Peri‐ictal magnetic resonance imaging characteristics in dogs with suspected idiopathic epilepsy

Nagendran, Aran; McConnell, J. Fraser; Risio, Luisa De; José-López, Roberto; Quintana, R. Gutierrez; Robinson, Kelsey; Platt, Simon; Masian, Daniel Sanchez; Maddox, Thomas W.; Gonçalves, Rita

doi:10.1111/jvim.16058

Cited by 20 publications

(17 citation statements)

References 30 publications

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“…Additional support for thalamic involvement has recently been reported by Unger et al that found bilateral rotary saturation effects in the thalamus using phase-cycled stimulus-induced rotary saturation sequence in an Old English Bulldog with generalized tonic–clonic seizures ( 55 ). Even peri-ictal MRI changes have been found in parts of the thalamus in dogs ( 56 ). Network analysis of peri-ictal lesions has shown high correlation with cingulate lesions.…”

Section: Discussionmentioning

confidence: 99%

Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs

Mauri

Richter²,

Steffen³

et al. 2022

Front. Vet. Sci.

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The role of magnetic resonance spectroscopy (MRS) in the investigation of brain metabolites in epileptic syndromes in dogs has not been explored systematically to date. The aim of this study was to investigate metabolites in the thalamus in dogs affected by idiopathic epilepsy (IE) with and without antiepileptic drug treatment (AEDT) and to compare them to unaffected controls. Our hypothesis is that similar to humans with generalized epilepsy and loss of consciousness, N-acetyl aspartate (NAA) would be reduced, and glutamate–glutamine (Glx) would be increased in treated and untreated IE in comparison with the control group. In this prospective case–control study, Border Collie (BC) and Greater Swiss Mountain dog (GSMD) were divided into three groups: (1) healthy controls, IE with generalized tonic–clonic seizures with (2) and without (3) AEDT. A total of 41 BC and GSMD were included using 3 Tesla single-voxel proton MRS of the thalamus (PRESS localization, shortest TE, TR = 2000 ms, NSA = 240). After exclusion of 11 dogs, 30 dogs (18 IE and 12 healthy controls) remained available for analysis. Metabolite concentrations were estimated with LCModel using creatine as reference and compared using Kruskal–Wallis and Wilcoxon rank-sum tests. The Kruskal–Wallis test revealed significant differences in the NAA-to-creatine (p = 0.04) and Glx-to-creatine (p = 0.03) ratios between the three groups. The Wilcoxon rank-sum test further showed significant reduction in the NAA/creatine ratio in idiopathic epileptic dogs under AEDT compared to epileptic dogs without AEDT (p = 0.03) and compared to healthy controls (p = 0.03). In opposite to humans, Glx/creatine ratio was significantly reduced in dogs with IE under AEDT compared to epileptic dogs without AEDT (p = 0.03) and controls (p = 0.02). IE without AEDT and healthy controls did not show significant difference, neither in NAA/creatine (p = 0.60), nor in Glx-to-creatine (p = 0.55) ratio. In conclusion, MRS showed changes in dogs with IE and generalized seizures under AEDT, but not in those without AEDT. Based upon these results, MRS can be considered a useful advanced imaging technique for the evaluation of dogs with IE in the clinical and research settings.

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Section: Discussionmentioning

confidence: 99%

Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs

Mauri

Richter²,

Steffen³

et al. 2022

Front. Vet. Sci.

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“…Idiopathic epilepsy was diagnosed after exclusion of reactive seizure etiologies, along with cerebrospinal fluid analysis and either normal magnetic resonance imaging of the brain or abnormalities consistent with postictal brain pathology. 15 , 16 Structural epilepsy included vascular, neoplastic, inflammatory, traumatic, degenerative, or congenital diseases capable of contributing to epileptic seizure episodes, which were identified using some combination of cerebrospinal fluid analysis, magnetic resonance imaging, and necropsy examination. Reactive seizures were diagnosed if a metabolic etiology or intoxication was identified or strongly suspected based on historical information (such as exposure to a seizurogenic toxin, hepatic encephalopathy, hypertriglyceridemia, hypoglycemia, electrolyte disturbances, hyperthermia, or cerebral hypoxia).…”

Section: Methodsmentioning

confidence: 99%

“…Possible underlying etiologies for SE were categorized as IE, structural epilepsy, or reactive seizures. Idiopathic epilepsy was diagnosed after exclusion of reactive seizure etiologies, along with cerebrospinal fluid analysis and either normal magnetic resonance imaging of the brain or abnormalities consistent with postictal brain pathology 15,16 . Structural epilepsy included vascular, neoplastic, inflammatory, traumatic, degenerative, or congenital diseases capable of contributing to epileptic seizure episodes, which were identified using some combination of cerebrospinal fluid analysis, magnetic resonance imaging, and necropsy examination.…”

Section: Methodsmentioning

confidence: 99%

Risk factors associated with short‐term mortality and recurrence of status epilepticus in dogs

Fentem

Stefani

Quintana

et al. 2022

Veterinary Internal Medicne

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Background Status epilepticus (SE) is an emergency associated with serious consequences for both patient and owner. Data regarding risk factors for short‐term mortality or recurrence in dogs with SE is limited. Objective Identify risk factors associated with short‐term mortality (euthanasia or spontaneous death) and recurrence of SE in dogs. Animals One hundred twenty‐four client‐owned dogs that sustained an episode of SE. Methods Retrospective multicenter study using data collected from medical records of dogs presented in SE to the contributing institutions. Multivariable logistic regression analysis was performed using a manual backwards stepwise approach to identify risk factors associated with short‐term mortality and recurrence of SE after discharge. Results Short‐term mortality for affected dogs was 29.8%. Factors significantly associated with short‐term mortality included increased patient age, shorter duration of hospitalization, development of SE before arrival, and SE caused by a potentially fatal etiology. Status epilepticus recurred in 27% of dogs that survived to discharge. Factors significantly associated with recurrence of SE included prior history of pharmacoresistant epilepsy and predominance of a focal seizure phenotype. Conclusions and Clinical Importance Our results may be used to inform clinicians and dog owners regarding risk factors for both short‐term mortality and recurrence in dogs with SE.

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“…Except for a few genetic epilepsies, the causes of canine epilepsy are poorly understood. Although the introduction of the MRI as a diagnostic tool of epileptic dogs has disclosed a variety of structural and functional brain abnormalities in such animals (38,39,(132)(133)(134)(135)(136), this by itself does not explain the exact molecular causes of spontaneous recurrent seizures as observed in epilepsy. Furthermore, epileptic dogs, including those with "idiopathic" epilepsy, may have heterogeneous underlying pathologies, including subtle structural changes that cannot be identified on conventional visual inspection of brain MRI.…”

Section: Neuroimaging Studiesmentioning

confidence: 99%

“…In a recent peri-ictal MRI study in 81 dogs with suspected idiopathic epilepsy, the most common brain areas affected were the hippocampus (39/81), cingulate gyrus (33/81), and piriform lobes (32/81) ( 135 ). This may suggest that, similar to humans, the limbic system (or mesial temporal lobe) is particularly affected in epileptic dogs.…”

Section: Pathogenesis Of Epilepsy In Dogsmentioning

confidence: 99%

Dogs as a Natural Animal Model of Epilepsy

Löscher

2022

Front. Vet. Sci.

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Epilepsy is a common neurological disease in both humans and domestic dogs, making dogs an ideal translational model of epilepsy. In both species, epilepsy is a complex brain disease characterized by an enduring predisposition to generate spontaneous recurrent epileptic seizures. Furthermore, as in humans, status epilepticus is one of the more common neurological emergencies in dogs with epilepsy. In both species, epilepsy is not a single disease but a group of disorders characterized by a broad array of clinical signs, age of onset, and underlying causes. Brain imaging suggests that the limbic system, including the hippocampus and cingulate gyrus, is often affected in canine epilepsy, which could explain the high incidence of comorbid behavioral problems such as anxiety and cognitive alterations. Resistance to antiseizure medications is a significant problem in both canine and human epilepsy, so dogs can be used to study mechanisms of drug resistance and develop novel therapeutic strategies to benefit both species. Importantly, dogs are large enough to accommodate intracranial EEG and responsive neurostimulation devices designed for humans. Studies in epileptic dogs with such devices have reported ictal and interictal events that are remarkably similar to those occurring in human epilepsy. Continuous (24/7) EEG recordings in a select group of epileptic dogs for >1 year have provided a rich dataset of unprecedented length for studying seizure periodicities and developing new methods for seizure forecasting. The data presented in this review substantiate that canine epilepsy is an excellent translational model for several facets of epilepsy research. Furthermore, several techniques of inducing seizures in laboratory dogs are discussed as related to therapeutic advances. Importantly, the development of vagus nerve stimulation as a novel therapy for drug-resistant epilepsy in people was based on a series of studies in dogs with induced seizures. Dogs with naturally occurring or induced seizures provide excellent large-animal models to bridge the translational gap between rodents and humans in the development of novel therapies. Furthermore, because the dog is not only a preclinical species for human medicine but also a potential patient and pet, research on this species serves both veterinary and human medicine.

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Peri‐ictal magnetic resonance imaging characteristics in dogs with suspected idiopathic epilepsy

Cited by 20 publications

References 30 publications

Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs

Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs

Risk factors associated with short‐term mortality and recurrence of status epilepticus in dogs

Dogs as a Natural Animal Model of Epilepsy

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