Orientational order in dipolar fluids consisting of nonspherical hard particles

We investigate fluids of dipolar hard particles by a certain variant of density-functional theory. The proper treatment of the long range of the dipolar interactions yields a contribution to the free energy which favors ferromagnetic order. This corrects previous theoretical analyses. We determine phase diagrams for dipolar ellipsoids and spherocylinders as a function of the aspect ratio of the particles and their dipole moment. In the nonpolar limit the results for the phase boundary between the isotropic and nematic phase agree well with simulation data. Adding a longitudinal dipole moment favors the nematic phase. For oblate or slightly elongated particles we find a ferromagnetic liquid phase, which has also been detected in computer simulations of fluids consisting of spherical dipolar particles. The detailed structure of the phase diagram and its evolution upon changing the aspect ratio are discussed in detail.Comment: 35 pages LaTeX with epsf style, 11 figures in eps format, submitted to Phys. Rev.

Dizziness and driving from a patient perspective

Background: People with dizziness may experience driving-related limitations. Few data are available about the impact of dizziness on driving. Aim: The aim of this study is to investigate the impact of dizziness on driving, factors related to impairment (age, gender, and type of diagnosis), and the potential consequences for patients' ability to work. We also investigated whether the patients expected and actually received information about their dizziness-related fitness to drive from their physician. Methods: A cross-sectional, observational study was conducted in the Apeldoorn Dizziness Centre, a tertiary care referral centre for patients with dizziness. A consecutive cohort of patients was asked to complete a study-specific questionnaire about driving. Results: Between January 1, 2020, and December 20, 2020, 432 patients were included. Fifty-six percent of the patients in this group were female. The average age of patients was 58.3 years (SD 16). Overall, 191 of the 432 patients (44%) experienced limitations related to driving, and 40% of the patients who experienced limitations also experienced limitations to work related to their inability to drive. The subject of fitness to drive had not been discussed with their physician in 92% of the patients, and 24% of the whole patient group indicated that they would have liked to discuss this topic. The following factors, independently from each other, increased the chance of experiencing driving-related limitations: younger age, female sex, and the diagnosis of Meniere's disease. Conclusion: Dizzy patients, especially younger patients, women, and patients with Meniere's disease, regularly experience limitations related to driving, and this often means that they are unable to work. Driving is hardly ever discussed during a medical consultation. In our opinion, the topic of driving and dizziness should always be addressed during medical consultations in dizzy patients.Disorders of the head and nec

Idiopathic labyrinthitis: symptoms, clinical characteristics, and prognosis

BACKGROUND: Labyrinthitis is an inner ear disorder of unknown incidence, characterized by sudden hearing loss and concurrent vertigo. Cohort studies of patients diagnosed with labyrinthitis are nonexistent. This study aims to describe the clinical characteristics and prognosis of patients diagnosed with idiopathic labyrinthitis.METHODS: Patients with labyrinthitis in the absence of a clear viral, bacterial, or autoimmune pathogenesis were retrospectively identified from electronic patient files. Symptoms at presentation and results from vestibular testing were retrieved. The 9-item Vestibular Activity Avoidance Instrument, administered during follow-up interviews by telephone, was used to assess the presence of persistent balance problems and activity avoidance behavior.RESULTS: Sixty-one patients with idiopathic labyrinthitis were included. All patients had vestibular weakness at presentation. After a median of 61 months of follow-up (interquartile range 81), 72.5% of patients still experienced balance problems. Subjective hearing recovery only occurred in 20% of cases.CONCLUSION: Patients presenting in a tertiary dizziness clinic with idiopathic labyrinthitis have a poor prognosis for both hearing and balance function impairment. Prospective observational cohorts are required to establish objectifiable vestibular and audiological follow-up data.Disorders of the head and nec

Cardiovascular risk factors, cerebral small vessel disease, and subsequent risk of stroke in patients with idiopathic sudden sensorineural hearing loss: systematic review and meta-analyses of the current literature

Vascular involvement in the pathophysiology of idiopathic sudden sensorineural hearing loss (iSSNHL) has been previously proposed. The objective of this study was to perform a systematic review of the current literature and conduct meta-analyses to evaluate associations between cardiovascular risk factors, cerebral small vessel disease, and subsequent stroke after presentation with iSSNHL. Three systematic literature reviews and meta-analyses were conducted using PubMed, Embase, and CINAHL. All studies investigating associations between iSSNHL and the cardiovascular risk factors: body mass index (BMI), diabetes mellitus, hyperlipidemia, hypertension, medical history of myocardial infarction (MI), smoking, the degree of white matter hyperintensities, and incidence of stroke were included. Adhering to the PRISMA guidelines, two independent reviewers reviewed the articles and assessed risk of bias. The cardiovascular risk factors of abnormal BMI, diabetes, hypertension, total cholesterol, low-density lipoprotein cholesterol, and a medical history of MI were significantly associated with iSSNHL. The adjusted hazard ratio of a higher degree of white matter hyperintensities was 0.70 (95% CI 0.44, 1.12). Patients with iSSNHL showed a higher risk of stroke compared to controls, with hazard ratios ranging from 1.22 up to 4.08. Several cardiovascular risk factors are more frequently present in patients with iSSNHL than in the general population. The degree of white matter hyperintensities does not appear to be increased in patients with iSSNHL, while the risk of stroke following ISSNHL is increased. Prospective studies with larger study populations are needed to confirm the associations between generalized cardiovascular disease and iSSNHL and to assess whether these patients benefit from cardiovascular risk management to prevent future cardiovascular and cerebrovascular disease. Otorhinolaryngolog

Treatment results of geotropic and apogeotropic horizontal canal benign paroxysmal positional vertigo in a tertiary dizziness clinic

Purpose: To determine the effectiveness of our treatment protocol for geotropic and apogeotropic horizontal canal benign paroxysmal positional vertigo (h-BPPV).Methods: We retrospectively evaluated patients with newly diagnosed geotropic and apogeotropic h-BPPV who visited our clinic between July 2017 and December 2019. Patients were treated according to our treatment protocol, which was implemented in 2017. Patients with geotropic h-BPPV were preferably treated with the Gufoni maneuver. In patients with apogeotropic h-BPPV we executed the modified Gufoni maneuver to achieve conversion to the geotropic type. We looked at the number of successful treatments and the number of recurrences within 1 year.Results: We included 102 patients with h-BPPV, 62 (61%) of whom were treated for geotropic h-BPPV. The ratio of apogeotropic to geotropic h-BPPV was 0.65. After the first visit, we observed resolution of horizontal canal BPPV in 71 and 63% of the geotropic and the apogeotropic group, respectively. After the second visit, this percentage increased to 92% for geotropic h-BPPV and 78% for apogeotropic h-BPPV. After 1 year of follow-up we determined a recurrence rate of 32 and 24% for the geotropic and apogeotropic group, respectively.Conclusion: With our treatment protocol we managed to achieve high rates of symptom resolution in the geotropic and apogeotropic type of h-BPPV with acceptable recurrence rates. We observed a relatively high ratio of apogeotropic h-BPPV to geotropic h-BPPV.Disorders of the head and nec

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Cerebral small vessel disease in elderly patients with vestibular neuritis

Background: Acute audiovestibular loss is a neurotologic emergency of which the etiology is frequently unknown. In vestibular neuritis a viral genesis is expected, although there is insufficient evidence to support viruses as the only possible etiological factor. In sudden deafness, a vascular etiology has been proposed in elderly patients, since cardiovascular risk factors are more frequently present and a higher risk of developing a stroke was seen compared to the general population. So far, very little research has been carried out on vascular involvement in elderly patients with vestibular neuritis. Cardiovascular risk factors have a positive correlation with cerebral small vessel disease, visible as white matter hyperintensities, brain infarctions, microbleeds and lacunes on MRI. The presence of these characteristics indicate a higher risk of developing a stroke. Aim: We investigated whether elderly patients with vestibular neuritis have a higher prevalence of vascular lesions on MRI compared to a control cohort. Materials and Methods: Patients of 50-years and older, diagnosed with vestibular neuritis in a multidisciplinary tertiary referral hospital, were retrospectively reviewed and compared to a control cohort. The primary outcome was the difference in cerebral small vessel disease on MRI imaging, which was assessed by the number of white matter hyperintensities using the ordinal Fazekas scale. Secondary outcomes were the presence of brain infarctions on MRI and the difference in cardiovascular risk factors. Results: Patients with vestibular neuritis (N = 101) had a 1.60 higher odds of receiving a higher Fazekas score than the control cohort (N = 203) (p = 0.048), there was no difference in presence of brain infarctions (p = 1.0). Hyperlipidemia and atrial fibrillation were more common in patients experiencing vestibular neuritis. Conclusion: We found a positive correlation of white matter hyperintensities and VN which supports the hypothesis of vascular involvement in the pathophysiology of vestibular neuritis in elderly patients. Further prospective research is necessary to confirm this correlation.Disorders of the head and nec

Identifying tests to evaluate in a diagnostic accuracy study for patients with vertigo in general practice: a Delphi study

IntroductionVertigo is a common symptom that strongly impacts patients’ quality of life. More than 80% of patients experiencing vertigo are primarily treated by their general practitioner (GP). The GP’s'diagnostic toolkit' for vertigo has serious limitations, though, because diagnostic accuracy studies on conditions that may cause vertigo have never been performed in a general practice setting. Our aim was to determine which tests should be investigated in a diagnostic accuracy study for patients with vertigo in general practice.MethodWe conducted an online Delphi procedure involving national and international experts. The experts were asked to judge a selection of 40 diagnostic tests based on the Dutch GP guideline on vestibular symptoms, supplemented by tests identified during a systematic review. Panellists were allowed to suggest additional tests after the first round. In case of consensus of at least 70%, a test was included or excluded. We also conducted a secondary sub-analysis of our Delphi procedure to demonstrate non-dominance of Dutch experts within our expert panel. Data were analysed using descriptive statistics and content analysis. Data were analysed using descriptive statistics and content analysis.ResultsA panel of 20 experts from five countries, including 7 specialists in otolaryngology, 6 neurologists and 7 GPs, participated in the Delphi procedure. The panel judged 46 diagnostic tests in total, with 6 additional tests added to the original selection based on suggestions by experts. After the first two rounds (100% response rate), 16 tests were included, 22 tests were excluded and no consensus was reached on 8 tests. During the consensus round, one of the 8 tests was added to the included 16 tests. Of these 17 tests, 15 are recommended by the Dutch GP guideline, supplemented by the non-recommended Tandem walking test and the Romberg test.ConclusionsAn international expert panel reached consensus on 17 tests for vertigo in general practice that should be investigated in a diagnostic accuracy study.Disorders of the head and nec

Risk factors and occurrence of small vessel disease in acute sensorineural hearing loss in the elderly: protocol for a multicentre cross-sectional study

Introduction The aetiology of sudden sensorineural hearing loss (SSNHL) is not certain in a significant number of cases. In 8%-31% of posterior fossa infarctions, acute hearing or vestibular loss precedes neurological symptoms. Also, several retrospective cohort analyses have indicated a higher chance of experiencing a stroke after SSNHL compared with the general population. This higher incidence of stroke suggests vascular involvement in the pathophysiology of SSNHL. The aim of this study is to evaluate the association of cardiovascular disease and idiopathic SSNHL (iSSNHL) by investigating the presence of cardiovascular risk factors and cerebral small vessel disease (CSVD), in patients with iSSNHL and compare this to controls. Method and analysis In this multicentre cross-sectional study, the ROSALIE study, 205 patients aged 50 years or higher diagnosed with iSSNHL, and 205 controls who are either suspected of trigeminus neuralgia, hemifacial spasm, vestibular paroxysmia or have a cerebellopontine angle neoplasm will be included. The primary outcome is the difference in CSVD, measured by the degree of white matter hyperintensities according to the Fazekas scale and the presence of brain infarctions on MRI, between patients with iSSNHL and controls. The secondary outcome is the difference in prevalence of the cardiovascular risk factors: hypertension, hypercholesterolaemia, smoking status, body mass index and cardiovascular comorbidities; diabetes, stroke and myocardial infarction, between both cohorts. Ethics and dissemination Ethics approval has been obtained by the institutional review boards of all participating hospitals. The Medical Research Involving Human Subjects Act does not apply to this study, as has been declared by the regional review board at Leiden University Hospital, registration number 22-3060. Patients will receive the standard diagnostic protocol for iSSNHL in the Netherlands, which consists of pure tone audiometric assessment before and after treatment with corticosteroids and an MRI of the cerebellopontine angle displaying the entire cerebrum. The data will not be available publicly but might be shared on a reasonable request. Ethics and dissemination Ethics approval has been obtained by the institutional review boards of all participating hospitals. The Medical Research Involving Human Subjects Act does not apply to this study, as has been declared by the regional review board at Leiden University Hospital, registration number 22-3060. Patients will receive the standard diagnostic protocol for iSSNHL in the Netherlands, which consists of pure tone audiometric assessment before and after treatment with corticosteroids and an MRI of the cerebellopontine angle displaying the entire cerebrum. The data will not be available publicly but might be shared on a reasonable request.Disorders of the head and nec