Glossary

This glossary intends to provide a standard terminology for health care workers to communicate what is observed and what a patient reports during a seizure. As this terminology is descriptive and phenomenological, its use would not imply or require knowledge of ictal pathophysiology, any pathological substrate or etiology.

Many terms are adjectives modifying "seizure" which itself is defined under "general terms". This pertains to seizures with single or multiple components.

Terms in this glossary, e.g. "seizure", "ictus", which have widespread applicability in other fields of clinical neuroscience, are herein defined according to their references to epilepsy.

Some terms of this glossary are "fundamental" i.e. they encompass other more precise words. These can be used as the sole descriptor when data to more precisely characterise a phenomenon are not available. Such include aura, automatism, experiential, motor and sensory.

A seizure will often consist of two or more phenomena occurring simultaneously or sequentially and would be described accordingly.

Quantitative terms, such as duration of motor events, are not intended as immutable confines, but as clarifying guides to describe clinically observed events.

Scientific progress dictates an evolution of terms to retain their relevance. However, needs of communication in everyday life require that changes be gradual and evolutionary than abrupt and revolutionary. The use of synonyms in this glossary reflects incidences where gradual changes are likely.

Terminology in some areas remains unresolved. Therefore, we view this glossary as a dynamic process for which feedback will be welcomed.

PRINCIPLES FOR TERMS AND DEFINITIONS

In developing the "lexique" of this report we adopted and applied the following principles.

Terms and definitions should:

Contain features which distinguish or modify seizure entities.
Be descriptive of the phenomena involved.
Comply with terminology of clinical neuroscience.
Employ current terminology and definitions wherever possible.
Contain new terms only if necessary.
Be easily translatable to other languages.
Be readily understood and employed by potential users.

DATA SOURCES

Adams RD, Victor M. Principles of Neurology. McGraw Hill Book, New York, 1993, 5th edition.

Aicardi, J. Epilepsy in Children. International Review of Child Neurology Series. Raven Press, New York, 1986, 1994.

Benson, D.F. The Neurology of Thinking. Oxford University Press, New York, 1994, pp 224-225.

Blume, WT, Berkovic S, Dulac O. (1997) Search for a better classification of the epilepsies. In: Epilepsy: A Comprehensive Textbook, Vol. 1. Edited by J. Engel Jr. and T.A. Pedley, Lippincott-Raven Publishers, Philadelphia, Chapter 69, pp 779-789.

Delgado-Escueta, A.V., Serratosa, J.M., Medina, M.T. Myoclonic seizures, and progressive myoclonus epilepsy syndromes. In: The Treatment of Epilepsy: Principles and Practice, 2nd ed. Edited by E. Wyllie, Williams & Wilkins, Baltimore, 1996, pp 467-483.

Engel, J.Jr. Seizures and Epilepsy. F.A. Davis Company, Philadelphia, 1989.

Engel, J.Jr. and Pedley, T.A. Epilepsy: A Comprehensive Textbook, Volumes 1-3, Lippincott-Raven Publishers, Philadelphia, 1997.

Gastaut, H. and Broughton, R. Epileptic Seizures. Clinical and Electrographic Features, Diagnosis and Treatment. Charles C. Thomas, Springfield, Ill, 1972.

Gloor, P. Consciousness as a neurological concept in epileptology: a critical review. Epilepsia 1986;27 (Suppl 2):S14-S26.

Gloor, P. The Temporal Lobe and Limbic System. Oxford University Press, 1997.

Hopkins AP, Michael WF. Spinal myoclonus. J Neurol Neurosurg Psychiatry 1974;37:1112-1115.

Luders H, et al. Semiological seizure classification. Epilepsia 1998;39:1006-1013.

Moscovitch, M. Information processing and the cerebral hemispheres. In: Gazzaniga MS, ed. Handbook of Behavioral Neurobiology: Neuropsychology. Vol 2. New York, NY: Plenum Publishing Corp; 1979:379-446.

Penfield, W. and Jasper, H.H. Epilepsy and Functional Anatomy of the Human Brain. Little, Brown and Company, 1954.

Pryse-Phillips, W. Companion to Clinical Neurology, Little, Brown and Company, 1995.

Rowland, L.P. Merritt's Textbook of Neurology, 8th Edition. Lea & Febiger, Philadelphia, 1989.

So, N. Epileptic auras. In: The Treatment of Epilepsy: Principles and Practice, 2nd ed. Edited by E. Wyllie, Williams & Wilkins, Baltimore, 1996, pp 376-384.

Wolf, P. Epileptic Seizures and Syndromes. John Libbey & Company Ltd., 1994.

Young, G.B. Coma and Impaired Consciousness: A Clinical Perspective. McGraw-Hill, New York, 1998.

Young, G.B. and Pigott, S.E. Neurobiological basis of consciousness. Archives of Neurology 1999;56:153-157.

Some non-medical texts:

The Concise Oxford Dictionary. 7th edition. Edited by J.B. Sykes. Clarendon Press; Oxford, England, 1982.

Dictionnaire Encyclopedique. Petit Larousse Illustre. Librairie Larousse, Paris, 1973.

Dictionary of Canadian English. The Senior Dictionary. Edited by W.S. Avis, P.D. Drysdale, R.J. Gregg, M.H. Scargill. W.J. Gage Limited; Toronto, Canada, 1967.

I. GENERAL TERMS

1.0 SEMEIOLOGY (SEMIOLOGY)
That branch of linguistics concerned with signs and symptoms.

2.0 EPILEPTIC SEIZURE
Manifestation(s) of epileptic (excessive and/or hypersynchronous), usually self-limited activity of neurons in the brain.

3.0 ICTUS
A sudden neurological occurrence such as a stroke or an epileptic seizure.

4.0 EPILEPSY
a) Epileptic Disorder: A chronic neurological condition characterised by recurrent epileptic seizures.
b) Epilepsies: Those conditions involving chronic recurrent epileptic seizures that can be considered epileptic disorders.

5.0 FOCAL (syn. partial)
A seizure whose initial semiology indicates, or is consistent with, initial activation of only part of one cerebral hemisphere.

6.0 GENERALISED (syn. bilateral)
A seizure whose initial semiology indicates, or is consistent with, more than minimal involvement of both cerebral hemispheres.

7.0 CONVULSION
Primarily a lay term. Episodes of excessive, abnormal muscle contractions, usually bilateral, which may be sustained or interrupted.

II. TERMS DESCRIBING EPILEPTIC SEIZURE SEMEIOLOGY

These are descriptors of seizures unless specified otherwise.

1.0 MOTOR
Involves musculature in any form. The motor event could consist of an increase (positive) or decrease (negative) in muscle contraction to produce a movement.

Unless noted, the following terms are adjectives modifying "motor seizure" or "seizure" e.g. "tonic motor seizure or dystonic seizure", and whose definitions can usually be understood as prefaced by: "refers to ...".

1.1 ELEMENTARY MOTOR
A single type of contraction of a muscle or group of muscles that is usually stereotyped and not decomposable into phases. (However, see Tonic-Clonic, an elementary motor sequence).

1.1.1 TONIC
A sustained increase in muscle contraction lasting a few seconds to minutes.

1.1.1.1 EPILEPTIC SPASM (Formerly Infantile Spasm)
Noun: A sudden flexion, extension or mixed extension-flexion of predominantly proximal and truncal muscles which is usually more sustained than a myoclonic movement but not as sustained as a tonic seizure i.e. about 1 sec. Limited forms may occur: grimacing, head nodding.. Epileptic spasms frequently occur in clusters.

1.1.1.2 POSTURAL
Adoption of a posture which may be bilaterally symmetrical or asymmetrical (as in a "fencing posture").

1.1.1.2.1 VERSIVE
A sustained, forced conjugate ocular, cephalic and/or truncal rotation or lateral deviation from the midline.

1.1.1.2.2 DYSTONIC
Sustained contractions of both agonist and antagonist muscles producing athetoid or twisting movements which when prolonged may produce abnormal postures.

1.1.2 MYOCLONIC (adjective); MYOCLONUS (noun)
Sudden, brief (< 100 msec) involuntary single or multiple contraction(s) of muscles(s) or muscle groups of variable topography (axial, proximal limb, distal).

1.1.2.1 NEGATIVE MYOCLONIC
Interruption of tonic muscular activity for < 500 msec without evidence of antecedent myoclonia.

1.1.2.2 CLONIC
Myoclonus which is regularly repetitive, involves the same muscle groups, at a frequency of about 2-3 c/sec, and is prolonged. Synonym: rhythmic myoclonus.

1.1.2.2.1 JACKSONIAN MARCH
Noun: Traditional term indicating spread of clonic movements through contiguous body parts unilaterally.

1.1.3 TONIC-CLONIC
A sequence consisting of a tonic followed by a clonic phase. Variants such as clonic-tonic-clonic may be seen.

1.1.3.1 GENERALISED TONIC-CLONIC SEIZURE (syn. bilateral tonic-clonic seizure (Formerly "Grand Mal" Seizure))
Noun: Bilateral symmetrical tonic contraction then bilateral clonic contractions of somatic muscles usually associated with autonomic phenomena.

1.1.4 ATONIC
Sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic event lasting one to two seconds or more, involving head, trunk, jaw or limb musculature.

1.1.5 ASTATIC
Loss of erect posture that results from an atonic, myoclonic or tonic mechanism. Synonym: drop attack.

1.1.6 SYNCHRONOUS (Asynchronous)
Motor events occurring (not) at the same time or at the same rate in sets of body parts.

1.2 AUTOMATISM
Noun: A more or less coordinated, repetitive, motor activity usually occurring when cognition is impaired and for which the subject is usually amnesic afterwards. This often resembles a voluntary movement, and may consist of inappropriate continuation of ongoing preictal motor activity.

The following adjectives are usually employed to modify "automatism".

1.2.1 OROALIMENTARY
Lip smacking, lip pursing, chewing, licking, tooth grinding or swallowing.

1.2.2 MIMETIC
Facial expression suggesting an emotional state, often fear.

1.2.3 MANUAL OR PEDAL

Indicates principally distal components, bilateral or unilateral.
Fumbling, tapping, manipulating movements.

1.2.4 GESTURAL
Often unilateral.

Fumbling or exploratory movements with the hand directed toward self or environment.
Movements resembling those intended to lend further emotional tone to speech.

1.2.5 HYPERKINETIC

Involves predominantly proximal limb or axial muscles producing irregular sequential ballistic movements, such as pedalling, pelvic thrashing, rocking movements.
Increase in rate of ongoing movements or inappropriately rapid performance of a movement.

1.2.6 HYPOKINETIC
A decrease in amplitude and/or rate or arrest of ongoing motor activity.

1.2.7 DYSPHASIC
Impaired communication involving language without dysfunction of relevant primary motor or sensory pathways, manifested as impaired comprehension, anomia, paraphasic errors or a combination of these.

1.2.8 DYSPRAXIC
Inability to perform learned movements spontaneously or on command or imitation despite intact relevant motor and sensory systems and adequate comprehension and cooperation.

1.2.9 GELASTIC
Bursts of laughter or giggling, usually without an appropriate affective tone.

1.2.10 DACRYSTIC
Bursts of crying.

1.2.11 VOCAL
Single or repetitive utterances consisting of sounds such as grunts or shrieks.

1.2.12 VERBAL
Single or repetitive utterances consisting of words, phrases or brief sentences.

1.2.13 SPONTANEOUS
Stereotyped, involve only self, and are virtually independent of environmental influences.

1.2.14 INTERACTIVE
Not stereotyped, involve more than self, and are environmentally influenced.

2.0 NON-MOTOR

2.1 AURA
Noun: A subjective ictal phenomenon that, in a given patient, may precede an observable seizure; if alone, constitutes a sensory seizure.

2.2 SENSORY
A perceptual experience not caused by appropriate stimuli in the external world. Modifies "seizure or "aura".

2.2.1 ELEMENTARY
A single, unformed phenomenon involving one primary sensory modality, e.g. somatosensory, visual, auditory, olfactory, gustatory, epigastric, or cephalic.

2.2.1.1 SOMATOSENSORY
Tingling, numbness, electric shock sensation, pain, sense of movement, or desire to move.

2.2.1.2 VISUAL
Flashing or flickering lights, spots, simple patterns, scotomata, or amaurosis.

2.2.1.3 AUDITORY
Buzzing, drumming sounds or single tones.

2.2.1.4 OLFACTORY
Odour, usually disagreeable.

2.2.1.5 GUSTATORY
Taste sensations including acidic, bitter, salty , sweet or metalic.

2.2.1.6 EPIGASTRIC
Abdominal discomfort including nausea, emptiness, tightness, churning, butterflies, malaise, pain, and hunger; sensation may rise to chest or throat. Some phenomena may reflect ictal autonomic dysfunction.

2.2.1.7 CEPHALIC
Sensation in the head such as light headedness, tingling or headache.

2.2.1.8 AUTONOMIC
A sensation consistent with involvement of the autonomic nervous system, including cardiovascular, gastrointestinal, sudomotor, vasomotor and thermoregulatory functions. (Thus, "autonomic aura"; cf. "autonomic seizure" 3.0).

2.2.2 EXPERIENTIAL
Affective, mnemonic or composite perceptual phenomena including illusory or composite hallucinatory events; these may appear alone or in combination. Included are feelings of depersonalisation. These phenomena have subjective qualities similar to those experienced in life but are recognised by the subject as occurring outside of actual context.

2.2.2.1 AFFECTIVE
Components include: fear, depression, joy and (rarely) anger.

2.2.2.2 MNEMONIC
Components which reflect ictal dysmnesia such as: feelings as familiarity (déjà-vu) and unfamiliarity (jamais-vu).

2.2.2.3 HALLUCINATORY
A creation of composite perceptions without corresponding external stimuli involving visual, auditory, somatosensory, olfactory and/or gustatory phenomena. Example: "hearing" and "seeing" people talking.

2.2.2.4 ILLUSORY
An alteration of actual percepts involving the visual, auditory, somatosensory, olfactory or gustatory systems.

2.3 DYSCOGNITIVE
The term describes events in which: 1) disturbance of cognition is the prominent or most apparent feature, and 2a) two or more of the following components are involved, or 2b) contributions of such components remain undetermined. Otherwise, use more specific term e.g. mnemonic experimental seziure or "hallucinatory experimental seizure."

Components of cognition:

perception: symbolic conception of sensory information
attention: appropriate selection of a principal perception or task
emotion: appropriate affective significance of a perception
memory: ability to store and retrieve percepts or concepts
executive function: anticipation, selection, monitoring of consequences, initiation of motor activity including praxis, speech

3.0 AUTONOMIC EVENTS

3.1 AUTONOMIC AURA
A sensation consistent with involvement of the autonomic nervous system, including cardiovascular, gastrointestinal, sudomotor, vasomotor and thermoregulatory functions. (see 2.3.1.8).

3.2 AUTONOMIC SEIZURE
An objectively documented and distinct alteration of autonomic nervous system function involving cardiovascular, pupillary, gastrointestinal, sudomotor, vasomotor and thermoregularity functions.

4.0 SOMATOTOPIC MODIFIERS

4.1 LATERALITY

4.1.1 UNILATERAL
Exclusive or virtually exclusive involvement of one side as a motor, sensory or autonomic phenomenon.

4.1.1.1 HEMI-
A prefix to other descriptors e.g. hemiclonic.

4.1.2 GENERALISED (syn. "bilateral")
More than minimal involvement of each side as a motor, elementary sensory or autonomic phenomenon.

Motor component: further modified as:

4.1.2.1 ASYMMETRICAL
Clear distinction in quantity and/or distribution of behaviour on the two sides.

4.1.2.2 SYMMETRICAL
Virtual bilateral equality in these respects.

4.2 BODY PART
Refers to area involved i.e. arm, leg, face, trunk and other.

4.3 CENTRICITY
Modifier describes proximity to the body axis.

4.3.1 AXIAL
Involves trunk, including neck.

4.3.2 PROXIMAL LIMB
Signifies involvement from shoulders to wrist, hip to ankle.

4.3.3 DISTAL LIMB
Indicates involvement of fingers, hands, toes, and/or feet.

5.0 MODIFIERS AND DESCRIPTORS OF SEIZURE TIMING
The following terms are listed in the form (adjective, noun, verb) according to principal usage; as adjective unless specified.

5.1 INCIDENCE
Noun: Refers to the number of epileptic seizures within a time period or the number of seizure days per unit of time.

5.1.1 REGULAR, IRREGULAR
Consistent (inconsistent) or predictable (unpredictable, chaotic) intervals between such events.

5.1.2 CLUSTER
1) Noun: Incidence of seizures within a given period (usually one or a few days) which exceeds the average of incidence over a longer period for the patient.
2) Verb: To vary in incidence as above.

5.1.3 PROVOCATIVE FACTOR
Noun: Transient and sporadic endogenous or exogenous element capable of augmenting seizure incidence in persons with chronic epilepsy and evoking seizures in susceptible non-epileptic individuals.

5.1.3.1 REACTIVE
Occurring in association with transient systemic perturbation such as intercurrent illness, sleep loss or emotional stress.

5.1.3.2 REFLEX
Objectively and consistently demonstrated to be evoked by a specific afferent stimulus or by activity of the patient. Afferent stimuli can be: elementary, i.e. unstructured (light flashes, startle, a monotone) or elaborate i.e. structured, (a symphony). Activity may be elementary, e.g. motor (a movement); or elaborate, e.g. cognitive function (reading, chess playing), or both (reading aloud).

5.2 STATE DEPENDENT
Occurring exclusively or primarily in the various stages of drowsiness, sleep, or arousal.

5.3 CATAMENIAL
Seizures occurring principally or exclusively in any one phase of the menstrual cycle.

6.0 DURATION
Time between the beginning of initial seizure manifestations, such as the aura, to the cessation of experienced or observed seizure activity. Does not include non-specific seizure premonitions or postictal states.

6.1 STATUS EPILEPTICUS
A seizure which shows no clinical signs of arresting after a duration encompassing the great majority of seizures of that type in most patients or recurrent seizures without resumption of baseline central nervous system function interictally.

7.0 SEVERITY
A multicomponent assessment of a seizure by observers and the patient.

Components primarily of observer assessment include: duration, extent of motor involvement, impairment of cognitive interaction with environment intraictally, maximum number of seizures per unit of time.

Components primarily of patient assessment: extent of injury; emotional, social and vocational consequences of the attack.

8.0 PRODROME
A preictal phenomenon. A subjective or objective clinical alteration, e.g. ill-localised sensation or agitation, that heralds the onset of an epileptic seizure but does not form part of it.

9.0 POSTICTAL PHENOMENON
A transient clinical abnormality of central nervous system function that appears or becomes accentuated when clinical signs of the ictus have ended.

9.1 LATERALISING (TODD'S (OR BRAVAIS')) PHENOMENON
Any unilateral postictal dysfunction relating to motor, speech, somatosensory and/or integrative functions including visual, auditory or somatosensory neglect phenomena.

9.2 NON-LATERALISING PHENOMENA
Impaired cognition, amnesia, psychosis.

9.2.1 IMPAIRED COGNITION
Decreased cognitive performance involving one or more of: perception, attention, emotion, memory, execution, praxis, speech (cf Dyscognitive, 2.3).

9.2.2 ANTEROGRADE AMNESIA
Impaired ability to remember new material.

9.2.3 RETROGRADE AMNESIA
Impaired ability to recall previously remembered material.

9.2.4 PSYCHOSIS
Misinterpretation of external world in an awake, alert person; involves thought disorder of emotion and socialisation.