Uwe Schönfeld

Treatment of Ménière's Disease by Low-Dosage Intratympanic Gentamicin Application : Effect on Otolith Function

Objectives: The intratympanic application of a low dosage of gentamicin is increasingly favored as treatment for Ménières disease. While posttreatment observations have confirmed a long‐term success of the therapy of vertigo attacks, clear differences in the posttreatment recovery interval can be observed. In addition to differences in central‐vestibular compensation, the degree of peripheral vestibular damage, i.e., to the saccule, utricle, and semicircular canal ampullae, varies among patients. This study provides comprehensive pre‐ and posttreatment results from unilateral functional tests of the individual vestibular receptors and of the cochlea in patients with Ménières disease.

Measuring unilateral otolith function via the otolith-ocular response and the subjective visual vertical.

In the present study, attention is directed to the unilateral response of the otolith system to static and dynamic tilt, as reflected by subjective estimation of the visual vertical (oculogravic perception). Measurements were performed with a variable radius rotary chair, which permits controlled modulation of the centripetal, or radial, acceleration. By limiting the radius, i.e. eccentric displacement of the head by 3.5 cm during constant-velocity rotation about the earth-vertical axis, adequate unilateral stimulation of the otolith organ - predominantly the utricle - is generated, without involving the semicircular canals. This paradigm has been employed to measure the unilateral utriculo-ocular response. In contrast to the otolith-ocular response (OOR), the subjective visual vertical (SVV) reflects the processing of otolithic information in the higher brain centres (thalamus, vestibular cortex). Exploitation of these two complementary approaches provides useful information for both experimental and clinical scientists. The findings also reveal that centripetal acceleratory stimulation during constant angular velocity with the subject centred on axis is sufficient to localize peripheral otolith dysfunction by means of SVV estimation. This represents a novel test of otolith function that can be easily integrated into routine clinical testing.In the present study, attention is directed to the unilateral response of the otolith system to static and dynamic tilt, as reflected by subjective estimation of the visual vertical (oculogravic perception). Measurements were performed with a variable radius rotary chair, which permits controlled modulation of the centripetal, or radial, acceleration. By limiting the radius, i.e. eccentric displacement of the head by 3.5 cm during constant-velocity rotation about the earth-vertical axis, adequate unilateral stimulation of the otolith organ--predominantly the utricle--is generated, without involving the semicircular canals. This paradigm has been employed to measure the unilateral utriculo-ocular response. In contrast to the otolith-ocular response (OOR), the subjective visual vertical (SVV) reflects the processing of otolithic information in the higher brain centres (thalamus, vestibular cortex). Exploitation of these two complementary approaches provides useful information for both experimental and clinical scientists. The findings also reveal that centripetal acceleratory stimulation during constant angular velocity with the subject centred on axis is sufficient to localize peripheral otolith dysfunction by means of SVV estimation. This represents a novel test of otolith function that can be easily integrated into routine clinical testing.

Evidence of unilateral isolated utricular hypofunction

Abstract Conclusions: The findings demonstrate that an enduring unilateral utricular dysfunction, possibly together with canal hypofunction, can occur after labyrinthine disease or injury. They also suggest that unilateral, isolated utricular dysfunction – or utricle paresis – can occur, representing a novel entity in the differential diagnosis of peripheral vestibular function. The occurrence of subjective visual vertical (SVV) asymmetry in the presence of symmetric vestibular evoked myogenic potentials (VEMPs) also confirms that the information from the utricles, rather than the saccules, dominates SVV estimation. Objectives: To determine the incidence of unilateral utricular hypofunction. Methods: The retrospective clinical study deals with a selection of those vestibular patients who showed pathological responses to utricle testing. Peripheral vestibular function was examined in a group of 110 patients. Utricular function was evaluated by estimation of SVV during unilateral centrifugation. Bithermal caloric testing was performed to assess unilateral semicircular canal function. Saccular function was tested by measurement of VEMPs. Results: A total of 46 patients were found with asymmetric SVV findings (p < 0.001 for healthy versus lesioned ear), but symmetric caloric responses and VEMPs. Statistical testing also verified that their SVV asymmetry factors were significantly higher than those calculated for caloric responses and VEMPs (p < 0.001).

Testing utricular function by means of on-axis rotation

Conclusions. Subjective visual vertical (SVV) estimation during on-axis rotation provides an efficient screening test of utricle function. The survey demonstrates that isolated disorders of peripheral utricular function can occur while SCC function appears normal. Objective. The present study aimed to investigate estimation of SVV during constant velocity yaw rotation (with the head held on-axis – to enhance any asymmetry between right and left utricular responses), as a useful screening test. Materials and methods. In all, 230 patients were recruited from the dizziness clinic. For each patient, the SVV was estimated (a) while held stationary, and (b) during constant angular velocity (240°/s), with the head centred on-axis. Bithermal caloric testing was also performed in 201 of the patients. Results. Of those patients with normal SVV results during stationary testing, 18.3% were pathological during rotation testing. In those cases with pathological SVV during stationary testing, a significantly greater deviation from the norm was observed during rotation (p<0.001). Of those patients with normal caloric responses, 44.4% showed pathological SVV estimates; this increased to 54.3% for cases with unilateral weakness, and 56.5% for unilateral loss. No clear correlation was found between reports of tilt illusion and pathological SVV, respectively, between rotatory vertigo and pathological caloric responses.

A clinical study of the subjective visual vertical during unilateral centrifugation and static tilt.

Abstract Conclusion: The present study demonstrates that various response patterns of subjective visual vertical (SVV) can be identified during unilateral centrifugation (UC). It is proposed that these response types correspond to different degrees of compensation after disease. This is advantageous for monitoring the effect of rehabilitative measures and is useful in medico-legal issues. It also emerges that diagnosis of unilateral utricle function requires the determination not only of asymmetry ratio but also offset of SVV estimates. Objectives: A retrospective clinical study of SVV test results was performed to establish a classification and model of response types in patients with suspected otolith disorder. Methods: SVV measurements were made in 473 patients recruited from the dizziness clinic. A control group of healthy subjects (n = 43) was tested with the same protocol. Testing with bilateral stimulation (stationary upright, 15°, 30° tilt) and UC was performed. A mathematical model for the UC results was developed. Results: During UC testing 61% of the patients showed an asymmetric response indicating a unilateral utricular hypofunction/dysfunction. These results could be classified into three subgroups, indicating different degrees of compensation. The model parameters can be adapted to reflect this classification.

CO2 laser revision stapedotomy

To evaluate the safety and efficacy of the one‐shot noncontact technique in stapedotomy for revision stapes surgery with a CO2 laser combined with a scanning system.

Active middle ear implant coupled bilaterally to the round window despite bilateral implanted stapes prostheses.

After stapes surgery, patients with mixed or moderate hearing loss have limited possibilities for hearing improvement. We are reporting on a patient who underwent stapedotomy bilaterally 20 years ago and had sensorineural and mixed hearing loss. Recurrent otitis externa prevented the use of hearing aids. This patient was treated bilaterally with the Vibrant Soundbridge (Med‐El, Innsbruck, Austria) successively. The Schuknecht piston stapes prostheses remained in situ. The Floating Mass Transducer (FMT; Med‐El) was coupled to the round window (RW) and provided good acoustic reinforcement bilaterally. In conclusion, for patients with otosclerosis and stapes surgery, the FMT–RW coupling (Bess AG, Berlin, DE) is a safe procedure with good acoustic amplification. Laryngoscope, 2016 127:500–503, 2017

Listing's plane and the 3D-VOR in microgravity - The role of the otolith afferences

The study addresses the question as to what extent the otolith-mediated gravity vector maintains the stability of the coordinate frames of the vestibulo-ocular reflex and the oculomotor system, described by Listings Plane. Under normal 1 G conditions it has been demonstrated in the monkey that Listings Plane (LP) and the 3D vestibulo-ocular response (3D-VOR) are close to collinear [10]. In the present study the coordinate frames of the oculomotor system and the three-dimensional vestibulo-ocular reflex (3D-VOR) system were measured under one-g gravity conditions and during a period of prolonged microgravity, on-board the International Space Station (ISS). To this end, the coordinate frame of the oculomotor system is described in Listings coordinates and that of the 3D-VOR system by the minimal gain vector. The findings demonstrate that under Earthbound, one-g conditions the two coordinate frames diverge by approximately 20° in the human. In the absence of the gravity vector the radical loss in the otolith-mediated contribution to the dynamic VOR leads to a reduction of the torsional VOR component and in turn to a forward tilt of the oculomotor coordinate frame, described by the minimal gain vector. In contrast, the torsional component of LP during horizontal and vertical saccades was found to increase, resulting in a backward tilt of LP. Together with the backward tilt of LP a small but consistent change in LP vergence was observed. The thickness of LP did not appear to change in the absence of gravity. The changes in coordinate frame orientation persisted over the six-month periods spent in zero gravity. The postflight measurements demonstrate that re-adaptation to preflight values proceeds over several days to weeks. The findings demonstrate that the gravity vector represents a common reference for vestibular and oculomotor responses. They also support the idea that the gravity vector provides a central reference for the entire sensorimotor complex.

Zur Validität von Screeninguntersuchungen

Eine vollstandige klinische Diagnostik aller Sinnesrezeptoren des peripheren Vestibular-systems ist heute durch neuere Forschungsergebnisse moglich geworden (vgl. Kapitel: 1). Zur unilateralen Funktionsprufung der Bogengange sind die Messungen der kalorischen Reizantwort und der Head-Thrust-Test (Halmagy und Curthoys 1988) etabliert. Die Ableitung der vestibular evozierten myogenen Potentiale (VEMP) stellt eine ebenfalls bereits weit verbreitete unilaterale Untersuchungsmoglichkeit der Sakkulusfunktion dar (z. B. Colebatch et al. 1994; de Waele et al. 2001; Welgampola und Colebatch 2005; Basta et al. 2006).