Leif Erik Walther

Detection of isolated covert saccades with the video head impulse test in peripheral vestibular disorders

OBJECTIVES The function of the semicircular canal receptors and the pathway of the vestibulo-ocular-reflex (VOR) can be diagnosed with the clinical head impulse test (cHIT). Recently, the video head impulse test (vHIT) has been introduced but so far there is little clinical experience with the vHIT in patients with peripheral vestibular disorders. The aim of the study was to investigate the horizontal VOR (hVOR) by means of vHIT in peripheral vestibular disorders. METHODS Using the vHIT, we examined the hVOR in a group of 117 patients and a control group of 20 healthy subjects. The group of patients included vestibular neuritis (VN) (n=52), vestibular schwannoma (VS) (n=31), Ménières disease (MD) (n=22) and bilateral vestibulopathy (BV) (n=12). RESULTS Normal hVOR gain was at 0.96 ± 0.08, while abnormal hVOR gain was at 0.44 ± 0.20 (79.1% of all cases). An abnormal vHIT was found in VN (94.2%), VS (61.3%), MD (54.5%) and BV (91.7%). Three conditions of refixation saccades occurred frequently in cases with abnormal hVOR: isolated covert saccades (13.7%), isolated overt saccades (34.3%) and the combination of overt and covert saccades (52.0%). CONCLUSIONS The vHIT detects abnormal hVOR changes in the combination of gain assessment and refixation saccades. Since isolated covert saccades in hVOR changes can only be seen with vHIT, peripheral vestibular disorders are likely to be diagnosed incorrectly with the cHIT to a certain amount.

Detection of human utricular otoconia degeneration in vital specimen and implications for benign paroxysmal positional vertigo

Otoconia are assumed to be involved in inner ear disorders such as benign paroxysmal positional vertigo (BPPV). Up to now, the distinct structure and morphology of intact and degenerate human utricular otoconia has been only poorly investigated on vital specimen. In this study, human otoconia were obtained from the utricle in five patients undergoing translabyrinthine vestibular schwannoma surgery. Specimens were examined by environmental scanning electron microscopy. Intact and degenerate otoconia as well as fracture particles of otoconia and bone were analyzed by energy dispersive X-ray microanalysis (EDX) and powder X-ray diffraction (XRD). Intact otoconia reveal a uniform size showing characteristic symmetry properties. Degenerative changes can be observed at several stages with gradual minor and major changes in their morphology including fragment formation. EDX analyses reveal the characteristic chemical composition also for otoconia remnants. XRD shows that intact and degenerate otoconia as well as remnants consist of the calcite modification. In conclusion, electron microscopy serves as a standard method for morphological investigations of otoconia. Human utricular otoconia show a uniform outer morphology corresponding to a calcite-based nanocomposite. Morphological changes provide further evidence for degeneration of utricular otoconia in humans, which might be a preconditioning factor causing BPPV. In case of uncertain origin, particles can be clearly assigned to otoconial origin using EDX and XRD analyses.

Ocular vestibular evoked myogenic potential to air conducted sound stimulation and video head impulse test in acute vestibular neuritis.

Background Air-conducted (ACS) cervical VEMP (cVEMP) reflect both saccular and inferior vestibular nerve function. Ocular VEMP (oVEMP) to air and bone-conducted vibration (BCV) are critically discussed, whether they reflect predominantly utricular and superior vestibular nerve function. The video head impulse test (vHIT) accurately detects changes in the high frequency range (5–7 Hz) of the vestibular ocular reflex (VOR) in all 3 planes and can be used to assess semicircular canals (SCC) impairment. Objectives To evaluate oVEMP and cVEMP in response to 500 Hz ACS stimulation and to compare these with vHIT results in acute unilateral vestibular neuritis (VN) to classify the probable involvement of SCC and otolith organs. Materials and Methods Patients with VN were studied. ACS oVEMP and ACS cVEMP (100 dB nHL 500 Hz tone burst stimulation) were recorded. The vHIT for the 3 SCC were performed simultaneously. Results ACS oVEMP and ACS cVEMP in combination with vHIT allows the differentiation of 4 types of VN: entire VN (EVN), superior VN (SVN), inferior VN (IVN), and ampullary VN (AVN). Lesions of EVN, SVN, and IVN may be either complete or partial. Conclusion ACS oVEMP and ACS cVEMP to 500 Hz stimulation together with the vHIT allows a better differentiation of receptor involvement in VN. Results suggest a different origin of AC oVEMP and AC cVEMP to 500 Hz in complete SVN and IVN. Partial SVN and IVN may indicate a role of saccular fibers in oVEMP.

Sonotubometry with perfect sequences: First results in pathological ears

Abstract Conclusion: Sonotubometry with perfect sequences (PSEQ) was able to detect eustachian tube (ET) openings in both normal and pathological ears. Impaired ears showed ET openings in almost all cases; however, these proved to be not only less frequent, but also with lower amplitude and shorter duration. Objectives: To investigate the function of impaired ET under physiological conditions, using a novel kind of sound stimulus for sonotubometry – the PSEQ. Methods: Twenty otologically healthy subjects (40 normal ears) and 32 patients with ear diseases (40 pathological ears) were examined sonotubometrically using noise signals with an ideally flat spectrum (PSEQ). Dry swallowing, water swallowing, and Toynbee maneuver were used to induce ET openings. Analysis was performed regarding the frequency of occurrence, duration, amplitude, and form of the ET openings. Results: PSEQ allowed the detection of an ET opening in all 40 normal ears (91% of the performed maneuvers) and in 87.5% of the ears with impaired ET function (but only 47% of the maneuvers). The average amplitude of the openings in healthy ears was 16.86 dB, the average duration was 363 ms. In diseased ears these values were significantly lower: 9.73 dB, p < 0.001 and 280 ms, p < 0.05.

Schwindel und Stürze im Alter

ZusammenfassungStörungen der Gleichgewichtsfunktion im Alter werden in den kommenden Jahren aufgrund der demographischen Veränderungen in Deutschland zunehmen. Neben einer Verminderung der Lebensqualität der betroffenen Patienten ist das Risiko, Stürze zu erleiden im Alter erhöht. Auf morphologischer Ebene lassen sich altersspezifische Modifikationen der peripheren vestibulären Strukturen, der Somatosensorik und des Visus nachweisen, wie degenerative Veränderungen, eine Reduktion der Zellzahl und der Rezeptoren oder eine Lipofuszinakkumulation. Eine gestörte Gleichgewichtsfunktion im Alter ist ein individuell unterschiedliches, komplexes Geschehen, das sich auf der Basis altersphysiologischer, degenerativer Veränderungen im Bereich der Bestandteile des gleichgewichtserhaltenden sensomotorischen Systems entwickelt und im Zusammenhang mit vestibulären und nichtvestibulären Begleiterkrankungen sowie seelischen Faktoren entstehen kann.AbstractDisorders of the equilibrium function in the elderly will increase in the coming years due to demographic changes in Germany. In addition to a reduction in the quality of life of affected patients, the risk of suffering from a fall increases with age. At the morphological level age-specific changes of the peripheral vestibular structures, somatosensory pathways and vision can be found, such as degenerative alterations, reduced number of cells and receptors and an accumulation of lipofuscin. Disorders of the equilibrium function in old age are individual-specific, complex procedures which develop from age-related physiological, degenerative alterations in the components of the sensomotor system which maintain equilibrium and can come into being together with vestibular and non-vestibular accompanying diseases as well as psychological factors.Disorders of the equilibrium function in the elderly will increase in the coming years due to demographic changes in Germany. In addition to a reduction in the quality of life of affected patients, the risk of suffering from a fall increases with age. At the morphological level age-specific changes of the peripheral vestibular structures, somatosensory pathways and vision can be found, such as degenerative alterations, reduced number of cells and receptors and an accumulation of lipofuscin. Disorders of the equilibrium function in old age are individual-specific, complex procedures which develop from age-related physiological, degenerative alterations in the components of the sensomotor system which maintain equilibrium and can come into being together with vestibular and non-vestibular accompanying diseases as well as psychological factors.

Endoscopic examination of the eustachian tube: a step-by-step approach.

Objective: The aim of this study was to develop a step-by-step approach for endoscopic examinations of the eustachian tube on awake patients and to report anatomic and functional findings. Study Design: Prospective study. Setting: University hospital. Patients: Convenience sample of seven individuals without a history of ear disease. Intervention: Diagnostic transnasal-transpharyngeal videoendoscopy of the eustachian tube with 30- and 70-degree rigid Hopkins rod endoscopes, 2.5- and 0.8-mm, 0-degree flexible fiber endoscopes performed under local anesthesia in 12 eustachian tubes. Main Outcome Measures: Utility of the various endoscopes for the diagnosis in the different parts of the eustachian tube; quality of vision and the patients comfort during the procedure. Results: The 2.5-mm flexible endoscope was most useful for examination of the pharyngeal ostium and the cartilaginous lumen of the tube. The isthmus region could only be passed using an 0.8-mm fiberscope. In all cases, it was possible to insert the endoscope into the middle ear cavity. Eleven of the 12 tube examinations showed normal findings. The mobility of the tubal cartilage could be visualized with sufficient quality. In 50% of all examinations, application of local anesthesia via a tube catheter was necessary to make the procedure tolerable. Conclusion: The presented approach allows an assessment of both anatomic and functional changes to the eustachian tube in awake patients. The assessment of middle ear structures is limited. To ensure a comfortable and safe procedure, the use of topical anesthesia in a supine position and, in certain cases, additional anesthesia via eustachian tube catheter is recommended.

Gentamicin-induced structural damage of human and artificial (biomimetic) otoconia

Abstract Conclusions: Gentamicin causes irreversible structural damage of human and artificial otoconia by progressive dissolution of calcite. The inner architecture of otoconia is strongly affected by degradation scenarios during gentamicin exposure. Artificial otoconia can be used as a model system mimicking the chemical attacks for detailed investigations. Objectives: To investigate the chemical interactions of gentamicin with natural calcite and human and artificial otoconia under in vivo conditions. Methods: Pure calcite crystals and artificial and human otoconia were exposed to gentamicin injection solutions at various concentrations. Morphological changes were observed in time steps by the use of environmental scanning electron microscopy (ESEM). Results: Dissolution of pure calcite crystals results in the formation of well oriented nanoshoots indicating an irreversible chemical reaction with gentamicin. Human and artificial otoconia reveal irreversible structural changes of their surface areas as well as of their inner structure, resulting in characteristic changes at different gentamicin concentrations. Minor changes are first observed by surface alterations and dissolution of calcite in the belly region. Major changes result in further reduction of the belly area reaching the center of symmetry. Finally, a complete dissolution of the branches takes place. Artificial otoconia provide detailed insight into surface alterations.

Principles of Calcite Dissolution in Human and Artificial Otoconia

Human otoconia provide mechanical stimuli to deflect hair cells of the vestibular sensory epithelium for purposes of detecting linear acceleration and head tilts. During lifetime, the volume and number of otoconia are gradually reduced. In a process of degeneration morphological changes occur. Structural changes in human otoconia are assumed to cause vertigo and balance disorders such as benign paroxysmal positional vertigo (BPPV). The aim of this study was to investigate the main principles of morphological changes in human otoconia in dissolution experiments by exposure to hydrochloric acid, EDTA, demineralized water and completely purified water respectively. For comparison reasons artificial (biomimetic) otoconia (calcite gelatin nanocomposits) and natural calcite were used. Morphological changes were detected in time steps by the use of environmental scanning electron microscopy (ESEM). Under in vitro conditions three main dissolution mechanisms were identified as causing characteristic morphological changes of the specimen under consideration: pH drops in the acidic range, complex formation with calcium ions and changes of ion concentrations in the vicinity of otoconia. Shifts in pH cause a more uniform reduction of otoconia size (isotropic dissolution) whereas complexation reactions and changes of the ionic concentrations within the surrounding medium bring about preferred attacks at specific areas (anisotropic dissolution) of human and artificial otoconia. Owing to successive reduction of material, all the dissolution mechanisms finally produce fragments and remnants of otoconia. It can be assumed that the organic component of otoconia is not significantly attacked under the given conditions. Artificial otoconia serve as a suitable model system mimicking chemical attacks on biogenic specimens. The underlying principles of calcite dissolution under in vitro conditions may play a role in otoconia degeneration processes such as BPPV.

The Inner Structure of Human Otoconia

Background The architecture of human otoconia has been only poorly understood up to now. Currently, it is assumed that otoconia contain a central core surrounded by a shell. Objectives To investigate the inner structure of human otoconia. Methods Human otoconia were investigated by environmental scanning electron microscopy (ESEM). The diffraction behavior was analyzed using X-ray techniques (XRD). Focused ion beam (FIB) slices of otoconia were investigated by transmission electron microscopy (TEM). The results were correlated with observations on degenerate human otoconia and decalcification experiments using ethylenediaminetetraacetic acid (EDTA). Artificial otoconia (calcite-gelatine and calcite-gelatine/agarose composites) were investigated in the same way and compared with human otoconia. Results Human otoconia represent highly mosaic-controlled calcite-based nanocomposites. The inner structure is composed of 3 + 3 branches with an ordered arrangement of nanocomposite particles and parallel orientation of fibrils. The surrounding belly is less ordered and appears more porous. Degenerate otoconia show a successive dissolution of the belly region exposing to the inner structure (branches) in later stages of degeneration. Artificial otoconia reveal identical chemical, crystallographic and morphologic patterns. They are, however, larger in size. Conclusion Human otoconia show an inner architecture consisting of a less dense belly region and 3 + 3 more dense branches meeting at a central point (center of symmetry). The differences in volume densities and the resulting solubility may play a role in BPPV. Artificial otoconia may serve as a model for further investigations.

Vertigo and falls in the elderly : part 1: epidemiology, pathophysiology, vestibular diagnostics and risk of falling

ZusammenfassungStörungen der Gleichgewichtsfunktion im Alter werden in den kommenden Jahren aufgrund der demographischen Veränderungen in Deutschland zunehmen. Neben einer Verminderung der Lebensqualität der betroffenen Patienten ist das Risiko, Stürze zu erleiden im Alter erhöht. Auf morphologischer Ebene lassen sich altersspezifische Modifikationen der peripheren vestibulären Strukturen, der Somatosensorik und des Visus nachweisen, wie degenerative Veränderungen, eine Reduktion der Zellzahl und der Rezeptoren oder eine Lipofuszinakkumulation. Eine gestörte Gleichgewichtsfunktion im Alter ist ein individuell unterschiedliches, komplexes Geschehen, das sich auf der Basis altersphysiologischer, degenerativer Veränderungen im Bereich der Bestandteile des gleichgewichtserhaltenden sensomotorischen Systems entwickelt und im Zusammenhang mit vestibulären und nichtvestibulären Begleiterkrankungen sowie seelischen Faktoren entstehen kann.AbstractDisorders of the equilibrium function in the elderly will increase in the coming years due to demographic changes in Germany. In addition to a reduction in the quality of life of affected patients, the risk of suffering from a fall increases with age. At the morphological level age-specific changes of the peripheral vestibular structures, somatosensory pathways and vision can be found, such as degenerative alterations, reduced number of cells and receptors and an accumulation of lipofuscin. Disorders of the equilibrium function in old age are individual-specific, complex procedures which develop from age-related physiological, degenerative alterations in the components of the sensomotor system which maintain equilibrium and can come into being together with vestibular and non-vestibular accompanying diseases as well as psychological factors.Disorders of the equilibrium function in the elderly will increase in the coming years due to demographic changes in Germany. In addition to a reduction in the quality of life of affected patients, the risk of suffering from a fall increases with age. At the morphological level age-specific changes of the peripheral vestibular structures, somatosensory pathways and vision can be found, such as degenerative alterations, reduced number of cells and receptors and an accumulation of lipofuscin. Disorders of the equilibrium function in old age are individual-specific, complex procedures which develop from age-related physiological, degenerative alterations in the components of the sensomotor system which maintain equilibrium and can come into being together with vestibular and non-vestibular accompanying diseases as well as psychological factors.