Can you go through the article and explain me in detail and the changes that were made in this article
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python3 -c " import pdfplumber pdf_path = '/home/daytona/workspace/attachments/c8ae28e2-67ef-44ec-be6c-dc73672cb506/updated-classification-of-epileptic-seizures-2025.pdf' with pdfplumber.open(pdf_path) as pdf: print(f'Total pages: {len(pdf.pages)}') full_text = '' for i, page in enumerate(pdf.pages): text = page.extract_text() if text: full_text += f'\n\n=== PAGE {i+1} ===\n' + text print(full_text) "
I've extracted the full text of the article. Here is a detailed breakdown:
Updated Classification of Epileptic Seizures (ILAE 2025) - Full Explanation
Article: "Updated classification of epileptic seizures: Position paper of the International League Against Epilepsy"
Published in: Epilepsia, 2025 | DOI: 10.1111/epi.18338
Lead authors: Sándor Beniczky & Eugen Trinka (equal contributions), with 37+ international experts
1. Background and Why the Update Was Needed
The ILAE (International League Against Epilepsy) published its operational seizure classification in 2017. That paper itself noted that real-world use would reveal areas needing refinement. After 8 years of clinical application, debate, and published feedback (22 research papers + 19 reviews/opinion papers), the ILAE convened a working group in January 2023 to:
- Assess strengths and weaknesses of the 2017 version
- Propose adjustments while preserving the core framework
- Achieve consensus via a modified Delphi process (required >2/3 majority vote for each change)
A key outcome: the 2025 update reduces 63 seizure types (2017) down to 21 seizure types, while maintaining the same four main classes.
2. The Four Main Seizure Classes (Unchanged)
The overarching structure is preserved from 2017:
| Class | Description |
|---|---|
| Focal | Originates within networks limited to one hemisphere |
| Generalized | Rapidly engages bilaterally distributed networks |
| Unknown (whether focal or generalized) | Insufficient info to classify as focal or generalized, but clearly epileptic |
| Unclassified | No information available; can be reclassified later |
3. The Six Key Changes from 2017 to 2025
These are listed explicitly in Table 3 of the paper:
Change 1: "Onset" Removed from Main Seizure Class Names
| 2017 Term | 2025 Term |
|---|---|
| Focal-onset seizure | Focal seizure |
| Generalized-onset seizure | Generalized seizure |
| Unknown-onset seizure | Unknown whether focal or generalized |
Why? Evidence from animal and human studies shows that even "generalized" seizures often have a focal point of onset. Keeping "onset" in the name for generalized seizures was potentially misleading. The new names now align with the ILAE's own formal definitions in position papers.
Change 2: Formal Distinction Between Classifiers and Descriptors (Taxonomic Rules)
The 2025 classification introduces clear taxonomic rules to differentiate:
-
Classifiers - Features that reflect biological seizure classes AND directly affect clinical management (syndrome diagnosis, medication choice, prognosis, surgical decisions). These define the seizure types.
- Examples: main seizure class (Focal/Generalized/Unknown), seizure type, level of consciousness
-
Descriptors - Important clinical characteristics that indirectly help management when combined with other data, but do not define the seizure type.
- Examples: motor phenomena (tonic, clonic, myoclonic), autonomic features, sensory features, cognitive features
This distinction was not clearly codified in 2017, leading to confusion in databases and clinical practice. The 2025 version provides a numbered taxonomic hierarchy (Table 1) specifically designed for use in electronic databases.
Change 3: "Consciousness" Replaces "Awareness" as the Classifier - with Operational Definition
This is one of the most debated changes:
| 2017 | 2025 |
|---|---|
| Aware / Impaired Awareness | Preserved Consciousness / Impaired Consciousness |
How consciousness is now operationally defined:
- Awareness = assessed by recall (can the patient remember what happened during the seizure?)
- Responsiveness = assessed by verbal and motor tasks (does the patient respond appropriately during the seizure?)
- If either is impaired in any way → seizure is classified as impaired consciousness
Why this change?
- "Consciousness" is a universally accepted, translatable medical term used across neurology (e.g., in differential diagnosis of transient loss of consciousness)
- "Awareness" was problematic to translate into Spanish, French, Portuguese, German, and other languages
- Many clinicians incorrectly used "impaired awareness" to mean "unresponsive," which is technically wrong
- In children under 4-5 years, awareness is very hard to assess, but responsiveness can be tested with age-appropriate methods
- The 2017 term "impaired awareness" was being misapplied to mean "impaired responsiveness," when they are distinct concepts
Practical guidance: Clinicians should ask patients/caregivers specifically about recall (awareness) and responsiveness during the seizure, then draw their own conclusion about consciousness. Seizures with impaired consciousness are automatically considered to have observable manifestations.
Change 4: "Motor vs. Nonmotor" Replaced by "Observable vs. Without Observable Manifestations"
| 2017 (Basic Classification) | 2025 (Basic Version) |
|---|---|
| Motor seizure / Nonmotor seizure | With observable manifestations / Without observable manifestations |
Why? "Nonmotor" was misleading - for example, absence seizures are classified as "nonmotor" in 2017, yet they frequently show motor features like eye blinks, automatisms, head retropulsion, and eyelid myoclonia. The new dichotomy is more accurate and more practical for clinical trials and resource-limited settings.
Observable manifestations are defined as: easily identified by eyewitnesses, non-volitional, and can include motor, aphasic, autonomic, or other features.
Two versions of seizure description exist:
- Basic version: Simply "with observable manifestations" or "without observable manifestations"
- Expanded version: Describes the full chronological sequence of semiological features using arrows (e.g., epigastric aura → oroalimentary automatisms → impaired responsiveness)
Change 5: Chronological Sequence of Semiology (Expanded Version)
The 2017 classification classified seizures primarily based on the first semiological sign. This was found to have limited clinical relevance - it does not guide medication choice, prognosis, or surgical localization in a reliable way.
The 2025 classification now describes seizures using the full chronological sequence of ictal events in the expanded version. This approach is:
- More relevant to presurgical evaluation
- More useful in long-term video-EEG monitoring units
- Better for characterizing the epileptic network
Example (from the paper): auditory aura → receptive aphasia → impaired responsiveness → postictal confusion
Change 6: Epileptic Negative Myoclonus Recognized as a Seizure Type
Epileptic negative myoclonus - a sudden, brief interruption of muscle tone caused by epileptic activity - was well-documented in the literature and included in the ILAE semiology glossary, but was not included as a seizure type in 2017.
The 2025 classification now formally recognizes:
- Generalized Negative Myoclonic Seizure (GNM) as a distinct seizure type under "Other Generalized Seizures"
- Epileptic negative myoclonus as a descriptor (semiological feature) for focal seizures and unknown origin seizures
Important note: epileptic negative myoclonus is distinct from the asterixis seen in toxic-metabolic encephalopathies.
4. Additional Notable Changes (Beyond the 6 Core Changes)
Absence Seizures: "Nonmotor" Removed
In 2017, absences were categorized under "nonmotor" seizures. This label has been removed in 2025 because absence seizures frequently have motor features - automatisms, head retropulsion, eye blinks, myoclonic jerks (myoclonic absence), and eyelid myoclonia are all motor phenomena characteristic of specific absence subtypes.
Absence seizure subtypes (unchanged):
- Typical absence
- Atypical absence
- Myoclonic absence
- Eyelid myoclonia with/without absence
Epileptic Spasms: Dual Classification Role
- In generalized seizures: epileptic spasm remains a seizure type (classifier) - associated with infantile epileptic spasms syndrome (IESS)
- In focal and unknown origin seizures: epileptic spasm is now a descriptor (e.g., "focal epileptic spasm") within seizure semiology
- A decision flowchart (Figure 3) was added to guide clinicians in classifying epileptic spasms and linking them to syndromic diagnosis and treatment
This distinction matters because pharmacological treatment differs: focal epileptic spasms may warrant early surgical evaluation if spasm-specific therapies fail.
5. The Full 2025 Seizure Classification Structure (21 Types)
Focal Seizures
- 1.1 Focal Preserved Consciousness Seizure (FPC)
- 1.2 Focal Impaired Consciousness Seizure (FIC)
- 1.3 Focal-to-Bilateral Tonic-Clonic Seizure (FBTC)
Unknown Whether Focal or Generalized
- 2.1 Unknown - Preserved Consciousness (PC)
- 2.2 Unknown - Impaired Consciousness (IC)
- 2.3 Unknown - Bilateral Tonic-Clonic (BTC)
Generalized Seizures
Absence Seizures:
- 3.1.1 Typical Absence (TA)
- 3.1.2 Atypical Absence (AA)
- 3.1.3 Myoclonic Absence (MA)
- 3.1.4 Eyelid Myoclonia with/without Absence (EMA)
Generalized Tonic-Clonic:
- 3.2 Generalized Tonic-Clonic (GTC)
- 3.2.1 Myoclonic Tonic-Clonic
- 3.2.2 Absence-to-Tonic-Clonic
Other Generalized Seizures:
- 3.3.1 Generalized Myoclonic (GM)
- 3.3.2 Generalized Clonic (GC)
- 3.3.3 Generalized Negative Myoclonic (GNM) ← NEW
- 3.3.4 Generalized Epileptic Spasms (GES)
- 3.3.5 Generalized Tonic (GT)
- 3.3.6 Generalized Atonic (GA)
- 3.3.7 Generalized Myoclonic-Atonic (GMA)
Unclassified
- Temporary class; reclassified when more information becomes available
6. Emphasis on Translatability and Global Use
Special effort went into ensuring the classification can be used worldwide:
- The classification has been translated into 14 languages: Arabic, Chinese, Danish, French, German, Hungarian, Italian, Japanese, Korean, Portuguese, Romanian, Russian, Spanish, and Ukrainian
- The term "consciousness" (vs. "awareness") was chosen partly because it translates better across all these languages
- The classification is designed for both resource-limited settings and highly specialized epilepsy centers
7. Process and Methodology
- Working group: 37 experts from all ILAE regions (North America, Latin America, Europe, Eastern Mediterranean, Asia-Oceania, Africa); 23 adult epileptologists + 13 pediatric epileptologists + 1 neurosurgeon
- Systematic review: 41 articles reviewed (22 research + 19 reviews/opinions)
- Delphi process: 7 rounds of iterative voting; >2/3 majority required for any change; unanimous final approval
- Public comment period: August-October 2024; 44 comments received; a revision task force then further refined the document
- Final approval: ILAE Executive Committee
8. Summary of All Changes at a Glance
| # | Change | From (2017) | To (2025) |
|---|---|---|---|
| 1 | Class names | "Focal-onset", "Generalized-onset", "Unknown-onset" | "Focal", "Generalized", "Unknown whether focal or generalized" |
| 2 | Taxonomic rules | Not formally defined | Classifiers vs. Descriptors explicitly distinguished |
| 3 | Consciousness classifier | Awareness (aware/impaired awareness) | Consciousness (preserved/impaired), defined by awareness + responsiveness |
| 4 | Basic descriptor dichotomy | Motor vs. Nonmotor | Observable vs. Without observable manifestations |
| 5 | Seizure description | First semiological sign | Chronological sequence of full seizure semiology |
| 6 | New seizure type | Not included | Epileptic negative myoclonus added |
| Bonus | Absence categorization | Under "nonmotor" | "Nonmotor" label removed from absence seizures |
| Bonus | Total seizure types | 63 | Simplified to 21 |
The overarching goal of these changes is to make seizure classification more clinically accurate, globally applicable, translatable, and consistent with broader neurological terminology - while preserving the core 2017 framework so that seizures already classified can be easily converted to the 2025 system (e.g., "impaired awareness" simply maps to "impaired consciousness").
seizure semiology
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seizure semiology classification clinical features epilepsy 2025
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Here is a comprehensive explanation of seizure semiology, drawing on the article you shared and authoritative textbook content from Bradley and Daroff's Neurology in Clinical Practice:
Seizure Semiology - A Complete Guide
What Is Seizure Semiology?
Semiology (from Greek: semeion = sign) refers to the clinical signs and symptoms that occur during a seizure - the observable and subjective manifestations from ictal onset to postictal period. It is essentially the "language" a seizure speaks about where it starts in the brain and how it spreads.
Semiology answers:
- What does the patient look like during a seizure?
- What does the patient feel during a seizure?
- What does the sequence of events tell us about the brain's epileptic network?
Role of Semiology in the 2025 ILAE Classification
In the updated 2025 classification, semiology has a specific, defined role within the taxonomic hierarchy:
- Semiology features are Descriptors - they characterize the seizure but do NOT alone define the seizure type (that is the role of classifiers like seizure class and level of consciousness)
- Semiology is used in two layers:
- Basic version: A simple dichotomy - seizure is described as "with observable manifestations" or "without observable manifestations"
- Expanded version: The full chronological sequence of semiological features is listed using arrows to show seizure evolution (e.g., epigastric aura → oroalimentary automatisms → impaired responsiveness → postictal confusion)
This is a key change from 2017, which used only the first observed semiological sign as a classifier. The 2025 classification recognizes the entire sequence as more clinically meaningful.
The Two Types of Semiological Features
A. Observable Manifestations
These are features visible to a bystander. They are non-volitional and include:
| Category | Examples |
|---|---|
| Elementary motor | Clonic jerking, tonic stiffening, myoclonus, atonic (drop), epileptic spasms, dystonic posturing, eye deviation |
| Complex motor | Automatisms (oroalimentary, gestural, hyperkinetic), versive movements |
| Autonomic | Flushing, piloerection, sweating, ictal tachycardia, apnea |
| Affective | Laughter (gelastic), crying (dacrystic) - visible to observer |
B. Non-Observable Manifestations (Subjective/Aura)
These are felt by the patient only - the aura - and represent the seizure's initial manifestation before spread:
| Category | Examples |
|---|---|
| Sensory | Epigastric rising sensation, somatosensory, visual (colors, flashes), auditory (tones), olfactory, gustatory, vestibular/dizziness |
| Cognitive/language | Déjà vu, jamais vu, dreamy state, forced thinking, dysmnesia, aphasia |
| Affective | Fear, anxiety, ecstatic feeling, sadness, mirth |
| Indescribable aura | Patient cannot put it into words |
An aura is itself a focal seizure with preserved consciousness - it represents ictal activity confined to a symptomatogenic cortical zone.
Semiological Localization: What Semiology Tells You About the Brain
One of the most powerful clinical uses of semiology is localization and lateralization of the seizure focus. The 2025 classification's emphasis on chronological sequence directly serves this purpose.
Temporal Lobe Seizures
Mesial Temporal (Amygdalohippocampal) Origin:
- Most common type, associated with hippocampal sclerosis
- Aura: Rising epigastric sensation (most classic), fear/anxiety, déjà vu/jamais vu, palpitation, gooseflesh
- Consciousness: Altered, often associated with arrest of motion and speech
- Automatisms: Oroalimentary automatisms are most prominent (lip smacking, chewing, swallowing); ipsilateral hand automatisms (picking, fumbling)
- Lateralizing signs: Contralateral upper limb dystonic posturing; postictal aphasia suggests dominant (left) hemisphere
- Duration: 30 seconds to 3 minutes
Lateral (Neocortical) Temporal Origin:
- Aura: Auditory hallucinations, vertigo, complex visual hallucinations
- Oroalimentary automatisms less common
- Tend to be shorter and evolve to bilateral tonic-clonic more frequently
Frontal Lobe Seizures
- Often nocturnal, brief, cluster in sleep
- Hyperkinetic/hypermotor behavior: Vigorous cycling, thrashing, pelvic thrusting
- Tonic posturing (often asymmetric - "fencing posture")
- Minimal or no postictal confusion (short postictal period)
- May have vocalization
Parietal Lobe Seizures
- Sensory aura: Contralateral somatosensory sensations (tingling, numbness, pain)
- May spread to produce motor phenomena
- Receptive or expressive language disturbance if dominant hemisphere
Occipital Lobe Seizures
- Visual aura: Elementary visual hallucinations (colored spots, flashes, circles), usually contralateral
- May have eye deviation or forced blinking
- May spread to temporal lobe and produce automatisms
Key Semiological Terms (From ILAE Glossary)
| Term | Definition |
|---|---|
| Aura | Subjective ictal phenomenon preceding observable signs; a focal seizure with preserved consciousness |
| Automatism | Repetitive, semi-purposeful motor activity during altered consciousness (oroalimentary, gestural, verbal) |
| Tonic | Sustained muscle contraction lasting seconds to minutes |
| Clonic | Rhythmic, repetitive jerking movements |
| Tonic-clonic | Tonic phase followed by clonic phase (the classic "grand mal") |
| Myoclonic | Brief (< 100ms), sudden muscle jerk |
| Atonic | Sudden loss of muscle tone - head drop or fall |
| Epileptic spasm | Brief flexion/extension of trunk and limbs, lasting 1-2 seconds; characteristic of infantile spasms |
| Epileptic negative myoclonus | Sudden, brief interruption of tonic muscle activity due to ictal discharge (NEW in 2025) |
| Versive | Forced, sustained, unnatural turning of the head/eyes (late versive = contralateral to focus) |
| Dystonic posturing | Sustained twisting limb posture due to simultaneous agonist-antagonist muscle contraction; contralateral to focus |
| Hyperkinetic | Vigorous proximal limb or axial movements (cycling, thrashing) |
| Gelastic | Ictal laughter (hypothalamic hamartoma, or temporal/frontal) |
| Ictal paresis | Weakness during a seizure |
Semiological Lateralizing Signs
These signs help identify which hemisphere a seizure originates from:
| Semiological Sign | Lateralization |
|---|---|
| Contralateral dystonic upper limb posturing | Contralateral to focus |
| Late forced head turning (versive) | Contralateral to focus |
| Early head turning | Ipsilateral to focus |
| Unilateral clonic activity | Contralateral to focus |
| Ipsilateral hand automatisms | Ipsilateral to focus (unaffected side) |
| Postictal aphasia | Dominant (usually left) hemisphere |
| Postictal Todd's paresis | Contralateral to focus |
| Figure-of-four arm posture | Extended arm contralateral to focus |
| Ictal speech (well-formed) | Non-dominant hemisphere |
Postictal Semiology
The period after a seizure also carries diagnostic information:
- Postictal confusion - common after temporal or generalized seizures; minimal after frontal lobe seizures
- Postictal aphasia - suggests dominant hemisphere temporal lobe involvement
- Todd's paresis - focal weakness contralateral to seizure focus; can last minutes to hours; indicates motor cortex involvement
- Headache - common after generalized tonic-clonic seizures
- Nose wiping - patients often wipe the nose ipsilateral to the temporal seizure focus in the postictal phase
Semiology in the 2025 Classification: Expanded Version Example
The article provides clear clinical examples of how semiology is recorded in the expanded version:
Example 1 - Focal Impaired Consciousness Seizure (FIC):
auditory aura → receptive aphasia → impaired responsiveness → postictal confusion (Temporal lobe, dominant hemisphere origin)
Example 2 - Focal Preserved Consciousness Seizure (FPC):
epigastric aura → oroalimentary automatisms + gestural automatisms (right hand) + preserved awareness and responsiveness (Mesial temporal, non-dominant or dominant)
Example 3 - Focal-to-Bilateral Tonic-Clonic (FBTC):
elementary visual aura on left → versive to left + loss of awareness and responsiveness → bilateral tonic-clonic (Occipital/posterior, right hemisphere → bilateral spread)
Why Semiology Matters Clinically
- Guides syndrome diagnosis - e.g., eyelid myoclonia + absence = Jeavons syndrome; hypermotor + tonic + spasms = suspect CDKL5 deficiency
- Guides medication choice - e.g., myoclonic seizures narrow the antiseizure medication selection; absence seizures have specific treatments
- Presurgical evaluation - semiology (especially by video-EEG) is key to identifying the epileptogenic zone before surgery
- Prognosis - seizure type/semiology informs likelihood of drug resistance
- Communication - a standardized semiological vocabulary allows consistent descriptions across clinicians, databases, and research
- Bradley and Daroff's Neurology in Clinical Practice, Chapter 100: Focal Seizure Semiology in Relation to Localization
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