Papers by Stefan C A Hegemann
Sensing gravity through the otolith receptors is crucial for bipedal stability and gait. The over... more Sensing gravity through the otolith receptors is crucial for bipedal stability and gait. The overall contribution of the otolith organs to eye movements, postural control, and perceptual functions is the basis for clinical testing of otolith function. With such a wide range of contributions, it is important to recognize that the functional outcomes of these tests may vary depending on the specific method employed to stimulate the hair cells. In this article, we review common methods used for clinical evaluation of otolith function and discuss how different aspects of physiology may affect the functional measurements in these tests. We compare the properties and performance of various clinical tests with an emphasis on the newly developed video ocular counter roll (vOCR), measurement of ocular torsion on fundus photography, and subjective visual vertical or horizontal (SVV/SVH) testing.
PubMed, Apr 1, 1994
At routinely performed autopsies as described by Hamperl in 1956, ENT-specific regions such as th... more At routinely performed autopsies as described by Hamperl in 1956, ENT-specific regions such as the naso- and mesopharynx usually remain untouched. However, in cases with pathological changes in these regions a topographical preparation is necessary. Moreover, there is great interest among ENT-surgeons for studying the pathology of this area and to practice endoscopic and microscopic operation techniques. In close cooperation with the pathologists at RWTH clinic, we re-examined and refined further an ENT-specific dissection technique that was first described by Gräff in 1932. It allows a complete en bloc resection of all ENT-relevant organs without disfiguring the body. It also provides an optimal anatomical overview and gives insight into interrelations of morphological findings (thus improving post-mortem diagnosis), as well as allows the possibility for practicing operative techniques apart from the corpse.
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Jul 9, 2013
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Mar 6, 2008
Frontiers in Neurology, Mar 10, 2023
The symptoms and severity of SARS-CoV-infection vary greatly across the spectrum, from asymptomat... more The symptoms and severity of SARS-CoV-infection vary greatly across the spectrum, from asymptomatic infection to severe pneumonia with acute respiratory distress syndrome and even death. Dizziness is a frequently reported symptom of SARS-CoV-viral infection. However, the extent to which this symptom results from the e ect of SARS-CoV-on the vestibular system remains unclear. In the present single-center, prospective cohort study, patients with a previous SARS-CoV-infection underwent a vestibular assessment consisting of the Dizziness Handicap Inventory to assess dizziness during and after infection, a clinical examination, the video head impulse test, and the subjective visual vertical test. When the subjective visual vertical test result was abnormal, vestibular-evoked myogenic potentials were performed. Vestibular testing results were compared to pre-existing normative data of healthy controls. In addition, we performed a retrospective data analysis of patients admitted to hospital presenting with acute symptoms of dizziness who were also diagnosed with acute SARS-CoV-infection. Results: A total of participants have been enrolled. During and after the SARS-CoV-infection, women were significantly more likely than men to su er from dizziness. A significantly reduced semicircular canal or otolith function was not observed in either women or men. Acute SARS-CoV-infection was diagnosed in nine patients who presented to the emergency room with acute vestibular syndrome. Six of the patients exhibited acute unilateral peripheral vestibulopathy upon diagnosis. A di erent patient was diagnosed with vestibular migraine, and two individuals had a posterior inferior cerebellar artery infarct revealed by magnetic resonance imaging. Discussion/conclusion: Overall, a persisting structural a ection of the vestibular system by SARS-CoV-seems to be unlikely and could not be confirmed by vHIT, SVV, and VEMPS in our study. It seems possible but unlikely that SARS-CoVinduces acute vestibulopathy. Nevertheless, dizziness is a common symptom in patients with COVID-, which should be taken and worked through seriously.
Klinische Monatsblatter Fur Augenheilkunde, Oct 1, 2001
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Mar 10, 2008
Journal of vestibular research, Jul 28, 2021
This paper provides a new hypothetical explanation for the etiopathology and pathophysiology of M... more This paper provides a new hypothetical explanation for the etiopathology and pathophysiology of Menière’s Disease (MD), which to date remain unexplained, or incompletely understood. The suggested hypothesis will explain the close connection of MD and Migraine, the coexistence of endolymphatic hydrops (ELH) and Menière attacks and the signs of inflammation detected in the inner ears of MD patients. Although as yet unproven, the explanations provided appear highly plausible and could pave the way for the generation of the first animal model of MD – an invaluable asset for developing new treatment strategies. Furthermore, if proven correct, this hypothesis could redefine and also reset the actual name of Menière’s Syndrome to Menière’s Disease.
Journal of Vestibular Research, 2016
BACKGROUND: Both the dynamic visual acuity (DVA) test and the video head-impulse test (vHIT) are ... more BACKGROUND: Both the dynamic visual acuity (DVA) test and the video head-impulse test (vHIT) are fast and simple ways to assess peripheral vestibulopathy. After losing peripheral vestibular function, some patients show better DVA performance than others, suggesting good compensatory mechanisms. It seems possible that compensatory covert saccades could be responsible for improved DVA. OBJECTIVE: To investigate VOR gain and compensatory saccades with vHIT and compare them to the DVA of patients with unilateral peripheral vestibulopathy. METHODS: VOR gain deficit and compensatory saccades were measured with vHIT. VOR gain was calculated for each trial as mean eye velocity divided by mean head velocity during 4 samples between 24 ms -40 ms after peak head acceleration. DVA was then assessed. VHIT was analyzed for percentage of covert saccades and for cumulative overt saccade amplitude. Twenty-four patients with unilateral vestibular deficit were included. A control group of 113 healthy subjects provided normal data. RESULTS: On the affected side, pathologic values for DVA (mean 0.83 logMAR ± 0.25 SD) and VOR gain (mean 0.16 ± 0.13) were obtained, whereas the healthy side showed normal values (0.53 logMAR ± 0.15 for DVA and 0.89 ± 0.18 for VOR gain). Yet, DVA performance on the affected side was significantly better in patients with higher covert saccade percentage (p = 0.012) and lower cumulative overt saccade amplitude (p < 0.001). CONCLUSION: Compensatory covert saccades seen in vHIT correlate with improved performance of DVA-testing in patients with unilateral peripheral vestibular loss. Hence, in addition to testing peripheral vestibulopathy, our results indicate a way for assessing rehabilitatory compensation in such patients by DVA in addition to vHIT.
HNO, 2013
Obwohl Störungen des Sehens als Sinneswahrnehmung eine zentrale Rolle beim Schwindel spielen, kom... more Obwohl Störungen des Sehens als Sinneswahrnehmung eine zentrale Rolle beim Schwindel spielen, kommt der Augenheilkunde, die Neuroophthalmologie einmal ausgeklammert, eine periphere Position bei der interdisziplinären Schwindelabklärung und -grundlagenforschung zu. Dies mag sich aber ändern, denn in einigen Bereichen, etwa beim altersbezogenen Schwindel (Presbyvertigo), wird der Einfluss peripher-ophthalmologischer Veränderungen postuliert. Ihre Behandlung könnte ein Element der Prophylaxe und Therapie sein.
Annals of Neurology, 1998
We report seven unrelated families with mitochondrial tRNAser(UCN) gene mutations at three differ... more We report seven unrelated families with mitochondrial tRNAser(UCN) gene mutations at three different loci. A novel G7497A mutation is found in two families, both of which present with progressive myopathy, ragged-red fibers, lactic acidosis, and deficiency of respiratory chain complexes I and IV. This mutation presumably affects the tertiary tRNASer(UCN) dihydrouridine interaction. Mutations 7472 insC and T75 12C, found in three and two families, respectively, are associated with myoclonus epilepsy, deafness, ataxia, cognitive impairment, and complex IV deficiency. No ragged-red fibers or ultrastructural abnormalities are seen. It is interesting that 6 of our 7 index patients are apparently homoplasmic, indicating a minor pathogenetic power of the tRNAser(UCN) mutations.
Medical Hypotheses, Jul 1, 2019
Lack of otoconia or otoconial loss may be the major reason for increasing imbalance with age, pos... more Lack of otoconia or otoconial loss may be the major reason for increasing imbalance with age, posttraumatic dizziness and residual dizziness as well as other so far unexplained imbalance affecting probably millions of people. Background: It is written in every textbook that we need sensation of gravity for stable gait and stance, especially on two legs. Lack of otoconia is known to cause lifelong balance problems in animals. Loss of otoconia is happening in aging humans, like shown by increasing incidence of benign paroxysmal positional vertigo (BPPV) and in histological sections. While hundreds of papers have been published on BPPV, increasing imbalance with age and increasing falls, none has ever described the loss of otoconia as a major reason for this imbalance. Maybe this is due to the problems to proof this hypothesis in an individual patient. We will explain why otoconial loss may cause dizziness, postural and locomotor instability in patients with no other identifiable cause or in addition to other causes. Several reasons can cause otoconial loss and lead to the described symptoms. We will describe the symptoms and the tests which could in combination support the diagnosis. Conclusion: Our hypothesis argues for the new diagnosis in many patients with so far undiagnosed or incorrectly or incompletely diagnosed dizziness or imbalance. Introduction/background Otoconial loss and BPPV Loss of otoconia from the utricle often leads to BPPV. We know, that the prevalence of BPPV increases continuously from a 1-year prevalence of 0.5% in the 18-39 year age group up to 3.4% in those aged 60 and older, reaching a cumulative lifetime incidence of 10% by the age of 80 [1]. The most common form of vertigo is idiopathic BPPV BPPV can also be caused by head trauma [2]. Patients often experience lightheadedness, dizziness, or short-lasting unsteadiness following successful repositioning maneuvers for BPPV, which is called residual dizziness (RD) [3]. RD occurs with an incidence of 31-61% and more often with increasing age above 65 years [4]. Several reasons for RD are debated, such as anxiety or loss of utricular function. The latter means, in general, a loss of utricular haircell function, rather than isolated otoconial degeneration, although von Brevern et al [5] suggested macular degeneration as consequence of a utricular lesion. One possible, so far overlooked, reason for RD may be isolated otoconial loss in the absence of haircell loss or damage, particularly for long lasting RD. The duration of RD is often estimated in weeks, but much longer imbalance is also reported [6,7]. The short lasting RD directly after successful repositioning maneuvers could also be explained by otoconia falling back on the utricle thus changing the sensation of gravity, i.e. our sensation of gravity could change with the changing weight of the otoconial membrane. Whether increasing or decreasing macular weights have different effects is still unknown. Other causes of imbalance Causes of postural and locomotor instability or dizziness other than RD are commonly thought to be nonspecific and multi-factorial; among
European Archives of Oto-Rhino-Laryngology, 2020
European Archives of Oto-Rhino-Laryngology, 2020
Benign paroxysmal positional vertigo (BPPV) is the most common type of vertigo, caused by otoconi... more Benign paroxysmal positional vertigo (BPPV) is the most common type of vertigo, caused by otoconia falling from the utricle into a semicircular canal (SCC). After successful repositioning maneuvers residual dizziness (RD) has been described and several reasons are used to explain RD. It can last for only a few days or weeks, but also much longer. We present a patient with a severe traumatic loss of otoconia from both maculae utriculi and a persistent imbalance more than 9 years. We think that the loss of otoconia from the utricular and probably also saccular macula induced a sudden reduction of her ability to sense gravity thus logically explaining her symptoms. We show the vestibular test results also supporting our hypothesis and we extrapolate this support to other forms of so far unexplained dizziness especially increasing imbalance with aging. We also discuss the normal c-and oVEMP indicating intact haircell function and supporting our hypothesis of isolated otoconial loss as the major cause for imbalance.
Head impulse testing (HIT) has become an internationally accepted and very helpful clinical tool ... more Head impulse testing (HIT) has become an internationally accepted and very helpful clinical tool for fast and easy diagnostic testing of the vestibulo-ocular reflex (VOR). However, there is still a problem concerning apparative testing and documentation of objective parameters in clinical practice. [for full text, please go to the a.m. URL]
Noise & Health, 2021
Objective: We made hypotheses that tinnitus will appear more likely in patients with sudden deafn... more Objective: We made hypotheses that tinnitus will appear more likely in patients with sudden deafness with superior hearing in unaffected ear or with more severe acute hearing loss. Methods: A retrospective cohort study was performed. Five hundred forty-one patients were identified with idiopathic sudden sensorineural hearing loss (ISSHL) from January 1995 to August 2006. The exclusion criteria for this study were as follows: bilateral sudden hearing loss and Meniere disease, previous tinnitus or bilateral tinnitus at initial evaluation, and onset of hearing loss less than 7 days. The cohort enrolled 454 patients. The enrolled patients were classified into two groups: patient with acute onset tinnitus in the affected ear and patients without tinnitus at initial visit. Main outcome measures were patient age, the presence or absence of vertigo and tinnitus, audiometric patterns, the severity of hearing loss, and hearing in the unaffected ear. Results: Better contralateral hearing (n = ...
Introduction: Aim of the study was to improve the dynamic visual acuity (DVA) test, which is used... more Introduction: Aim of the study was to improve the dynamic visual acuity (DVA) test, which is used for a simple assessment of the peripheral vestibular function. Methods: A new DVA-test was designed and standardised by examining 100 otologically healthy subjects. By comparison, 43 patients with peripheral vestibular deficit were studied. All healthy subjects and patients underwent quantitative head impulse testing with scleral search coils as a reference. DVA was determined by horizontal head rotations >150°/s and >100°/s, during which a Landolt ring was presented for 100 ms. Head rotations were performed actively by the patient and passively by the examiner. Results: In consideration of the age dependency of DVA and optimal test parameters (passive head-thrusts >150°/s), sensitivity and specificity were higher than 90%. The number of head-thrusts was limited on an average number of 40. Discussion: The DVA-test enables the diagnosis of a peripheral vestibulopathy in a simple...
Der Kopfimpulstest (KIT, englisch head impulse testing oder HIT) ist ein Verfahren, mit welchem e... more Der Kopfimpulstest (KIT, englisch head impulse testing oder HIT) ist ein Verfahren, mit welchem ein Hauptteil der Gleichgewichtsrezeptoren, namlich die Funktion jedes einzelnen Bogenganges, nahezu isoliert untersucht werden kann. Er wurde erstmals vor uber 20 Jahren beschrieben [Halmagyi and Curthoys] und hat sich seither als enorm hilfreicher Test in der Vestibularisforschung und im klinischen Alltag weltweit durchgesetzt. Bis dahin waren die einzigen Verfahren zur Messung der Gleichgewichtsfunktion die kalorische vestibulare Testung (vereinfachend Kalorik genannt) und die Drehstuhluntersuchungen. Beide Verfahren haben deutliche Nachteile gegenuber dem KIT. Beide messen nur die Funktion der horizontalen Bogengange (sofern der Drehstuhl nicht dreiachsig ist). Die Kalorik liefert eher unprazise Messwerte und ist nur mit technischen Hilfsmitteln durchfuhrbar. Auserdem misst die Kalorik ausschlieslich im sehr niedrigen Frequenzbereich, der fur die Blickstabilisierung eine sehr untergeo...
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Papers by Stefan C A Hegemann