Generalized seizures
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Generalized tonic–clonic |
Bilaterally increased tone, followed by sustained bilateral rhythmic limb jerking. |
Clonic |
Sustained bilateral rhythmic jerking. |
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Absence
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Typical absence |
Abrupt onset of altered awareness. Memory of events usually impaired. Oral and manual automatisms are common. Clonic movements of parts of the face may occur. |
Atypical absence |
Less abrupt onset and offset than typical absence. May be associated with loss of muscle tone, or subtle myoclonic jerks. Often longer than typical absences. Alteration in awareness variable. |
Myoclonic absence |
Rhythmic myoclonic jerks of the shoulders and arms with tonic abduction, resulting in progressive lifting of the arms during the seizure. The myoclonic jerks are typically bilateral, but may be unilateral or asymmetric. Last 10–60 s. Alteration in awareness variable. |
Absence with eyelid myoclonia |
Absence seizures accompanied by brief, repetitive, often rhythmic, fast myoclonic jerks of the eyelids, with simultaneous upward deviation of the eyeballs and extension of the head. Seizures are typically very brief (<6 s in duration) and multiple seizures occur on a daily basis. Mostly awareness is retained. |
Tonic |
Bilaterally increased tone of the limbs lasting seconds to a minute. Often occur out of sleep and in runs of varying intensity. The individual is unaware during these events. Individuals may make an expiratory sound at onset. May cause drop attacks. |
Atonic |
Sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic features. Very brief (<2 s) and may involve the head, trunk, or limbs. |
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Myoclonic
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Myoclonic |
Single or series of jerks (brief muscle contractions). Each jerk is typically milliseconds in duration. |
Negative myoclonus |
Brief cessation of background muscle tone, lasting less than 500 ms. The resulting movement produced can have two components, an initial loss of posture caused by the negative myoclonus, and a subsequent voluntary, compensatory movement to restore posture. May occur in isolation or in a series. |
Myoclonic–atonic |
Myoclonic seizure followed by an atonic seizure. Sometimes a series of myoclonic jerks occurs prior to the atonia. The head and limbs are affected, typically resulting in rapid fall. |
Myoclonic–tonic |
Myoclonic seizure followed by a tonic seizure. Sometimes a cluster of myoclonic jerks occurs prior to the increased tone. |
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Focal seizures: can be classified by features, and/or laterality, and/or lobar localization
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By features (clinical): one or more type of feature may be present during any single focal seizure
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Aura |
Auras are subjective and may be sensory or experiential. A sensory aura involves a sensation without an objective clinical sign, which may be visual, auditory, olfactory, epigastric, etc. An experiential aura involves affective, mnemonic, or perceptual subjective phenomena, including depersonalization and hallucinatory events. |
Motor |
A motor feature involves motor activity and may consist of an increase (positive) or decrease (negative) in muscle contraction. |
Autonomic |
Characterized by autonomic phenomena, which can involve cardiovascular, gastrointestinal, vasomotor, and thermoregulatory functions. Examples include palpitations, nausea, butterflies, hunger, chest pain, urge to urinate or defecate, goosebumps, sexual sensation, feeling hot or cold, piloerection, pallor, tachycardia or bradycardia/asystole, flushing, pupillary changes, and lacrimation. |
Dyscognitive |
Involves altered awareness or responsiveness. |
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By hemispheric localization (clinical or electrophysiological)
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Right Left |
Indications of hemispheric localization may be subtle, particularly in seizures that rapidly engage bilateral networks. Head turning, eye deviation, and unilateral clonic movements all lateralize to the contralateral hemisphere. |
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By lobar localization (clinical or electrophysiological)
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Frontal |
Frontal lobe seizures are usually brief. Motor features are prominent. There may be vocalization, bizarre behavior, head and eye deviation, and urinary incontinence. |
Temporal |
Characterized by behavioral arrest and dyscognitive features. Automatisms and auras are common. |
Parietal |
Ictal features are often subjective, and include positive and/or negative sensory features such as paresthesia, disorientation, and complex visual hallucinations. |
Occipital |
Characterized by visual aura, typically multi-colored shapes. |
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Epileptic Spasms
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Sudden flexion, extension or mixed flexion-extension of proximal and truncal muscles, lasting 1–2 s, i.e., longer than a myoclonic jerk (which lasts milliseconds) but not as long as a tonic seizure (which lasts >2 s). Spasms typically occur in a series, usually on wakening. Subtle forms may occur with only chin movement, grimacing, or head nodding. Spasms may be bilaterally symmetric, asymmetric, or unilateral. |