, sodium, pregnancy test. Lumbar puncture with lysate examination is needed to exclude neuroinfection and autoimmune process.

Differential diagnosis

The distinction between epileptic and non-epileptic seizures is essential, especially when deciding whether to initiate antiepileptic therapy.

The two most common differential diagnoses are syncope and psychogenic seizures.

Syncope

A sudden, short-term loss of consciousness that is accompanied by a fall. After syncope, the adjustment of consciousness is usually rapid. Various sensations, such as "lightness" of the head, darkness in front of the eyes, light-headedness, whistling in the ears, etc., are precursors of syncope.

Convulsions may be present during unconsciousness, at which time differentiation from epilepsy is more challenging. Cardiological examination is helpful, with ECG and ECG Holter testing which may point to a vascular or cardiac origin of the syncope.

Psychogenic seizures

Up to 20-30% of patients with suspected pharmacoresistant epilepsy actually have this type of seizure.

These are hysterical seizures, technically called dissociative or conversion seizures.

They are caused by a psychological defence mechanism that the patient uses unconsciously when he is unable to cope with previous psychological trauma.

This results in a splitting off (dissociation) of the psychological problem from consciousness. The patient is unable to cope with it any longer, which causes a psychiatric disorder. Often somatisation occurs. This means that these psychological problems start to manifest themselves in actual physical difficulties.

These seizures are very dramatic. There is usually no doubt that they are epileptic seizures. Only video EEG monitoring will give a correct diagnosis.

Epilepsy is a seizure disorder that usually has a sudden onset and rapid course.

An epileptic seizure can vary in duration depending on the type of seizure. Absence seizures last a few seconds, grand mal seizures last approximately 5 minutes. Status epilepticus is a condition that lasts up to 30 minutes and is a serious complication of epilepsy.

Before the seizure itself, patients may have a strange sensation known as an aura. It lasts for only a few seconds or a minute. Very often these sensations are localized to an area around the stomach.

After the seizure, patients suffer from momentary confusion, amnesia and drowsiness. This post-seizure state may last 10-20 minutes. It is a differential sign when there is doubt as to whether the seizure was epileptic or non-epileptic.

Forecast

In a 10-year follow-up of patients with epilepsy, approximately 60% of patients will reach 5 years without seizures.

The most important factor in the prognosis of the disease is the number of seizures in the first six months of treatment. The more seizures that occur, the less chance of achieving full control of the disease.

Only half of the patients can discontinue antiepileptic therapy without the risk of relapse. Discontinuation of treatment is considered if the patient has not had a single seizure for 2-3 years, has no epileptiform activity on EEG examination and has reached the age of 13-15 years.

In some syndromes accompanied by epilepsy, it is not possible to discontinue therapy at all and treatment becomes lifelong. This is the case in cases of generalized idiopathic epilepsy with clonicotonic grand mal convulsions.

The most serious syndrome in this disease is the syndrome of sudden and unexpected death in epilepsy (SUDEP).

This is the sudden death of an epilepsy patient, usually in sleep, without witnesses. The cause of such death has not been established. Decompensation in the early post-seizure period is presumed.

The incidence of SUDEP is estimated to be 1 in 100 severe epilepsy patients and 1 in 2500 milder epilepsy patients.

Risk factors are poor medication compensation of the disease, combination of multiple drugs, long duration of treatment and age 20-40 years.