Evaluation of a multimodal diagnostic algorithm for prediction of cognitive impairment in elderly patients with dizziness.

BACKGROUND: The current diagnostic workup for chronic dizziness in elderly patients often neglects neuropsychological assessment, thus missing a relevant proportion of patients, who perceive dizziness as a subjective chief complaint of a concomitant cognitive impairment. This study aimed to establish risk prediction models for cognitive impairment in chronic dizzy patients based on data sources routinely collected in a dizziness center. METHODS: One hundred patients (age: 74.7 ± 7.1 years, 41.0% women) with chronic dizziness were prospectively characterized by (1) neuro-otological testing, (2) quantitative gait assessment, (3) graduation of focal brain atrophy and white matter lesion load, and (4) cognitive screening (MoCA). A linear regression model was trained to predict patients' total MoCA score based on 16 clinical features derived from demographics, vestibular testing, gait analysis, and imaging scales. Additionally, we trained a binary logistic regression model on the same data sources to identify those patients with a cognitive impairment (i.e., MoCA < 25). RESULTS: The linear regression model explained almost half of the variance of patients' total MoCA score (R2 = 0.49; mean absolute error: 1.7). The most important risk-predictors of cognitive impairment were age (ß = - 0.75), pathological Romberg's sign (ß = - 1.05), normal caloric test results (ß = - 0.8), slower timed-up-and-go test (ß = - 0.67), frontal (ß = - 0.6) and temporal (ß = - 0.54) brain atrophy. The binary classification yielded an area under the curve of 0.84 (95% CI 0.70-0.98) in distinguishing between cognitively normal and impaired patients. CONCLUSIONS: The need for cognitive testing in patients with chronic dizziness can be efficiently approximated by available data sources from routine diagnostic workup in a dizziness center.

Spontaneous visual exploration during locomotion in patients with phobic postural vertigo.

BACKGROUND: Earlier studies on stance and gait with posturographic and EMG-recordings and automatic gait analysis in patients with phobic postural vertigo (PPV) or visual height intolerance (vHI) revealed similar patterns of body stiffening with muscle co-contraction and a slow, cautious gait. Visual exploration in vHI patients was characterized by a freezing of gaze-in-space when standing and reduced horizontal eye and head movements during locomotion. OBJECTIVE: Based on the findings in vHI patients, the current study was performed with a focus on visual control of locomotion in patients with PPV while walking along a crowded hospital hallway. METHODS: Twelve patients with PPV and eleven controls were recruited. Participants wore a mobile infrared video eye-tracking system that continuously measured eye-in-head movements in the horizontal and vertical planes and head orientation and motion in the yaw, pitch, and roll planes. Visual exploration behavior of participants was recorded at the individually preferred speed for a total walking distance of 200 m. Gaze-in-space directions were determined by combining eye-in-head and head-in-space orientation. Walking speeds were calculated based on the trial duration and the total distance traversed. Participants were asked to rate their feelings of discomfort during the walk on a 4-point numeric rating scale. The examiners rated the crowdedness of the hospital hallway on a 4-point numeric rating scale. RESULTS: The major results of visual exploration behavior in patients with PPV in comparison to healthy controls were: eye and head positions were directed more downward in the vertical plane towards the ground ahead with increased frequency of large amplitude vertical orientation movements towards the destination, the end of the ground straight ahead. The self-adjusted speed of locomotion was significantly lower in PPV. Particularly those patients that reported high levels of discomfort exhibited a specific visual exploration of their horizontal surroundings. The durations of fixating targets in the visual surroundings were significantly shorter as compared to controls. CONCLUSION: Gaze control of locomotion in patients with PPV is characterized by a preferred deviation of gaze more downward and by horizontal explorations for suitable auxiliary means for potential postural support in order to prevent impending falls. These eye movements have shorter durations of fixation as compared to healthy controls and patients with vHI. Finally, the pathological alterations in eye-head coordination during locomotion correlate with a higher level of discomfort and anxiety about falling.

Approach to an experimental model of Mal de Debarquement Syndrome.

INTRODUCTION: Mal de Debarquement Syndrome (MdDS) is the rare condition of enduring rocking sensations and subjective unsteadiness following a lengthy exposure to passive motion. The pathogenesis of MdDS is unknown and the available treatment is limited. Here, we developed an experimental model of MdDS that may facilitate systematic inquiry of MdDS pathophysiology and the development of prevention or treatment strategies for this condition. METHODS: In an initial series of pilot experiments, suitable stimulation devices and conditions were evaluated. The final paradigm consisted of a low-frequency oscillatory motion stimulation, simultaneously deployed as roll and pitch rotation as well as heave on a six-degrees-of-freedom motion platform. Twelve healthy participants were stimulated under this condition for 30 min during free stance. Aftereffects with respect to rocking sensations and posturographic sway were monitored up to 60 min post-stimulation and compared to an initial pre-stimulation assessment as well as to posturographic recordings of spontaneous sway in ten patients with MdDS. RESULTS: Motion stimulation consistently evoked MdDS-like rocking sensations and postural alterations that lasted up to 45 min after cessation of passive motion exposure. Body sway alterations were most pronounced in anterior-posterior dimension during standing with eyes closed and primarily characterized by a distinct peak in the low-frequency sway spectrum close to stimulation frequency. These postural aftereffects further closely resembled spontaneous oscillatory low-frequency sway observed in patients with MdDS. CONCLUSION: Subsequent neurophysiological and imaging examinations are required to investigate whether the model of transient, experimental MdDS actually shares a common substrate with the enduring pathological condition of MdDS.

[Fear of Heights in Primary School Children]. / Auch Grundschulkinder haben Höhenschwindel.

The life-time prevalence of visual height intolerance in adults is 28 percent, whereas in primary school children, as recently shown, it develops in 34 percent. Triggers and symptoms are similar in children and adults. A significant difference in visual height intolerance of prepubertal children compared to adults is the good prognosis with mostly spontaneous remission within a few years, possibly facilitated by repeated exposure to the triggering situations.

Acid effect on excited Auramine-O molecular rotor relaxations in solution and adsorbed on insulin fibrils.

Steady-state and time-resolved UV-Vis spectroscopy techniques were employed to study the non-radiative process of Auramine-O (AuO). We focused our attention on the ultrafast nonradiative decay of Auramine-O in water and on the acid effect on Auramine-O spectroscopy. We found that weak acids like formic acid shorten the excited-state decay times of both the emission and the transient pump-probe spectra of Auramine-O. We found three time domains in the relaxation of the excited states back to the ground state. In mixtures of acetic and formic acids, the three decay times associated with the relaxation process are shorter in the presence of formic acid in Auramine-O solutions. We qualitatively explain the very large non-radiative rate in water and in formic-acetic acid mixtures by a protic nonradiative model proposed by Sobolewski and Domcke. The steady-state emission spectrum of AuO adsorbed on insulin fibrils consists of two bands assigned to protonated and deprotonated forms and the emission intensity increases by three orders of magnitude. We conclude that the nonradiative process prevails in the liquid state, whereas when AuO is adsorbed on fibrils the nonradiative rate is reduced by three orders of magnitude and thus enables a slow ESPT process to occur.

[Do German articles in medical journals require a"guide to anglicisms"?]. / Braucht es einen "Anglizismus-Guide" für deutschsprachige Medizinjournale?

Effective communication of scientific results depends on conceptually clear and precise language, especially with regards to the use of discipline-specific terminology. German scientific language might be more comprehensible if the overuse of anglicisms is avoided. As an example commonly used anglicisms in ten clinical studies published in Der Nervenarzt were selected, listed according to the field of application and evaluated. Adequate German terms are offered for them showing that it is possible to use German terms for most issues and facts.

[How acrophobia impairs visual exploration and gait]. / Wie Höhenschwindel die visuelle Exploration und den Gang beeinträchtigt.

The life-time prevalence of visual height intolerance is 28 % in the general population. More than 50 % of those affected suffer from an impairment of daily behavior and quality of life when confronted with heights. Simultaneous measurements of spontaneous eye and head movements of these subjects while looking from a balcony revealed that visual exploration of the surroundings was restricted compared to that of control subjects. Spontaneous head movements were severely diminished and saccadic eye movements were reduced. Gaze in space was preferably directed towards structures on the horizon. Those susceptible to visual height intolerance exhibited a cautious slowing of gait with small and precarious steps. Restriction of visual exploration during locomotion in a complex terrain may result in falls because obstacles can be overlooked.

Understanding and controlling organic-inorganic interfaces in mesostructured hybrid photovoltaic materials.

The chemical compositions and structures of organic-inorganic interfaces in mesostructurally ordered conjugated polymer-titania nanocomposites are shown to have a predominant influence on their photovoltaic properties. Such interfaces can be controlled by using surfactant structure-directing agents (SDAs) with different architectures and molecular weights to promote contact between the highly hydrophobic electron-donating conjugated polymer species and hydrophilic electron-accepting titania frameworks. A combination of small-angle X-ray scattering (SAXS), scanning and transmission electron microscopy (SEM, TEM), and solid-state NMR spectroscopy yields insights on the compositions, structures, and distributions of inorganic and organic species within the materials over multiple length scales. Two-dimensional NMR analyses establish the molecular-level interactions between the different SDA blocks, the conjugated polymer, and the titania framework, which are correlated with steady-state and time-resolved photoluminescence measurements of the photoexcitation dynamics of the conjugated polymer and macroscopic photocurrent generation in photovoltaic devices. Molecular understanding of the compositions and chemical interactions at organic-inorganic interfaces are shown to enable the design, synthesis, and control of the photovoltaic properties of hybrid functional materials.

Follow-up of vestibular function in bilateral vestibulopathy.

OBJECTIVE: Bilateral vestibulopathy (BV) leads to a bilateral deficit of the vestibulo-ocular reflex and has various aetiologies. The main goal of this study was to determine the frequency and degree of recovery or worsening of vestibular function over time. METHODS: 82 patients (59 males, 23 females; mean age at the time of diagnosis 56.3 (SD 17.6) years) were re-examined 51 (36) months after the first examination. All patients underwent a standardised neuro-ophthalmological and neuro-otological examination. Electronystagmography with bithermal caloric irrigation was analysed by measurement of the mean peak slow phase velocity (SPV) of the induced nystagmus. Patients evaluated the course of their disease in terms of balance, gait unsteadiness and health related quality of life. RESULTS: Statistical analysis of the mean peak SPV of caloric induced nystagmus revealed a non-significant worsening over time (initial mean peak SPV 3.0 (3.5) degrees/s vs 2.1 (2.8) degrees/s). With respect to subgroups of aetiology, only patients with BV due to meningitis exhibited an increasing, but non-significant SPV (1.0 (1.4) degrees/s vs 1.9 (1.6) degrees/s). Vestibular outcome was independent of age, gender, time course of manifestation and severity of BV. Single analysis of all patients showed that a substantial improvement > or = 5 degrees/s occurred in two patients on both sides (idiopathic n = 1, Sjögren's syndrome n = 1) and in eight patients on one side (idiopathic n = 6, meningitis n = 1, Menière's disease n = 1). In 84% of patients there was impairment of their health related quality of life (42% slight, 24% moderate, 18% severe). Forty-three per cent of patients rated the course of their disease as stable, 28% as worsened and 29% as improved. CONCLUSIONS: Our data support the view that more than 80% of patients with BV do not improve. Thus the prognosis of BV is less favourable than assumed.

Low recurrence rate of vestibular neuritis: a long-term follow-up.

We examined 103 patients with vestibular neuritis (VN) in a follow-up study (5.7 to 20.5 years, mean 9.8 years). Two patients (1.9%) had developed a second occurrence of VN 29 to 39 months after the first. VN affected the contralateral ear in both and caused less severe distressing vertigo and postural imbalance. Unlike Bell's palsy and sudden hearing loss, a relapse in the same ear did not occur.

Phobic postural vertigo--a long-term follow-up (5 to 15 years) of 106 patients.

One hundred and six patients diagnosed between 1987 and 1998 to have somatoform phobic postural vertigo were examined in a follow-up study with a self-evaluating questionnaire. The improvement rate after a mean follow-up time of 8.5 years (5 to 15.9 years) was 75% (27% of the patients reported a complete remission). While the majority of these patients experienced improvement or remission during the first year after assessment of diagnosis and a short-term psychotherapeutic approach, some patients also had considerable improvement even after two or more years. There was a negative correlation between the duration of the condition before assessment of the diagnosis and the improvement/regression rate. The improvement/regression rate was independent of gender, age, preceding vestibular or non-vestibular organic disorders, and the various medical, physical, or psychotherapeutic interventions. Transient relapses occurred in 47% of the improved patients once or repeatedly. The probability of developing a relapse remained constant throughout the entire follow-up. None of the patients required a revision of the initial diagnosis on the basis of the questionnaire.

Experimental evidence for a kinetic transition in reversible reactions.

We provide a first experimental verification of a theoretical prediction of a kinetic transition in a reversible binding reaction, AB right harpoon over left harpoon A+B, driven by the difference in effective lifetimes of the bound and the unbound states. We consider the kinetics of excited-state proton transfer to solvent from a photoacid whose conjugate anionic base possesses an extremely short unbound anion lifetime. Its solvent variation relative to the overall dissociation rate coefficient induces a transition in the kinetics, from power law to exponential.

Time-resolved study of the inner space of lactose permease.

Pyranine (8-hydroxy pyrene-1,3,6-trisulfonate) is a commonly used photoacid that discharges a proton when excited to its first electronic singlet state. Follow-up of its dissociation kinetics reveals the physicochemical properties of its most immediate environment. At vanishing ionic strength the dye adsorbs to the Escherichia coli lactose permease with stoichiometry of 1:1 and an association constant of 2.5 x 10(5) M(-1). The reversal of the binding at high ionic strength and the lower pK value of the bound dye imply that positive charge(s) stabilize the dye in its site. The fluorescence decay curve of the bound dye was measured by time-correlated single photon counting and the measured transient was subjected to kinetic analysis based on the geminate recombination model. The analysis indicated that the binding domain is a cleft (between 9 and 17 A deep) characterized by low activity of water (a((water)) = 0.71), reduced diffusivity of protons, and enhanced electrostatic potential. The binding of pyranine and a substrate are not mutually exclusive; however, when the substrate is added, the dye-binding environment is better solvated. These properties, if attributed to the substrate-conducting pathway, may explain some of the forces operating on the substrate in the cavity. The reduced activities of the water strips the substrate from some of its solvation water molecules and replace them by direct interaction with the protein. In parallel, the lower dielectric constant enhances the binding of the proton to the protein, thus keeping a tight seal that prevents protons from diffusing.

Course of illness in phobic postural vertigo.

Forty-two patients with phobic postural vertigo took part in a neurological and psychiatric follow-up study. During the follow-up time of about 2.5 years the neurological diagnosis remained stable (41 of 42 patients). PPV can be assigned to various psychiatric categories according to DSM-III-R. Although an association of PPV with anxiety disorders is evident, not all patients present with symptoms of anxiety or panic during attacks of vertigo. However most patients develop a disabling "phobic-avoidance pattern" with recurrent attacks. Important psychosocial stressors can be identified at the onset of the condition. Motives of secondary gain have also to be taken into consideration. The course of illness varies depending on the neurological syndrome of vertigo, on the one hand, and concomitant psychopathological syndromes, on the other. Despite a considerable rate of improvement in vertigo complaints (79%), the group of patients with phobic postural vertigo as a whole presented with significant psychological problems at follow-up term (74%), requiring specific psychiatric and/or psychotherapeutic interventions. Dependent or avoidant personality, and hypochondria were prognostic of a more negative course of illness.

Production of patulin by different strains of Penicillium expansum in pear and apple cultivars stored at different temperatures and modified atmospheres.

It was shown that the ability of three different strains of Penicillium expansum (NRRL 2034, NRRL 6069, and CBS 481.84) to grow and to produce patulin in pears (cv. Spadona) and apples (cv. Starking) varied under the different temperatures tested (0, 3, 6, 17 and 25 degrees C). Strain NRRL 2034 did not produce patulin at 0 or 25 degrees C while the two other strains produced the toxin at all temperatures, the maximum production occurring at 25 degrees C (for pears) and 17 degrees C (for apples). No significant differences in pathogenicity, as determined by lesion diameter, was recorded among the strains. Patulin production was totally inhibited when the fungi were grown in apples stored under 3% CO2/2% O2 (25 degrees C). The weight of infected tissue in apples contaminated with any of the strains and stored at that modified atmosphere was 70% that of the control. Under 3% CO2/10% O2 or 3% CO2/20% O2, strain NRRL 2034 did not produce patulin while the two other strains produced the toxin in different amounts.