Vertical saccades during horizontal head impulses: a sign of posterior semicircular canal hypofunction.

Objective: We describe an uncharacteristic vestibular-ocular reflex (VOR) pattern, studied by video head impulse tests (VHIT) in patients suffering from unilateral isolated posterior semicircular canal (PSC) hypofunction. In these patients, we found an upward sliding of the eyes, followed by an oblique downward catch-up saccade during horizontal head impulse to the healthy side. Methods: We present a retrospective study of all VHIT exams presenting isolated PSC hypofunction between May 2020 and November 2022. Results: We found 37 patients, which led to the discovery of such incongruent eye movement in 19 cases; their gain data are shown and compared to the remaining 18 cases in which such an anomaly was absent. A control group of 31 healthy subjects was recruited to define the reference criteria for VHIT gain values. The correlation between the amplitude of the vertical saccade and the relative functional imbalance of the vertical semicircular canals was studied. Conclusions: We have observed that in approximately half of the subjects with isolated CSP deficiency, there is a VOR anomaly. A possible pathophysiological explanation of the unbalanced effect of vertical semicircular canal stimulation of a labyrinth during horizontal head thrust toward the opposite side is proposed. The planar incongruity of the response of the VOR described here appears more evident at the onset of the CSP deficit. Current VHIT systems do not detect this incongruent eye reflex. They can lead to an error in gain evaluation (pseudo-deficit) of the lateral semicircular canal of the healthy side and problems in performing the test (trace rejected). In the future, software for VHIT should take into account the possibility of non-coplanar ocular responses to cephalic stimuli.

Is Skull-Vibration-Induced Nystagmus Modified with Aging?

BACKGROUND: Despite clinical practice utilizing the Dumas test (SVINT), some questions remain unanswered, including the age-related changes in frequency (FN) and slow-phase angular velocity (SPAV). This study aims to retrospectively evaluate their variations in subjects affected by unilateral peripheral vestibular loss (UPVL). METHODS: We evaluated the selected samples based on the results of the SVINT, the results of the vestibular-evoked potentials (C-VEMP and O-VEMP), and the results of the head impulse test (HIT) and we compared the results against the age of the patients. We calculated the timing between the onset of UPVL and clinical evaluation in days. The presence or absence of VEMP indicated the UPVL severity. UPVL and BPPV patients with spontaneous or pseudo-spontaneous nystagmus were compared. RESULTS: Statistical analysis showed changes in the FN and SPAV depending on age and the side of the application of the stimulus. We also observed that, in the UPVL, the severity of the disease modifies the SPAV, but not the frequency. CONCLUSIONS: The SVINT is a simple, reliable, and straightforward test that, if evaluated instrumentally, can show significant differences with aging. Further studies need to be performed to refine the clinical significance of the test and clarify its physiological background.

MRI With Intratympanic Gadolinium: Comparison Between Otoneurological and Radiological Investigation in Menière's Disease.

Objectives/hypothesis: To compare findings obtained using both magnetic resonance imaging plus intratympanic gadolinium and audiovestibular testing for Menière's disease. Study design: Retrospective cohort study. Methods: Patients with definite unilateral Menière's disease (n = 35) diagnosed according to 2015 Barany Criteria were included. Three-dimensional real inversion recovery (3D-real-IR) MRI was executed 24 h after intratympanic gadolinium injection to assess the presence and degree of endolymphatic hydrops. Pure tone audiometry, bithermal caloric test, head impulse test, ocular, and cervical VEMPs using air-conducted sound were performed to evaluate the level of hearing and vestibular loss. The results were compared to verify precision of the method in providing correct diagnoses. Results: Different degrees of endolymphatic hydrops were observed in the MRI of the cochlea and vestibule in the affected ears of Menière's disease patients, even though it was impossible to radiologically distinguish the two otolithic structures separately. The correlation between the degree of linked alterations between instrumental and MRI testing was statistically significant. In particular, an 83% correspondence with audiometry, a 63% correspondence for cVEMPs and 60% correspondence for cVEMPs were seen. While for HIT the accordance was 70 and 80% for caloric bithermal test. Conclusions: MRI using intratympanic gadolinium as a contrast medium has proved to be a reliable and harmless method, even though there is an objective difficulty in disclosing macular structures. The study revealed that there is no complete agreement between instrumental values and MRI due to the definition of the image and fluctuation of symptoms. The present work highlights the greater (but not absolute) sensitivity of otoneurological tests while MRI, although not yet essential for diagnosis, is certainly important for understanding the disease and its pathogenic mechanisms.

Menière's disease patients improve specific posturographic parameters following diagnostic intratympanic injection.

PURPOSE: Evaluation of specific computerized posturographic parameters in patients with Menière's disease (MD) following the intratympanic injection of gadolinium, a contrast agent, used in radiological diagnosing. MATERIALS AND METHODS: We have observed 12 adult patients with unilateral Menière's Disease subjected to inner ear magnetic resonance imaging (MRI) examination after intratympanic gadolinium injection (ITG). The diagnoses have been performed according to the guidelines of the American Academy of otolaryngology. Before and after 24 h the ITG, all patients were subjected to the clinical evaluation and computerized posturography (CP), in 4 conditions depending on open/closed eyes and with/without foam cushion under feet. RESULTS: After ITG, in the affected ear the MRI confirmed the endolymphatic hydrops revealing a thin or even disappeared perilymphatic space. The statokinesigram showed improvement of stability only with closed eyes on a foam cushion. The CP performed 24 h after the contrast intratympanic injection showed a significant reduction of Path Length and Confidence Ellipse Area, due to an improvement of vestibular function on static balance. This improvement could be directly dependent to intratympanic pressure modification mediated by volume of contrast liquid, by "columella effect". CONCLUSIONS: This study demonstrates the absence of vestibular damage in patients undergoing intratympanic gadolinium infiltration and confirms the relationship between intratympanic pressure and vestibular stability modifications providing positive evidences for an applicative use of CP as a functional assessment to better address diagnosis and follow-up in MD patients treated with intratympanic injections.