[A new positioning maneuver for treating a subtype of postural unsteadiness - based on a modified model of the utricular macula]. / Ein neues Lagerungsmanöver zur Behandlung einer Form von Schwankschwindel auf der Basis eines modifizierten Modells der Macula utriculi

Objectives: A new method for the treatment of a subtype of postural unsteadiness frequently seen in the medical office is proposed. Ten years of successful practical application and continuous refining of this new treatment lead to the definition of symptom-criteria, which are useful to distinguish patients, who get benefit by this new procedure and to a modified model of the utricular macula. Materials and Methods: In a retrospective collection, the data of 15 patients with postural unsteadiness (mean duration of symptoms 61.7 months) successfully treated with the new maneuver are reported. Before treatment, all patients showed normal results in testing the caloric responses of the labyrinth, normal neurological investigation and no signs for cervical vertigo. Before and after treatment the DHI-score (Dizziness Handicap Index) was achieved by using the German version of the DHI-questionnaire. In all groups before and after treatment balance testing was performed using a posturography platform. Results: Application of the new treatment lead to a significant improvement of the DHI-scores and of the posturographic results (significant reduction of body sway). Discussion: The patients, who were successfully treated by the new maneuver have had presented the same symptoms like patients with a proven utricular dysfunction. This leads to a slightly modified model of the utricular macula. Beyond correctly positioned otoconia in the utricular macula and free otoconia in the endolymphatic utricular space, a third fraction of dysfunctional partially detached otoconia is postulated (causing the unsteadiness). Based on this theory, the single hair-cell with its accompanied otoconium might be the smallest receptor-unit of the macula-organ. This smallest receptor-unit might represent a biological mass-spring-system. According to technical mass-spring-systems used as accelerometers, the different sizes of the otoconia for a distinct direction of acceleration are necessary for covering different frequency-bands. Finally, a many years successfully tested modified variation of the new maneuver for treatment in the medical office and for self-treatment is proposed.

Superior canal dehiscence reveals concomitant unilateral utricular loss (UUL).

CONCLUSION: We report enhanced symmetrical cervical vestibular evoked myogenic potential (cVEMP) but asymmetrical ocular VEMP (oVEMP) responses in a patient with CT-verified bilateral superior semicircular canal dehiscence (SCD) but with acute vestibular syndrome. This implies that absence of unilateral utricular macula function alone is sufficient to cause symptoms of acute vertigo. Acute vertigo should not automatically be presumed to originate from semicircular canal dysfunction. OBJECTIVES: To identify the cause of an acute vertigo attack in a patient with bilateral SCD. METHODS: The functional state of all peripheral vestibular sense organs was tested using the video head impulse test (vHIT) for all semicircular canals and VEMPs to air-conducted sound (ACS) or bone-conducted vibration (BCV) to test all otolith organs. The cVEMP tested mainly saccular function and the oVEMP mainly utricular function. RESULTS: All semicircular canals showed normal function. The cVEMPs showed enhanced, but symmetrical saccular function. In contrast, oVEMPs showed an enhanced but asymmetric n10 component - it was greatly reduced beneath the left eye, implying decreased function in the right utricular macula. That result was confirmed using very high frequency stimuli which are effective in SCD: 4000 Hz BCV stimuli showed that oVEMP n10 was present beneath the right eye but absent beneath the left eye.

[Isolated functional loss of the lateral semicircular canal in vestibular neuritis]. / Isolierte Rezeptorfunktionsstörung des horizontalen Bogengangs.

Today, modern tools in vestibular testing are feasible to provide information about functional status of all five peripheral vestibular receptors. Isolated or combined loss of crista and macula receptor function can be determined in the diagnostic process. We describe a seldom case of isolated functional loss of lateral semicircular canal receptor function in a 55-year-old patient. Whereas there was no ispilateral caloric response and video head impulse test revealed a catch-up saccade, air-conducted (AC) cervical and ocular vestibular-evoked myogenic potentials (cVEMP, oVEMP), subjective visual vertical and MRI were normal.

Model experiments of otoconia stability after canalith repositioning procedure of BPPV.

CONCLUSION: Postural restrictions are probably not necessary after the canalith repositioning procedure (CRP). OBJECTIVES: Epley reported the effect of CRP for benign paroxysmal positional vertigo (BPPV). After CRP, patients are often requested to restrict postural change. However, some studies suggested that CRP may work without postural restrictions. The present study aimed to determine the necessity of post-maneuver postural restriction using the frog labyrinth model. METHODS: The otoconial mass from the sacculus was placed on the utricular macular otoconia, mimicking a condition after CRP. The stability of the otoconial mass was observed by tilting the preparation, immediately, 3 min, and 5 min after it was placed on the macular otoconia. The utricular macula was maintained in the vertical plane for 10 s, during which period the behavior of the otoconial mass was observed. In experiment 1 the utricular macula was intact, in experiment 2 otoconia were partially removed, and in experiment 3 they were totally removed from the macula. RESULTS: In experiments 1 and 2, in all preparations the otoconial mass became stabilized after 3 min. Even in experiment 3, in most preparations the otoconial mass became stabilized after 5 min.

[Testing of the macula induced vestibuloocular reflex--possibilities and problems in the clinical routine]. / Untersuchung makulainduzierter vestibulookulärer Reflexe--Möglichkeiten und Probleme in der klinischen Routineanwendung.

INTRODUCTION: During the last years, an increasing number of papers is presented dealing with diseases and diagnostic procedures of the macula function. On the other hand, there are just a few distinct test setups for this purpose. In clinical routine, this kind of test system has to be efficient and effective to diagnostic and therapeutic findings. METHODS: The presented test setup includes examination of the semicircular canals by means of harmonic acceleration pendular rotation test and the bilateral, bithermal test as well as otolith function tests i. e. off vertical axis rotation (OVAR) and eccentric rotation. From March 1999 to May 2000 522 patients with dizziness were examined. RESULTS: Otolith tests results could be assessed in a range between 87 % to 95 % of the cases. The quality failure rate was significantly higher than in findings of semicircular canals examination procedures. The major caused technical problem were artifacts. Looking for the diagnostic relevance of the method, 37 % of the patients. Suffering from dizziness and who have normal findings in cupula VOR testing procedures revealed isolated macular dysfunctions. DISCUSSION: The relevance for diagnostic is demonstrated. Otolith function tests can be applied in clinical routine and give relevant information for diagnosis and treatment. Macula test procedures are still sophisticated. Technical development of VOG-recording is necessary for their general application in otology.

Hyper-vision in a patient with central and paracentral vision loss reflects cortical reorganization.

SM, a 21-year-old female, presents an extensive central scotoma (30 deg) with dense absolute scotoma (visual acuity = 10/100) in the macular area (10 deg) due to Stargardt's disease. We provide behavioral evidence of cortical plastic reorganization since the patient could perform several visual tasks with her poor-vision eyes better than controls, although high spatial frequency sensitivity and visual acuity are severely impaired. Between 2.5-deg and 12-deg eccentricities, SM presented (1) normal acuity for crowded letters, provided stimulus size is above acuity thresholds for single letters; (2) a two-fold sensitivity increase (d-prime) with respect to controls in a simple search task; and (3) largely above-threshold performance in a lexical decision task carried out randomly by controls. SM's hyper-vision may reflect a long-term sensory gain specific for unimpaired low spatial-frequency mechanisms, which may result from modifications in response properties due to practice-dependent changes in excitatory/inhibitory intracortical connections.

Intractable benign paroxysmal positional vertigo in patients with Meniere's disease.

OBJECTIVE: To provide a detailed description of the coexistence of benign paroxysmal positional vertigo (BPPV) and Meniere's disease in individuals and to offer a possible mechanism that explains the findings in these patients. STUDY DESIGN: Retrospective. METHODS: Chart review. RESULTS: Of 162 patients diagnosed with Meniere's disease between January 1998 and January 1999, 9 were found to have both "definite" Meniere's disease and "certain" BPPV. Meniere's symptoms preceded the onset of BPPV in all of our patients. Seven of the 9 patients were female. Except for one patient who experienced BPPV bilaterally, BPPV was limited to the same ear as the Meniere's disease. All patients presented with intractable BPPV that did not respond completely to otolith repositioning procedures. A detailed description of five patients is presented. CONCLUSION: Our data, in conjunction with that of others, suggest that Meniere's disease may predispose patients to intractable BPPV. Hydropically induced damage to the maculae of the utricle and saccule or partial obstruction of the membranous labyrinth may be possible mechanisms that explain the coexistence of Meniere's disease and BPPV.

Study of the gerbil utricular macula following treatment with gentamicin, by use of bromodeoxyuridine and calmodulin immunohistochemical labelling.

Effects of ototoxic drugs on the gerbil vestibular sensory epithelium were probed by use of immunocytochemical labelling with antibodies to both a mitogenic marker (bromodeoxyuridine) and a hair cell specific protein (calmodulin). Nine animals had gentamicin administered once daily for 5 days, as a transtympanic injection into the right middle ear. They additionally were given a daily intraperitoneal injection of bromodeoxyuridine, starting on the same day as the gentamicin injection and continuing until the day of sacrifice. Nine other animals, serving as controls for bromodeoxyuridine incorporation, received only the intraperitoneal injections of bromodeoxyuridine. The inner ears from three gerbils were obtained at 1, 2 or 4 weeks following the last gentamicin injection and utricles from the injected ears were processed for immunohistochemical analysis. In specimens where gentamicin was administered, we found evidence of bromodeoxyuridine incorporation in 17 cells (10 single cells and 7 pairs of cells) in a total of 216 sections taken from the central regions of the 9 utricles. However, in control specimens, no bromodeoxyuridine labelling was found in any cells of the 216 sections examined. Of 10 single cells labelled with bromodeoxyuridine, two cells in the hair cell layer were labelled with antibodies against calmodulin. One had a faint labelling in the nucleus and the other in the stereocilia, but not in the cell bodies. Of 7 pairs of cells, two pairs with nuclei localized in the hair cell layer had faint labelling for calmodulin in the nuclei, but no labelling in any other part of the cell. The other 13 cells labelled with antibodies to bromodeoxyuridine were not labelled with antibodies to calmodulin. Our results suggest that the bromodeoxyuridine-labelled cells could not be positively identified as hair cells based on immunohistochemical labelling for calmodulin.

Effect of macular ablation on frequency and latency of motion-induced emesis in the squirrel monkey.

Three previously motion-emetic sensitive squirrel monkeys were rendered refractory to a standard motion-emetic regimen by a two-stage utriculosacculectomy procedure which preserved the cristae ampullares of semicircular canals. Three non-operated control squirrel monkeys tested on the same motion-emetic regimen time schedule as the operated animals remained motion-emetic sensitive with regard to incidence, frequency, and latency of motion-induced emetic responses. Following a sham surgical procedure (stapedectomy) performed on two of the latter animals and one additional new animal, the emetic incidence decreased from 100% to 89%, but the frequency and latency were not altered significantly.

Observations on the Tullio phenomenon.

Vestibular responses (vertigo, nystagmus-like eye movements) to acoustic stimuli are known as the "Tullio phenomenon". Detailed electro-oculographic analysis of this reaction, as observed in a 30-year-old patient, revealed the following: a maximum amplitude of eye movement (mainly vertical) was achieved by sine wave bursts of high intensity, a frequency of 500 to 1000 Hz and a duration of 100 ms. The ocular deviation was composed of a fast initial component, followed by a slower resetting movement that was often divided into two parts of different velocities. At longer stimulus durations (more than 100 ms) the electro-oculogram showed a fractionation of the eye deviation, terminating in an "off-response". Various positions of the patient's head influenced the direction of the eye motion. The possibility that the Tullio phenomenon may be due to an abnormal excitation of the statolith organs is discussed.