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Peek SI, Twele F, Meller S, Packer RMA, Volk HA. Epilepsy is more than a simple seizure disorder: Causal relationships between epilepsy and its comorbidities. Vet J 2024; 303:106061. [PMID: 38123062 DOI: 10.1016/j.tvjl.2023.106061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 11/10/2023] [Accepted: 12/15/2023] [Indexed: 12/23/2023]
Abstract
This review draws connections between the pathogenesis of canine epilepsy and its most commonly recognised comorbidities: cognitive impairment (CI), attention deficit hyperactivity disorder (ADHD)-like behaviour, fear and anxiety. Uni/bidirectional causalities and the possibility of a common aetiology triggering both epilepsy and the associated diseases are considered. Research on this topic is sparse in dogs, so information has been gathered and assessed from human and laboratory animal studies. Anatomical structures, functional connections, disrupted neurotransmission and neuroinflammatory processes collectively serve as a common foundation for epilepsy and its comorbidities. Specific anatomical structures, especially parts of the limbic system, such as the amygdala and the hippocampus, are involved in generating seizures, as well as cognitive- and behavioural disorders. Furthermore, disturbances in inhibitory and excitatory neurotransmission influence neuronal excitability and networks, leading to underlying brain dysfunction. Functional magnetic resonance imaging (fMRI), interictal epileptiform discharges (IEDs), and electroencephalography (EEG) have demonstrated functional brain connections that are related to the emergence of both epilepsy and its various comorbidities. Neuroinflammatory processes can either cause or be a consequence of seizures, and inflammatory mediators, oxidative stress and mitochondrial dysfunction, can equally evoke mood disorders. The extensive relationships contributing to the development and progression of seizures and comorbid cognitive and behavioural conditions illustrate the complexity of the disease that is epilepsy.
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Affiliation(s)
- Saskia I Peek
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, Germany
| | - Friederike Twele
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, Germany
| | - Sebastian Meller
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, Germany
| | | | - Holger A Volk
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, Germany.
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Mizuno S, Asada R, Yu Y, Hamamoto Y, Hasegawa D. Investigation of the effect and availability of ketamine on electroencephalography in cats with temporal lobe epilepsy. Front Vet Sci 2023; 10:1236275. [PMID: 37559886 PMCID: PMC10407800 DOI: 10.3389/fvets.2023.1236275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 07/10/2023] [Indexed: 08/11/2023] Open
Abstract
In recent years, electroencephalography (EEG) in veterinary medicine has become important not only in the diagnosis of epilepsy, but also in determining the epileptogenic focus. In cats, sedation and immobilization, usually with medetomidine or dexmedetomidine, are necessary to place the electrodes and to obtain stable scalp EEG recordings. In this study, we hypothesized that, for cats with temporal lobe epilepsy (TLE), ketamine, a sedative/anesthetic and N-methyl-D-aspartate (NMDA) antagonist that activates the limbic system and is also used to treat refractory status epilepticus in dogs, would induce sufficient sedation and immobilization for EEG, as well as induce interictal epileptiform discharges (IEDs) that are more pronounced than those induced with medetomidine. We obtained EEG recordings from TLE cats and healthy cats administered either ketamine or medetomidine alone (study 1) or ketamine after medetomidine sedation (study 2). In study 1, the frequency of IEDs showed no statistically significant difference between ketamine and medetomidine in both TLE and healthy cats. Seizures were observed in 75% (9/12) cats of the TLE group with ketamine alone. When ketamine was administered after sedation with medetomidine (study 2), 3/18 cats in the TLE group developed generalized tonic-clonic seizure and 1/18 cats showed subclinical seizure activity. However, no seizures were observed in all healthy cats in both study 1 and study 2. Slow wave activity at 2-4 Hz was observed in many individuals after ketamine administration regardless studies and groups, and quantitative analysis in study 2 showed a trend toward increased delta band activities in both groups. While there was no significant difference in the count of IEDs between medetomidine and ketamine, ketamine caused seizures in cats with TLE similar to their habitual seizure type and with a higher seizure frequency. Our results suggest that ketamine may activate epileptiform discharges during EEG recordings. However, caution should be used for cats with TLE.
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Affiliation(s)
- Satoshi Mizuno
- Laboratory of Veterinary Clinical Neurology, Graduate School of Nippon Veterinary and Life Science University, Musashino, Japan
| | - Rikako Asada
- Laboratory of Veterinary Clinical Neurology, Graduate School of Nippon Veterinary and Life Science University, Musashino, Japan
| | - Yoshihiko Yu
- Laboratory of Veterinary Clinical Neurology, Graduate School of Nippon Veterinary and Life Science University, Musashino, Japan
| | - Yuji Hamamoto
- Laboratory of Veterinary Clinical Neurology, Graduate School of Nippon Veterinary and Life Science University, Musashino, Japan
- Veterinary Medical Teaching Hospital, Nippon Veterinary and Life Science University, Musashino, Japan
| | - Daisuke Hasegawa
- Laboratory of Veterinary Clinical Neurology, Graduate School of Nippon Veterinary and Life Science University, Musashino, Japan
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The Potential of Bemegride as an Activation Agent in Electroencephalography in Dogs. Animals (Basel) 2022; 12:ani12223210. [PMID: 36428437 PMCID: PMC9686807 DOI: 10.3390/ani12223210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/13/2022] [Accepted: 11/14/2022] [Indexed: 11/22/2022] Open
Abstract
The present study investigated the potential of bemegride as a pharmacological activation agent that elicits epileptiform discharges (EDs) in interictal electroencephalogram (EEG) recordings in dogs. Four laboratory dogs with idiopathic epilepsy and four without epilepsy were included. The dogs were anesthetized using sevoflurane during EEG recordings. Bemegride was administered intravenously and repeatedly until EDs were enhanced or induced, or until the maximum dose (20 mg/kg) had been administered. Bemegride activated EDs in all dogs with epilepsy. These EDs predominantly occurred in each dog's spontaneous irritative zones, which were identified without the administration of bemegride. EDs occurred after the administration of bemegride in 50% of dogs without epilepsy. The dose required for activation was significantly lower in dogs with epilepsy (median; 7.3 mg/kg) than in those without (median; 19.7 mg/kg) (p = 0.0294). The only suspected adverse effect associated with the administration of bemegride was vomiting in two dogs after awakening from anesthesia. There were no other adverse effects, including seizures. The present results demonstrated the potential of bemegride as a safe and effective pharmacological activation agent of EDs in anesthetized dogs with epilepsy and provided more options for the diagnosis and therapeutic planning of epilepsy, including presurgical evaluations, in dogs.
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Yu Y, Hasegawa D, Kanazono S, Saito M. Clinical characterization of epileptic seizures in Pomeranians with idiopathic epilepsy or epilepsy of unknown cause. Vet Med (Auckl) 2022; 36:2113-2122. [DOI: 10.1111/jvim.16578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Yoshihiko Yu
- Laboratory of Veterinary Radiology Nippon Veterinary and Life Science University Tokyo Japan
| | - Daisuke Hasegawa
- Laboratory of Veterinary Radiology Nippon Veterinary and Life Science University Tokyo Japan
- The Research Center for Animal Life Science Nippon Veterinary and Life Science University Tokyo Japan
| | - Shinichi Kanazono
- Neurology and Neurosurgery Service Veterinary Specialists & Emergency Center Saitama Japan
| | - Miyoko Saito
- Laboratory of Small Animal Surgery (Neurology), School of Veterinary Medicine Azabu University Kanagawa Japan
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Unger DM, Wiest R, Kiefer C, Raillard M, Dutil GF, Stein VM, Schweizer D. Neuronal current imaging: An experimental method to investigate electrical currents in dogs with idiopathic epilepsy. J Vet Intern Med 2021; 35:2828-2836. [PMID: 34623697 PMCID: PMC8692176 DOI: 10.1111/jvim.16270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 09/04/2021] [Accepted: 09/10/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The diagnosis of idiopathic epilepsy (IE) in dogs is based on exclusion of other potential causes of seizures. Recently, a novel magnetic resonance imaging (MRI) sequence that utilizes a variant of the rotary saturation approach has been suggested to detect weak transient magnetic field oscillations generated by neuronal currents in humans with epilepsy. HYPOTHESIS/OBJECTIVES Effects on the magnetic field evoked by intrinsic epileptic activity can be detected by MRI in the canine brain. As proof-of-concept, the novel MRI sequence to detect neuronal currents was applied in dogs. ANIMALS Twelve dogs with IE and 5 control dogs without a history of epileptic seizures were examined. METHODS Prospective case-control study as proof-of-concept. All dogs underwent a clinical neurological examination, scalp electroencephalography, cerebrospinal fluid analysis, and MRI. The MRI examination included a spin-locking (SL) experiment applying a low-power on-resonance radiofrequency pulse in a predefined frequency domain in the range of oscillations generated by the epileptogenic tissue. RESULTS In 11 of 12 dogs with IE, rotary saturation effects were detected by the MRI sequence. Four of 5 control dogs did not show rotary saturation effects. One control dog with a diagnosis of neuronal ceroid lipofuscinosis had SL-related effects, but did not have epileptic seizures clinically. CONCLUSIONS AND CLINICAL IMPORTANCE The proposed MRI method detected neuronal currents in dogs with epileptic seizures and represents a potential new line of research to investigate neuronal currents possibly related to IE in dogs.
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Affiliation(s)
- Daniela M Unger
- Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Roland Wiest
- Support Center of Advanced Neuroimaging (SCAN), Institute of Diagnostic and Interventional Neuroradiology, Inselspital Bern, University of Bern, Bern, Switzerland
| | - Claus Kiefer
- Support Center of Advanced Neuroimaging (SCAN), Institute of Diagnostic and Interventional Neuroradiology, Inselspital Bern, University of Bern, Bern, Switzerland
| | - Mathieu Raillard
- Division of Clinical Anesthesiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Guillaume F Dutil
- Division of Clinical Neurology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Veronika M Stein
- Division of Clinical Neurology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Daniela Schweizer
- Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Ukai M, Parmentier T, Cortez MA, Fischer A, Gaitero L, Lohi H, Nykamp S, Jokinen TS, Powers D, Sammut V, Sanders S, Tai T, Wielaender F, James F. Seizure frequency discrepancy between subjective and objective ictal electroencephalography data in dogs. J Vet Intern Med 2021; 35:1819-1825. [PMID: 34002887 PMCID: PMC8295668 DOI: 10.1111/jvim.16158] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 04/30/2021] [Accepted: 04/30/2021] [Indexed: 01/24/2023] Open
Abstract
Background Many studies of epilepsy in veterinary medicine use subjective data (eg, caregiver‐derived histories) to determine seizure frequency. Conversely, in people, objective data from electroencephalography (EEG) are mainly used to diagnose epilepsy, measure seizure frequency and evaluate efficacy of antiseizure drugs. These EEG data minimize the possibility of the underreporting of seizures, a known phenomenon in human epileptology. Objective To evaluate the correlation between reported seizure frequency and EEG frequency of ictal paroxysmal discharges (PDs) and to determine whether seizure underreporting phenomenon exists in veterinary epileptology. Animals Thirty‐three ambulatory video‐EEG recordings in dogs showing ≥1 ictal PD, excluding dogs with status epilepticus. Methods Retrospective observational study. Ictal PDs were counted manually over the entire recording to obtain the frequency of EEG seizures. Caregiver‐reported seizure frequency from the medical record was categorized into weekly, daily, hourly, and per minute seizure groupings. The Spearman rank test was used for correlation analysis. Results The coefficient value (rs) comparing reported seizure to EEG‐confirmed ictal PD frequencies was 0.39 (95% confidence interval [CI] = 0.048‐0.64, P = .03). Other rs values comparing history against various seizure types were: 0.36 for motor seizures and 0.37 for nonmotor (absence) seizures. Conclusions and Clinical Importance A weak correlation was found between the frequency of reported seizures from caregivers (subjective data) and ictal PDs on EEG (objective data). Subjective data may not be reliable enough to determine true seizure frequency given the discrepancy with EEG‐confirmed seizure frequency. Confirmation of the seizure underreporting phenomenon in dogs by prospective study should be carried out.
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Affiliation(s)
- Masayasu Ukai
- Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Thomas Parmentier
- Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Miguel A Cortez
- Division of Neurology, Department of Paediatrics, Faculty of Medicine, University of Toronto, Peter Gilgan Center Research Learning, SickKids Research Institute, Toronto, Ontario, Canada
| | - Andrea Fischer
- Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-Universität München, München, Germany
| | - Luis Gaitero
- Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Hannes Lohi
- Departments of Medical and Clinical Genetics and Veterinary Biosciences, University of Helsinki, Helsinki, Finland.,Folkhälsan Research Center, Helsinki, Finland
| | - Stephanie Nykamp
- Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Tarja S Jokinen
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Danielle Powers
- Neurology and Neurosurgery Service, Animal Medical and Surgical Center, Scottsdale, Arizona, USA
| | - Veronique Sammut
- Neurology Department, VCA West Los Angeles Animal Hospital, Los Angeles, California, USA
| | - Sean Sanders
- Seattle Veterinary Neurosurgery, Seattle, Washington, USA
| | - Tricia Tai
- Neurology Department, VCA West Los Angeles Animal Hospital, Los Angeles, California, USA
| | - Franziska Wielaender
- Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-Universität München, München, Germany
| | - Fiona James
- Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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