Effect of Sound Source Location and Spatial Hearing on the Vestibulo-Ocular Reflex.

BACKGROUND: There have been conflicting results on the effect of auditory stimulation on the vestibulo-ocular reflex (VOR) with some studies indicating suppression, enhancement, or no effect. No studies to date have assessed the effect of sound source location on VOR gain or the relationship between spatial hearing ability and VOR gain. PURPOSE: The purpose of the present study was to determine if VOR gain was affected by moving the location of the sound source within participants and to determine if these effects were related to spatial hearing ability. RESEARCH DESIGN: A between subjects repeated measures experimental design was utilized. STUDY SAMPLE: Two groups of participants (adult and child) with normal otologic, vestibular, and neurologic function. 22 adults (20 female and 2 male; average age = 23 years) and 16 children (9 female and 7 male; average age = 7.5 years) were included in data analysis. DATA COLLECTION AND ANALYSIS: VOR gain was measured using rotational chair stimulation in the following auditory conditions: silent, insert earphones, external loudspeaker at 0° azimuth rotating with participant, and external stationary speaker. Localization ability was measured using root mean square (RMS) error. RESULTS: Results indicated a significant effect for sound source location on VOR gain and VOR difference gain in both groups. RMS error was positively correlated for the moving and fixed sound source locations for both adults and children. CONCLUSION: VOR gain was significantly affected by location of the sound source. Findings suggest the presence and location of an auditory stimulus during rotational testing can alter results during the assessment.

Outcomes and Patient Experience in Individuals With Longstanding Dizziness.

PURPOSE: This study aimed to describe the relationship between changes in pre and post self-perceived dizziness handicap, scores on the patient health questionnaire, and perceptions of patient's value of being evaluated and managed by a multidisciplinary team. METHOD: Seventy-eight patients completed the Dizziness Handicap Inventory (DHI) and Patient Health Questionnaire-Fourth Edition (PHQ-4) questionnaires post multidisciplinary clinical consultations and testing for the chief complaints of dizziness, unsteadiness, vertigo, or balance problems. The diagnoses of each patient were recorded from the clinical reports of each specialty consultation and were classified as structural, functional, or psychiatric. They were contacted by phone at least 6 months after their visit to obtain feedback regarding their symptoms and overall patient experience. RESULTS: The change in DHI total score did not differ significantly by diagnosis (p = .56), indicating that patients experienced an improvement in DHI total score regardless of diagnosis. PHQ-4 anxiety scores worsened by a mean of 0.7 points for those with structural diagnoses (p = .04), improved by a mean of 0.7 points for psychiatric diagnoses (p = .16), and improved by a mean of 0.3 points for functional diagnoses (p = .39). Only seven patients would not recommend the team to a family or friend; these patients tended to report worsening DHI total scores (p = .27) compared to the significant improvement in DHI total scores for patients who would make such a recommendation (p < .001). Similarly, only 13 patients did not feel the information they received had a positive impact; these patients tended to report worsening DHI total scores (p = .18) compared to the significant improvement in DHI total scores for patients who did feel the information had a positive impact (p < .001). DISCUSSION: The assessment and management of patients with chronic dizziness is challenging due to symptoms arising from multiple etiologies. Our finding of a vast difference between high satisfaction and relatively unchanged dizziness handicap suggests that there is value in seeing a multidisciplinary team where consultations are unhurried, care is coordinated, and expectations regarding treatment can be managed.

Development and validation of a new disease-specific quality of life instrument for sporadic vestibular schwannoma: the Mayo Clinic Vestibular Schwannoma Quality of Life Index.

OBJECTIVE: Facial nerve function, hearing preservation, and tumor control have been the primary benchmarks used to assess vestibular schwannoma (VS) outcomes. Acknowledging the frequent discrepancy between what physicians prioritize and what patients value, there has been increasing prioritization of patient-reported outcome measures when evaluating the impact of VS diagnosis and its treatment. Motivated by reported limitations of prior instruments used to assess quality of life (QOL) in patients with VS, the authors describe the development and validation of a new disease-specific QOL measure: the Vestibular Schwannoma Quality of Life (VSQOL) Index. METHODS: The content development phase comprised identification of clinically important domains and prioritization of feelings or concerns individuals with VS may have. The validation phase encompassed determining how items were grouped into domains and eliminating redundant items. Both phases leveraged data from cross-sectional and longitudinal surveys, expertise from a multidisciplinary working group, and patients with a broad range of experiences with VS (n = 42 during content development and n = 263 during validation). Domain scores from the new instrument were assessed for reliability and correlation with other measures of similar constructs. RESULTS: The VSQOL Index consists of 40 items that evaluate the impact of VS diagnosis and its management on QOL, treatment satisfaction, and employment and is estimated to take 8-10 minutes to complete. Domain scores range from 0 (worst) to 100 (best) and demonstrate excellent psychometric properties, including content, construct, and convergent validity and both internal consistency (Cronbach's alphas 0.83 to 0.91) and test-retest reliability (reliability coefficients 0.86 to 0.96). CONCLUSIONS: The VSQOL Index is a valid and reliable measure that overcomes several limitations of prior instruments, including omission or underrepresentation of domains that frequently impact well-being, such as pain, cognition, satisfaction or regret surrounding treatment decisions, and occupational limitations, to comprehensively evaluate the impact of VS diagnosis or its treatment on QOL.

Electrocochleography in the diagnosis of third window conditions.

Introduction: Superior semicircular canal dehiscence (SSCD) is the best-known and most common presentation of so-called "third window conditions." There are a variety of diagnostic measures and tests for this condition in the current literature, including air-bone gap, vestibular-evoked myogenic potentials, and electrocochleography (EcochG). The purpose of this study was to investigate the diagnostic utility of EcochG and its relationship to air-bone gap in a cohort of patients with confirmed SSCD. Methods: We reviewed data from 20 patients (11 female and 9 male subjects, age ranging 21-78 years), with confirmed unilateral or bilateral superior canal dehiscence. In total, 11 patients had unilateral SSCD and 9 patients had bilateral SSCD as determined by high-resolution CT scan. This resulted in the inclusion of twenty-nine ears with superior canal dehiscence and 11 normal ears. Results: Our results indicated that all confirmed SSCD ears presented with an abnormal EcochG SP/AP value and that there was a statistically significant difference between normal and dehiscent ears. There was no statistically significant relationship between air-bone gap and SP/AP ratio in the ears diagnosed with SSCD nor was there a significant difference between dehiscent and normal ears in terms of air-bone gap at three frequencies. Discussion: These results are consistent with previous studies showing the diagnostic utility of EcochG for this condition and the variability of air-bone gap. While an unexpected air-bone gap continues to be a red flag for SSCD, its absence along with the presence of subjective symptoms is a reasonable indicator for further clinical investigation to include EcochG.

Oculomotor and Perceptual Measures of Visual Motion Sensitivity in Patients With Chronic Dizziness Symptoms.

OBJECTIVE: The purpose of this study was to provide empirical data describing the relationship between behavioral responses to dynamic visual motion in adults with chronic dizziness symptoms with and without clinically identifiable peripheral vestibular impairment. DESIGN: Prospective, quasi-experimental study including individuals with chronic dizziness symptoms with identified unilateral peripheral vestibular impairment (n=27), and individuals with chronic dizziness symptoms without identified vestibular impairment (n=26). We measured (a) visual perception of verticality in a dynamic background, (b) postural displacement in a dynamic background, (c) eye movement behaviors in various visual contexts, and (d) self-rating degree of anxiety. RESULTS: Status of peripheral vestibular function was not a significant predictor of behavioral responses to visual motion. The data show that the ability to fixate on a visual target was predictive of postural control in a dynamic visual background. Trial-to-trial variability in verticality responses and degree of self-rated anxiety were also associated with postural control. CONCLUSIONS: Apart from vestibular function, oculomotor control is important for maintaining control of whole-body motor responses during exposure to a dynamic visual stimulus. Vertical perception precision-not accuracy-may be more important for understanding real-world consequences of visual motion sensitivity. Traditional diagnostic evaluations focusing exclusively on characterizing the peripheral vestibular system may not provide insight into the behaviors associated with visual motion sensitivity.

Characterization of Postural Sway in Patients With Persistent Postural-Perceptual Dizziness (PPPD) Using Wearable Motion Sensors.

OBJECTIVE: To extend previous investigations of postural control in patients with persistent-postural perceptual dizziness (PPPD). STUDY DESIGN: Case-controlled, cross-sectional, observational investigation. SETTING: Tertiary care center. PATIENTS: Fifteen patients with PPPD, 15 control volunteers. INTERVENTIONS: Measurement of anterior-posterior (AP) and medial-lateral (ML) sway at the waist using wearable accelerometers during posturography; assessment of reach and gait. MAIN OUTCOME MEASURES: Peak-to-peak AP and ML sway displacement on the six conditions of the Sensory Organization Test (SOT); Scores on the SOT, Functional Reach Test (FRT), and Dynamic Gait Index (DGI). RESULTS: Compared to control volunteers, patients with PPPD had significantly greater sway displacement at the waist in the AP direction in SOT conditions 3, 5, and 6 and in the ML direction in SOT conditions 2 and 4, resulting in significantly lower median equilibrium scores on the composite index and all six SOT conditions. Patients with PPPD had significantly lower scores on the FRT and DGI that were not correlated with SOT performance. AP sway in conditions 3 and 6 differentiated patients with PPPD from controls with high sensitivity (≥0.87) and specificity (≥0.87). CONCLUSIONS: This study replicated previous work showing poor SOT performance by patients with PPPD who had greater AP sway associated with visual dependence and greater ML sway in low demand conditions than controls. Patients with PPPD also performed poorer on the FRT and DGI, but lack of correlation with SOT scores suggested different mechanisms of impairment in postural control, reach, and ambulation. AP sway demonstrated potential as a diagnostic marker.

The Supine Superior Semicircular Canal Dehiscence Test.

Purpose The purpose of this clinical focus article is to describe a new method for assessment of superior semicircular canal dehiscence by laying the patient supine during Valsalva-induced nystagmus testing. Method The traditional Valsalva-induced nystagmus test is described, followed by a new method for assessment of superior semicircular dehiscence conducted by laying the patient supine during testing. A case study is presented to illustrate this new testing technique known as the Supine Superior Semicircular Canal Dehiscence Test. Results It is hypothesized that during Valsalva-induced nystagmus testing performed in the upright, seated position, the dura mater could potentially seal the superior semicircular canal fistula, thereby concealing a defect in the bony labyrinth and yielding a false-negative test. To circumvent this, the patient should be placed in the supine position during Valsalva-induced nystagmus testing in order to prevent the dura mater from inadvertently sealing itself against the petrous portion of the temporal bone. The Supine Superior Semicircular Canal Dehiscence Test may reveal the defect in the bony labyrinth and improve the sensitivity of the Valsalva-induced nystagmus test. Conclusions The Supine Superior Semicircular Canal Dehiscence Test may be more sensitive for identifying superior semicircular canal dehiscence in patients with traditional symptoms and a negative Valsalva-induced nystagmus test in the seated position. While a case study is presented to illustrate the potential benefits of including the Supine Superior Semicircular Canal Dehiscence Test in the battery of diagnostic tests, further research is needed in larger samples.

Agreement between the Skull Vibration-Induced Nystagmus Test and Semicircular Canal and Otolith Asymmetry.

BACKGROUND: How significant asymmetries in otolith organ function in the presence of symmetrical and asymmetrical semicircular canal function influence skull vibration-induced nystagmus testing (SVINT) has not been well described. PURPOSE: The aim of the study is to examine the agreement between SVINT and caloric testing, ocular vestibular-evoked myogenic potentials (oVEMP), and cervical vestibular-evoked myogenic potentials (cVEMP) for detecting asymmetric vestibular function. RESEARCH DESIGN: This is a retrospective study of patients presenting with the chief complaint of vertigo, dizziness, or imbalance. STUDY SAMPLE: A total of 812 patients were studied with a median age at testing of 59 years (interquartile range 46-70; range 18-93) and included 475 (59%) women. INTERVENTION: Either the monothermal warm caloric test or alternate binaural bithermal caloric test, oVEMP, and cVEMP tests were administered to all patients. All patients underwent the SVINT prior to vestibular laboratory testing. DATA COLLECTION AND ANALYSIS: Agreement between tests categorized as normal versus abnormal was summarized using percent concordance (PC). Sensitivity and specificity values were calculated for SVINT compared with other tests of vestibular function. RESULTS: There was higher agreement between ipsilateral and contralateral SVINT with the caloric test (PC = 80% and 81%, respectively) compared with oVEMP (PC = 63% and 64%, respectively) and cVEMP (PC = 76% and 78%, respectively). Ipsilateral and contralateral SVINT showed higher sensitivity for the caloric test (sensitivity = 47% and 36%, respectively) compared with oVEMP (sensitivity = 26% and 21%, respectively), or cVEMP (sensitivity = 33% vs. 27%, respectively). Specificity of SVINT was high (>80%) for all assessments of vestibular function. CONCLUSION: The presence of SVIN is a useful indicator of the asymmetry of vestibular function between the two ears when making judgments about semicircular canal asymmetry but is less sensitive to asymmetries in otolith organ function.

Vestibular Evoked Myogenic Potentials and Postural Control in Adults with Age-Related Hearing Loss.

BACKGROUND: Age-related changes to auditory function have been attributed to, through histopathological study, specific degradation of the sensory, supporting, and afferent structures of the cochlea. Similar to age-related hearing loss (ARHL), age-related changes to the vestibular sensory and supporting structures with specific degeneration of the saccule, utricle, otoconia, primary vestibular afferents have also been noted. Significant decreases in postural control with age are also well-documented in the literature attributed to multifactorial changes in function. PURPOSE: The purpose of this study is to further evaluate the association of ARHL and saccule/utricle function as measured by VEMPs and postural control measures. STUDY SAMPLE: Audiologic, vestibular and postural control results from 34 participants were analyzed. The age range was from 50 to 70 years old with 16 males and 18 females. Group 1 consisted of 33 ears from participants age 50-70 with normal hearing with average age of 60.8 years (sd 6.287 years) and an average speech-frequency PTA of 14.8 dB HL. Group 2 consisted of 27 ears from participants age 50-70 years with ARHL and an average age of 62.9 years (sd 4.984 years) with an average speech-frequency PTA of 39.9 dB HL. DATA COLLECTION AND ANALYSIS: Independent samples t-tests were used to assess group mean differences for dependent variables. The independent variable was group with 2 levels (normal hearing, ARHL). The dependent variables were cVEMP P1/N1 Amplitude, cVEMP P1 Latency, cVEMP N1 Latency, cVEMP P2 Latency, oVEMP N1/P1 Amplitude, oVEMP N1 Latency, and oVEMP P1 Latency. Additional analyses were completed using Pearson correlation to evaluate the relationship of audiometric findings to the dependent variables. RESULTS: Results indicated significantly decreased cVEMP P1/N1 amplitude and oVEMP N1/P1 amplitude adults 50-70-years of age with ARHL compared with their normal counterparts. Significant correlations were also found for audiometric results and both cVEMP and oVEMP measures. CONCLUSIONS: Overall, the results of this study describe concomitant auditory and vestibular degeneration as measured by audiometric testing and vestibular function testing involving the saccule and to a lesser degree the utricle.

A Comparison of Dizziness Handicap Inventory Scores by Categories of Vestibular Diagnoses.

OBJECTIVE: The Dizziness Handicap Inventory (DHI) is a 25-item self-report quantifying dizziness-related physical and emotional symptoms and restrictions in daily activities. DHI scores do not correlate with severity of structural vestibular deficits; thus, high DHI scores may reflect other causes of morbidity. This study investigated the relationship between total DHI scores and the presence of structural, functional, and psychiatric disorders in tertiary neurotology patients. STUDY DESIGN: Retrospective. SETTING: Tertiary center. PATIENTS: Eighty-five patients who underwent multidisciplinary neurotologic evaluations. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURE(S): Active illnesses identified by a multidisciplinary neurotology team were abstracted from medical records, cataloged as structural, functional, or psychiatric disorders, and used to group patients into diagnostic categories: structural (structural disorders only), functional (functional disorders with/without structural disorders), and psychiatric (psychiatric disorders with/without other conditions). DHI scores were compared across diagnostic categories. Sensitivities and specificities of DHI scores for identifying structural versus functional or psychiatric disorders were calculated. RESULTS: Mean DHI scores differed significantly by diagnostic category (structural 35 ±â€Š18, functional 64 ±â€Š15, and psychiatric 65 ±â€Š19), before and after adjusting for age and sex (p < 0.001, Hedges' g>1.62 for structural versus functional and psychiatric categories). DHI≤30 (mild handicap) had specificity = 0.98 for structural disorders alone, whereas DHI>60 (severe handicap) had specificity = 0.88 for functional or psychiatric disorders. CONCLUSIONS: In this tertiary cohort, categories of illnesses had large effects on total DHI scores. Patients with scores ≤30 were likely to have structural disorders alone, whereas those with scores >60 were likely to have functional or psychiatric disorders, with or without coexisting structural conditions.