Seizure Phenomenology Research Articles

Ecstatic or Mystical Experience through Epilepsy.

Ecstatic epilepsy is a rare form of focal epilepsy, so named because the seizures' first symptoms consist of an ecstatic/mystical experience, including feelings of increased self-awareness, mental clarity, and "unity with everything that exists," accompanied by a sense of bliss and physical well-being. In this perspective article, we first describe the phenomenology of ecstatic seizures, address their historical context, and describe the primary brain structure involved in the genesis of these peculiar epileptic seizures, the anterior insula. In the second part of the article, we move onto the possible neurocognitive underpinnings of ecstatic seizures. We first remind the reader of the insula's role in interoceptive processing and consciously experienced feelings, contextualized by the theory of predictive coding. This leads us to hypothesize that temporary disruptions to activity in the anterior insula could interrupt the generation of interoceptive prediction errors, and cause one to experience the absence of uncertainty, and thereby, a sense of bliss. The absence of interoceptive prediction errors would in fact mimic perfect prediction of the body's physiological state. This sudden clarity of bodily perception could explain the ecstatic quality of the experience, as the interoceptive system forms the basis for unified conscious experience. Our alternative hypothesis is that the anterior insula plays an overarching role in the processing of surprise and that the dysfunction caused by the epileptic discharge could interrupt any surprise exceeding expectations, resulting in a sense of complete control and oneness with the environment.

Epilepsy in nonhuman primates.

Nonhuman primates (NHPs) are model organisms for understanding the pathophysiology and treatment of epilepsy in humans, while data from human patients informs the diagnosis and treatment of NHP with seizures and epilepsy. We reviewed the literature and surveyed veterinarians at zoos and NHP research centers to (a) better define the range of seizures and epilepsy in NHP, (b) understand how NHPs can inform our knowledge of the pathophysiology and treatment of epilepsy in humans, and (c) identify gaps of knowledge and develop more effective guidelines to treat seizures and epilepsy in NHP. We searched PrimateLit, PubMed, and Google Scholar for studies on experimental models of epilepsy in NHPs and on naturally occurring seizures and epilepsy in NHPs in captivity. In addition, we created a survey to assess methods to diagnose and treat epilepsy in NHPs. This survey was sent to 41 veterinarians at major international zoos and research facilities with NHP populations to study seizure phenomenology, diagnostic criteria for seizures and epilepsy, etiology, and antiseizure therapies in NHPs. We summarize the data from experimental and natural models of epilepsy in NHPs and case reports of epilepsy of unknown origin in captive primates. In addition, we present survey data collected from veterinarians at eight zoos and one research facility. Experimental data from NHP epilepsy models is abundant, whereas data from primates who develop epilepsy in the wild or in zoos is very limited, constraining our ability to advance evidence-based medicine. Characterization of seizure or epilepsy models in NHPs will provide insights into mechanisms and new therapies that cannot be addressed by other animal models. NHP research will better inform species-specific diagnoses and outcomes.

Cortical epileptogenesis and David Ferrier

ABSTRACTThere was an increasing medical interest in the localization of representation of function in the cerebral cortex after Broca in 1861 identified a cortical area that appeared responsible for expressive speech. By the late 1860s, John Hughlings Jackson—based on clinico-pathological correlations mainly in persons with focal motor seizures—had reasoned that contralateral somatic motor function was represented in another area of the cortex. This localization was supported by Fritsch and Hitzig (1870) in experimental cortical stimulation studies in dogs. These authors also reported producing events resembling contralateral motor convulsing in their animals. Their work, and Jackson’s ideas, prompted David Ferrier, in Great Britain, to begin a program of cerebral cortical stimulation studies in various vertebrate species, trying to locate cortical sites of representation of functions other than expressive speech and motor activity. In his initial report of his investigations (1873), he noted that appropriately sited Faradic stimulation evoked immediate or delayed contralateral focal motor seizures, some of which evolved into generalized convulsions. On this basis he reasoned that focal motor and generalized seizures were expressions of the same disorder; that nearly all epilepsies originated in the cerebral cortex and not in the lower brain stem, as hitherto thought; and that the clinical pattern of epileptic seizure phenomenology depended on the function of the cortical site of origin and the extent and direction of spread of seizure activity in the brain. He not only provided experimental verification for Jackson’s reasoning about epileptic seizure mechanisms but expressed the ideas a good deal more clearly than Jackson ever managed to do. Ferrier’s achievement in this regard has tended to escape notice, lost sight of because of the great importance of his investigations into localization of cerebral function.

Stress is associated with an increased risk of recurrent seizures in adults.

The literature is sparse on the complex interrelationships between stressors, depression, anxiety disorders, and epilepsy. We hypothesized that a relationship exists between stress and epilepsy. We evaluated whether markers of stress are associated with seizure recurrence in a low income community-based cohort of adults with single unprovoked seizure or newly diagnosed epilepsy. We ascertained adult residents of Northern Manhattan and Harlem, New York City, with a first unprovoked seizure or newly diagnosed epilepsy, between December 2010 and January 2013. At enrollment, we collected information about seizure phenomenology, demographics, clinical information, and measures of stress (environmental stress, stressful life events, facets of allostatic load-i.e., the cumulative effect of adaptation to stress, psychiatric disorders, and low collective efficacy). Collective efficacy assesses neighborhood characteristics and incorporates social cohesion and informal social control. All subjects were followed for 2years for further seizures. Cox proportional hazard regression models were used to estimate the hazard ratios of seizure recurrence during the 2years of follow-up. We identified 52 subjects (64.2%) with a single unprovoked seizure and 29 (35.9%) with newly diagnosed epilepsy. Seizure recurrence was recorded in 38.5% (N=20) of subjects with a single unprovoked seizure and in 69% of those with epilepsy (N=20) (p=0.01). In the overall sample, the hazard of seizure recurrence was increased by lifetime generalized anxiety disorder (3.0-fold) and by low collective efficacy (2.7-fold). In a second model, the hazard was increased by lifetime mood disorder (2.1-fold) and low collective efficacy (2.5-fold). Markers of stress (i.e., low collective efficacy, lifetime mood disorder, and lifetime generalized anxiety disorder) were associated with an increased risk for seizure recurrence in adults with a single unprovoked seizure or newly diagnosed epilepsy. Stress-reducing interventions, such as mindfulness, may be a useful, safe, and inexpensive adjunctive treatment for epilepsy.

The Spectrum of Epilepsies with Fixation off Sensitivity: A Case Report and Review of Literature

Fixation off sensistivity is a electrographic marker of occipital lobe epilepsy. The report describes a 11 year old with infrequent seizures responsive to treatment with valproate who was found to have occipital epileptiform discharges which appeared only during eye closure. The typical phenomenology of visual aura or autonomic seizures as seen in benign occipital epilepsies is not mandatory to be associated with FOS. The spectrum of various epilepsy syndrome which display this typical finding is discussed.

P34 – 2727: Optimization of approaches in treatment of patients with epilepsy

Objective Optimization of adequate plasma concentrations of antiepileptic drugs (AED)s to achieve a prolonged and sustained remission of epilepsy. Methods The study is based on the results of a survey of 40 patients with epilepsy, varying in age debut, duration and etiology of the disease, clinical phenomenology of seizures, but all of them taking carbamazepine as AED. Conducted therapeutic drug monitoring (TDM), MRI, EEG. Results The majority of patients were between the ages of 1 to 5 years of life 52.5%. Selection criteria were the children taking AEDs for at least 3 months. Therapeutic range of carbamazepine concentration is 4–12 mkg/ml, toxicity develops at the level of circulating carbamazepine above 15 mkg/ml TDM allowed to establish causes of no adequate treatment strategy, such as, prescribing AEDs in unreasonable low doses, the appointment of two and more AEDs from different groups without regard to their pharmacokinetic interactions, that caused subtherapeutic drug levels in the blood serum in 33 (82.5%) cases. Level of drugs was at the recommended therapeutic range in 6 (15%) cases, which directly reflects the high individual variability between the received dose and drug levels in the blood. Feedback was analyzed assignable dose of drugs in mg per patient's weight with its concentration in blood plasma. In patients with low drug concentration in blood plasma confirmed adequate calculation of the drug per body weight. Its once again confirm individual tolerability of each patient and the presence of unknown causes which impact on the drug perception, such as helminthes, enzymes deficiency, lack of the liver functional activity and not identified blood minerals. Conclusion Treatment correction on the basis of TDM in patients with various forms of epilepsy lead to the decreasing of the attacks frequency. Clinical positive trend was confirmed by EEG data.

Standardized assessment of seizures in patients with juvenile neuronal ceroid lipofuscinosis.

To evaluate seizure phenomenology, treatment, and course in individuals with juvenile neuronal ceroid lipofuscinosis (JNCL). Data from an ongoing natural history study of JNCL were analyzed using cross-sectional and longitudinal methods. Seizures were evaluated with the Unified Batten Disease Rating Scale, a disease-specific quantitative assessment tool. Eighty-six children (44 males, 42 females) with JNCL were assessed at an average of three annual visits (range 1-11). Eighty-six percent (n=74) experienced at least one seizure, most commonly generalized tonic-clonic, with mean age at onset of 9years 7months (SD 2y 10mo). Seizures were infrequent, typically occurring less often than once every 3months, and were managed with one to two medications for most participants. Valproate (49%, n=36) and levetiracetam (41%, n=30) were the most commonly used seizure medications. Myoclonic seizures occurred infrequently (16%, n=14). Seizure severity did not vary by sex or genotype. Seizures showed mild worsening with increasing age. The neuronal ceroid lipofuscinoses (NCLs) represent a group of disorders unified by neurodegeneration and symptoms of blindness, seizures, motor impairment, and dementia. While NCLs are considered in the differential diagnosis of progressive myoclonus epilepsy, we show that myoclonic seizures are infrequent in JNCL. This highlights the NCLs as consisting of genetically distinct disorders with differing natural history.

Similar semiology of epileptic and psychogenic nonepileptic seizures recorded during stereo-EEG

We report two adolescents with refractory seizure disorders in whom both epileptic and psychogenic nonepileptic seizures (PNES) were recorded with intracerebral EEG. The ictal phenomenology of epileptic seizures (ES) and PNES, consisting of hypermotor attacks in the first patient and left-sided painful episodes in the second patient, proved remarkably similar in both cases, highlighting the difficulties which can arise with the distinction of epileptic seizures and PNES based on ictal phenomenology alone.

Risk Factors for Febrile Status Epilepticus: A Case-Control Study

To identify risk factors for developing a first febrile status epilepticus (FSE) among children with a first febrile seizure (FS). Cases were children with a first FS that was FSE drawn from the Consequences of Prolonged Febrile Seizures in Childhood and Columbia cohorts. Controls were children with a first simple FS and separately, children with a first complex FS that was not FSE. Identical questionnaires were administered to family members of the 3 cohorts. Magnetic resonance imaging protocol and readings were consistent across cohorts, and seizure phenomenology was assessed by the same physicians. Risk factors were analyzed using logistic regression. Compared with children with simple FS, FSE was associated with younger age, lower temperature, longer duration (1-24 hours) of recognized temperature before FS, female sex, structural temporal lobe abnormalities, and first-degree family history of FS. Compared with children with other complex FS, FSE was associated with low temperature and longer duration (1-24 hours) of temperature recognition before FS. Risk factors for complex FS that was not FSE were similar in magnitude to those for FSE but only younger age was significant. Among children with a first FS, FSE appears to be due to a combination of lower seizure threshold (younger age and lower temperatures) and impaired regulation of seizure duration. Clinicians evaluating FS should be aware of these factors as many episodes of FSE go unnoticed. Further work is needed to develop strategies to prevent FSE.

A new perspective for Epileptic Disorders

Since its launch in late 1999 under the direction of Jean Aicardi, founding Editor-in-Chief, Epileptic Disorders has served the medical and scientific community in an expanding discipline of epileptology in which new diagnostic techniques and approaches to management are continually being developed. A significant amount of new information in all areas of epileptology has accumulated at a brisk pace, leading to a steady increase in the number of articles submitted to the journal. As intended from the outset, the descriptive detailed clinical symptomatology and phenomenology of epileptic seizures and syndromes, in relation to diagnosis and management, published in Epileptic Disorders has served to complement other journals in the field. Epileptic Disorders continues to provide audiovisual material

Human herpesvirus 6 and 7 in febrile status epilepticus: The FEBSTAT study

In a prospective study, Consequences of Prolonged Febrile Seizures in Childhood (FEBSTAT), we determined the frequency of human herpesvirus (HHV)-6 and HHV-7 infection as a cause of febrile status epilepticus (FSE). Children ages 1 month to 5 years presenting with FSE were enrolled within 72 h and received a comprehensive assessment including specimens for HHV-6 and HHV-7. The presence of HHV-6A, HHV-6B, or HHV-7 DNA and RNA (amplified across a spliced junction) determined using quantitative polymerase chain reaction (qPCR) at baseline indicated viremia. Antibody titers to HHV-6 and HHV-7 were used in conjunction with the PCR results to distinguish primary infection from reactivated or prior infection. Of 199 children evaluated, HHV-6 or HHV-7 status could be determined in 169 (84.9%). HHV-6B viremia at baseline was found in 54 children (32.0%), including 38 with primary infection and 16 with reactivated infection. No HHV-6A infections were identified. HHV-7 viremia at baseline was observed in 12 children (7.1%), including eight with primary infection and four with reactivated infection. Two subjects had HHV-6/HHV-7 primary coinfection at baseline. There were no differences in age, characteristics of illness or fever, seizure phenomenology or the proportion of acute EEG or imaging abnormalities in children presenting with FSE with or without HHV infection. HHV-6B infection is commonly associated with FSE. HHV-7 infection is less frequently associated with FSE. Together, they account for one third of FSE, a condition associated with an increased risk of both hippocampal injury and subsequent temporal lobe epilepsy.

Are developmental dysplastic lesions epileptogenic?

Cortical dysplasia of various types, reflecting abnormalities of brain development, have been closely associated with epileptic activities. Yet, there remains considerable discussion about if/how these structural lesions give rise to seizure phenomenology. Animal models have been used to investigate the cause-effect relationships between aberrant cortical structure and epilepsy. In this article, we discuss three such models: (1) the Eker rat model of tuberous sclerosis, in which a gene mutation gives rise to cortical disorganization and cytologically abnormal cellular elements; (2) the p35 knockout mouse, in which the genetic dysfunction gives rise to compromised cortical organization and lamination, but in which the cellular elements appear normal; and (3) the methylazoxymethanol-exposed rat, in which time-specific chemical DNA disruption leads to abnormal patterns of cell formation and migration, resulting in heterotopic neuronal clusters. Integrating data from studies of these animal models with related clinical observations, we propose that the neuropathologic features of these cortical dysplastic lesions are insufficient to determine the seizure-initiating process. Rather, it is their interaction with a more subtly disrupted cortical "surround" that constitutes the circuitry underlying epileptiform activities as well as seizure propensity and ictogenesis.

In support of the ILAE Commission classification proposal

Our attempts to understand and classify seizures and epilepsies have been progressing over recent decades. Originally based on the phenomenology of behavioral seizures and scalp electroencephalography (EEG), the International League Against Epilepsy (ILAE)–endorsed Classification system has evolved as newer technologies, such as neuroimaging and genetics, have expanded what we understand to be epilepsy syndromes. The recent report of the ILAE 2005–2009 Commission on Classification and Terminology published in Epilepsia in 2010 (Berg et al., 2010) proposed a flexible approach, along multiple axes, to incorporate newer, albeit ongoing, understandings of the epilepsies. In their commentary, Berg and Scheffer (2011) emphasize that the current state of the classification is in flux, as they state: “these recommendations are admittedly imperfect and follow perhaps too closely the old idiopathic-symptomatic-cryptogenic distinctions. …they were intended as part of a transition phase toward the goal of developing rational, scientifically justifiable approaches for a true classification of causes based on scientific understanding of how they are related. This approach must be constructed in such a way as to allow updating and revision as knowledge grows.” As a coauthor of the original Berg et al. (2010) report, I endorsed it because the new Classification system represents a significant step forward and a valuable reference tool for prognosis, and possibly for treatment-related decisions for those with epilepsy. The new Classification system also begins to address the use of better terms to describe major classes of seizures. In his commentary, Shorvon (2011) emphasizes the need to provide an etiologic classification of epilepsy—which is indeed a key component of the new Classification system. He also offers a divergent view, suggesting a return to the older nomenclature—which the new proposal is trying to change as it begins to address the mechanisms and causes of epilepsy. Therefore, although I thank Dr. Shorvon for his thought-provoking commentary, I propose that we start using and testing the new terminology, which best reflects our current state of knowledge. The need for a mechanistic approach based on our evolving understanding of pathophysiology and on the information derived from the impressive explosion of technology, has also been voiced by others. The participants of a workshop on “Conceptual dichotomies in classifying epilepsies,” organized by Capovilla in Monreale, Italy and published in the Gray Matters of Epilepsia (2009), agreed that the nomenclature should depict state-of-the-art concepts. Because they could not identify an optimum nomenclature, the terms type 1, type 2, and type 3 were proposed. The Commission’s 2010 proposal further elaborated on this issue, providing a justification for adopting the terms: Genetic, Symptomatic/Metabolic, and Unknown, instead of type 1, type 2, and type 3. It is my opinion that the terms “idiopathic” and “cryptogenic” should be replaced by more specific terms that better reflect the underlying etiology. Another suggestion by Shorvon is the addition of a new category of “provoked epilepsies.” This is an interesting concept. However, within our epilepsy community, it is highly debated whether drug-induced seizures, febrile seizures, etc. are actually the expression of an epilepsy syndrome. In fact, in basic science studies, the use of proconvulsants to provoke seizures is considered to represent a model of seizures and not a model of epilepsy (see Pitkanen et al., 2006). The latter should depict the chronic, enduring changes that characterize epilepsy. Before the publication of its report in 2010, the Commission’s proposal was circulated to all ILAE Chapters and placed on the Web for commentaries. In the published report (Berg et al., 2010), the authors took into account the suggestions received from many of our colleagues. Additional discussions along with further advances in biogenetics and imaging will help us to clarify the remaining issues and further evolve the Classification system. The 2005–2009 Commission on Classification and Terminology deserves a great deal of thanks from the international epilepsy community for tackling a topic in which we all have a stake and for which we all want a voice. The current Commission on Classification (2009–2013) is preparing a final draft, to be submitted for approval by the ILAE General Assembly at the 2013 International Epilepsy Congress as the official ILAE position on classification. Each proposed change to the Classification system involves consensus and compromise. As President of the ILAE, I sincerely hope that we will continue to maintain an open dialogue and to work together to reach a consensus for the most appropriate terminology. I receive research support from NIH: R01-NS20253-22 (PI), (R01-NS043209 (Investigator), 2U01-NS045911 (Investigator), V01-NS053998 (Investigator), and the Heffer Family Foundation (PI). I am Associate Editor of Neurobiology of Disease and serve on the Editorial Boards of Epileptic Disorders and Brain and Development. I am currently a consultant to Eisai. I confirm that I have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

Prognosis and outcome predictors in psychogenic nonepileptic seizures.

It is estimated that one in five patients referred to specialist epilepsy clinics for refractory seizures have psychogenic nonepileptic seizures (PNES). Despite the high prevalence, little is known about the prognosis of patients with PNES. In this paper we set out to systematically assess published original studies on the prognosis and outcome predictors of patients with PNES. Our literature search across the databases Medline, PsycINFO, and EMBASE generated 18 original studies meeting the search criteria. Prognosis was found to be poor in adults, but good in children. Predictors of poor outcome included the presence of coexisting epilepsy or psychiatric comorbidities, violent seizure phenomenology, dependent lifestyle, and poor relationships. Overall, too much reliance is placed on seizure remission as an outcome measurement for patients with PNES, and the impact of many of the outcome predictors requires evaluation using larger studies with longer followup.

Focal epilepsy in the Belgian shepherd: evidence for simple Mendelian inheritance

To establish the mode of inheritance and describe the clinical features of epilepsy in the Belgian shepherd, taking the outset in an extended Danish dog family (199 individuals) of Groenendael and Tervueren with accumulated epilepsy. Epilepsy positive individuals (living and deceased) were ascertained through a telephone interview using a standardised questionnaire regarding seizure history and phenomenology. Living dogs were invited to a detailed clinical evaluation. Litters more than five years of age, or where epilepsy was present in all offspring before the age of five, were included in the calculations of inheritance. results: Out of 199 family members, 66 dogs suffered from epilepsy. The prevalence of epilepsy in the family was 33%. Fifty-five dogs experienced focal seizures with or without secondary generalisation, while four dogs experienced primary generalised seizures. In seven dogs, seizures could not be classified. The mode of inheritance of epilepsy was simple Mendelian. This study identified that the Belgian shepherd suffers from genetically transmitted focal epilepsy. The seizure phenomenology expressed by family members have a strong resemblance to what has been reported for familial partial (focal) epilepsy in humans with variable foci with suggestion of linkage to chromosome 2 and chromosome 22q12.

Prevalence and characteristics of epilepsy in the Belgian shepherd variants Groenendael and Tervueren born in Denmark 1995–2004

BackgroundThe Belgian shepherd Groenendael and Tervueren is believed to be at higher risk of developing epilepsy than dogs of the common population. This epidemiological study was designed to estimate the prevalence of epilepsy in the Danish population of Groenendael and Tervueren born between 1995 and 2004. Furthermore, it was the intention to describe the clinical manifestation (seizure types and phenomenology) of epilepsy and to identify risk factors for euthanasia once the dog was diagnosed as having epilepsy.MethodsAll owners of Groenendael and Tervueren dogs born between January 1995 and December 2004 and registered in the Danish Kennel Club (1,248 dogs) were contacted and asked to answer a mailed questionnaire concerning epilepsy. Positive responders were subsequently validated in a follow-up interview conducted by telephone using a standardized questionnaire. Owners were questioned about age at first seizure, seizure frequency, seizure duration, a detailed description of seizure phenomenology, post-ictal signs and if a veterinarian had diagnosed the dog with epilepsy.ResultsPrevalence of epilepsy was estimated at 9.5%. Mean age of epilepsy debut was 3.3 years (range 0.5–8.0 years). There was an almost equal number of Groenendael (25) and Tervueren (24). The distribution of females and males was 31 and 18 respectively. Twenty-five per cent experienced focal seizures, 53% experienced focal seizures with secondary generalization and 18% experienced primary generalized seizures. In four percent seizures were unclassifiable. The most commonly reported focal seizure phenomenology included ataxia, crawling, swaying, fearful behavior, salivation, excessive attention seeking and disorientation. In 16% of the cases, epilepsy led to euthanasia. Intact dogs with epilepsy had a significantly increased risk of being euthanized because of epilepsy compared to neutered dogs with epilepsy. In 22% of the cases the owners reported that anxiety/hyperactivity/stress could act as a seizure provoking factor.ConclusionA high prevalence of epilepsy appears to be present in the Danish Groenendael and Tervueren population. The relatively late debut age of epilepsy in this breed contributes greatly to the increased prevalence of epileptic individuals, because dogs developing epilepsy late in life are used for breeding unintended.

Melancholic major depression and epilepsy

An analysis is carried out of a set of psychic phenomena appearing always in the same way: an experience suddenly invades the consciousness, unfolding automatically and with great intensity. This psychic automatism, of which the patient is a passive observer, is accompanied by an overwhelming feeling of strangeness. Our hypothesis is that these phenomena are the expression of partial seizures with a psychic content, and the name Paroxysmal Psychic Automatisms is proposed for all of them. A comparative study is then made of the phenomenology of partial seizures with a psychic content, on the one hand, and of that of melancholic major depression, on the other. It reveals a wealth of clinical information indicating an overlap between the two conditions. Finally, a set of well-established scientific data is analysed concerning epilepsy and depression, especially epidemiological and psychopharmacological information, which takes on a new meaning in the light of the hypothesis developed in this paper.

Status Epilepticus in Idiopathic Generalized Epilepsy

Status epilepticus (SE) can take various forms in idiopathic generalized epilepsy (IGE), some of which forms also occur in symptomatic or focal epilepsies. Although the clinical semiology of the SE episodes may be similar in these different epilepsies, the frequency, response to treatment and prognosis differ. (a) Convulsive SE is surprisingly uncommon in IGE and much less common than in the secondarily generalized or partial epilepsies. Also, when it does occur, it usually responds rapidly to treatment. (b) Typical absence SE occurs only in patients with IGE (the subcategories with typical absence seizures) and also in the syndrome of de novo absence SE of late onset. This form of nonconvulsive SE should be differentiated from atypical absence SE, which occurs in the secondarily generalized epilepsy encephalopathies, and from complex partial SE which occurs in focal epilepsy. The clinical symptoms of these three types overlap but the prognosis and response to treatment are different. The mechanisms underlying absence SE are uncertain and may include both genetic and environmental factors. The termination of absence seizures has been hypothesized to be due to persistent activation of a depolarizing current in thalamocortical neurons that inactivates T-type calcium channels. SE could thus result from dysfunction of this channel or mechanisms that hyperpolarize thalamocortical neurons-these include decreased cortical inhibition, increased reticular thalamic neuronal activity or increased thalamocortical neuron GABA(B)-receptor activation. (c) Generalized electrographic SE is encountered in IGE in the syndrome of phantom absence with GTCS. It also occurs in ESES and in the Landau-Kleffner syndrome. The seizure phenomenology overlaps with the focal SE of temporal or frontal lobe epilepsy. (d) Myoclonic SE is also uncommon in IGE but occurs in juvenile myoclonic epilepsy. It is more commonly encountered in progressive myoclonic epilepsies, myoclonic-astatic epilepsy and in the Dravet syndrome. (e) Autonomic status occurs largely in the Panayiotopoulos syndrome. It is included here under the rubric of IGE, although the epilepsy has focal as well as generalized features and its nosological position is controversial. Fifty percent of seizures in this syndrome could be classified as status epilepticus. There is no doubt that convulsive SE can result in cerebral damage. In animal models of focal SE, nonconvulsive forms can also result in cerebral damage, but cerebral damage is not observed in animal models of absence SE. Similarly, cerebral damage seems not to occur in the forms of nonconvulsive SE in human IGE.

Characteristics and phenomenology of epileptic partial seizures in dogs: similarities with human seizure semiology

Dogs with spontaneous occurring epilepsy with partial seizures express symptomatology resembling what is found in humans with partial epileptic seizures. Questionnaires on clinical signs from 70 dogs, with a confirmed diagnosis of epilepsy with partial seizures with or without secondary generalization, were reviewed in order to characterize and classify clinical signs of partial seizure activity in dogs and compare them to partial seizure phenomenology in humans. Signs of partial seizure activity were distributed into three categories: motor signs, autonomic signs and paroxysms of behavioral signs. Motor signs were described in 48 dogs (69%), autonomic signs in 16 dogs (23%) and paroxysms of behavioral signs in 56 dogs (80%). The majority of dogs expressed signs from more than one group. Sixty-one dogs (87%) had partial seizures with secondary generalization. Nine dogs (13%) had partial seizures without secondary generalization. The study shows a remarkable resemblance between the seizure phenomenology expressed in humans and canines with partial epileptic seizures.

A Cross‐Sectional Study of Epilepsy in Danish Labrador Retrievers: Prevalence and Selected Risk Factors

The purpose of this study was to investigate the prevalence and selected risk factors of epilepsy, the proportion of dogs with epilepsy in remission, and the types of seizures in Danish Labrador Retrievers. A prospective cross‐sectional study of epilepsy was conducted in 1999–2000. The study was carried out in 2 phases in a reference population consisting of 29,602 individuals. In phase 1, 550 dogs were selected by random sampling stratified by year of birth. A telephone interview was used to identify dogs with possible epilepsy. In phase 2, dogs judged during phase 1 as possibly suffering from epilepsy were further subjected to physical and neurologic examination, CBC, blood chemistry, and a questionnaire on seizure phenomenology. Seventeen dogs were diagnosed with epilepsy, yielding a prevalence of 3.1% (95% CI 1.6–4.6%) in the Danish population of Labrador Retrievers. A diagnosis of epilepsy was 6 times more probable in dogs >4 years (born before 1995) than in younger dogs (born between 1995 and 1999) (P= .004, relative risk = 6.5). No significant difference in risk between genders was observed, nor could any effect of neutering be proven statistically. The frequencies of primary generalized seizures and partial seizures (with or without secondary generalization) were 24 and 70%, respectively. The type of seizures could not be classified in 6%. In conclusion, the 3.1% prevalence of epilepsy in Danish Labrador Retrievers is higher than the 1% prevalence of epilepsy described in the general canine population, establishing that this breed is at increased risk.