Nystagmus Slow Phase Velocity Research Articles

A Quantitative Study of the Head Pitching Test for Lateral Canal BPPV.

Lateral semicircular canal BPPV (LSC-BPPV) is diagnosed with the Head Yaw Test (HYT) by observing nystagmus direction and comparing the nystagmus intensity on both sides according to Ewald's laws. Head Pitching Test (HPT) is a diagnostic maneuver performed in the upright position by bending the patient's head forward (bowing) and backward (leaning) and observing the evoked nystagmus. We aimed to assess the sensitivity of HPT in correctly diagnosing LSC-BPPV through the quantitative measurement of Bowing and Leaning nystagmus slow-phase velocity (SPV). One hundred cases of LSC-BPPV were prospectively enrolled. HPT was performed, looking for pseudospontaneous, bowing, and leaning nystagmus. HYT was considered for the "final diagnosis." HPT was defined as "diagnostic" if the nystagmus was present in at least one position, "undiagnostic" if no nystagmus was detectable. The direction and the SPV of nystagmus in all positions were analyzed and compared to determine the degree of agreement between HPT and HYT. Sixty-four geotropic and 36 apogeotropic forms were diagnosed. HPT was diagnostic in 80 cases, with no difference between the two forms. According to Ewald's laws, the direction of stronger nystagmus evoked by HPT agreed with the HYT results in 39/52 (75%) cases in geotropic forms and 21/28 (75%) cases in apogeotropic forms. The agreement between HPT and HYT was "substantial" considering all the cases and "almost complete" considering only the patients with diagnostic HPT. Quantitative HPT is a valid test in diagnosing the affected side and form of LSC-BPPV, even if less reliable than HYT.

Audiometric and Vestibular Function after Classic and Reverse Stapedotomy.

Background and Objectives: Besides classical stapedotomy, reverse stapedotomy has been used for many years in the management of otosclerosis. Our study aims to investigate whether reversing the surgical steps in stapedotomy impacts vestibular function and hearing improvement. Materials and Methods: A cohort of 123 patients underwent either classic or reverse stapedotomy procedures utilizing a fiber-optic argon laser. Audiological assessments, following the guidelines of the Committee on Hearing and Equilibrium, were conducted, including pure tone average, air-bone (AB) gap, overclosure, and AB gap closure. Vestibular evaluation involved pre- and postoperative comparison of rotatory test parameters, including frequency, amplitude, and slow phase velocity of nystagmus. Results: The study demonstrated an overall median overclosure of 3.3 (3.3, 5.0) dB and a mean AB gap closure of 20.3 ± 8.8 dB. Postoperative median AB gap was 7.5 (7.5, 11.3) dB in the reverse stapedotomy group and 10.0 (10.0, 12.5) dB in the classic stapedotomy group. While overclosure and AB gap closure were marginally superior in the reverse stapedotomy group, these differences did not reach statistical significance. No significant disparities were observed in the frequency, slow phase velocity, or amplitude of nystagmus in the rotational test. Conclusions: Although not always possible, reverse stapedotomy proved to be a safe surgical technique regarding postoperative outcomes. Its adoption may mitigate risks associated with floating footplate, sensorineural hearing loss, and incus luxation/subluxation, while facilitating the learning curve for less experienced ear surgeons.

Investigation on biomechanical responses in bilateral semicircular canals and nystagmus in vestibulo-ocular reflex experiments under different forward-leaning angles.

Different head positions affect the responses of the vestibular semicircular canals (SCCs) to angular movement. Specific head positions can relieve vestibular disorders caused by excessive stimulating SCCs. In this study, we quantitatively explored responses of human SCCs using numerical simulations of fluid-structure interaction and vestibulo-ocular reflex (VOR) experiments under different forward-leaning angles of the head, including 0°, 10°, 20°, 30°, 40°, 50°, and 60°. It was found that the horizontal nystagmus slow-phase velocity and corresponding biomechanical responses of the cupula in horizontal SCC increased with the forward-leaning angles of the head, reached a maximum when the head was tilted 30° forward, and then gradually decreased. However, no obvious vertical or torsional nystagmus was observed in the VOR experiments. In the numerical model of bilateral SCCs, the biomechanical responses of the cupula in the left anterior SCC and the right anterior SCC showed the same trends; they decreased with the forward-leaning angles, reached a minimum at a 40° forward tilt of the head, and then gradually increased. Similarly, the biomechanical responses of the cupula in the left posterior SCC and in the right posterior SCC followed a same trend, decreasing with the forward-leaning angles, reaching a minimum at a 30° forward tilt of the head, and then gradually increasing. Additionally, the biomechanical responses of the cupula in both the anterior and posterior SCCs consistently remained lower than those observed in the horizontal SCCs across all measured head positions. The occurrence of these numerical results was attributed to the consistent maintenance of mutual symmetry in the bilateral SCCs with respect to the mid-sagittal plane containing the axis of rotation. This symmetry affected the distribution of endolymph pressure, resulting in biomechanical responses of the cupula in each pair of symmetrical SCCs exhibiting same tendencies under different forward-leaning angles of the head. These results provided a reliable numerical basis for future research to relieve vestibular diseases induced by spatial orientation of SCCs.

Three-dimensional characteristics of nystagmus induced by low frequency in semicircular canals of healthy young people.

The study aimed to analyze the three-dimensional characteristics of nystagmus induced by different semicircular canal combinations in healthy young people, and to determine the reference range of nystagmus slow phase velocity (SPV) and its asymmetry. Fifty-two healthy volunteers (26 males and 26 females, aged 17-42 years, average 23.52 ± 6.59), were recruited to perform the manual triaxial rotation testing with a 3D-Videonystagmography (3D-VNG) device (VertiGoggles (ZT-VNG-II), Shanghai ZEHNIT Medical Technology Co., Ltd., Shanghai, China) using a 0.3 Hz prompt beat and a 90° amplitude, respectively. The induced nystagmus around the Z-, X-, and Y-axes were recorded in the yaw, pitch, and roll planes. The directions and slow phase velocities of the horizontal, vertical, and torsional components of the induced nystagmus under different semicircular canal combinations (the left lateral and right lateral semicircular canal combination, bilateral anterior semicircular canals, bilateral posterior semicircular canals combination, and the anterior and posterior semicircular canals combination of each ear), as well as their asymmetry, were taken as the observation indexes to analyze the characteristics of the nystagmus vectors of different combinations. Fifty-two healthy volunteers had no spontaneous nystagmus. The characteristic nystagmus was induced by the same head movement direction in all three axial rotation tests. The SPVs of the left and right nystagmus were 44.45 ± 15.75°/s and 43.79 ± 5.42°/s, respectively, when the subjects' heads were turned left or right around the Z-axis (yaw). The SPVs of vertically upward and downward nystagmus were 31.67 ± 9.46°/s and 30.01 ± 9.20°/s, respectively, when the subjects' heads were pitched around the X-axis (pitch). The SPVs of torsional nystagmus, with the upper poles of the eyes twisting slowly to the right and left ears (from the participant's perspective), were 28.99 ± 9.20°/s and 28.35 ± 8.17°/s, respectively, when the subjects' heads were turned left or right around the Y-axis (roll). There was no significant difference in the SPVs of nystagmus induced by the same rotation axis in two opposite directions (p > 0.05). The reference ranges for the slow phase velocities (SPVs) of nystagmus induced by the triaxial rotation testing were as follows: For the Z-axis (yaw), the SPVs were 13.58-75.32°/s for leftward head rotation and 13.56-74.02°/s for rightward head rotation. For the X-axis (pitch), the SPVs were 13.13-50.21°/s for upward head nystagmus and 11.98-48.04°/s for downward head nystagmus. For the Y-axis (roll), the SPVs were 10.97-47.02°/s for the left-sided head rotation and 12.34-44.35°/s for the right-sided head rotation. This study clarified the three-dimensional characteristics of nystagmus induced by different semicircular canal combinations in healthy young people. It also established a preliminary reference range of SPVs and SPV asymmetry of nystagmus induced by the vertical semicircular canal. It can further provide a basis for the mechanism of semicircular canal-induced nystagmus and the traceability of nystagmus in patients with otogenic vertigo. It is shown that the portable 3D-VNG eye mask can be used for the manual triaxial rotation testing to achieve the evaluation of the low-frequency angular vestibulo-ocular reflex (aVOR) function of the vertical semicircular canal, which is convenient, efficient, and practical.

Subjective and objective responses to caloric stimulation help separate vestibular migraine from other vestibular disorders

BackgroundNystagmus generated during bithermal caloric test assesses the horizontal vestibulo-ocular-reflex. Any induced symptoms are considered unwanted side effects rather than diagnostic information.AimWe hypothesized that nystagmus slow-phase-velocity (SPV) and subjective symptoms during caloric testing would be higher in vestibular migraine (VM) patients compared with peripheral disorders such as Meniere’s disease (MD) and non-vestibular dizziness (NVD).MethodsConsecutive patients (n = 1373, 60% female) referred for caloric testing were recruited. During caloric irrigations, patients scored their subjective sensations. We assessed objective-measures, subjective vertigo (SVS), subjective nausea (SNS), and test completion status.ResultsNystagmus SPV for VM, MD (unaffected side), and NVD were 29 ± 12.8, 30 ± 15.4, and 28 ± 14.2 for warm irrigation and 24 ± 8.9, 22 ± 10.0, and 25 ± 12.8 for cold-irrigation. The mean SVS were 2.5 ± 1.1, 1.5 ± 1.33, and 1.5 ± 1.42 for warm irrigation and 2.2 ± 1.1, 1.1 ± 1.19, and 1.1 ± 1.16 for cold-irrigation. Age was significantly correlated with SVS and SNS, (p < 0.001) for both. The SVS and SNS were significantly higher in VM compared with non-VM groups (p < 0.001), and there was no difference in nystagmus SPV. VM patients SVS was significantly different to the SVS of migraineurs in the other diagnostic groups (p < 0.001). Testing was incomplete for 34.4% of VM and 3.2% of MD patients. To separate VM from MD, we computed a composite value representing the caloric data, with 83% sensitivity and 71% specificity. Application of machine learning to these metrics plus patient demographics yielded better separation (96% sensitivity and 85% specificity).ConclusionPerceptual differences between VM and non-VM patients during caloric stimulation indicate that subjective ratings during caloric testing are meaningful measures. Combining objective and subjective measures could provide optimal separation of VM from MD.

Clinical, oculographic and vestibular test characteristics of Ménière's disease.

Seventy Ménière's disease (MD) patients with spontaneous vertigo (100%), unilateral aural fullness (57.1%), tinnitus (78.6%), and subjective hearing loss (75.7%) self-recorded nystagmus during their episodes of vertigo using portable video oculography goggles. All demonstrated ictal spontaneous nystagmus, horizontal in 94.3% (n = 66) and vertical in 5.7% (n = 4), with a mean slow-phase velocity (SPV) of 42.8 ± 31.1°/s (range 5.3-160.1). Direction reversal of spontaneous horizontal nystagmus was captured in 58.6%, within the same episode in 34.3%, and over different days in 24.3%. In 18.6%, we observed ipsiversive then contraversive nystagmus, and in 12.9% contraversive to ipsiversive direction reversal. Ictal nystagmus SPV (42.8 ± 31.1°/s) was significantly faster than interictal (1.4 ± 3.1°/s, p < 0.001, CI 34.277-48.776). Compared to age-matched healthy controls, interictal video head impulse test gains in MD ears were significantly lower, cumulative and first saccade (S1) amplitudes were significantly larger, and S1 peak velocities were significantly faster (p = 0.038/0.019/0.008/ < 0.001, CI 0.002-0.071/0.130-1.444/0.138-0.909/14.614-41.506). Audiometry showed asymmetrically increased thresholds in 100% of MD ears (n = 70). Significant caloric, air-conducted (AC) cervical vestibular-evoked myogenic potential (VEMP), and AC ocular VEMP asymmetries were found in 61.4, 37.9, and 44.4% of patients (MD ear reduced). Transtympanic electrocochleography tested in 36 ears (23 patients) showed 81.8% of MD ears had a positive result for hydrops (either a summating potential at 1/2kHz < - 6µV, or an SP/AP ratio > 40%). Using ictal nystagmus findings of SPV > 12°/s, and a caloric canal paresis > 25%, we correctly separated a diagnosis MD from Vestibular Migraine with a sensitivity and specificity of 95.7% and 85.1% (CI 0.89-0.97).

Quantitative analysis of the biomechanical response of semicircular canals and nystagmus under different head positions

The semicircular canals (SCCs) in the vestibular system can sense angular motion of the head, which performs a crucial role in maintaining the human's sense of balance. The different spatial orientations of the head affect the response of human SCCs to rotational movement. In this study, we combined the numerical model of bilateral human SCCs with vestibulo-ocular reflex experiments, and quantitatively investigated the responses of SCCs to constant angular acceleration when the head was in different left-leaning positions, including the head tilted 0°, 15°, 30°, 45°, 60°, 70°, 80°, and 90° to the left. The results showed that the vertical nystagmus slow-phase velocity (SPV) and the corresponding maximal cupula shear strain at the crista surface rose with an increase in the left-leaning angle of the head, reached a maximum at the position of the head tilted approximately 70° to the left, and then decreased gradually. Both the horizontal nystagmus SPV and the corresponding maximal cupula shear strain at the crista surface were the largest under the position of the head tilted 0° to the left, and decreased gradually as the left-leaning angle of the head increased. The numerical results of cupula shear strain at the crista surface in bilateral SCCs can quantitatively explain the combined effects of each SCC's excitation or inhibition on volunteers’ nystagmus SPV under different head positions. In addition, a fluid-structure interaction investigation revealed that different left-leaning head positions changed the endolymphatic pressure gradient distribution in SCCs, which determined the transcupular pressure, cupula shear strain at the crista surface, and nystagmus SPV.

Nystagmus characteristics of healthy controls.

BACKGROUND:Healthy controls exhibit spontaneous and positional nystagmus which needs to be distinguished from pathological nystagmus.OBJECTIVE:Define nystagmus characteristics of healthy controls using portable video-oculography.METHODS:One-hundred and one asymptomatic community-dwelling adults were prospectively recruited. Participants answered questions regarding their audio-vestibular and headache history and were sub-categorized into migraine/non-migraine groups. Portable video-oculography was conducted in the upright, supine, left- and right-lateral positions, using miniature take-home video glasses.RESULTS:Upright position spontaneous nystagmus was found in 30.7% of subjects (slow-phase velocity (SPV)), mean 1.1±2.2 degrees per second (°/s) (range 0.0 – 9.3). Upright position spontaneous nystagmus was horizontal, up-beating or down-beating in 16.7, 7.9 and 5.9% of subjects. Nystagmus in at least one lying position was found in 70.3% of subjects with 56.4% showing nystagmus while supine, and 63.4% in at least one lateral position. While supine, 20.8% of subjects showed up-beating nystagmus, 8.9% showed down-beating, and 26.7% had horizontal nystagmus. In the lateral positions combined, 37.1% displayed horizontal nystagmus on at least one side, while 6.4% showed up-beating, 6.4% showed down-beating. Mean nystagmus SPVs in the supine, right and left lateral positions were 2.2±2.8, 2.7±3.4, and 2.1±3.2°/s. No significant difference was found between migraine and non-migraine groups for nystagmus SPVs, prevalence, vertical vs horizontal fast-phase, or low- vs high-velocity nystagmus (<5 vs > 5°/s).CONCLUSIONS:Healthy controls without a history of spontaneous vertigo show low velocity spontaneous and positional nystagmus, highlighting the importance of interictal nystagmus measures when assessing the acutely symptomatic patient.

Modulatory effects of magnetic vestibular stimulation on resting-state networks can be explained by subject-specific orientation of inner-ear anatomy in the MR static magnetic field

Strong static magnetic fields, as used in magnetic resonance imaging (MRI), stimulate the vestibular inner ear leading to a state of imbalance within the vestibular system that causes nystagmus. This magnetic vestibular stimulation (MVS) also modulates fluctuations of resting-state functional MRI (RS-fMRI) networks. MVS can be explained by a Lorentz force model, indicating that MVS is the result of the interaction of the static magnetic field strength and direction (called “B0 magnetic field” in MRI) with the inner ear’s continuous endolymphatic ionic current. However, the high variability between subjects receiving MVS (measured as nystagmus slow-phase velocity and RS-fMRI amplitude modulations) despite matching head position, remains to be explained. Furthermore, within the imaging community, an “easy-to-acquire-and-use” proxy accounting for modulatory MVS effects in RS-fMRI fluctuations is needed. The present study uses MRI data of 60 healthy volunteers to examine the relationship between RS-fMRI fluctuations and the individual orientation of inner-ear anatomy within the static magnetic field of the MRI. The individual inner-ear anatomy and orientation were assessed via high-resolution anatomical CISS images and related to fluctuations of RS-fMRI networks previously associated with MVS. More specifically, we used a subject-specific proxy for MVS (pMVS) that corresponds to the orientation of the individual inner-ear anatomy within the static magnetic field direction (also called “z-direction” in MR imaging). We found that pMVS explained a considerable fraction of the total variance in RS-fMRI fluctuations (for instance, from 11% in the right cerebellum up to 36% in the cerebellar vermis). In addition to pMVS, we examined the angle of Reid’s plane, as determined from anatomical imaging as an alternative and found that this angle (with the same sinus transformation as for pMVS) explained considerably less variance, e.g., from 2 to 16%. In our opinion, an excess variability due to MVS should generally be addressed in fMRI research analogous to nuisance regression for movement, pulsation, and respiration effects. We suggest using the pMVS parameter to deal with modulations of RS-fMRI fluctuations due to MVS. MVS-induced variance can easily be accounted by using high-resolution anatomical imaging of the inner ear and including the proposed pMVS parameter in fMRI group-level analysis.

Numerical modeling and verification by nystagmus slow-phase velocity of the function of semicircular canals.

The malfunctioning of semicircular canals (SCCs) in the vestibular system results in diseases that disrupt the individual's daily life. Vestibular diseases can be treated more effectively if the functioning of the SCCs is better understood. However, the SCC is difficult to dissect, because it is a complex structure buried deep in the inner ear. To thoroughly understand the function of SCCs and provide better treatment plans for vestibular diseases, we constructed a numerical model of human SCCs and validated it experimentally. Based on the principle of the vestibulo-ocular reflex, the cupula deformation deflects embedded sensory hair cell bundles, transmitting signals to the brain and inducing a slow compensatory eye movement. The slow-phase velocity (SPV) is the characteristic of the slow compensatory eye movement. We investigated the cupula deformation in the numerical model and the SPV under different conditions. The relationship between the cupula deformation and the SPV was quantified for three volunteers. It was observed that the maximal cupula deformation is proportional to the angular acceleration, while the SPV is changing nonlinearly with the angular acceleration. For three volunteers, the relationship between the cupula deformation and the SPV can be expressed by same type function of which the parameters are dependent on individual differences. These results validate the reliability of the numerical model.

New methods of differentiating cases of “heavy cupula”

In cases of “heavy cupula”, the adhesive strength of the otoconia to the cupula or the adhesive side of the cupula is often unclear. To investigate this further, the course after treatment and the natural course were investigated in 31 cases of heavy cupula that we encountered at our clinic over a one-year period. First, the cases were divided into two groups by the responses to the affected-ear-down 135° maneuver; the group with the lateral canal BPPV-canalolithiasis apogeotropic variant (: L-BPPV-Can-a), in which the otoconia came in contact with the cupula on the canal side, and the group with the lateral canal BPPV-cupulolithiasis (: L-BPPV-Cup), in which the otoconia adhered to the cupula. In the L-BPPV-Can-a group, rolling the head and trunk from the affected-ear-down 135° to the supine position caused detachment of the otoconia from the canal side of the cupula and moved them further in the posterior direction. The maximum slow-phase velocity of nystagmus in the healthy-ear-down position to that in the affected-ear-down position (H/A) was examined in both groups. In the L-BPPV-Cup group, the affected-ear-up lateral decubitus method was employed. Sleeping in the affected-ear-up lateral decubitus position all through the night could detach the otoconia from the utricular side of the cupula and restore them back into the utriculus. The H/A in the L-BPPV-Can-a group was significantly greater than that in the L-BPPV-Cup group (P<0.005). Use of the ratio of 2.5 as the cutoff point to distinguish between the two groups was associated with a sensitivity of 0.8 and specificity of 0.8. The affected-ear-up lateral decubitus method was effective in 58% of the cases. The results suggest that among the 31 cases of heavy cupula, there were 13 with the L-BPPV-Can-a variant and 18 with the L-BPPV-Cup, including 4 with the otoconia adhering to the cupula on the canal side, 12 with the otoconia adherent to the cupula on the utricular side, and 2 undetermined.

Perioperative vestibular assessment and testing

Vestibular disorders can be difficult to accurately diagnose and manage. A careful history and focused physical examination are typically adequate to establish a diagnosis and initiate medical treatment. Vestibular testing is an important component of the work-up, but it is particularly essential for patients being considered for surgical intervention for a vestibular disorder, where the testing can be used to more definitively confirm a suspected diagnosis and to determine baseline vestibular organ function. In this article, we will first briefly review key components of the history and physical examination of patients with vestibular complaints. We will then discuss the most commonly used vestibular tests and their role in the preoperative assessment of patients undergoing vestibular surgery, including nystagmography, caloric testing, rotary chair testing, video head impulse testing, and vestibular evoked myogenic potential testing.

004 Vestibular event monitoring in the emergency department

IntroductionAcute vertigo is often accompanied by ictal-nystagmus which may assist with diagnosis. We examine the merits of a structured assessment combined with vestibular event-monitoring in the Emergency Department (ED).MethodsWe undertook a structured clinical assessment and video-nystagmography in 220 non-consecutive patients presenting to a public-hospital ED with acute vertigo, during a 10-month period. The records of 115 consecutive vertiginous patients who underwent standard-assessment were compared.ResultsFor the structured assessment group: 54% presented with acute vestibular syndrome (AVS), 24% with episodic spontaneous vertigo (EVS), and 20% with recurrent positional-vertigo (RPV).For AVS (n=119), most common diagnoses were vestibular neuritis (34%), stroke (34%) and vestibular migraine (13%). Nystagmus slow-phase velocity (SPV) for VN, stroke and VM were 11±5.5o/s, 5.6±2.5o/s, 5.4±5.9o/s; Mean ipsilesional video-head impulse gains were 0.51±0.29, 0.89±0.20 and 0.96±0.13. For EVS(n=53), diagnoses included vestibular migraine (63%), Meniere’s Disease (11%) and others (26%). Nystagmus SPV was 5.4±3.6o/s, 7.6±6.3o/s, 4.1±1.5o/s. In RPV (n=43), common diagnoses were posterior-canal BPPV (66%), horizontal-canal BPPV (23%), migraine (7%). Positional nystagmus SPV profile showed Peak SPV of 42.5o/s, 77.6o/s, 20.64o/s and Time-constants of 6.52s, 22.51s, 34.56s for Posterior-canal BPPV, Horizontal-canal BPPV and Atypical Positional-Vertigo. A final diagnosis was reached in 96% of patients.In the ED control group, only 77% were separated into spontaneous or positional-vertigo. A diagnosis was provided in 57% and was concordant with the history and examination in 34%.ConclusionVestibular event-monitoring and structured clinical assessment secured a diagnosis in 96% of cases compared with 34% for the control group, reinforcing its merit.

021 Profiles of benign positional vertigo tested on the epley omniax chair

IntroductionBenign positional vertigo (BPV) has a characteristic pattern of nystagmus specific to the affected semicircular canal and the underlying mechanism of canalithiasis (where otoconia float freely) or cupulolithiasis (where otoconia are adherent to the cupula).MethodsWe analysed the nystagmus slow-phase velocity (SPV) profiles of 100 subjects with posterior-canalithiasis, 30 with lateral-canalithiasis, 10 with lateral-cupulolithiasis and 3 with anterior-canalithiasis. Subjects were examined on the Epley Omniax Rotator, a mechanical chair with real-time video-oculography. Video data was analysed using custom-made LabVIEW software. Nystagmus onset, duration, peak-velocity, peak-latency and time taken for the peak-velocity to halve (t50), were measured.ResultsIn posterior-canalithiasis, nystagmus occurred within 14.2 seconds of positioning and lasted 2.5–34.5 seconds. The median vertical peak-SPV was 37.3°/s. The median peak-latency was 2.9 seconds and the median t50 was 3.4 seconds. In lateral-canalithiasis, nystagmus onset was mostly immediate. With the affected ear down, the median peak-SPV was 52.2°/s and the median peak-latency was 3.6 seconds; the t50 was 7 seconds (median) and the paroxysms lasted 9.9–48.5 seconds. In lateral-cupulolithiasis, nystagmus onset was instantaneous. With the unaffected ear down, the median peak-SPV was 69.6°/s. The peak-latency (median 18.6 s) and t50 (median 34.5 s) were significantly prolonged compared to canalithiasis. For anterior-canalithiasis, the onset was 0–2.9 seconds, the peak-latency was 3–5.4 seconds, the t50 was 6.4–10.5 seconds and the duration was 13.4–23.1 seconds.ConclusionsCanalithiasis and cupulolithiasis produce distinct SPV profiles, which enable their identification and the separation of BPV from other causes of positional nystagmus.

The Functional Head Impulse Test to Assess Oscillopsia in Bilateral Vestibulopathy.

Introduction: Bilateral vestibulopathy (BV) is a chronic condition in which vestibular function is severely impaired or absent on both ears. Oscillopsia is one of the main symptoms of BV. Oscillopsia can be quantified objectively by functional vestibular tests, and subjectively by questionnaires. Recently, a new technique for testing functionally effective gaze stabilization was developed: the functional Head Impulse Test (fHIT). This study compared the fHIT with the Dynamic Visual Acuity assessed on a treadmill (DVAtreadmill) and Oscillopsia Severity Questionnaire (OSQ) in the context of objectifying the experience of oscillopsia in patients with BV.Methods: Inclusion criteria comprised: (1) summated slow phase velocity of nystagmus of <20°/s during bithermal caloric tests, (2) torsion swing tests gain of <30% and/or phase <168°, and (3) complaints of oscillopsia and/or imbalance. During the fHIT (Beon Solutions srl, Italy) patients were seated in front of a computer screen. During a passive horizontal head impulse a Landolt C optotype was shortly displayed. Patients reported the seen optotype by pressing the corresponding button on a keyboard. The percentage correct answers was registered for leftwards and rightwards head impulses separately. During DVAtreadmill patients were positioned on a treadmill in front of a computer screen that showed Sloan optotypes. Patients were tested in static condition and in dynamic conditions (while walking on the treadmill at 2, 4, and 6 km/h). The decline in LogMAR between static and dynamic conditions was registered for each speed. Every patient completed the Oscillopsia Severity Questionnaire (OSQ).Results: In total 23 patients were included. This study showed a moderate correlation between OSQ outcomes and the fHIT [rightwards head rotations (rs = −0.559; p = 0.006) leftwards head rotations (rs = −0.396; p = 0.061)]. No correlation was found between OSQ outcomes and DVAtreadmill, or between DVAtreadmill and fHIT. All patients completed the fHIT, 52% of the patients completed the DVAtreadmill on all speeds.Conclusion: The fHIT seems to be a feasible test to quantify oscillopsia in BV since, unlike DVAtreadmill, it correlates with the experienced oscillopsia measured by the OSQ, and more BV patients are able to complete the fHIT than DVAtreadmill.

Clinical and electrophysiological results of eye muscle surgery in 17 patients with downbeat nystagmus.

Purpose:To test the hypothesis that eye muscle surgery in treatment of patients with acquired downbeat nystagmus results in improvement measures of visual and ocular motor function.Methods:This is a prospective, interventional case series analysis of clinical and electrophyisological data before and after eye muscle surgery in 17 patients with acquired downbeat nystagmus who did not respond to medical treatments. Outcome measures included: 1) routine demography and clinical characteristics, 2) subjective oscillopsia (SO), 3) binocular best-corrected visual acuity in the null position (BVA), 3) primary position strabismic deviation (SD), 5) anomalous head posture (AHP), 6) contrast sensitivity function (CS), and 7) nystagmus slow phase velocity (SPV). All patients were followed at least 12 months. Parametric and non-parametric statistical analysis of outcome measure data above pre- and post-treatment were perfomed using standard software on grouped data using computerized software.Results:Patients’ age ranged from 5 to 85 years (average 27 years). About 59% were male. Follow up ranged from 1–10 years (average 2.0 years). Around 70% had an associated central nervous systemic diagnosis, 100% had an AHP, oscillopsia and decreased CS, 53% had other eye disease, and 59% had strabismus. There were no complications from surgery. There were signficant post-treatment improvements in mean/median group BVA, SO, SD, AHP, CS, and SPV.Conclusion:This study supports the hypothesis that eye muscle surgery as treatments for patients with acquired downbeat nystagmus can result in improvements in multiple aspects of ocular motor and visual functions.

Abnormal vestibular asymmetries in patients with major depression

Background and objectives: The precedents about the existence of bilateral modulatory neuronal pathways between vestibular nuclei and higher brain centers involved in mood regulation, plus previous reports of abnormal vestibular function in major depression, support the relevance of further investigation inquiring the role of the vestibular system in depression's physiopathology and vice versa. The aim of this investigation is to study the vestibular activity in major depression patients using the rotatory test technique. Methods: Totally 21 major depression subjects (average age 37.9 years) according to Diagnostic and Statistical Manual of Mental Disorders-V criterion, who scored 12 or more in the 21-item Hamilton Rating Scale for Depression (HRS-D21), and 20 control healthy subjects (average age 41.1 years) who scored less than 7 in the HRS-D21, were tested in the rotatory chair. The nystagmus (vestibular-ocular reflex consisting of ocular movements induced by the vestibular system), was registered by electronystagmography. For the quantification of right or left vestibular activity, we measured the nystagmus's slow phase velocity induced by right and leftward rotation of the chair correspondingly. Results: Depression group showed an asymmetric vestibular pattern of activity (right/left vestibular activity ratio = 0.77 ± 0.2), significantly different (P Conclusion: Major depressive patients show an abnormal pattern of vestibular activity with lower function at the right side compared to left. We discuss the meaning and the possible underlying physiopathologic mechanisms of this finding. Also, we raise the possibility to consider this particular kind of vestibular asymmetry as a potential biomarker of major depression. Trial registration: ClinicalTrials.gov identifier: NCT03421847.

Compensated Vestibular Dysfunction Post Cochlear Implantation in Children with Sensorineural Hearing Loss: A Prospective Study

Children with sensorineural hearing loss have risk of surgically induced vestibular dysfunction post cochlear implantation due to instrumentation. It is clinically important to estimate the risk of vestibular loss post cochlear implant so the patient can be made fully aware of these risks when considering cochlear implantation. The aim of the study was to identify compensated vestibular dysfunction post cochlear implantation. Vestibular function was evaluated both pre and post CI using monothermal warm air caloric testing. Recordings were made using head band camera on SYNAPSYS Ulmer VNG software. 'Monothermal caloric asymmetry' (MCA) was depicted as 'unilateral weakness' based on the slow phase velocity of nystagmus. MCA of >15% was taken as evidence of canal paresis. The incidence of compensated vestibular dysfunction post CI surgery was found to be 16.66%. The results were statistically significant (p value 0.02) and indicated worsening of canal paresis indicative of vestibular dysfunction. Children for cochlear implantation should undergo evaluation of their vestibular system pre and post surgery. Caution should be exercised before planning bilateral cochlear implantation in the same sitting.

Bilateral Vestibular Hypofunction: Insights in Etiologies, Clinical Subtypes, and Diagnostics.

To evaluate the different etiologies and clinical subtypes of bilateral vestibular hypofunction (BVH) and the value of diagnostic tools in the diagnostic process of BVH. A retrospective case review was performed on 154 patients diagnosed with BVH in a tertiary referral center, between 2013 and 2015. Inclusion criteria comprised (1) imbalance and/or oscillopsia during locomotion and (2) summated slow phase velocity of nystagmus of less than 20°/s during bithermal caloric tests. The definite etiology of BVH was determined in 47% of the cases and the probable etiology in 22%. In 31%, the etiology of BVH remained idiopathic. BVH resulted from more than 20 different etiologies. In the idiopathic group, the percentage of migraine was significantly higher compared to the non-idiopathic group (50 versus 11%, p < 0.001). Among all patients, 23.4% were known with autoimmune disorders in their medical history. All four clinical subtypes (recurrent vertigo with BVH, rapidly progressive BVH, slowly progressive BVH, and slowly progressive BVH with ataxia) were found in this population. Slowly progressive BVH with ataxia comprised only 4.5% of the cases. The head impulse test was abnormal in 94% of the cases. The torsion swing test was abnormal in 66%. Bilateral normal hearing to moderate hearing loss was found in 49%. Blood tests did not often contribute to the determination of the etiology of the disease. Abnormal cerebral imaging was found in 21 patients. BVH is a heterogeneous condition with various etiologies and clinical characteristics. Migraine seems to play a significant role in idiopathic BVH and autoimmunity could be a modulating factor in the development of BVH. The distribution of etiologies of BVH probably depends on the clinical setting. In the diagnostic process of BVH, the routine use of some blood tests can be reconsidered and a low-threshold use of audiometry and cerebral imaging is advised. The torsion swing test is not the "gold standard" for diagnosing BVH due to its lack of sensitivity. Future diagnostic criteria of BVH should consist of standardized vestibular tests combined with a history that is congruent with the vestibular findings.

From nystagmus to the air and water caloric tests

The caloric test is an important tool for the assessment of labyrinthine function.Objective: To compare the nystagmus response in the caloric tests with air at 50°C and 24°C and with water at 44°C and 30°C. Study Design: Randomized crossover clinical trial.Materials and Methods: 40 healthy individuals were submitted to a neurotological evaluation, including caloric tests with air at 50°C and 24°C and water at 44°C and 30°C.Results: Comparing the air and water caloric tests, there were no significant differences among the post-caloric nystagmus slow-phase velocity in relation to the stimulation order, between ears and between the values of unilateral weakness and directional preponderance. The slow-phase velocity values were higher with water (p = 0.008, p < 0.001), and cold stimulation produced stronger responses (p < 0.001).Conclusion: Comparing 50°C and 24°C air caloric test and 44°C and 30°C water caloric test, we observed similar slow-phase velocity values for both ears, higher responses in the cold temperature and in the test with water, and similar results of unilateral weakness or directional preponderance for post-caloric nystagmus in both tests.