Identification of Neural Mechanisms in First Single-Sweep Analysis in oVEMPs and Novel Normative Data

Background: Bone-conducted (BC) VEMPs provide important tools for measuring otolith function. However, two major drawbacks of this method are encountered in clinical practice—small n10 amplitude and averaging technique. In this study, we present the results of a new VEMP setup measuring technique combined with a novel single-sweep analysis. Methods: The study included BC oVEMP data from 92 participants for the evaluation of normative data using a novel analysis technique. For evaluating test-retest reliability, the intraclass correlation coefficient (ICC) was used. Results: We found significant n10 amplitude differences in single-sweep analyses after the first and second measurements. Thereby, mathematical analyses of the head movement did not show any differences in the first or second measurements. The normative n10 amplitude was 20.66 µV with an asymmetric ratio (AR) of 7%. The new value of late shift difference (LSD) was 0.01 ms. The test retest-reliability showed good to excellent ICC results in 9 out of 10 measurements. Conclusions: Our results support a phenomenon in single-sweep analysis of the first stimuli independent of head movement and signal morphology. Furthermore, the values obtained with the new measurement method appear to be more sensitive and may allow an extended diagnostic range due to the new parameter LSD

Unklare chronische Schwindelsyndrome – Erfahrungen mit einem interdisziplinären stationären Diagnostikkonzept

Dizziness is a common leading symptom. Especially patients with chronic vertigo syndromes experience a significant impairment in quality of life up to a limitation of their ability to work in the case of employed persons. The consequences are financial and capacitive burdens on the health system due to frequently multiple examinations and sick leave up to occupational invalidity of the affected patient. In 150 patients with chronic vertigo syndromes and an unclear outpatient diagnosis, at least one diagnosis that justified the complaint was made in over 90% of cases on the basis of a structured interdisciplinary inpatient diagnostic concept. Chronic vertigo syndromes are often multifactorial. Psychosomatic (accompanying) diagnoses were found in more than half of the patients. Targeted therapy can only be recommended after establishing a specific diagnosis. This justifies an interdisciplinary inpatient diagnostic concept for persistently unclear cases

Validation of first chemistry mode retrieval results from the new limb-imaging FTS GLORIA with correlative MIPAS-STR observations

We report first chemistry mode retrieval results from the new airborne limb-imaging infrared FTS (Fourier transform spectrometer) GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) and comparisons with observations by the conventional airborne limb-scanning infrared FTS MIPAS-STR (Michelson Interferometer for Passive Atmospheric Sounding – STRatospheric aircraft). For GLORIA, the flights aboard the high-altitude research aircraft M55 Geophysica during the ESSenCe campaign (ESa Sounder Campaign 2011) were the very first in field deployment after several years of development. The simultaneous observations of GLORIA and MIPAS-STR during the flight on 16 December 2011 inside the polar vortex and under conditions of optically partially transparent polar stratospheric clouds (PSCs) provided us the first opportunity to compare the observations by two different infrared FTS generations directly. We validate the GLORIA results with MIPAS-STR based on the lower vertical resolution of MIPAS-STR and compare the vertical resolutions of the instruments derived from their averaging kernels. The retrieval results of temperature, HNO3, O3, H2O, CFC-11 and CFC-12 show reasonable agreement of GLORIA with MIPAS-STR and collocated in situ observations. For the horizontally binned hyperspectral limb images, the GLORIA sampling outnumbered the horizontal cross-track sampling of MIPAS-STR by up to 1 order of magnitude. Depending on the target parameter, typical vertical resolutions of 0.5 to 2.0 km were obtained for GLORIA and are typically a factor of 2 to 4 better compared to MIPAS-STR. While the improvement of the performance, characterization and data processing of GLORIA are the subject of ongoing work, the presented first results already demonstrate the considerable gain in sampling and vertical resolution achieved with GLORIA

A new approach for a clinical test of unilateral utricular function

Die klinische Funktionsdiagnostik des Gleichgewichtsorgans im Innenohr erfordert seiten-getrennte und isolierte Untersuchungen für alle fünf Teilorgane (3 Bogengänge sowie den Otolithenorganen Sakkulus und Utrikulus). Die etablierten Prüfverfahren geben jedoch nur Auskunft über die Bogengangs- (kalorische Prüfung, Drehpendelprüfung, postrotatorische Prüfung, Kopfimpulstest) und Sakkulusfunktion (cVEMP). Ein Untersuchungsverfahren zur Utrikulusfunktion stand bisher nicht zur Verfügung und wurde in dieser Arbeit entwickelt. Die verwendete Methode ist eine Kombination aus dem Messverfahren zur Bestimmung der subjektiven visuellen Vertikalen (SVV) mit dem Stimulusverfahren des unilateralen Zentrifugierens (UC). Neben der technischen Entwicklung des Verfahrens waren die Hauptziele der Arbeit dessen Verifizierung, die Einbindung in die klinische Routine und die Durchführung erster klinischer Studien. Zusätzlich wurden technisch einfachere aber bilateral wirkende Stimulationsverfahren (statische Kippung, zentrische Rotation) in die Studien mit einbezogen, um deren Aussagekraft zu bewerten. Die Ergebnisse zeigen, dass die SVV-Untersuchung mit UC eine adäquate Methode für die unilaterale Utrikulusfunktionsdiagnostik darstellt und gut für die klinische Diagnostik geeignet ist. Eine Vergleichstudie mit Normalpersonen und Patienten mit einseitig durchtrenntem N. vestibularis ergab, das die Methode eine hohe Sensitivität und Spezifität aufweist. Die geringe Abbruchquote von 13% bei inzwischen insgesamt 778 durchgeführten Unter-suchungen (637 Patienten) beweist die hohe Akzeptanz durch die Patienten. Von den bilateralen Stimulationsverfahren stellt die zentrische Rotation einen akzeptablen Kompromiss dar und ist mit vielen bereits installierten Drehstühlen umsetzbar. Nur bei Patienten mit guter zentraler Kompensation eines Defizits würde die Gefahr von falsch negativen Befunden bestehen. Mit dem Verfahren konnte erstmals gezeigt werden, dass offenbar eine isolierte Utrikulus- funktionsstörung bei intakter Bogengangs- und Sakkulusfunktion auftreten kann. Bei 46 Patienten konnte eine entsprechende Befundskombination (asymmetrische SVV bei UC und symmetrische kalorische Erregbarkeit sowie cVEMPs) nachgewiesen werden. Neben der Lokalisation einer Utrikulusläsion gibt die zusätzliche Bewertung der Reiz-antworten auf der gesunden Seite und bei der bilateral wirkenden zentrischen Rotation die Möglichkeit, unterschiedliche Grade einer zentral vestibulären Kompensation eines peripheren Defizits ableiten zu können. Mit dieser Arbeit wurde erstmals eine vollständige Differentialdiagnostik des Gleichgewichts-organs möglich. Aufgrund der wesentlichen Funktion der Otolithenorgane, permanent die Stellung des Kopfes in Relation zum Gravitätsvektor zu erfassen, wirken sich Funktions-störungen auf die gesamte Körperkoordination aus. Untersuchungen von Schwindelpatienten mit dem neuen Verfahren zur Utrikulusfunktion können nun dazu beitragen, das Verständnis der durch die Otolithenorgane verursachten Störungen zu verbessern.For the diagnosis of peripheral vestibular disorders it is desirable that a comprehensive, examination of the semicircular canal and otolith functions be conducted. In particular, unilateral testing is essential for accurate differential diagnosis. To date, the caloric and head-impulse tests provide information on semicircular canal function. The measurement of cervical VEMP (cVEMP) has become established as a test of saccular function. An effective clinical test for assessing unilateral utricle function was not available at the beginning of this research. The thesis describes the development and clinical evaluation of a test for unilateral utricle function based on the measurement of the subjective visual vertical (SVV) combined with unilateral centrifugation (UC). In addition to the technical refinement of the stimulus and measurement approach, the main objective was its verification and introduction into the clinical diagnostic process. In order to confirm the advantages of UC stimulation, additional measurements of the SVV were performed during static tilt and on-axis rotation. The results demonstrate that SVV estimation during UC represents an adequate and reliable method for assessing the unilateral utricle function, and is thus of significance for the clinical diagnostic process. The high sensitivity of the method was verified in a comparative study with normal subjects versus patients with unilateral section of N. vestibularis. The test procedure has also proved to be highly acceptable, with only 10-15% of 778 cases where the procedure had to be discontinued Further, it has been demonstrated that unilateral otolith disorders can in many cases be recognized from SVV testing during on-centre rotation, i.e. bilateral stimulation. Accordingly the procedure can be used with a standard Bárány rotating chair. The risk of false negative results exists in those patients with a high degree of central compensation of a unilateral deficit. Various response patterns of SVV estimations during UC were identified which could be classified into three subgroups, indicating different degrees of compensation. Testing in UC and bilateral static tilt proves useful in discriminating peripheral and central disorders. The findings also reveal the apparent occurrence of unilateral, isolated utricular dysfunction – or utricle paresis. This represents a novel entity in the differential diagnosis of peripheral vestibular function. In total, of 110 analysed patients with suspected otolith dysfunction, a total of 46 patients were found with asymmetric SVV findings, coupled with normal symmetric caloric responses and cVEMPs. This research establishes for the first time a comprehensive diagnosis of all structures in the vestibular organ. Based on the fact that the otolith organs sense head tilt with respect to the gravity vector utricule deficits influence spatial orientation and postural stability. The employment of the presented test procedure should contribute to the improvement of the differential diagnosis of such cases

A Comparison of Interpolyelectrolyte Complexes (IPECs) Made from Anionic Block Copolymer Micelles and PDADMAC or q-Chitosan as Polycation

Block copolymers synthesized via Atom Transfer Radical Polymerization from alkyl acrylate and t-butyl acrylate and the subsequent hydrolysis of the t-butyl acrylate to acrylic acid were systematically varied with respect to their hydrophobic part by the variation in the alkyl chain length and the degree of polymerisation in this block. Depending on the architecture of the hydrophobic part, they had a more or less pronounced tendency to form copolymer micelles in an aqueous solution. They were employed for the preparation of IPECs by mixing the copolymer aggregates with the polycations polydiallyldimethylammonium chloride (PDADMAC) or q-chit. The IPEC structure as a function of the composition was investigated by Static Light and Small Angle Neutron Scattering. For weakly-associated block copolymers (short alkyl chain), complexation with polycation led to the formation of globular complexes, while already existing micelles (long alkyl chain) grew further in mass. In general, aggregates became larger upon the addition of further polycation, but this growth was much more pronounced for PDADMAC compared to q-chit, thereby leading to the formation of clusters of aggregates. Accordingly, the structure of such IPECs with a hydrophobic block depended largely on the type of complexing polyelectrolyte, which allowed for controlling the structural organisation via the molecular architecture of the two oppositely charged polyelectrolytes

Identification of Neural Mechanisms in First Single-Sweep Analysis in oVEMPs and Novel Normative Data

Background: Bone-conducted (BC) VEMPs provide important tools for measuring otolith function. However, two major drawbacks of this method are encountered in clinical practice—small n10 amplitude and averaging technique. In this study, we present the results of a new VEMP setup measuring technique combined with a novel single-sweep analysis. Methods: The study included BC oVEMP data from 92 participants for the evaluation of normative data using a novel analysis technique. For evaluating test-retest reliability, the intraclass correlation coefficient (ICC) was used. Results: We found significant n10 amplitude differences in single-sweep analyses after the first and second measurements. Thereby, mathematical analyses of the head movement did not show any differences in the first or second measurements. The normative n10 amplitude was 20.66 µV with an asymmetric ratio (AR) of 7%. The new value of late shift difference (LSD) was 0.01 ms. The test retest-reliability showed good to excellent ICC results in 9 out of 10 measurements. Conclusions: Our results support a phenomenon in single-sweep analysis of the first stimuli independent of head movement and signal morphology. Furthermore, the values obtained with the new measurement method appear to be more sensitive and may allow an extended diagnostic range due to the new parameter LSD