Mette BerendtpersName, Robyn G. FarquharpersName, Paul J. J. MandigerspersName, Akos PakozdypersName, Sofie F. M. BhattipersName, Luisa De RisiopersName, Andrea FischerpersName, Sam LongpersName, Kaspar MatiasekpersName, Karen MuñanapersName, Edward E. PattersonpersName, Jacques PenderispersName, Simon PlattpersName, Michael PodellpersName, Heidrun PotschkapersName, Martí Batlle PumarolapersName, Clare RusbridgepersName, Veronika M. SteinpersName, Andrea TipoldpersName, Holger A. VolkpersName (2015date). “International veterinary epilepsy task force consensus report on epilepsy definition, classification and terminology in companion animals..” BMC Veterinary Researchtitle·j.
Object of study — the definition, classification and terminology of epilepsyterm·dom in companion animals
Research question — how epilepsyterm·dom and epileptic seizuresterm·key in companion animals should be defined and classified
Contribution — a classification of companion-animal epilepsyterm·dom with an aetiological element and a seizure-type element
phenomenon · claim-type · cross-domain-transfer · mechanism · claim-relation · replication-status · limitation — grounded in the full text| phenomenon | no common language for epilepsy classification and terminology between veterinary and human specialists — “There remains, however, a lack of a consensus, a common ‘language’, for the classification and terminology used between veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists.” | |
| claim-type | critique — “Put in a scientific and educational perspective, the existing lack of uniformity with respect to definitions and terminology furthermore represents a major problem, as comparisons between research studies are compromised.” | |
| method — evidence | — “To ensure we have all stakeholders involved, the consensus-working group is composed of veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists.” | |
| object of study — evidence | — “In this document the International Veterinary Epilepsy Task Force (IVETF) discusses current understanding of canine epilepsy and presents our 2015 proposal for terminology and classification of epilepsy and epileptic seizures.” | |
| research question — evidence | — “This consensus statement group aims to provide the veterinary community with a proposal focused on the classification of epilepsy and epileptic seizures.” | |
| contribution — evidence | — “The classification has two elements: (a) an aetiological element and (b) a seizure type classification.” | |
| mechanism | genetic defect In some purebred dogs epilepsy is a direct result of a genetic defect, with seizures as the core clinical sign. — “Although the mechanisms behind companion animal epilepsy are largely uncovered, it is clear that epilepsy in some purebred dogs is a direct result of a genetic defect, where seizures are the core clinical sign of disease.” | mechanisms[0] |
| sense | epilepsy (ILAE 2005) - a brain disorder with an enduring predisposition to seizures together with its neurobiological, cognitive, psychological and social consequences — “Here an epileptic seizure was defined as: “A transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain”, and epilepsy was defined as: “A disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological, and social consequences of this condition.” | senses[0] |
| sense | aura (human epileptology) - subjective sensory phenomena and vegetative signs, excluding motor phenomena; the group advises against the term in veterinary medicine — “This term originated from human epileptology where aura in early ILAE classifications was used “to denote symptomatology that encompasses subjective sensory phenomena as well as vegetative signs (for example, the epigastric sensations accompanying mesial temporal epilepsy)” and thus did not include motor phenomena.” | senses[1] |
| relation | abnormal activity in neuronal networks —causes→ seizures — Epilepsy is a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures characterised by motor, autonomic and/or behavioural features. — “Epilepsy is a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures characterised by motor, autonomic and/or behavioural features.” | concept_edges[0] |
| weight | abnormal activity in neuronal networks —causes→ seizures — 0.8 — “Epilepsy is a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures characterised by motor, autonomic and/or behavioural features.” | concept_edges[0] |
| relation | Prodromal signs —contrasted-with→ focal seizures — Prodromal signs are defined by their long lasting nature whereas focal seizures which may display similar signs when they occur alone or before generalized convulsive seizures are very short (seconds to minutes). — “Prodromal signs are defined by their long lasting nature whereas focal seizures which may display similar signs when they occur alone or before generalized convulsive seizures are very short (seconds to minutes).” | concept_edges[1] |
| weight | Prodromal signs —contrasted-with→ focal seizures — 0.8 — “Prodromal signs are defined by their long lasting nature whereas focal seizures which may display similar signs when they occur alone or before generalized convulsive seizures are very short (seconds to minutes).” | concept_edges[1] |
| relation | International League Against Epilepsy —same-as→ ILAE — A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE). — “A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE).” | concept_edges[2] |
| weight | International League Against Epilepsy —same-as→ ILAE — 0.9 — “A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE).” | concept_edges[2] |
| relation | electroencephalography —same-as→ EEG — Typically electroencephalography (EEG) is an impractical tool in animals and so cannot contribute to a general classification scheme—in contrast to the situation in human medicine. — “Typically electroencephalography (EEG) is an impractical tool in animals and so cannot contribute to a general classification scheme—in contrast to the situation in human medicine.” | concept_edges[3] |
| weight | electroencephalography —same-as→ EEG — 0.9 — “Typically electroencephalography (EEG) is an impractical tool in animals and so cannot contribute to a general classification scheme—in contrast to the situation in human medicine.” | concept_edges[3] |
| replication | not-applicable | |
| limitation | Consciousness cannot be assessed objectively in animals, so focal seizures are not subclassified by it. — “Although animals may appear as if consciousness is impaired during focal epileptic seizures (awake but being confused, not recognizing the owner, not responding to commands) we cannot assess this objectively.” | limitations[0] |
| limitation | The mechanisms of companion-animal epilepsy are not yet understood well enough to apply the ILAE's level of classification. — “Although we need to move veterinary epilepsy classification forward we also must, as in human medicine, consider carefully whether any change of terminology is meaningful [ 5 ]; we must accept that currently we have not advanced the scientific understanding of the mechanisms leading to epilepsy in companion animals to the level applicable to the ILAE.” | limitations[1] |
finding · quantity · variable · definition · key-term — grounded in the full text| finding | A focal seizure that evolves into a generalized convulsive seizure is the most common seizure type observed in dogs. — “The seizure will start with regional motor, autonomic and/or behavioural signs and then rapidly be followed by a convulsive stage with bilateral tonic, clonic or tonic-clonic activity and loss of consciousness. This is the most common seizure type observed in the dog.” | content_tags.findings[0] |
| quantity | 0.6–0.75 % — — “The true prevalence of epilepsy in dogs is unknown and has been estimated to be 0.6–0.75 % in the general dog population [ 6 , 7 ].” | content_tags.quantities[0] |
| key-terms | epilepsy, epileptic seizure, idiopathic epilepsy, structural epilepsy, focal epileptic seizures, generalized epileptic seizures, ILAE, semiology, prodrome, status epilepticus |
| concept | epilepsy — a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures — “Epilepsy is a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures characterised by motor, autonomic and/or behavioural features.” | concepts[0] |
| concept | abnormal activity in neuronal networks — not defined in this paper's own words; disordered firing of groups of connected brain cells — “Epilepsy is a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures characterised by motor, autonomic and/or behavioural features.” | concepts[1] |
| concept | seizures — not defined in this paper's own words; episodes of motor, autonomic or behavioural disturbance — “Epilepsy is a complex brain disease where sudden and abnormal activity in neuronal networks causes the prominent clinical sign of seizures characterised by motor, autonomic and/or behavioural features.” | concepts[2] |
| concept | Focal epileptic seizures — lateralized and/or regional signs (motor, autonomic or behavioural signs, alone or in combination) — “Focal epileptic seizures are characterized by lateralized and/or regional signs (motor, autonomic or behavioural signs, alone or in combination).” | concepts[3] |
| concept | Generalized epileptic seizures — bilateral involvement (both sides of body and therefore both cerebral hemispheres involved) — “Generalized epileptic seizures are characteried by bilateral involvement (both sides of body and therefore both cerebral hemispheres involved).” | concepts[4] |
| concept | prodrome — a long-term (hours to days) change in disposition and indicator of forthcoming seizures — “In some animals (but not so common), ictus may be preceded by a so-called prodrome, a long-term (hours to days) change in disposition and indicator of forthcoming seizures.” | concepts[5] |
| concept | Prodromal signs — not defined in this paper's own words; the long-lasting changes in behaviour that come before a seizure — “Prodromal signs are defined by their long lasting nature whereas focal seizures which may display similar signs when they occur alone or before generalized convulsive seizures are very short (seconds to minutes).” | concepts[6] |
| concept | focal seizures — not defined in this paper's own words; brief seizures arising in one part of the brain — “Prodromal signs are defined by their long lasting nature whereas focal seizures which may display similar signs when they occur alone or before generalized convulsive seizures are very short (seconds to minutes).” | concepts[7] |
| concept | International League Against Epilepsy — not defined in this paper's own words; the international professional body that classifies human epilepsy — “A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE).” | concepts[8] |
| concept | ILAE — International League Against Epilepsy — “A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE).” | concepts[9] |
| concept | electroencephalography — not defined in this paper's own words; recording of the brain's electrical activity from electrodes — “Typically electroencephalography (EEG) is an impractical tool in animals and so cannot contribute to a general classification scheme—in contrast to the situation in human medicine.” | concepts[10] |
| concept | EEG — electroencephalography — “Typically electroencephalography (EEG) is an impractical tool in animals and so cannot contribute to a general classification scheme—in contrast to the situation in human medicine.” | concepts[11] |
| concept | structural epilepsy — not defined in this paper's own words; epilepsy caused by an identifiable disease or lesion of the brain — “Lafora disease progressive myoclonic epilepsy would be classified under structural epilepsy as the gene defect results in a storage disease which alters the brain structurally and where the epileptic seizures associated with the structural changes in the brain are one of the multiple clinical and neurological signs associated with the primary storage disease [ 50 ].” | concepts[12] |
Full text — tagged
International veterinary epilepsyterm·dom task force consensus report on epilepsyterm·dom definition, classification and terminology in companion animals.
Abstract Dogs with epilepsyterm·dom are among the commonest neurological patients in veterinary practice and therefore have historically attracted much attention with regard to definitions, clinical approach and management. A number of classification proposals for canine epilepsyterm·dom have been published during the years reflecting always in parts the current proposals coming from the human epilepsyterm·dom organisation the International League Against Epilepsyterm·dom (ILAEterm·dom). It has however not been possible to gain agreed consensus, “a common language”, for the classification and terminology used between veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists. This has led to an unfortunate situation where different veterinary publications and textbook chapters on epilepsyterm·dom merely reflect individual author preferences with respect to terminology, which can be confusing to the readers and influence the definition and diagnosis of epilepsyterm·dom in first line practice and research studies.
In this document the International Veterinary Epilepsyterm·dom Task Force (IVETF) discusses current understanding of canine epilepsyterm·dom and presents our 2015 proposal for terminology and classification of epilepsyterm·dom and epileptic seizuresterm·key. We propose a classification system which reflects new thoughts from the human ILAEterm·dom but also roots in former well accepted terminology. We think that this classification system can be used by all stakeholders.
Keywords: Epilepsyterm·dom, Seizuresterm, Dog, Classification, Semiologyterm·key Background Epilepsyterm·dom is a complex brain disease where sudden and abnormal activity in neuronal networksterm causes the prominent clinical sign of seizuresterm characterised by motor, autonomic and/or behavioural features. Epileptic seizuresterm·key are episodic and brief (in most cases less than 2–3 min). Epilepsyterm·dom can rise from a plethora of causes. A few rare cases are purely genetic (e.g. channelopathies), some are developmental and have complex genetic and epigenetic influences (e.g. neuronal migration disorders) and some are caused by injury to the brain (e.g. trauma, infectious, inflammatory, vascular or neoplastic disease). In a significant number of cases, the cause is not clear. Although the mechanisms behind companion animal epilepsyterm·dom are largely uncovered, it is clear that epilepsyterm·dom in some purebred dogs is a direct result of a genetic defect, where seizuresterm are the core clinical sign of disease. This has been described for the Lagotto Romagnolo, Belgian shepherd and Boerboels [ 1 – 4 ]. A high epilepsyterm·dom prevalence in a specific breed or the accumulation of epileptic individuals within specific dog families are strong indicators of inherited epilepsyterm·dom, but often it is unknown if genetic defects are the sole cause of the epilepsyterm·dom or if the epilepsyterm·dom might arise from multifactorial causal influences including environmental, developmental, provoking and genetic factors, and similar issues apply to human cases [ 5 ].
The true prevalence of epilepsyterm·dom in dogs is unknown and has been estimated to be 0.6–0.75 % in the general dog population [ 6 , 7 ]. Epidemiological population prevalence studies in specific breeds with idiopathic epilepsyterm·key has been conducted in the Labrador retriever (3.1 %), Belgian shepherd (9.4 %) and petit Basset Griffon vendeen (8.9 %), and pedigree studies in the Boxer, Irish wolfhound, English Springer spaniel, Vizsla, Bernese mountain dog, Standard poodle, Belgian shepherd, Border collie, Australian shepherd and Border terrier among others, and these have provided evidence for inherited epilepsyterm·dom [ 8 – 25 ] (for further information on epilepsyterm·dom related to specific breeds see Hülsmeyer et al. [ 26 ]). Given the heterogeneity of epilepsyterm·dom where causes and signs of disease are greatly variable, a standardised terminology and classification system for epilepsyterm·dom is crucial in order to provide accurate descriptive information for diagnostic and communicative processes.
Since 1964 epilepsyterm·dom and epileptic seizuresterm·key have in human medicine been organized and categorized in a classification and terminology system, published by the International League Against Epilepsyterm·dom—ILAEterm·dom [ 27 – 33 ]. The ILAEterm·dom sees itself as “the world's preeminent association of physicians and other health professionals working towards a world where no persons’ life is limited by epilepsyterm·dom” and the noble mission of this organization is “to ensure that health professionals, patients and their care providers, governments, and the public world-wide have the educational and research resources that are essential in understanding, diagnosing and treating persons with epilepsyterm·dom” (ILAEterm·dom homepage www.ilaeterm·dom.org ).
The 1985 classification of seizureterm types and the 1989 classification of the epilepsies continues to be used worldwide in human epilepsyterm·dom [ 32 , 34 ]. However, in recent years, the ILAEterm·dom classification task force has taken to continually updating and revising on the subject of epilepsyterm·dom producing new consensus documents approximately every 5 years with the most recent being published in 2010 and a further version is currently under much debate [ 27 ]. The terminology and classification framework they provide is seen as an ever evolving process, reflecting the constant gain in our understanding of the disease and the complications inherent in ambiguous, misinterpreted and potentially stigmatising vocabulary. This has generated considerable discussion amongst their members reflecting the complexity of the task.
In veterinary medicine, a number of classification proposals for canine epilepsyterm·dom have been published over the years always reflecting in part the current ILAEterm·dom proposals (e.g. [ 35 – 38 ]). There remains, however, a lack of a consensus, a common ‘language’, for the classification and terminology used between veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists. Companion animal epilepsyterm·dom papers reflect a variety of modifications of the definitions of epilepsyterm·dom and epileptic seizuresterm·key derived from the core classification documents of the ILAEterm·dom (e.g. [ 1 , 7 , 9 – 15 , 17 , 23 – 25 , 27 , 28 , 30 – 36 , 38 – 46 ]. This has led to an unfortunate situation where different veterinary publications and textbook chapters on epilepsyterm·dom merely reflect individual author preferences with respect to terminology, which can be confusing for the reader. Put in a scientific and educational perspective, the existing lack of uniformity with respect to definitions and terminology furthermore represents a major problem, as comparisons between research studies are compromised. Even more important, it prevents the implementation of a common understanding of epilepsyterm·dom and standardized professional guidelines which can help clinicians when diagnosing animals with epilepsyterm·dom and advising the owners.
Terminology and classification of epilepsyterm·dom should be a ‘user friendly’, reliable and valid tool for the benefit of different users and the patient [ 47 ]. There is a ‘chain of care’ from the pet’s owner through the primary clinician to neurology specialists and researchers. The language should be concise to reduce errors and to simplify conversation. The first opinion veterinarian and specialists alike should be able to use the classification framework to manage the disease appropriately and to communicate with others using the same language. In the age of the internet, the pet owner also needs to be able to, at least in part, comprehend the terminology used. The scientist should find in the classification a pragmatic and reliable instrument to investigate the disease’s aetiology, pathophysiology, treatment, and outcome. Finally terminology should reflect current knowledge and not be changed for the sake of change, which has recently also been emphasized by Shorvon (2014) [ 5 ] and others with respect to the ILAEterm·dom discussions on classification. Otherwise important historical data might be lost and in some cases it might be wise to stay with terms which are in widespread use and have stood a test of time instead of a rapid change of terminology emanating from academic discussions [ 5 ]. Considering these issues, terminology and classification needs to fulfil dissimilar and sometimes antagonistic needs and at the same time be adaptable to change.
In adopting the terms associated with human epilepsyterm·dom we should acknowledge some of the very significant differences when applying it to small animal patients. We cannot interview our patients as in human medicine and the clinician’s interpretation of the patient’s seizureterm signs are invariably restricted to the owner's description and often a poor quality video(s). Typically electroencephalographyterm (EEGterm) is an impractical tool in animals and so cannot contribute to a general classification scheme—in contrast to the situation in human medicine. Furthermore some owners will decline diagnostic investigation due to financial concerns or because some procedures require general anaesthesia, and therefore the owners’ report of seizureterm history and phenomenology, supported by digital (video) recordings, remain the most central diagnostic epilepsyterm·dom marker in companion animals (in fact as it does in humans).
Another discrepancy between people and animals which must be addressed is the assessment of possible impairment of consciousness during seizuresterm. The determination of consciousness impairment is challenging and often very important to people because of personal and public safety. The ILAEterm·dom classification cites consciousness as an important factor for diagnosis. Veterinary medicine is better aligned with the challenges facing paediatric medicine in this regard.
This consensus statement group aims to provide the veterinary community with a proposal focused on the classification of epilepsyterm·dom and epileptic seizuresterm·key. To ensure we have all stakeholders involved, the consensus-working group is composed of veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists.
Proposal In recent years the ILAEterm·dom has been able to advance human epilepsyterm·dom classification to a sophisticated level as a consequence of advanced diagnostics and the uncovering of an increasing number of mechanisms (including genetic) that lead to epilepsyterm·dom. The definition of epilepsyterm·dom accepted by the ILAEterm·dom in 2005 reflected the immense progress with respect to the identification of aetiologies and the understanding of seizureterm generation. Here an epileptic seizureterm·key was defined as: “A transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain”, and epilepsyterm·dom was defined as: “A disorder of the brain characterized by an enduring predisposition to generate epileptic seizuresterm·key and by the neurobiologic, cognitive, psychological, and social consequences of this condition. The definition of epilepsyterm·dom requires the occurrence of at least one epileptic seizureterm·key” [ 30 ] . In 2010 the ILAEterm·dom refined the definitions even further [ 27 ]; to demonstrate the on-going discussions in the ILAEterm·dom, it has recently been proposed that epilepsyterm·dom should be considered a true disease of the brain [ 48 ]. This contradicts the previous understanding of epilepsyterm·dom as a condition of the brain—or a collection of signs from the brain. Berg and Scheffer stated back in 2011 [ 28 ]: “These proposals are not meant to be permanent, but form part of a transition to a system that will ultimately allow for meaningful translation of scientific understanding to the classification of the epilepsies for clinical and other purposes”. Although we need to move veterinary epilepsyterm·dom classification forward we also must, as in human medicine, consider carefully whether any change of terminology is meaningful [ 5 ]; we must accept that currently we have not advanced the scientific understanding of the mechanisms leading to epilepsyterm·dom in companion animals to the level applicable to the ILAEterm·dom.
In the following sections the IVETF discusses the current understanding of companion animal epilepsyterm·dom and presents our 2015 proposal for terminology and classification of epilepsyterm·dom and epileptic seizuresterm·key. We propose a classification system which reflects new thoughts from the human ILAEterm·dom but also has its roots in former well accepted terminology. We think that this classification system can be used by all stakeholders. The classification has two elements: (a) an aetiological element and (b) a seizureterm type classification.
Definitions In human medicine, epilepsyterm·dom can often be confirmed by electroencephalographyterm (EEGterm) although epileptic people may have a normal EEGterm and an abnormal EEGterm can also exist in people without epilepsyterm·dom. The use of EEGterm in veterinary medicine is currently of questionable routine clinical value and therefore our definitions should be seen as clinically operational and reflecting expert knowledge in the field with respect to the typical appearance of epileptic seizuresterm·key and their symptomatology. This is not a major drawback, and for definition purposes, it is reasonable (in human and animal epilepsyterm·dom) to define seizuresterm and epilepsyterm·dom by the clinical appearance of seizuresterm. Please also refer to the glossary for further definitions not listed in the main text.
Seizureterm The term can be used for any sudden, short lasting and transient event. It does not imply that the event is epileptic.
Epileptic seizureterm·key Manifestation(s) of excessive synchronous, usually self-limiting epileptic activity of neurons in the brain. This results in a transient occurrence of signs which may be characterized by short episodes with convulsions or focal motor, autonomic or behavioural features and due to abnormal excessive and/or synchronous epileptic neuronal activity in the brain.
Reactive seizureterm A reactive seizureterm is a seizureterm occurring as a natural response from the normal brain to a transient disturbance in function (metabolic or toxic in nature)—which is reversible when the cause or disturbance is rectified. A provoked seizureterm can be considered as being synonymous with a reactive seizureterm.
Epilepsyterm·dom Epilepsyterm·dom is defined as a disease of the brain characterized by an enduring predisposition to generate epileptic seizuresterm·key. This definition is usually practically applied as having at least two unprovoked epileptic seizuresterm·key >24 h apart [ 48 ].
Classification Historically veterinary medicine has operated with various terminology/synonyms for epilepsyterm·dom types defined by aetiology and phenotypic manifestations which are themselves defined by the distribution of abnormal electrical activity in the brain. The development of ILAEterm·dom classifications and changes in veterinary epilepsyterm·dom terminology throughout time are detailed in Table 1 and 2 .
Veterinary terminology and its most common amendments over time Development of ILAEterm·dom classifications Epilepsyterm·dom types defined by aetiology Idiopathic epilepsyterm·key Idiopathic epilepsyterm·key (idiopathic defined as a disease in its own right, per se) should be seen as the overarching and bridging term, which can be sub-classified into three sub-groups reflecting the advancements in the field: Idiopathic epilepsyterm·key (genetic epilepsyterm·dom)—a causative gene for epilepsyterm·dom has been identified/confirmed genetic background Idiopathic epilepsyterm·key (suspected genetic epilepsyterm·dom)—a genetic influence supported by a high breed prevalence (>2 %), genealogical analysis and/or familial accumulation of epileptic individuals *,** . * Shorvon stated in 2014 [ 5 ] : “It seems very likely that the genetic influences in idiopathic epilepsies probably are complex involving multiple genes and interactions between genes (epistatic) and between genes and the environment (epigenetic)”. ** A list of breeds with a high epilepsyterm·dom incidence or prevalence compared to the general background population can be found in Hülsmeyer et al. [ 26 ] . Please note that the epilepsyterm·dom status within breeds may fluctuate over time and furthermore be influenced by differences between countries (e.g. due to preferences with respect to currently popular breeding lines).
Idiopathic epilepsyterm·key (epilepsyterm·dom of unknown cause)—epilepsyterm·dom in which the nature of the underlying cause is as yet unknown and with no indication of structural epilepsyterm·dom.
Please see consensus on Diagnostic approach to epilepsyterm·dom in dogs [ 49 ] for further information on diagnostic work-up.
Structural epilepsyterm·dom Structural epilepsyterm·dom is characterized by epileptic seizuresterm·key which are provoked by intracranial/cerebral pathology including vascular, inflammatory/infectious, traumatic, anomalous/developmental, neoplastic and degenerative diseases confirmed by diagnostic imaging, cerebrospinal fluid examination, DNA testing or post mortem findings (see consensus on Diagnostic approach to epilepsyterm·dom in dogs [ 49 ]). Lafora disease progressive myoclonic epilepsyterm·dom would be classified under structural epilepsyterm·dom as the gene defect results in a storage disease which alters the brain structurally and where the epileptic seizuresterm·key associated with the structural changes in the brain are one of the multiple clinical and neurological signs associated with the primary storage disease [ 50 ].
Classification by seizureterm semiologyterm·key (seizureterm type classification) Focal epileptic seizuresterm·dom Focal epileptic seizuresterm·dom are characterized by lateralized and/or regional signs (motor, autonomic or behavioural signs, alone or in combination). The ictal onset is consistent from one epileptic seizureterm·key to another. They may be discretely localised or more widely distributed. Focal epileptic seizuresterm·dom may originate in subcortical structures, with preferential propagation patterns that can involve the contralateral hemisphere. With focal epileptic seizuresterm·dom, the abnormal electrical activity arises in a localized group of neurons or network within one hemisphere. The clinical signs reflect the functions of the area or areas involved.
Focal epileptic seizuresterm·dom can present as: Motor (episodic focal motor phenomena e.g. facial twitches, repeated jerking head movements, rhythmic blinking, twitching of facial musculature or repeated rhythmic jerks of one extremity) Autonomic (with parasympathetic and epigastric components e.g. dilated pupils, hypersalivation or vomiting) Behavioural (focal epileptic seizureterm·dom activity which in humans can represent psychic and/or sensory seizureterm phenomena may in animals result in a short lasting episodic change in behaviour such as e.g. anxiousness, restlessnesss, unexplainable fear reactions or abnormal attention seeking/‘clinging’ to the owner.
Generalized epileptic seizuresterm·dom Generalized epileptic seizuresterm·dom are characteried by bilateral involvement (both sides of body and therefore both cerebral hemispheres involved). Generalized epileptic seizuresterm·dom may occur alone or evolve from a focal epileptic seizureterm·dom start. In dogs and cats generalized epileptic seizuresterm·dom predominantly present as tonic, clonic or tonic-clonic epileptic seizuresterm·key. As a rule the animal will lose consciousness during convulsive epileptic seizuresterm·key (myoclonic seizuresterm excluded). Salivation, urination and/or defecation furthermore often also occur (myoclonic seizuresterm excluded).
Generalized convulsive epileptic seizuresterm·key involving bilateral motor activity Tonic-clonic Tonic Clonic Myoclonic (Jerking movements usually affecting both sides of the body) Non-convulsive generalized epileptic seizuresterm·dom Atonic (also called ‘drop attacks’—sudden and general loss of muscle tone which usually cause the animal to collapse) Focal epileptic seizuresterm·dom evolving into generalized epileptic seizuresterm·dom Focal epileptic seizuresterm·dom can spread from initial regional cerebral involvement to bilateral cerebral involvement. The seizureterm will start with regional motor, autonomic and/or behavioural signs and then rapidly be followed by a convulsive stage with bilateral tonic, clonic or tonic-clonic activity and loss of consciousness. This is the most common seizureterm type observed in the dog. The onset of the focal epileptic seizureterm·dom is often very short (seconds to minutes) after which follows the secondary generalisation with convulsions. The focal epileptic seizureterm·dom onset may be difficult to detect due to its brief nature. When taking the seizureterm history, clients should be interviewed thoroughly about what (or if something) happens before convulsions (please see De RisiopersName et al. [ 49 ] for further information on diagnostic work-up).
The semiological description of an epileptic seizureterm·key If classification is to be carried out according to seizureterm type, it makes sense to have a systematic way of describing seizuresterm. The evolution of the seizureterm over time is what is important.
Phases associated with epileptic seizuresterm·key The epileptic seizureterm·key is classified as the ictus (seizureterm activity)—followed by a postictal phase (where the normal brain function is restored). The ictus may consist of a generalized epileptic seizureterm·dom alone, a focal epileptic seizureterm·dom alone, or a focal epileptic seizureterm·dom which evolves into a generalized seizureterm. In the postictal phase, the brain restores its normal function. The postictal phase may be very short or last for several hours to days. Typically, the animal is disoriented, may have behavioural abnormalities such as repetitive vocalisation, compulsive locomotion failing to avoid obstacles, be tired, ataxic, hungry or thirsty, express a need to urinate, defecate or appear exhausted and sleep for a longer period of time. Postictal blindness or aggression may also be present.
Prodrometerm·dom In some animals (but not so common), ictus may be preceded by a so-called prodrometerm·dom, a long-term (hours to days) change in disposition and indicator of forthcoming seizuresterm. Humans may experience days of, for example, irritability, withdrawal or other emotional aberrations. In dogs the most common prodromal signsterm described are hours or days of restlessness, anxiousness, appear as being irritated (e.g. with uncharacteristic aggression towards other pets), or attention-seeking behaviour which is known to the owner as a long-term marker of a forthcoming seizureterm episode. Prodromesterm·dom (if present) can represent a potential important therapeutic window for pulse therapy. Prodromal signsterm must be discriminated from focal seizureterm signs. Prodromal signsterm are defined by their longpersName lasting nature whereas focal seizuresterm which may display similar signs when they occur alone or before generalized convulsive seizuresterm are very short (seconds to minutes).
Consciousness in focal epileptic seizuresterm·dom Variable to no impairment of consciousness may appear during focal seizuresterm. However, we propose that no attempt should be made to evaluate if consciousness is unimpaired or impaired (previously described as simple or complex focal (or partial) seizuresterm respectively). Although animals may appear as if consciousness is impaired during focal epileptic seizuresterm·dom (awake but being confused, not recognizing the owner, not responding to commands) we cannot assess this objectively. It will always be a subjective interpretation in animals that cannot report what they are experiencing. Therefore it is not meaningful to subclassify focal epileptic seizuresterm·dom using consciousness.
Agreed modified glossary of descriptive terminology for ictal semiologyterm·key in accordance with the ILAEterm·dom guidelines (based on Blume et al. [ 51 ]) The glossary of descriptive terminology was discussed within the IVETF in 2014. The terms that the majority of the group (>50 % of 95%CI from 14 raters) felt could be also used to describe ictal semiologyterm·key are listed below: I. General terms 1.0 Semiologyterm·key That branch of linguistics concerned with clinical signs.
2.0 Epileptic seizureterm·key Manifestation(s) of excessive synchronous, usually self-limiting epileptic activity of neurons in the brain. This results in a transient occurrence of signs which may be characterized by short episodes with convulsions or focal motor, autonomic or behavioural features and due to abnormal excessive or synchronous epileptic neuronal activity in the brain.
3.0 ICTUS A sudden neurological occurrence such as a stroke or an epileptic seizureterm·key.
4.0 Epilepsyterm·dom Epilepsyterm·dom is defined as a disease of the brain characterized by an enduring predisposition to generate epileptic seizuresterm·key. This definition is usually practically applied as having at least two unprovoked epileptic seizuresterm·key >24 h apart [ 48 ].
5.0 Focal epileptic seizuresterm·dom are conceptualized as originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed. Focal epileptic seizuresterm·dom may originate in subcortical structures. For each epileptic seizureterm·key type, ictal onset is consistent from one seizureterm to another, with preferential propagation patterns that can involve the contralateral hemisphere [ 27 ].
6.0 Generalised epileptic seizureterm·key An epileptic seizureterm·key whose initial semiologyterm·key indicates, or is consistent with, more than minimal involvement of both cerebral hemispheres. Generalized epileptic seizuresterm·dom are conceptualized as originating at some point within, and rapidly engaging, bilaterally distributed networks [ 27 ].
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 seizureterm·key semiologyterm·key These are descriptors of seizuresterm unless specified otherwise.
1.0 Motor Involves skeletal musculature resulting in any phenotypic manifestation. 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 seizureterm” or “seizureterm” e.g. “tonic motor seizureterm or dystonic seizureterm”, and whose definitions can usually be understood as prefaced by: “refers to …”. 1.1.1 Tonic A sustained increase in muscle contraction lasting a few seconds to minutes. 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 Clonic Myoclonus which is regularly repetitive, involves the same muscle groups, at a frequency of about 2–3 seconds, and is prolonged. Synonym: rhythmic myoclonus. 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 epileptic seizureterm·key (Formerly "Grand Mal" Seizureterm) 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 an apparent preceding myoclonic or tonic event lasting one to two seconds or more, involving head, trunk, jaw or limb musculature. 1.1.5 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, teeth grinding or swallowing. 1.2.2 Pedal Indicates principally distal component involvement, bilateral or unilateral. Usually running movement.
2.0 Non-motor 2.1 Aura* Noun: A ‘subjective’ ictal phenomenon that, in a given patient, may precede an observable seizureterm; if alone, constitutes a sensory seizureterm. This can result in behavioral changes such as fear, aggression, searching behaviour, attention, body sensation.
*What is an aura? Commonly owners report that they can foresee a motor seizureterm when specific, and to the owner, well known signs repeatedly appear within seconds or minutes prior to convulsions. The term aura has in the past been used to describe such a forewarning of convulsions. This term originated from human epileptology where aura in early ILAEterm·dom classifications was used “to denote symptomatology that encompasses subjective sensory phenomena as well as vegetative signs (for example, the epigastric sensations accompanying mesial temporal epilepsyterm·dom)” and thus did not include motor phenomena. The group recommends that the term aura is not used in veterinary medicine. The signs occurring as the first indication of seizureterm activity (marking the beginning of ictus) and interpreted by the dog owner as a warning sign is indeed a focal seizureterm onset and should be referred to as such.
2.2 Autonomic A sensation consistent with involvement of the autonomic nervous system, including cardiovascular, gastrointestinal, sudomotor, vasomotor and thermoregulatory functions. In companion animals, salivation, mydriasis, urination and/or defecation may commonly be observed.
3.0 Somatotopic modifiers 3.1 Laterality 3.1.1 Unilateral Exclusive or virtually exclusive involvement of one side as a motor, sensory or autonomic phenomenon. 3.1.1.1 HEMI- A prefix to other descriptors e.g. hemiclonic. 3.1.2 Generalised (syn. “bilateral”) More than minimal involvement of each side as a motor or autonomic phenomenon. Motor component: further modified as: 3.1.2.1 Asymmetrical Clear distinction in quantity and/or distribution of activity on the two sides. 3.1.2.2 Symmetrical Virtual bilateral equality in these respects.
3.2 Body part Refers to area involved i.e. limb, face, trunk and other. 3.2.1 Axial Involves trunk, including neck. 3.2.2 Proximal limb Signifies involvement from shoulders to metacarpus, hip to metatarsus. 3.2.3 Distal limb Indicates involvement of paws.
4.0 Modifiers and descriptors of epileptic seizureterm·key timing The following terms are listed in the form (adjective, noun, verb) according to principal usage; as adjective unless specified.
4.1 Incidence Noun: Refers to the number of epileptic seizuresterm·key within a time period or the number of seizureterm days per unit of time. 4.1.1 Regular, irregular Consistent (inconsistent) or predictable (unpredictable, chaotic) intervals between such events. 4.1.2 Cluster Incidence of epileptic seizuresterm·key within a given period (usually one or a few days) which exceeds the average of incidence over a longer period for the patient. Cluster seizuresterm can be defined clinically as two or more seizuresterm within a 24-h period. 4.1.3 Provocative factor Noun: Transient and sporadic endogenous or exogenous element capable of augmenting seizureterm incidence in the patient with chronic epilepsyterm·dom and evoking seizuresterm in susceptible non-epileptic individuals. 4.1.3.1 Reactive A reactive seizureterm is a seizureterm occurring as a natural response from the normal brain to a transient disturbance in function (metabolic or toxic in nature)—which is reversible when the cause or disturbance is rectified. A provoked seizureterm can be considered as being synonymous with a reactive seizureterm. 4.1.3.2 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 sound) or elaborate i.e. structured, (a symphony). Activity may be elementary, e.g. motor (a movement).
5.0 Duration Time between the beginning of initial epileptic seizureterm·key manifestations, such as the e.g., focal epileptic seizureterm·dom signs or full body convulsions to the cessation of experienced or observed epileptic seizureterm·key activity. Does not include non-specific seizureterm premonitions or postictal states.
5.1 Status epilepticusterm·key An epileptic seizureterm·key which shows no clinical signs of arresting after a duration encompassing the great majority of seizuresterm of that type in most patients or recurrent epileptic seizuresterm·key without resumption of baseline central nervous system function interictally. Status epilepticusterm·key can be defined clinically as (a) greater than 5 min of continuous epileptic seizuresterm·key or (b) two or more discrete epileptic seizuresterm·key between which there is incomplete recovery of consciousness (for generalized convulsive seizuresterm).
6.0 Severity A multicomponent assessment of an epileptic seizureterm·key by observers and the patient.
Components primarily of observer assessment include: duration, extent of motor involvement, impairment of interaction with environment intra-ictally, maximum number of seizuresterm per unit of time.
7.0 Prodrometerm·dom A pre-ictal phenomenon. A subjective or objective clinical alteration that heralds the onset of an epileptic seizureterm·key but does not form part of it. Prodrometerm·dom is a longpersName lasting event (hours to days) and should not be confused with focal onset seizureterm signs which are very brief events (seconds to minutes).
8.0 Postictal phenomenon A transient clinical abnormality of central nervous system function that appears or becomes accentuated when clinical signs of the ictus have ended.
8.1 Lateralising (TODD‘S (or bravais’)) phenomenon Any unilateral postictal dysfunction relating to motor, somatosensory and/or integrative functions including visual, auditory or somatosensory.
8.1 Non-lateralising phenomenon Behavioural changes such as fear, aggression, increased appetite.
Acknowledgements The authors are grateful to all owners of epileptic pets and veterinary colleagues who have inspired the group to create consensus statements. We thank all the breeders and breed clubs for their support. We would especially like to thank Professor Simon Shorvon for the critical review of the consensus statements. His great insight has been immensely helpful. The authors also would like to thank the research office for assessing the manuscript according to the Royal Veterinary College’s code of good research practice (Authorisation Number – CCS_ 01023). This study was not financially supported by any organization or grant.
Other members of the classification, definition and terminology working group (alphabetically listed).
Abbreviations International Veterinary Epilepsyterm·dom Task Force International League Against Epilepsyterm·dom Footnotes Contributor Information Mette BerendtpersName, Email: mbe@sund.ku.dk.
Robyn G. FarquharpersName, robyn.fernside@googlemail.com Paul J. J. MandigerspersName, Email: P.J.J.MandigerspersName@uu.nl Akos PakozdypersName, Email: akos.pakozdypersName@vetmeduni.ac.at.
Sofie F. M. BhattipersName, Email: sofie.bhattipersName@ugent.be Luisa De RisiopersName, Email: luisa.derisio@aht.org.uk.
Andrea FischerpersName, Email: andreafischer@lmu.de.
Sam LongpersName, Email: snlong@unimelb.edu.au.
Kaspar MatiasekpersName, Email: matiasekpersName@patho.vetmed.uni-muenchen.de.
Karen MuñanapersName, Email: krmunana@ncsu.edu.
Edward E. PattersonpersName, Email: patte037@umn.edu Jacques PenderispersName, Email: jacques.penderispersName@vet-neurology.co.uk.
Simon PlattpersName, Email: srplatt@uga.edu.
Michael PodellpersName, Email: mpodell@comcast.net.
Heidrun PotschkapersName, Email: potschkapersName@pharmtox.vetmed.uni-muenchen.de.
Martí Batlle PumarolapersName, Email: marti.pumarolapersName@uab.cat.
Clare RusbridgepersName, Email: ClareR@fitzpatrickreferrals.co.uk.
Veronika M. SteinpersName, Email: Veronika.SteinpersName@tiho-hannover.de Andrea TipoldpersName, Email: Andrea.TipoldpersName@tiho-hannover.de.
Holger A. VolkpersName, Email: hvolk@rvc.ac.uk References