Seizure types

In ~2500 B.C., the Sumerians provided the first writings about seizures.[3]^: 458 Later in ~1050 B.C., the Babylonian scholars developed the first seizure classification, inscribing their medical knowledge in the stone tablets called Sakikku or in English "All Diseases."[3]^: 458 This early classification identified febrile seizures, absence seizures, generalized tonic-clonic seizures, focal seizures, impaired awareness seizures, and status epilepticus.[3]^: 458 Samuel-Auguste Tissot (1728–1797) authored Traité de l’Epilepsie, a book describing grand état (generalized tonic-clonic seizures) and petit état (absence seizures).[3]^: 460 Jean-Étienne Dominique Esquirol (1772–1840) later introduced grand mal (generalized tonic-clonic seizures) and petit mal to describe these seizures.[3]^: 460 In 1937, Gibbs and Lennox introduced psychomotor seizures, seizures with "mental, emotional, motor, and autonomic phenomena."[4] Henri Gastaut led the effort to develop the ILAE 1969 classification of seizures based on clinical seizure type, electroencephalogram (EEG), anatomical substrate, etiology, and age of onset.[2]^: 491 The ILAE 1981 classification of seizure included information from EEG-video seizure recordings, but excluded anatomical substrate, etiology, and age factors as these factors were "historical or speculative" rather than directly observed.[2]^: 491 The ILAE 2017 classification of seizures closely reflects clinical practice, using observed seizure behavior and additional data to identify seizure types.[1]^: 523

A seizure is a paroxysmal episode of symptoms or altered behavior arising from abnormal excessive or synchronous brain neuronal activity.[5] A focal onset seizure arises from a biological neural network within one cerebral hemisphere, while a generalized onset seizure arises from within the cerebral hemispheres rapidly involving both hemispheres.[1]^: 526 Seizure symptoms, seizure behavior, neuroimaging, seizure etiology, EEG, and video recordings help distinguish focal from generalized onset seizures.[1]^: 526 Unknown onset seizures occur if the available information is insufficient to distinguish focal from generalized onset seizures with a ${\textstyle \geq 80\%}$ confidence.[1]^{: 524, 527} Focal to bilateral tonic-clonic seizure indicates that the seizure begins as focal seizure then later evolves to a bilateral tonic-clonic seizure.[1]^: 525

The classification distinguishes focal aware seizures from focal impaired awareness seizures.[1]^: 524 Aware means aware of self and surroundings during the seizure, verified when a person can recall events having occurred during the seizure.[1]^: 527 Impaired awareness occurs even if the recall of events is only partially impaired.[1] Impaired awareness may occur at any time during the seizure.[1] If the level of awareness cannot be determined, the level of awareness is unspecified; this usually occurs for atonic seizures and epileptic spasm seizures.[1]^: 525

A motor seizure has prominent movement, increased muscle contraction, or decreased muscle contraction as the initial predominant seizure feature.[1]

Atonic seizures are a brief 0.5-2 second lapses in muscle tone commonly leading to a fall.[6] Epileptic spasm seizures are brief 1-2 second proximal limb and truncal flexion or extension movements, often repeated.[6] Hyperkinetic seizures occur as high amplitude truncal and limb movements such as pedaling, thrashing, and rocking movements.[6] Myoclonic seizures are brief jerks of limbs or body lasting milliseconds.[6] Tonic seizures are abrupt increases in muscle tone greater than 2 seconds in duration.[6] Clonic seizures occur as rhythmic body jerks.[6] Myoclonic-atonic seizures begins with one or more jerks (myoclonic phase) followed by a loss of muscle tone (atonic phase).[6] Myoclonic-tonic-clonic seizures begin with one or more jerks (myoclonic phase), then body stiffening (tonic-phase), then rhythmic jerks (clonic phase).[6] Tonic-clonic seizures begin as symmetrical bilateral body stiffening (tonic phase) followed by rhythmic jerks (clonic phase).[6]. Myoclonic, atonic, tonic, and myoclonic-atonic seizures may cause abrupt falls, called drop attacks, similar to cataplexy.[6] Automatism seizures occur with repetitive stereotyped behaviors.

A non-motor seizure may begin with a sensory, cognitive, autonomic, or emotional symptom, behavioral arrest of activity, or impaired awareness with minor motor activity as the initial predominant seizure feature.[1]

Sensory seizures occur with somatosensory, olfactory, visual, gustatory, vestibular, or thermal sensations.[6] Cognitive seizures occur with language impairment (e.g. aphasia, dysphasia, anomia), memory impairments (deja vu, jamais vu), hallucinations, persistent thought (forced thinking), and neglect.[6] Autonomic seizures occur with palpitations, heart rate changes, nausea, vomiting, piloerection, lacrimation, pupil size changes or urge to urinate or defecate.[6] Emotional seizures occur with fear, anxiety, laughing, crying, pleasure, or anger sensations.[6] These initial symptoms are seizure auras.[6] Behavioral arrest seizures occur as an abrupt cessation of movement.[6]

Absence seizures occur with a sudden brief impairment in awareness, commonly less than 45 seconds.[6] Typical absence seizures may be accompanied by rhythmic facial 3 per second facial movements.[6] Atypical absence seizures occur with a less sudden impairment in awareness, often accompanied by a gradual head, limb, or truncal slumping.[6] Myoclonic absence seizures occur with myoclonic jerks of arms and shoulders.[6] Absence with eyelid myoclonia seizures occur with 4-6 per second eyelid myoclonic jerks and upward eye movement.[6]

Descriptors are additional seizure behaviors or symptoms that are appended to the seizure diagnosis. Descriptors may be a non-predominant or non-initial seizure feature.[1] Descriptors provide a more complete description of the seizure.[1]

1 - Classify focal seizures as focal aware, focal impaired awareness, or focal unspecified awareness.[1]^: 525

Dyscognitive, simple partial, complex partial, psychic, and secondarily generalized are terms that apply only to the ILAE 1981 classification of seizures.[1]^: 525 The ILAE 2017 classification relies on intact awareness of self and surroundings, but the ILAE 1981 classification relies on intact consciousness, defined as a normal response to an external stimulus due to intact awareness and intact ability to respond.[2]^: 493[1]^: 525 Unlike the ILAE 2017 classification, the ILAE 1981 classification specifies specific EEG patterns for each seizure type.[2]^{: 493–495}

The associated EEG patterns are not included.[2]^: 493

Partial seizures.[2]^: 493

Simple partial seizures: consciousness is not impaired.

• With motor signs
• With somatosensory or special-sensory symptoms
• With autonomic symptoms or signs
• With psychic symptoms

Complex partial seizures: consciousness is impaired.

• Simple partial onset, followed by impairment of consciousness
• With impairment of consciousness at onset

Partial seizures evolving to secondarily generalized seizures

• Simple partial seizures evolving to generalized seizures
• Complex partial seizures evolving to generalized seizures
• Simple partial seizures evolving to complex partial seizures evolving to generalized seizures

Generalized seizures.[2]^: 493

Absence seizures

• Absence seizures
• Atypical absence seizures

Myoclonic seizures

Clonic seizures

Tonic seizures

Tonic-clonic seizures

Atonic seizures

Unclassified epileptic seizures