Search

The Spanish neurohistologist Santiago Ramón y Cajal (1852–1934) is widely regarded as the father of modern Neuroscience. In addition to identifying the individuality of cells in the nervous system (the neuron theory) or the direction followed by nerve impulses (the principle of dynamic polarization), he described numerous details regarding the organization of the different structures of the nervous system. This task was compiled in his magnum opus, “Textura del Sistema Nervioso del Hombre y los Vertebrados,” first published in Spanish between 1899 and 1904, and later revised and updated in French as “Histologie du système nerveux de l’homme et des vertébrés” between 1909 and 1911 for wider distribution among the international scientific community. Some of Cajal’s findings are fundamental to our understanding of the anatomy and histology of the vestibular system. He depicted the nerve endings in the sensory epithelia, the structure of the vestibular nerve and Scarpa ganglion, afferent vestibular fibers, vestibular nuclei, lateral vestibulospinal tract, vestibulocerebellar connections, and the fine structure of the cerebellum. However, most of these pioneering descriptions were published years earlier in Spanish journals with limited circulation. Our study aimed to gather Cajal’s findings on the vestibular system and identify his original publications. After this endeavor, we claim a place for Cajal among the founders of anatomy and histology of the vestibular system.

The Spanish neurohistologist Santiago Ramón y Cajal (1852-1934) is widely regarded as the father of modern Neuroscience. In addition to identifying the individuality of cells in the nervous system (the neuron theory) or the direction followed by nerve impulses (the principle of dynamic polarization), he described numerous details regarding the organization of the different structures of the nervous system. This task was compiled in his magnum opus, "Textura del Sistema Nervioso del Hombre y los Vertebrados," first published in Spanish between 1899 and 1904, and later revised and updated in French as "Histologie du système nerveux de l'homme et des vertébrés" between 1909 and 1911 for wider distribution among the international scientific community. Some of Cajal's findings are fundamental to our understanding of the anatomy and histology of the vestibular system. He depicted the nerve endings in the sensory epithelia, the structure of the vestibular nerve and Scarpa ganglion, afferent vestibular fibers, vestibular nuclei, lateral vestibulospinal tract, vestibulocerebellar connections, and the fine structure of the cerebellum. However, most of these pioneering descriptions were published years earlier in Spanish journals with limited circulation. Our study aimed to gather Cajal's findings on the vestibular system and identify his original publications. After this endeavor, we claim a place for Cajal among the founders of anatomy and histology of the vestibular system. [ABSTRACT FROM AUTHOR]

Migraine (MI) is the most common neurological disease, affecting with 20% of the world population. A subset of 25% of MI patients showcase concurrent vestibular symptoms, which may classify as vestibular migraine (VM). Meniere's disease (MD) is a complex inner ear disorder defined by episodes of vertigo associated with tinnitus and sensorineural hearing loss with a significant autoimmune/autoinflammatory contribution, which symptoms overlap with VM. Blood samples from 18 patients with MI (5), VM (5) and MD (8) and 6 controls were collected and compared in a case–control study. Droplet‐isolated nuclei from mononuclear cells used to generate scRNAseq and scATACseq data sets from MI, VM and MD. MI and VM have no differences in their immune transcriptome; therefore, they were considered as a single cluster for further analyses. Natural Killer (NK) cells transcriptomic data support a polarisation triggered by Type 1 innate immune cells via the release of interleukin (IL)‐12, IL‐15 and IL‐18. According to the monocyte scRNAseq data, there were two MD clusters, one inactive and one driven by monocytes. The unique pathways of the MI + VM cluster were cellular responses to metal ions, whereas MD monocyte‐driven cluster pathways showed responses to biotic stimuli. MI and MD have different immune responses. These findings support that MI and VM have a Type 1 immune lymphoid cell response, and that there are two clusters of MD patients, one inactive and one Monocyte‐driven. [ABSTRACT FROM AUTHOR]

Background: tinnitus is a heterogeneous condition associated with audiological and/or mental disorders. Chronic, severe tinnitus is reported in 1% of the population and it shows a relevant heritability, according to twins, adoptees and familial aggregation studies. The genetic contribution to severe tinnitus is unknown since large genomic studies include individuals with self-reported tinnitus and large heterogeneity in the phenotype. The aim of this study was to identify genes for severe tinnitus in patients with extreme phenotype. Methods: for this extreme phenotype study, we used three different cohorts with European ancestry (Spanish with Meniere disease (MD), Swedes tinnitus and European generalized epilepsy). In addition, four independent control datasets were also used for comparisons. Whole-exome sequencing was performed for the MD and epilepsy cohorts and whole-genome sequencing was carried out in Swedes with tinnitus. Findings: we found an enrichment of rare missense variants in 24 synaptic genes in a Spanish cohort, the most significant being PRUNE2, AKAP9, SORBS1, ITGAX, ANK2, KIF20B and TSC2 (p < 2E−04), when they were compared with reference datasets. This burden was replicated for ANK2 gene in a Swedish cohort with 97 tinnitus individuals, and in a subset of 34 Swedish patients with severe tinnitus for ANK2, AKAP9 and TSC2 genes (p < 2E−02). However, these associations were not significant in a third cohort of 701 generalized epilepsy individuals without tinnitus. Gene ontology (GO) and gene-set enrichment analyses revealed several pathways and biological processes involved in severe tinnitus, including membrane trafficking and cytoskeletal protein binding in neurons. Interpretation: a burden of rare variants in ANK2, AKAP9 and TSC2 is associated with severe tinnitus. ANK2, encodes a cytoskeleton scaffolding protein that coordinates the assembly of several proteins, drives axonal branching and influences connectivity in neurons.

Abstract Epidemiological studies have found a higher prevalence of allergic symptoms and positive prick tests in patients with Meniere’s disease (MD); however the effect of allergenic extracts in MD has not been established. Thus, this study aims to determine the effect of Aspergillus and Penicillium stimulation in cytokine release and gene expression profile in MD. Patients with MD showed higher basal levels of IL-1β, IL-1RA, IL-6 and TNF-α when compared to healthy controls. We observed that IL-1β levels had a bimodal distribution suggesting two different subgroups of patients, with low and high basal levels of cytokines. Gene expression profile in peripheral blood mononuclear cells (PBMC) showed significant differences in patients with high and low basal levels of IL-1β. We found that both mold extracts triggered a significant release of TNF-α in MD patients, which were not found in controls. Moreover, after mold stimulation, MD patients showed a different gene expression profile in PBMC, according to the basal levels of IL-1β. The results indicate that a subset of MD patients have higher basal levels of proinflammatory cytokines and the exposure to Aspergillus and Penicillium extracts may trigger additional TNF-α release and contribute to exacerbate inflammation.

Vestibular Migraine (VM) and Meniere's Disease (MD) are episodic vestibular syndromes defined by a set of associated symptoms such as tinnitus, hearing loss or migraine features during the attacks. Both conditions may show symptom overlap and there is no biological marker to distinguish them. Two subgroups of MD patients have been reported, according to their IL-1β profile. Therefore, considering the clinical similarity between VM and MD, we aimed to investigate the cytokine profile of MD and VM as a means to distinguish these patients. We have also carried out gene expression microarrays and measured the levels of 14 cytokines and 11 chemokines in 129 MD patients, 82 VM patients, and 66 healthy controls. Gene expression profile in peripheral blood mononuclear cells (PBMC) showed significant differences in MD patients with high and low basal levels of IL- 1β and VM patients. MD patients with high basal levels of IL- 1β (MDH) had overall higher levels of cytokines/chemokines when compared to the other subsets. CCL4 levels were significantly different between MDH, MD with low basal levels of IL- 1β (MDL), VM and controls. Logistic regression identified IL- 1β, CCL3, CCL22, and CXCL1 levels as capable of differentiating VM patients from MD patients (area under the curve = 0.995), suggesting a high diagnostic value in patients with symptoms overlap.

Ménière’s disease (MD) represents a heterogeneous group of relatively rare disorders with three core symptoms: episodic vertigo, tinnitus, and sensorineural hearing loss involving 125 to 2,000 Hz frequencies. The majority of cases are considered sporadic, although familial aggregation has been recognized in European and Korean populations, and the search for familial MD genes has been elusive until the last few years. Detailed phenotyping and cluster analyses have found several clinical predictors for different subgroups of patients, which may indicate different mechanisms, including genetic and immune factors. The genes associated with familial MD are COCH, FAM136A, DTNA, PRKCB, SEMA3D, and DPT. At least two mechanisms have been involved in MD: (a) a pro-inflammatory immune response mediated by interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNFα), and IL-6, and (b) a nuclear factor-kappa B (NF-κB)-mediated inflammation in the carriers of the single-nucleotide variant rs4947296. It is conceivable that microbial antigens trigger inflammation with release of pro-inflammatory cytokines at different sites within the cochlea, such as the endolymphatic sac, the stria vascularis, or the spiral ligament, leading to fluid imbalance with an accumulation of endolymph. Computational integration of clinical and “omics” data eventually should transform the management of MD from “one pill fits all” to precise patient stratification and a personalized approach. This article lays out a proposal for an algorithm for the genetic diagnosis of MD. This approach will facilitate the identification of new molecular targets for individualized treatment, including immunosuppressant and gene therapy, in the near future.

BACKGROUND: Rafael Lorente de Nó was a neuroscientist that worked alongside two of the giants of Medicine, the Nobel Prize winners Cajal and Bárány. OBJECTIVE: To describe the contributions of Lorente de Nó to vestibular neuroscience. METHODS: Detailed review of the publications of Lorente de Nó and analysis of the archives from Junta para Ampliación de Estudios e Investigaciones Científicas at Residencia de Estudiantes (Madrid, Spain), Casa de Salud Valdecilla at Hospital Universitario Marqués de Valdecilla (Santander, Spain), Becker Medical Library at Washington University (St. Louis, MO, USA), Rockefeller Archive Center (Sleepy Hollow, New York, NY, USA), Archivo Fernando de Castro (Madrid, Spain), Biblioteca Nacional de España (Madrid, Spain) and Legado Cajal at Instituto Cajal (Madrid, Spain). Most of this material is unpublished and includes over a hundred letters to or from Lorente. RESULTS: Lorente de Nó made a substantial contribution to our understanding of the vestibular system. Amongst these, he meticulously detailed the course of the vestibular nerve and its central projections. He described the vestibulo-ocular reflex as the consequence of an integration of the various nuclei and connections across the vestibular system, rather than a simple three-neuron arc. He also highlighted the role of the reticular formation in the generation of the fast phase of the nystagmus. CONCLUSIONS: Lorente de Nó was a pioneer of modern neuro-otology, having made outstanding contributions to vestibular neuroscience, forging novel discoveries that still burn true today. [ABSTRACT FROM AUTHOR]

Migraine is a common neurological disorder characterized by episodic headaches with specific features, presenting familial aggregation. Migraine is associated with episodic vertigo, named Vestibular Migraine (VM) whose diagnosis mainly rely on clinical history showing a temporary association of symptoms. Some patient refers symptoms occurring in pediatric age, defined “episodic symptoms which may be associated with migraine.” The aim of this cross sectional observational study was to assess migraine-related clinical features in VM subjects. For the purpose, 279 patients were recruited in different centers in Europe; data were collected by a senior neurologist or ENT specialist through a structured questionnaire. The age of onset of migraine was 21.8 ± 9. The duration of headaches was lower than 24 h in 79.1% of cases. Symptoms accompanying migrainous headaches were, in order of frequency, nausea (79.9%), phonophobia (54.5%), photophobia (53.8%), vomiting (29%), lightheadedness (21.1%). Visual or other auras were reported by 25.4% of subjects. A familial aggregation was referred by 67.4%, while migraine precursors were reported by 52.3% of subjects. Patients reporting nausea and vomiting during headaches more frequently experienced the same symptoms during vertigo. Comparing our results in VM subjects with previously published papers in migraine sufferers, our patients presented a lower duration of headaches and a higher rate of familial aggregation; moreover some common characters were observed in headache and vertigo attacks for accompanying symptoms like nausea and vomiting and clustering of attacks.

BackgroundVisually enhanced vestibulo–ocular reflex (VVOR) is a well-known bedside clinical test to evaluate visuo–vestibular interaction, with clinical applications in patients with neurological and vestibular dysfunctions. Owing to recently developed diagnostic technologies, the possibility to perform an easy and objective measurement of the VVOR has increased, but there is a lack of computational methods designed to obtain an objective VVOR measurement.ObjectivesTo develop a method for the assessment of the VVOR to obtain a gain value that compares head and eye velocities and to test this method in patients and healthy subjects.MethodsTwo computational methods were developed to measure the VVOR test responses: the first method was based on the area under curve of head and eye velocity plots and the second method was based on the slope of the linear regression obtained for head and eye velocity data. VVOR gain and vestibulo–ocular reflex (VOR) gain were analyzed with the data obtained from 35 subjects divided into four groups: healthy (N = 10), unilateral vestibular with vestibular neurectomy (N = 8), bilateral vestibulopathy (N = 12), and cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) (N = 5).ResultsIntra-class correlation index for the two developed VVOR analysis methods was 0.99. Statistical differences were obtained by analysis of variance statistical method, comparing the healthy group (VVOR mean gain of 1 ± 0) with all other groups. The CANVAS group exhibited (VVOR mean gain of 0.4 ± 0.1) differences when compared to all other groups. VVOR mean gain for the vestibular bilateral group was 0.8 ± 0.1. VVOR mean gain in the unilateral group was 0.6 ± 0.1, with a Pearson’s correlation of 0.52 obtained when VVOR gain was compared to the VOR gain of the operated side.ConclusionTwo computational methods to measure the gain of VVOR were successfully developed. The VVOR gain values appear to objectively characterize the VVOR alteration observed in CANVAS patients, and also distinguish between healthy subjects and patients with some vestibular disorders.

Meniere’s disease (MD) is a rare disorder characterized by episodic vertigo, sensorineural hearing loss, tinnitus, and aural fullness. It is associated with a fluid imbalance between the secretion of endolymph in the cochlear duct and its reabsorption into the subarachnoid space, leading to an accumulation of endolymph in the inner ear. Epidemiological evidence, including familial aggregation, indicates a genetic contribution and a consistent association with autoimmune diseases (AD). We conducted a case–control study in two phases using an immune genotyping array in a total of 420 patients with bilateral MD and 1,630 controls. We have identified the first locus, at 6p21.33, suggesting an association with bilateral MD [meta-analysis leading signal rs4947296, OR = 2.089 (1.661–2.627); p = 1.39 × 10−09]. Gene expression profiles of homozygous genotype-selected peripheral blood mononuclear cells (PBMCs) demonstrated that this region is a trans-expression quantitative trait locus (eQTL) in PBMCs. Signaling analysis predicted several tumor necrosis factor-related pathways, the TWEAK/Fn14 pathway being the top candidate (p = 2.42 × 10−11). This pathway is involved in the modulation of inflammation in several human AD, including multiple sclerosis, systemic lupus erythematosus, or rheumatoid arthritis. In vitro studies with genotype-selected lymphoblastoid cells from patients with MD suggest that this trans-eQTL may regulate cellular proliferation in lymphoid cells through the TWEAK/Fn14 pathway by increasing the translation of NF-κB. Taken together; these findings suggest that the carriers of the risk genotype may develop an NF-κB-mediated inflammatory response in MD.

Meniere disease (MD) is a heterogeneous clinical condition characterized by sensorineural hearing loss, episodic vestibular symptoms and tinnitus associated with several comorbidities such as migraine or autoimmune disorders (AD). The frequency of bilateral involvement may range from 5-50% and it depends on the duration of the disease. We have performed a two-step cluster analysis in 398 patients with bilateral MD to identify the best predictors to define clinical subgroups with a potential different etiology to improve the phenotyping of bilateral MD and to develop new treatments. We have defined five clinical variants in bilateral MD. Group 1 is the most frequently found, includes 46% of patients, and is defined by metachronic hearing loss without migraine and without AD. Group 2 is found in 17% of patients, and it is defined by synchronic hearing loss without migraine or AD. Group 3, with 13% of patients, is characterized by familial MD, while group 4, that includes 12% of patients, is associated by the presence of migraine in all cases. Group 5 is found in 11% of patients and is defined by AD. This approach can be helpful in selecting patients for genetic and clinical research. However, further studies will be required to improve the phenotyping in these clinical variants for a better understanding of the diverse etiological factors contributing to bilateral MD.

The head impulse, nystagmus type, test of skew (HINTS) protocol set a new paradigm to differentiate peripheral vestibular disease from stroke in patients with acute vestibular syndrome (AVS). The relationship between degree of truncal ataxia and stroke has not been systematically studied in patients with AVS. We studied a group of 114 patients who were admitted to a General Hospital due to AVS, 72 of them with vestibular neuritis (based on positive head impulse, abnormal caloric tests and negative MRI), and the rest with Stroke: 32 in the PICA territory (positive HINTS findings, positive MRI) and 10 in the AICA territory (variable findings and grade 3 Ataxia, positive MRI). Truncal ataxia was measured by independent observers as grade 1, mild to moderate imbalance with walking independently; grade 2, severe imbalance with standing, but cannot walk without support; and grade 3, falling at upright posture.When we applied the HINTS protocol to our sample, we obtained 100% sensitivity and 94.4% specificity, similar to previously published findings. Only those patients with stroke presented with grade 3 ataxia. Of those with grade 2 ataxia (n = 38), 11 had cerebellar stroke and 28 had vestibular neuritis, not related to the patient's age. Grade 2-3 ataxia was 92.9% sensitive and 61.1% specific to detect AICA/PICA stroke in patients with AVS, with 100% sensitivity to detect AICA stroke. In turn, two signs (nystagmus of central origin and grade 2-3 Ataxia) had 100% sensitivity and 61.1% specificity. Ataxia is less sensitive than HINTS but much easier to evaluate.