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Frontiers in Neuroanatomy 2024Auditory information is relayed from the cochlea via the eighth cranial nerve to the dorsal and ventral cochlear nuclei (DCN, VCN). The organization, neurochemistry and...
INTRODUCTION
Auditory information is relayed from the cochlea via the eighth cranial nerve to the dorsal and ventral cochlear nuclei (DCN, VCN). The organization, neurochemistry and circuitry of the cochlear nuclei (CN) have been studied in many species. It is well-established that glycine is an inhibitory transmitter in the CN of rodents and cats, with glycinergic cells in the DCN and VCN. There are, however, major differences in the laminar and cellular organization of the DCN between humans (and other primates) and rodents and cats. We therefore asked whether there might also be differences in glycinergic neurotransmission in the CN.
METHODS
We studied brainstem sections from humans, chimpanzees, and cats. We used antibodies to glycine receptors (GLYR) to identify neurons receiving glycinergic input, and antibodies to the neuronal glycine transporter (GLYT2) to immunolabel glycinergic axons and terminals. We also examined archival sections immunostained for calretinin (CR) and nonphosphorylated neurofilament protein (NPNFP) to try to locate the octopus cell area (OCA), a region in the VCN that rodents has minimal glycinergic input.
RESULTS
In humans and chimpanzees we found widespread immunolabel for glycine receptors in DCN and in the posterior (PVCN) and anterior (AVCN) divisions of the VCN. We found a parallel distribution of GLYT2-immunolabeled fibers and puncta. The data also suggest that, as in rodents, a region containing octopus cells in cats, humans and chimpanzees has little glycinergic input.
DISCUSSION
Our results show that glycine is a major transmitter in the human and chimpanzee CN, despite the species differences in DCN organization. The sources of the glycinergic input to the CN in humans and chimpanzees are not known.
PubMed: 38425805
DOI: 10.3389/fnana.2024.1331230 -
Frontiers in Neurology 2024In addition to hearing loss, damage to the cochlea can lead to gain of function pathologies such as hyperacusis. It has been proposed that painful hyperacusis,... (Review)
Review
In addition to hearing loss, damage to the cochlea can lead to gain of function pathologies such as hyperacusis. It has been proposed that painful hyperacusis, noxacusis, may be carried to the central nervous system by type II cochlear afferents, sparse, unmyelinated neurons that share morphological and neurochemical traits with nociceptive C-fibers of the somatic nervous system. Also like in skin, damage elicits spreading calcium waves within cochlear epithelia. These are mediated by extracellular ATP combined with IP3-driven release from intracellular calcium stores. Type II afferents are excited by ATP released from damaged epithelia. Thus, the genesis and propagation of epithelial calcium waves is central to cochlear pathology, and presumably hyperacusis. Damage-evoked signals in type II afferents and epithelial cells have been recorded in cochlear explants or semi-intact otic capsules. These efforts have included intracellular electrical recording, use of fluorescent calcium indicators, and visualization of an activity-dependent, intrinsic fluorescent signal. Of relevance to hyperacusis, prior noise-induced hearing loss leads to the generation of prolonged and repetitive activity in type II neurons and surrounding epithelia.
PubMed: 38419694
DOI: 10.3389/fneur.2024.1361747 -
Cephalalgia : An International Journal... Feb 2024To date, a number of studies on migraine have cross-sectionally evaluated sensory sensitivity with aversion thresholds/scores along the migraine cycle, reporting a...
BACKGROUND
To date, a number of studies on migraine have cross-sectionally evaluated sensory sensitivity with aversion thresholds/scores along the migraine cycle, reporting a decreased tolerance to sensory stimuli in different sensory modalities. Our hypothesis was that patients with migraine would exhibit heightened sensitivity to sound, light, touch and smell on days where they reported greater headache intensity.
METHODS
This is an exploratory, longitudinal study, carried out over the course of 27 days. Aversion thresholds or scores to sound, light, touch and smell were quantified in six patients with migraine (11.33 ± 6.53 headache days/month).
RESULTS
Patients reported an increased sensitivity to light ( = 0.0297), touch ( = 0.0077), and smell (p = 0.0201) on days with higher headache intensity. However, a greater sensitivity to sound on days with higher headache intensity was only reported when anxiety levels were high ( = 1.4e-06). Interestingly, variable levels of tolerance to bothersome light over time can also influence the correlation between light sensitivity and headache intensity ( = 1.4e-06).
CONCLUSIONS
Based on the present findings, future longitudinal studies evaluating sensory threshold changes along the migraine cycle in patients with migraine should account for the increased tolerance to bothersome light over time as well as the effect of anxiety on auditory sensitivity.
Topics: Humans; Longitudinal Studies; Migraine Disorders; Headache; Touch Perception; Sensory Thresholds
PubMed: 38416486
DOI: 10.1177/03331024241230279 -
European Journal of Neurology Jun 2024The aim was to provide insights to the characteristics of headache in the context of COVID-19 on behalf of the Headache Scientific Panel and the Neuro-COVID-19 Task...
BACKGROUND AND PURPOSE
The aim was to provide insights to the characteristics of headache in the context of COVID-19 on behalf of the Headache Scientific Panel and the Neuro-COVID-19 Task Force of the European Academy of Neurology (EAN) and the European Headache Federation (EHF).
METHODS
Following the Delphi method the Task Force identified six relevant questions and then conducted a systematic literature review to provide evidence-based answers and suggest specific diagnostic criteria.
RESULTS
No data for facial pain were identified in the literature search. (1) Headache incidence during acute COVID-19 varies considerably, with higher prevalence rates in prospective compared to retrospective studies (28.9%-74.6% vs. 6.5%-34.0%). (2) Acute COVID-19 headache is usually bilateral or holocranial and often moderate to severe with throbbing pain quality lasting 2-14 days after first signs of COVID-19; photo-phonophobia, nausea, anosmia and ageusia are common associated features; persistent headache shares similar clinical characteristics. (3) Acute COVID-19 headache is presumably caused by immune-mediated mechanisms that activate the trigeminovascular system. (4) Headache occurs in 13.3%-76.9% following SARS-CoV-2 vaccination and occurs more often amongst women with a pre-existing primary headache; the risk of developing headache is higher with the adenoviral-vector-type vaccines than with other preparations. (5) Headache related to SARS-CoV-2 vaccination is mostly bilateral, and throbbing, pressing, jolting or stabbing. (6) No studies have been conducted investigating the underlying mechanism of headache attributed to SARS-CoV-2 vaccines.
CONCLUSION
The results of this joint EAN/EHF initiative provide a framework for a better understanding of headache in the context of SARS-CoV-2 infection and vaccination.
Topics: Humans; COVID-19; COVID-19 Vaccines; Facial Pain; Headache; SARS-CoV-2; Vaccination
PubMed: 38415282
DOI: 10.1111/ene.16251 -
Audiology Research Feb 2024The aim of the present study was to investigate adverse effects of head injury, neck trauma, and chronic noise exposure on the complaint profile in people with...
The aim of the present study was to investigate adverse effects of head injury, neck trauma, and chronic noise exposure on the complaint profile in people with Ménière's disease (MD). The study used a retrospective design. Register data of 912 patients with MD from the Finnish Ménière Federation database were studied. The data comprised case histories of traumatic brain injury (TBI), neck trauma and occupational noise exposure, MD specific complaints, impact related questions, and the E-Qol health-related quality of life instrument. TBI was classified based on mild, moderate, and severe categories of transient loss of consciousness (TLoC). The mean age of the participants was 60.2 years, the mean duration of the disease was 12.6 years, and 78.7% were females. Logistic regression analysis, linear correlation, and pairwise comparisons were used in evaluating the associations. 19.2% of the participants with MD had a history of TBI. The phenotype of participants with TBI was associated with frequent vestibular drop attacks (VDA), presyncope, headache-associated vertigo, and a reduction in the E-QoL. Logistic regression analysis explained the variability of mild TBI in 6.8%. A history of neck trauma was present in 10.8% of the participants. Neck trauma associated with vertigo (NTwV) was seen in 47 and not associated with vertigo in 52 participants. The phenotype of NTwV was associated with balance problems, VDA, physical strain-induced vertigo, and hyperacusia. Logistic regression analysis explained 8.7% of the variability of the complaint profile. Occupational noise exposure was recorded in 25.4% of the participants and correlated with the greater impact of tinnitus, hyperacusis, and hearing loss. Neither the frequency, duration, or severity of vertigo or nausea were significantly different between the baseline group and the TBI, NTwV, or noise-exposure groups. The results indicate that TBI and NTwV are common among MD patients and may cause a confounder effect.
PubMed: 38391776
DOI: 10.3390/audiolres14010019 -
Best Practice & Research. Clinical... Feb 2024Cervicogenic headache, described almost 100 years ago, only had its clinical awakening at the end of the century with the work of Professor Sjaastad. Its classic... (Review)
Review
Cervicogenic headache, described almost 100 years ago, only had its clinical awakening at the end of the century with the work of Professor Sjaastad. Its classic definition is the induction of trigeminal symptoms from cervical disorders, thanks to trigeminocervical convergence mechanisms. For this reason, it can manifest several features typical of migraine, leading to diagnostic errors. Classically, subjects complain of fixed unilateral headaches, with cervical onset and trigeminal irradiation, associated with reduced neck mobility and flexion strength. The headache is mild to moderate, described as pulsatile or compressive, accompanied by nausea, vomiting, photophobia, phonophobia, and may present autonomic symptoms and dizziness. The pain duration varies from one day to weeks, and its frequency is unpredictable. A history of whiplash injury is common. The differential diagnosis encompasses migraine and tension-type headache. Management includes physiotherapy rehabilitation, anesthetic blocks, and selectively surgical procedures. In this article, all these aspects were extensively covered.
PubMed: 38388233
DOI: 10.1016/j.berh.2024.101931 -
Frontiers in Cellular and Infection... 2023Migraine is a prevalent clinical disorder characterized by recurrent unilateral throbbing headache episodes accompanied by symptoms such as nausea, vomiting,...
Migraine is a prevalent clinical disorder characterized by recurrent unilateral throbbing headache episodes accompanied by symptoms such as nausea, vomiting, photophobia, and phonophobia. Despite its common occurrence, the diagnosis, pathophysiology, and treatment of migraine remain controversial. Extensive research has implicated the gut microbiota in various central nervous system disorders, including anxiety disorders, depression, and Parkinson's disease. Some studies have also suggested that migraine may stem from disruptions to neurohormones and metabolism. This study aimed to investigate the disparities in gut microbiota and metabolites between migraine mice model and normal mice to shed light on the underlying mechanisms and potential therapeutic approaches. Distinct differences in gut microbial composition were observed between the migraine mouse model and normal mouse, indicating a potential correlation between these variations and the pathogenesis of migraine. This study provides evidence of differences in gut microbiota composition and metabolites between a migraine mouse model and normal mice, which showed that Akkermansiaceae constituted the most abundant taxon in the sham injection mouse group, while Lachnospiraceae constituted the most prevalent group in the migraine mouse model group. The associations between the abundances of and Lachnospiraceae bacteria and metabolites suggested their potential roles in the pathogenesis of migraine. The altered abundance of Lachnospiraceae observed in migraine-afflicted mice and its correlations with changes in metabolites suggest that it may affect the host's health. Thus, probiotic therapy emerges as a possible treatment for migraine. Moreover, significant disparities in gut metabolites were observed between the migraine mouse model and normal mice. These alterations encompass multiple metabolic pathways, suggesting that metabolic disturbances may also contribute to the development of migraines.
Topics: Animals; Mice; Gastrointestinal Microbiome; Migraine Disorders; Nausea; Clostridiales; Disease Models, Animal; Verrucomicrobia; RNA, Ribosomal, 16S
PubMed: 38357211
DOI: 10.3389/fcimb.2023.1322059 -
Journal of the Association For Research... Feb 2024To assess the available evidence to support a genetic contribution and define the role of common and rare variants in tinnitus.
PURPOSE
To assess the available evidence to support a genetic contribution and define the role of common and rare variants in tinnitus.
METHODS
After a systematic search and quality assessment, 31 records including 383,063 patients were selected (14 epidemiological studies and 17 genetic association studies). General information on the sample size, age, sex, tinnitus prevalence, severe tinnitus distribution, and sensorineural hearing loss was retrieved. Studies that did not include data on hearing assessment were excluded. Relative frequencies were used for qualitative variables to compare different studies and to obtain average values. Genetic variants and genes were listed and clustered according to their potential role in tinnitus development.
RESULTS
The average prevalence of tinnitus estimated from population-based studies was 26.3% for any tinnitus, and 20% of patients with tinnitus reported it as an annoying symptom. One study has reported population-specific differences in the prevalence of tinnitus, the white ancestry being the population with a higher prevalence. Genome-wide association studies have identified and replicated two common variants in the Chinese population (rs2846071; rs4149577) in the intron of TNFRSF1A, associated with noise-induced tinnitus. Moreover, gene burden analyses in sequencing data from Spanish and Swede patients with severe tinnitus have identified and replicated ANK2, AKAP9, and TSC2 genes.
CONCLUSIONS
The genetic contribution to tinnitus is starting to be revealed and it shows population-specific effects in European and Asian populations. The common allelic variants associated with tinnitus that showed replication are associated with noise-induced tinnitus. Although severe tinnitus has been associated with rare variants with large effect, their role on hearing or hyperacusis has not been established.
Topics: Humans; Tinnitus; Genome-Wide Association Study; Hearing; Hearing Loss, Sensorineural; Hyperacusis
PubMed: 38334885
DOI: 10.1007/s10162-024-00925-6 -
Journal of the American Academy of... Jan 2024We previously reported the results of exploratory factor analysis (EFA) of the Hyperacusis Impact Questionnaire (HIQ), the Sound Sensitivity Symptoms Questionnaire...
Confirmatory factor analysis of the Hyperacusis Impact Questionnaire, Sound Sensitivity Symptoms Questionnaire, and Screening for Anxiety and Depression in Tinnitus, including preliminary analyses of the parent versions for use with children.
BACKGROUND
We previously reported the results of exploratory factor analysis (EFA) of the Hyperacusis Impact Questionnaire (HIQ), the Sound Sensitivity Symptoms Questionnaire (SSSD) and the Screening for Anxiety and Depression in Tinnitus (SAD-T). Confirmatory Factor Analysis (CFA) is necessary to confirm the latent constructs determined using EFA. CFA should use different samples but with similar characteristics to those used for EFA.
PURPOSE
The aim was to use CFA to confirm latent constructs derived using EFA of the HIQ, SSSQ and SAD-T. We further evaluated the psychometric properties of parent versions of these questionnaires (indicated by -P), which are intended for use with children.
RESEARCH DESIGN
This was a retrospective cross-sectional study.
STUDY SAMPLE
Data for 323 consecutive adults and 49 children who attended a Tinnitus and Hyperacusis Therapy Clinic in the UK within a six-month period were included.
DATA COLLECTION AND ANALYSIS
Data were collected retrospectively from the records of patients held at the audiology department. CFA with the weighted least-squares mean and variance-adjusted estimator was applied to assess the previously proposed factor structures of the HIQ, SSSQ and SAD-T. The internal consistency of the scales was assessed via Cronbach's alpha (α). The items of the HIQ, SSSQ and SAD-T were tested for measurement invariance regarding age and gender using the multiple indicator multiple cause (MIMIC) model.
RESULTS
All questionnaires showed good to excellent internal consistency, with α = 0.93 for the HIQ, 0.87 for the SSSQ, and 0.91 for the SAD-T. The parent versions showed acceptable to good internal consistency, with α = 0.88 for the HIQ-P, 0.71 for the SSSQ-P, and 0.86 for the SAD-T-P. CFA showed that the HIQ, SSSQ, and SAD-T were all one-factor questionnaires and the factors generally were similar to those obtained for the EFA. The MIMIC model showed that all three questionnaires can be considered as measurement invariant, with scores similar across genders and ages.
CONCLUSIONS
The HIQ, SSSQ and SAD-T are internally consistent one-factor questionnaires that can be used in clinical and research settings to assess the impact of hyperacusis, the severity of sound sensitivity symptoms, and to screen for anxiety and depression symptoms. Future studies should further explore the psychometric properties of the parent versions of the HIQ and SSSQ and SAD-T.
PubMed: 38286425
DOI: 10.1055/a-2255-7643