Editorial: Reviews in Veterinary Neurology and Neurosurgery

John Henry Rossmeisl ^1* Andrea Tipold ²

• ¹ Department of Small Animal Clinical Sciences, Virginia Tech, Blacksburg, Virginia, United States
• ² University of Veterinary Medicine Hannover, Hanover, Lower Saxony, Germany

In recent years, knowledge generation in the field of veterinary and comparative neurology and neurosurgery has grown exponentially. 1 The impact, diversity, and potential future applications of this knowledge are showcased in the 13 papers featured in this research collection. These papers address a variety of problems pertinent to practitioners of veterinary neurology from common and long-recognized but persistently challenging conditions, such as chronic pain, cognitive dysfunction, epilepsy, and non-infectious meningoencephalitis, to more recently described diseases including craniocervical junctional abnormalities and paroxysmal dyskinesias, as well as highly technically focused and specific reviews of the neurosurgical management of congenital malformations.Several articles hosted in this topic introduce new conceptual frameworks intended to facilitate the diagnosis, optimized management, or harmonized design of future studies of neurologic diseases. The contributions by Parker and Pedersen et al. address the complexities associated with the recognition and management of neuropathic pain in animals. These authors provide clinically relevant summaries of nociceptive network form and function in health and disease and review advancements in comparative pain research that collectively serve to improve the objective diagnosis of neuropathic pain, rational selection of neuropathic pain modifying agents, and development of new and effective analgesics. In their review of meningoencephalitis of unknown origin (MUO), Nessler and Tipold present a novel and holistic 'polythetic' approach to the classification and treatment of MUO. Their proposal incorporates the heterogeneity and spectrum of clinical, neuroimaging, and immunopathologic manifestations of the disease burden that may be present in each case in an effort to improve our understanding of the etiopathogenesis of MUO variants and identify patient-specific therapeutic strategies. Santifort and Platt review the reported causes, treatments and outcomes associated with conditions presenting with intraparenchymal hemorrhage in the brain or spinal cord of humans, dogs, and cats, and subsequently propose a novel and succinct veterinary classification schema for hemorrhagic encephalopathies and myelopathies that synthesizes comparative, etiologic, and neuroanatomic localization data.The clinical utilities of pervasive and emerging transformative technologies are illustrated in three papers included in this topic. In their extensive review of paroxysmal dyskinesias (PD), Mandigers et al. highlight the value that phenotypic analyses of owner acquired videos of paroxysmal events in conjunction with a focused historical probe and comprehensive clinical examination have in the diagnosis and classification of canine PD. Robertson et al. provide an overview of the principles, promises, and limitations of a high throughput molecular analytical technique, Raman spectroscopy (RS), and demonstrate how RS-derived urine spectral fingerprinting might be used to identify and discriminate various etiologies of central nervous system disease in a rapid and economical manner. The paper by Kim et al. describes the methodological development of a library of blood-based proteomic biomarkers of canine cognitive dysfunction, their validation against well-established mouse models of Alzheimer's and Parkinson's disease, 2,3 and the use of a machine learning analytical framework that revealed robust accuracies of the combination of retinol binding protein 4 and NAPH oxidase 4 concentrations to clinically predict early neurobehavioral indicators of canine cognitive dysfunction.Three articles in this topic focus on epilepsy, emphasizing both the progress that has been made in the diagnosis and treatment of this disorder as well as the current challenges veterinarians face when managing epileptic animals. Gouveia et al. provide a historical narrative and comprehensive multispecies review of the oldest known antiseizure drug, bromide, which is infused with numerous evidence-based and practical pearls of wisdom related to the indications for, efficacy, toxicity, and nuances of therapeutic monitoring associated with bromide therapy. Articles by Foss and Billhymer and Kadler et al. provide state-of-the art reviews on established and evolving uses of qualitative and quantitative brain magnetic resonance imaging techniques in the context of epilepsy, and highlight how these techniques have advanced the field of human epileptology, as well as the limitations that remain to incorporation of these techniques into routine use in veterinary practice.The final thematic area covered in this research topic relates to the diagnosis and treatment of congenital malformations affecting the brain, vertebral column, and spinal cord of dogs and cats. Schmidt and Farke provide a critical appraisal of the benefits, operative techniques, and possible adverse events associated with ventriculoperitoneal shunting (VPS) for treatment of internal hydrocephalus. This paper includes excellent overviews of the diverse inventory of VPS instrumentation available for use, as well as strategies for prevention and mitigation of the range of complications that may be encountered in hydrocephalic patients treated with VPS. In their systematic review of the literature, Wess and Kneissl determine the prevalences of a spectrum of craniocervical junctional abnormalities including occipital hypoplasia (OH), syringomyelia (SM) and atlanto-occipital overlap (AO) in dogs, and compare the frequencies and potential clinical significance of these abnormalities between dogs with and without a brachycephalic conformation. They identified that OH, SM, and AO are significantly more likely to occur in small breed, brachycephalic dogs, attributable clinical signs were infrequent in dogs with OH or AO that did not have contemporaneous SM, and only 1% of all dogs had concurrent imaging evidence of all three conditions. Roynard and Dewey summarize the currently available literature reporting on the neurosurgical management of lumbosacral meningomyeloceles (MMC) in dogs, and contribute new clinical, diagnostic imaging, operative technical, and outcome data derived from the author's experiences managing an additional 9 dogs with MMC. Although the current body of literature reporting post-operative outcomes in dogs with MMC remains extremely limited, the work of these and other authors of recent studies suggest that early surgical intervention in dogs with MMC may result in improvement of pelvic limb neurologic function deficits and urinary and fecal incontinence in some dogs, as well as prevent neurological deterioration associated with tethered cord syndrome. 4 The reviews included in this research topic provide a wealth of practical information on a broad range of subjects relevant to all levels of clinicians and researchers engaged in the study or practice of veterinary neurology. To continue generating rigorous evidenced-based research, best practices for patient care, and realizing the potentials of the tools and techniques covered in this topic, it will be important for future studies to incorporate, critically evaluate, and subsequently refine the conceptual frameworks introduced here, as well as apply and further validate these novel diagnostic technologies and therapeutic approaches in larger and more diverse animal populations.