What is not epilepsy
A diagnosis is not made on the basis of a single ("accidental") seizure. In addition, seizures provoked by obvious external or acute internal factors are not classified as epilepsy:
- Acute structural brain damage: the hyperacute period of a stroke, recent traumatic brain injury, encephalitis, a rapidly growing tumor, or a hematoma.
- Toxic-metabolic disorders: severe hypoglycemia, alcohol intoxication, or other substance intoxication.
Febrile seizures in children (occurring against the background of high fever) last no longer than 10 minutes and are also not considered epilepsy. Only 3% of such patients develop true epilepsy later in life.
Etiology and general classification
By origin, epilepsy is divided into two major groups:
- Idiopathic form: there is no structural brain damage, and the disease is primary in nature.
- Symptomatic form: seizures are the consequence of an organic defect—a prior infection, circulatory disorder, trauma, developmental anomaly, or cyst.
Depending on the localization and spread of the neuronal discharge, seizures are classified as generalized (affecting both hemispheres) and focal, or partial (the discharge is limited to a specific area of the cortex).
Generalized convulsive seizures
The main sign of a generalized seizure is loss of consciousness. A classic major convulsive seizure proceeds through several successive phases:
- Tonic phase: sudden loss of consciousness and a fall. Due to vocal cord spasm and diaphragmatic contraction, the patient may emit a cry. All muscles tense up abruptly, the jaws clamp shut (risk of tongue biting), breathing stops, and cyanosis develops. Involuntary urination is characteristic due to contraction of the abdominal wall muscles.
- Clonic phase: rhythmic twitching of the limbs, trunk, and face begins. Foaming at the mouth may occur.
- Postictal stage: seizures cease, muscles relax (atonia), and shallow breathing resumes. Consciousness returns after a few minutes, but the patient remains drowsy and confused for another 10–30 minutes. Complete amnesia for the events of the seizure develops.
Non-convulsive seizures (absence seizures)
Absence seizures are short, generalized, non-convulsive episodes of loss of consciousness. They occur predominantly in childhood (4–12 years) and can recur dozens of times a day.
During a simple absence seizure, the child does not fall but suddenly freezes (a blank stare is noted, sometimes with blinking). After 2–10 seconds, consciousness clears, and the patient continues the interrupted activity without noticing the memory "gap". Complex absence seizures are accompanied by mild involuntary movements or a sharp drop in muscle tone (atonic variant).
Focal seizures
Focal seizures reflect the function of the cortical zone where the discharge originated. Their duration ranges from 10 seconds to 3 minutes. They are divided into:
- Simple: occur with clear consciousness. They can be motor (twitching in one arm/leg), sensory (numbness, flashes of light), or autonomic (nausea, sweating). A striking example is the Jacksonian march, where seizures begin locally and "crawl" across an entire half of the body.
- Complex: consciousness is altered. The patient may perform unconscious automatic actions (lip-smacking, swallowing, aimless walking), experience hallucinations or psychic phenomena—depersonalization, derealization, the feeling of déjà vu ("already seen") or jamais vu ("never seen").
Diagnostic Principles
The diagnosis is established based on the clinical presentation and electroencephalography (EEG) data. A typical EEG pattern in absence seizures is spike-wave discharges at a frequency of about 3 Hz.
Because interictal pathological activity is visible in only half of patients, provocative tests are used: hyperventilation, intermittent photic stimulation, sleep deprivation, or multi-hour video-EEG monitoring.
Golden rule: a normal interictal EEG does not rule out a diagnosis of epilepsy, and the presence of epileptiform waves without clinical seizures is not a basis for making a diagnosis.
Briefly: answers to topical questions
What forms of epilepsy are distinguished by etiology according to the modern classification?
According to etiology, several main forms of epilepsy are distinguished. Following the current classification (ILAE, 2017), etiology is divided into:
- Structural
- Genetic
- Infectious
- Metabolic
- Immune
- Unknown
Also, the basic taxonomy distinguishes:
- Idiopathic forms — no structural brain pathology is detected.
- Symptomatic forms — caused by organic brain damage (trauma, infections, tumors, circulatory disorders).
What types of motor disorders can be observed during simple focal seizures?
During simple focal seizures, various motor disorders may be observed while consciousness remains intact.
- Focal motor seizures — manifest as repetitive movements in one part of the body, as well as masticatory, rotatory (twisting), and postural-tonic movements.
- Jacksonian march — the most illustrative variant, in which clonic seizures begin in isolated muscles (of an arm or leg) and sequentially spread to the entire half of the body.
Which drugs are first-line agents for terminating status epilepticus?
First-line agents for terminating status epilepticus are benzodiazepine derivatives.
- Diazepam (Diazepam) — the drug of choice, administered intravenously slowly.
- Lorazepam (Lorazepam) is superior to diazepam in terms of efficacy for terminating status epilepticus.
- Clonazepam (Clonazepam) — administered intravenously for emergency care.
Phenytoin is also mentioned as a drug of choice for intravenous administration.
Which antiseizure medications are prescribed for the baseline therapy of generalized convulsive seizures?
A wide range of antiseizure medications is prescribed for the baseline therapy of generalized convulsive seizures. These include:
- Valproic acid preparations
- Gabapentin
- Zonisamide
- Carbamazepine
- Lamotrigine
- Levetiracetam
- Oxcarbazepine
- Pregabalin
- Tiagabine
- Topiramate
- Phenytoin
- Phenobarbital
Drugs are selected individually, starting with monotherapy at the minimum dose. Clonazepam and ethosuximide are not used for treating this type of seizure.
To easily remember the differences in focal seizures: Simple — Sensed clearly (consciousness is preserved), Complex — Clouded (consciousness is altered).
Class and exam questions
Can a diagnosis be made after a single seizure?
No, the diagnosis is made only in the presence of recurrent unprovoked seizures. A single episode may be accidental or situationally provoked.
Do febrile seizures in children always turn into epilepsy?
No. True epilepsy develops in the future in only 3% of children who have experienced febrile seizures.
What is the «Jacksonian march»?
This is a variant of a simple focal motor seizure, inซึ่ง clonic twitching begins in a local muscle group (e.g., in the fingers) and gradually spreads to the entire half of the body.
Does a normal EEG rule out the presence of epilepsy?
No. During the interictal period, epileptiform activity is recorded in only half of patients. To increase accuracy, provocative methods and video-EEG monitoring are used.
What else to study on this topic
- Status epilepticus: criteria for a life-threatening condition
- Types of epileptic auras (olfactory, visual, auditory) and their topical significance
- Differential diagnosis between simple and complex absence seizures
- Comorbid cognitive and emotional disorders in long-standing disease
- Secondary generalized seizures: mechanism of transition of a focal discharge to both hemispheres
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