Utricular Dysfunction and Hearing Impairment Affect Spatial Navigation in Community-dwelling Healthy Adults: Analysis from the Baltimore Longitudinal Study of Aging.

INTRODUCTION: Spatial navigation, the ability to move through one's environment, is a complex skill utilized in everyday life. The effects of specific vestibular end-organ deficits and hearing impairments on spatial navigation have received little to no attention. We hypothesized that hearing impairment adversely affects spatial navigation and that bi-modal impairments (vestibular and hearing) further impair navigation ability. METHODS: Data from 182 participants in the Baltimore Longitudinal Study of Aging who had interpretable results for the video head impulse test (vHIT), cervical (cVEMP) and ocular (oVEMP) vestibular evoked myogenic potentials, audiometric testing, and the triangle completion test (TCT) were retrospectively analyzed. Multiple linear regression, controlling for age, sex, and cognition, was employed to identify predictors of TCT performance in terms of end-point error, angle deviation, and distance walked. RESULTS: oVEMP abnormalities were associated with larger end-point error (p=0.008) and larger angle deviation (p=0.002) but were not associated with distance walked (p=0.392). Abnormalities on cVEMP and vHIT were not associated with distance walked (p=0.835, p=0.300), end-point error (p=0.256, p=0.808), or angle deviation (p=0.192, p=0.966). Compared with normal hearing adults, hearing impaired adults walked a shorter distance during the TCT (p=0.049) but had similar end-point error (p=0.302) and angle deviation (p=0.466). There was no interaction between vestibular and hearing function for predicting spatial navigation ability. CONCLUSION: In this cohort analysis, utricular dysfunction and hearing impairment were associated with poorer spatial navigation performance. We postulate that hearing impairment negatively affects one's ability to use real-time, intrinsic auditory cues and/or prior experience to guide navigation.

Healthcare Utilization Among Adults With Vestibular Vertigo in the United States.

OBJECTIVES: Vestibular vertigo has been shown to have a high lifetime prevalence. Previous studies have described the increased morbidities associated with vestibular vertigo. DESIGN: In this cross-sectional study of the 2016 National Health Interview Study, we sought to explore whether individuals with vestibular vertigo were more likely to utilize healthcare resources compared with those without vestibular vertigo. We characterized utilization of specific healthcare resources including general doctors, specialist doctors, emergency departments, mental health professionals, and others among individuals with vestibular vertigo to better understand how individuals with vertigo interact with the US healthcare system. RESULTS: In multivariable analyses, participants with vestibular vertigo had an increased number of nights in the hospital in the last 12 months (mean difference = 0.67 days, 95% confidence interval [CI] = 0.37 to 0.97), increased odds of receiving healthcare 10 or more times in the last 12 months (odds ratio = 2.22, 95% CI = 1.99 to 2.48) and increased number of visits to a healthcare professional in the last 2 weeks (mean difference = 0.17 visits, 95% CI = 0.14 to 0.21). In addition, participants with vestibular vertigo had increased odds of visiting both general doctors, specialist doctors, and other healthcare professionals. CONCLUSIONS: These findings characterize how individuals with vestibular vertigo utilize and interact with healthcare resources compared with those without vestibular vertigo.

Staying Virtual: A Survey Study of the Virtual Lecture Experience in Academic Medicine.

BACKGROUND: Increasing clinical demands can adversely impact academic advancement, including the ability to deliver lectures and disseminate scholarly work. The virtual lecture platform became mainstream during the height of the coronavirus-19 pandemic. Lessons learned from this period may offer insight into supporting academic productivity among physicians who must balance multiple demands, including high clinical workloads and family care responsibilities. We evaluated perceptions on delivering virtual lectures to determine whether virtual venues merit continuation beyond the pandemic's initial phase and whether these perceptions differ by gender and rank. METHODS: In a survey study, faculty who spoke in 1 of 3 virtual lecture programs in the Departments of Anesthesiology and Critical Care Medicine, Otolaryngology, and Radiology at a university hospital in 2020 to 2022 were queried about their experience. Speakers' motivations to lecture virtually and the perceived advantages and disadvantages of virtual and in-person lectures were analyzed using descriptive statistics and qualitative analyses. RESULTS: Seventy-two of 95 (76%) faculty members responded (40% women, 38% men, and 22% gender undisclosed). Virtual lectures supported the speakers "a lot" to "extremely" with the following goals: enhancing one's reputation and credibility (76%), networking (70%), receiving feedback (63%), and advancing prospects for promotion (59%). Virtual programs also increased the speakers' sense of accomplishment (70%) and professional optimism (61%) by at least "a lot," including instructors and assistant professors who previously had difficulty obtaining invitations to speak outside their institution. Many respondents had declined prior invitations to speak in-person due to clinical workload (66%) and family care responsibilities (58%). Previous opportunities to lecture in-person were also refused due to finances (39%), teaching (26%), and research (19%) requirements, personal medical conditions or disabilities (9%), and religious obligations (5%). Promotion was a stronger motivating factor to lecture virtually for instructors and assistant professors than for associate and full professors. By contrast, disseminating work and ideas was a stronger motivator for associate and full professors. Associate and full professors also reported greater improvement in work-related well-being than earlier career faculty from the virtual lecture experience. Very few differences were found by gender. CONCLUSIONS: Virtual lecture programs support faculty who might not otherwise have the opportunity to lecture in-person due to multiple constraints. To increase the dissemination of scholarly work and expand opportunities to all faculty, virtual lectures should continue even as in-person venues are reestablished.

Sensory and motor deficits as contributors to early cognitive impairment.

INTRODUCTION: Age-related sensory and motor impairment are associated with risk of dementia. No study has examined the joint associations of multiple sensory and motor measures on prevalence of early cognitive impairment (ECI). METHODS: Six hundred fifty participants in the Baltimore Longitudinal Study of Aging completed sensory and motor function tests. The association between sensory and motor function and ECI was examined using structural equation modeling with three latent factors corresponding to multisensory, fine motor, and gross motor function. RESULTS: The multisensory, fine, and gross motor factors were all correlated (r = 0.74 to 0.81). The odds of ECI were lower for each additional unit improvement in the multisensory (32%), fine motor (30%), and gross motor factors (12%). DISCUSSION: The relationship between sensory and motor impairment and emerging cognitive impairment may guide future intervention studies aimed at preventing and/or treating ECI. HIGHLIGHTS: Sensorimotor function and early cognitive impairment (ECI) prevalence were assessed via structural equation modeling. The degree of fine and gross motor function is associated with indicators of ECI. The degree of multisensory impairment is also associated with indicators of ECI.

Characterization of Balance Control and Postural Stability in Patients With Alzheimer Disease.

Balance in Alzheimer disease (AD) patients is not rigorously understood. In this study, we characterize balance using qualitative [Berg Balance Scale (BBS)] and quantitative measures (posturography) and assess relationships between qualitative and quantitative balance measures in AD. Patients with mild-moderate AD (n=48) were recruited. BBS scores and posturography metrics, including medial-lateral sway range, anterior-posterior sway range, sway area, and sway velocity, were assessed in eyes-open and eyes-closed conditions. Adjusted linear regressions were used to assess relationships between posturography and BBS score. Mean BBS score was 50.4±5.3. In eyes-open conditions, posturography and BBS score were not significantly associated. In eyes-closed conditions, better BBS score was significantly associated with lower sway area (ß=-0.91; P =0.006). Better scores of BBS items involving turning and reduced base of support were associated with greater eyes-closed sway area. Posturography in the more challenging eyes-closed condition may predict functional balance deficits in AD patients.

Vestibular Vertigo and Disparities in Healthcare Access Among Adults in the United States.

OBJECTIVE: Vertigo and dizziness have a high lifetime prevalence with significant impacts on daily life. We sought to explore differences in access to and ability to afford care among adults with vestibular vertigo by race/ethnicity, income, and insurance type. DESIGN: This is a cross-sectional study using the 2016 National Health Interview Survey. A total of 32,047 adults who completed the 2016 National Health Interview Survey Balance Supplement were analyzed. We used a previously validated definition of vertigo defined as (1) positional vertigo, (2) rotational vertigo, or (3) recurrent dizziness with nausea and either oscillopsia or imbalance. We examined several self-reported measures of healthcare utilization and access. RESULTS: Among adults with vestibular vertigo, African Americans had significantly increased odds of delayed care due to lack of transportation; Hispanic ethnicity was associated with decreased odds of skipping medication doses and asking a doctor for a lower-cost medication. Adults with public insurance had significantly lower odds of reporting delayed care due to worry about cost, not receiving medical care due to cost, and delayed filling of a prescription, but had greater odds of reporting delayed care due to lack of transportation. Lack of insurance and lower income were associated with increased odds of delaying and not receiving care due to cost. CONCLUSION: These findings demonstrate significant differences in access to care among adults with vestibular vertigo in the United States based on race, income, and health insurance status.

Application and validation of an algorithmic classification of early impairment in cognitive performance.

OBJECTIVE: Due to the long prodromal period for dementia pathology, approaches are needed to detect cases before clinically recognizable symptoms are apparent, by which time it is likely too late to intervene. This study contrasted two theoretically-based algorithms for classifying early cognitive impairment (ECI) in adults aged ≥50 enrolled in the Baltimore Longitudinal Study of Aging. METHOD: Two ECI algorithms were defined as poor performance (1 standard deviation [SD] below age-, sex-, race-, and education-specific means) in: (1) Card Rotations or California Verbal Learning Test (CVLT) immediate recall and (2) ≥1 (out of 2) memory or ≥3 (out of 6) non-memory tests. We evaluated concurrent criterion validity against consensus diagnoses of mild cognitive impairment (MCI) or dementia and global cognitive scores using receiver operating characteristic (ROC) curve analysis. Predictive criterion validity was evaluated using Cox proportional hazards models to examine the associations between algorithmic status and future adjudicated MCI/dementia. RESULTS: Among 1,851 participants (mean age = 65.2 ± 11.8 years, 50% women, 74% white), the two ECI algorithms yielded comparably moderate concurrent criterion validity with adjudicated MCI/dementia. For predictive criterion validity, the algorithm based on impairment in Card Rotations or CVLT immediate recall was the better predictor of MCI/dementia (HR = 3.53, 95%CI: 1.59-7.84) over 12.3 follow-up years. CONCLUSIONS: Impairment in visuospatial ability or memory may be capable of detecting early cognitive changes in the preclinical phase among cognitively normal individuals.

Loss of peripheral vestibular input alters the statistics of head movement experienced during natural self-motion.

KEY POINTS: Sensory systems are adapted to the statistical structure of natural stimuli, thereby optimizing neural coding. Head motion during natural activities is first sensed and then processed by central vestibulo-motor pathways to influence subsequent behaviour, thereby establishing a feedback loop. To investigate the role of this vestibular feedback on the statistical structure of the head movements, we compared head movements in patients with unilateral vestibular loss and healthy controls. We show that the loss of vestibular feedback substantially alters the statistical structure of head motion for activities that require rapid online feedback control and predict this change by modelling the effects of increased movement variability. Our findings suggest that, following peripheral vestibular loss, changes in the reliability of the sensory input to central pathways impact the statistical structure of head motion during voluntary behaviours. ABSTRACT: It is widely believed that sensory systems are adapted to optimize neural coding of their natural stimuli. Recent evidence suggests that this is the case for the vestibular system, which senses head movement and contributes to essential functions ranging from the most automatic reflexes to voluntary motor control. During everyday behaviours, head motion is sensed by the vestibular system. In turn, this sensory feedback influences subsequent behaviour, raising the questions of whether and how real-time feedback provided by the vestibular system alters the statistical structure of head movements. We predicted that a reduction in vestibular feedback would alter head movement statistics, particularly for tasks reliant on rapid vestibular feedback. To test this proposal, we recorded six-dimensional head motion in patients with variable degrees of unilateral vestibular loss during standard balance and gait tasks, as well as dynamic self-paced activities. While distributions of linear accelerations and rotational velocities were comparable for patients and age-matched healthy controls, comparison of power spectra revealed significant differences during more dynamic and challenging activities. Specifically, consistent with our prediction, head movement power spectra were significantly altered in patients during two tasks that required rapid online vestibular feedback: active repetitive jumping and walking on foam. Using computational methods, we analysed concurrently measured torso motion and identified increases in head-torso movement variability. Taken together, our results demonstrate that vestibular loss significantly alters head movement statistics and further suggest that increased variability and impaired feedback to internal models required for accurate motor control contribute to the observed changes.

Physical and Vestibular Physical Therapy Referrals in People With Alzheimer Disease.

People with Alzheimer disease (AD) are at increased risk of falls and disproportionately burdened with vestibular impairment compared with healthy older adults. Although physical therapy (PT) and vestibular physical therapy (VPT) are effective rehabilitation interventions in improving balance and fall risk, referral patterns for these services in the AD population are understudied. A retrospective chart review was conducted of patients seen for primary AD care at a tertiary AD referral center to investigate the frequency of rehabilitation referrals. Of the 801 people with AD seen for AD care in 1 year, 48 individuals (6.0%) were referred to PT and 5 individuals (0.6%) to VPT. People with AD appear to receive very infrequent PT and VPT referrals, despite the potentially large number of people with AD who could benefit from PT and VPT services to improve their balance and vestibular function.

Association Between Saccule and Semicircular Canal Impairments and Cognitive Performance Among Vestibular Patients.

OBJECTIVES: Growing evidence suggests that vestibular function impacts higher-order cognitive ability such as visuospatial processing and executive functioning. Despite evidence demonstrating vestibular functional impairment impacting cognitive performance, it is unknown whether cognitive ability is differentially affected according to the type of vestibular impairment (semicircular canal [SCC] versus saccule) among patients with diagnosed vestibular disease. DESIGN: Fifty-four patients who presented to an academic neurotologic clinic were recruited into the study. All patients received a specific vestibular diagnosis. Forty-one patients had saccule function measured with the cervical vestibular-evoked myogenic potential, and 43 had SCC function measured using caloric irrigation. Cognitive tests were administered to assess cognitive performance among patients. One hundred twenty-five matched controls were recruited from the Baltimore Longitudinal Study of Aging to compare cognitive performance in patients relative to age-matched healthy controls. RESULTS: Using multivariate linear regression analyses, patients with bilaterally absent cervical vestibular-evoked myogenic potential responses (i.e., bilateral saccular impairments) were found to take longer in completing the Trail-Making test (ß = 25.7 sec, 95% confidence interval = 0.3 to 51.6) and to make significantly more errors on the Benton Visual Retention test part-C (ß = 4.5 errors, 95% confidence interval [CI] = 1.2 to 7.8). Patients with bilateral SCC impairment were found to make significantly more errors on the Benton Visual Retention test part-C (ß = 9.8 errors, 95% CI = 0.2 to 19.4). From case-control analysis, for each SD difference in Trail-Making test part-B time, there was a corresponding 142% increase in odds of having vestibular impairment (odds ratio = 2.42, 95% CI = 1.44 to 4.07). CONCLUSIONS: These data suggest that bilateral saccule and SCC vestibular impairments may significantly affect various domains of cognitive performance. Notably, the cognitive performance in patients in this study was significantly poorer relative to age-matched healthy adults. Cognitive assessment may be considered in patients with saccule and SCC impairments, and cognitive deficits in vestibular patients may represent an important target for intervention.

Vestibular impairment, cognitive decline and Alzheimer's disease: balancing the evidence.

The vestibular (inner ear balance) system senses head movement and orientation in space. Vestibular sensory input plays a critical role in spatial cognitive abilities such as spatial memory and spatial navigation. Vestibular function declines with age, and recent studies have shown that age-related vestibular impairment is associated with poorer spatial cognitive skills in healthy older adults. Moreover, vestibular impairment is disproportionately prevalent among individuals with mild cognitive impairment and Alzheimer's disease, and specifically in cognitively-impaired individuals who have spatial deficits such as disorientation and difficulty driving. Indeed, emerging evidence suggests that age-related vestibular impairment contributes to a 'spatial' subtype of Alzheimer's disease, characterized by highly morbid symptoms such as wandering and falls. Given that vestibular impairment can be treated through simple, physical-therapy based exercises, identifying and treating vestibular deficits in older adults with and without cognitive impairment may offer substantial benefit in preventing, mitigating and forestalling cognitive decline.

Sexual dimorphism in vestibular function and dysfunction.

It has been recognized for some time that females appear to be overrepresented in the incidence of many vestibular disorders, and recent epidemiological studies further support this idea. While it is possible that this is due to a reporting bias, another possibility is that there are actual differences in the incidence of vestibular dysfunction between males and females. If this is true, it could be due to a sexual dimorphism in vestibular function and therefore dysfunction, possibly related to the hormonal differences between females and males, although the higher incidence of vestibular dysfunction in females appears to last long after menopause. Many other neurochemical differences exist between males and females, however, that could be implicated in sexual dimorphism. This review critically explores the possibility of sexual dimorphism in vestibular function and dysfunction, and the implications it may have for the treatment of vestibular disorders.

Failure on the Foam Eyes Closed Test of Standing Balance Associated With Reduced Semicircular Canal Function in Healthy Older Adults.

OBJECTIVES: Standing on foam with eyes closed (FOEC) has been characterized as a measure of vestibular function; however, the relative contribution of vestibular function and proprioceptive function to the FOEC test has not been well described. In this study, the authors investigate the relationship between peripheral sensory systems (vestibular and proprioception) and performance on the FOEC test in a cohort of healthy adults. DESIGN: A total of 563 community-dwelling healthy adults (mean age, 72.7 [SD, 12.6] years; range, 27 to 93 years) participating in the Baltimore Longitudinal Study of Aging were tested. Proprioceptive threshold (PROP) was evaluated with passive motion detection at the right ankle. Vestibulo-ocular reflex (VOR) gain was measured using video head impulses. Otolith function was measured with cervical and ocular vestibular-evoked myogenic potentials. Participants stood on FOEC for 40 sec while wearing BalanSens (BioSensics, LLC, Watertown, MA) to quantify center of mass sway area. A mixed-model multiple logistic regression was used to examine the odds of passing the FOEC test based on PROP, VOR, cervical vestibular-evoked myogenic potential, and ocular vestibular-evoked myogenic potential function in a multisensory model while controlling for age and gender. RESULTS: The odds of passing the FOEC test decreased by 15% (p < 0.001) for each year of increasing age and by 8% with every 0.1 reduction in VOR gain (p = 0.025). Neither PROP nor otolith function was significantly associated with passing the FOEC test. CONCLUSIONS: Failure to maintain balance during FOEC may serve as a proxy for rotational vestibular contributions to postural control. Semicircular canals are more sensitive to low-frequency motion than otoliths that may explain these relationships because standing sway is dominated by lower frequencies. Lower VOR gain and increased age independently decreased the odds of passing the test.

Vestibular Physical Therapy in Individuals With Cognitive Impairment: A Theoretical Framework.

Falls are a major health care concern in individuals with Alzheimer disease (AD) and their caregivers. Vestibular impairment is a known risk factor for falls, and individuals with AD have been shown to have an increased prevalence of vestibular loss compared with age-matched controls. Vestibular physical therapy (VPT) is effective in improving balance and reducing fall risk in cognitively-intact persons with vestibular impairment. However, the effectiveness of VPT in improving balance and reducing falls in individuals with AD who have vestibular loss has never been explored. SUMMARY OF KEY POINTS:: In this article, we apply prevailing ideas about rehabilitation and motor learning in individuals with cognitive impairment (IwCI) to VPT. RECOMMENDATIONS FOR CLINICAL PRACTICE:: We propose a modification of current evidence-based VPT protocols for IwCI using the strength-based theoretical framework that emphasizes the motor learning abilities of IwCI. In addition, we highlight the importance of establishing an excellent rapport with IwCI, and present key strategies for optimizing the therapeutic relationship. In ongoing work, we are assessing the efficacy of this modified VPT protocol in IwCI to improve balance and reduce falls.

Association Between Vestibular Vertigo and Motor Vehicle Accidents: Data From the 2016 National Health Interview Survey.

Recent evidence has shown that individuals with vestibular impairment have higher rates of self-reported driving difficulty compared with individuals without vestibular impairment. However, it is unknown whether individuals with vestibular impairment are more likely to be involved in motor vehicle accidents. We used data from the 2016 National Health Interview Survey of U.S. adults to evaluate whether individuals with vestibular vertigo are more likely to experience motor vehicle accidents relative to individuals without vestibular vertigo. In multivariate analysis, vestibular vertigo was associated with an over threefold increased odds of motor vehicle accidents (odds ratio, 3.5; 95% confidence interval, 1.7-7.3). This study supports an association between vestibular dysfunction and driving impairment, and provides a relative risk of motor vehicle accidents associated with vestibular vertigo that clinicians may utilize in counseling patients on the potential safety hazards of driving.

Saccular Impairment in Alzheimer's Disease Is Associated with Driving Difficulty.

BACKGROUND/AIMS: Patients with Alzheimer's disease (AD) experience increased rates of vestibular loss. Recent studies suggest that saccular impairment in mild cognitive impairment (MCI) and AD patients is associated with impaired spatial cognitive function. However, the impact of saccular impairment on everyday behaviors that rely on spatial cognitive function is unknown. METHODS: We recruited 60 patients (21 MCI and 39 AD) from an interdisciplinary Memory Clinic. Saccular function was measured, and a visuospatial questionnaire was administered to assess whether participants experienced impairments in terms of driving difficulty, losing objects, falls, and fear of falling. RESULTS: In multiple logistic regression analyses, MCI and AD patients with bilateral saccular impairment had a significant, greater than 12-fold odds of driving difficulty (OR 12.1, 95% CI 1.2, 117.7) compared to MCI and AD patients with normal saccular function, and the association appears to be mediated by spatial cognition as measured by the Money Road Map Test. CONCLUSION: This study suggests a novel link between saccular impairment and driving difficulty in MCI and AD patients and demonstrates that driving difficulty may be a real-world manifestation of impaired spatial cognition associated with saccular impairment.

Vestibular vertigo and comorbid cognitive and psychiatric impairment: the 2008 National Health Interview Survey.

BACKGROUND/AIMS: Patients with vestibular disease have been observed to have concomitant cognitive and psychiatric dysfunction. We evaluated the association between vestibular vertigo, cognitive impairment and psychiatric conditions in a nationally representative sample of US adults. METHODS: We performed a cross-sectional analysis using the 2008 National Health Interview Survey (NHIS), which included a Balance and Dizziness Supplement, and questions about cognitive function and psychiatric comorbidity. We evaluated the association between vestibular vertigo, cognitive impairment (memory loss, difficulty concentrating, confusion) and psychiatric diagnoses (depression, anxiety and panic disorder). RESULTS: We observed an 8.4% 1-year prevalence of vestibular vertigo among US adults. In adjusted analyses, individuals with vestibular vertigo had an eightfold increased odds of 'serious difficulty concentrating or remembering' (OR 8.3, 95% CI 4.8 to 14.6) and a fourfold increased odds of activity limitation due to difficulty remembering or confusion (OR 3.9, 95% CI 3.1 to 5.0) relative to the rest of the US adults. Individuals with vestibular vertigo also had a threefold increased odds of depression (OR 3.4, 95% CI 2.9 to 3.9), anxiety (OR 3.2, 95% CI 2.8 to 3.6) and panic disorder (OR 3.4, 95% CI 2.9 to 4.0). CONCLUSIONS: Our findings indicate that vestibular impairment is associated with increased risk of cognitive and psychiatric comorbidity. The vestibular system is anatomically connected with widespread regions of the cerebral cortex, hippocampus and amygdala. Loss of vestibular inputs may lead to impairment of these cognitive and affective circuits. Further longitudinal research is required to determine if these associations are causal.

Race and fall risk: data from the National Health and Aging Trends Study (NHATS).

OBJECTIVES: the objective of this study was to explore whether race-based difference in fall risk may be mediated by environmental and physical performance risk factors. METHODS: using data from a nationally representative longitudinal survey of 7,609 community-dwelling participants in the National Health and Aging Trends Study (NHATS), we evaluated whether racial differences in fall risk may be explained by physical performance level (measured by the Short Physical Performance Battery), mobility disability, physical activity level and likelihood of living alone. Multivariate Poisson regression and mediation models were used in analyses. RESULTS: in whites and blacks, the annual incidence of 'any fall' was 33.8 and 27.1%, respectively, and the annual incidence of 'recurrent falls' was 15.5 and 12.3%, respectively. Compared with whites, blacks had relative risks of 0.7 (95% confidence interval 0.6-0.8) and 0.6 (0.5-0.8) for sustaining any fall and recurrent falls, respectively, in adjusted analyses. Blacks had poorer performance on the SPPB (P < 0.001), higher levels of mobility disability (P < 0.001), similar levels of physical activity (P = 0.19) and were equally likely to live alone relative to whites (P = 0.77). Mediation analysis revealed that these risk factors collectively acted as suppressors and none of these factors accounted for the racial differences in fall risk observed. CONCLUSIONS: relative to whites, blacks were at 30 and 40% decreased risk of sustaining any fall and recurrent falls, respectively. This difference in risk remains unexplained.

Compensatory saccades benefit from prediction during head impulse testing in early recovery from vestibular deafferentation.

The head impulse test (HIT) can identify a deficient vestibulo-ocular reflex (VOR) by the compensatory saccade (CS) generated once the head stops moving. The inward HIT is considered safer than the outward HIT, yet might have an oculomotor advantage given that the subject would presumably know the direction of head rotation. Here, we compare CS latencies following inward (presumed predictable) and outward (more unpredictable) HITs after acute unilateral vestibular nerve deafferentation. Seven patients received inward and outward HITs delivered at six consecutive postoperative days (POD) and again at POD 30. All head impulses were recorded by portable video-oculography. CS included those occurring during (covert) or after (overt) head rotation. Inward HITs included mean CS latencies (183.48 ms ± 4.47 SE) that were consistently shorter than those generated during outward HITs in the first 6 POD (p = 0.0033). Inward HITs induced more covert saccades compared to outward HITs, acutely. However, by POD 30 there were no longer any differences in latencies or proportions of CS and direction of head rotation. Patients with acute unilateral vestibular loss likely use predictive cues of head direction to elicit early CS to keep the image centered on the fovea. In acute vestibular hypofunction, inwardly applied HITs may risk a preponderance of covert saccades, yet this difference largely disappears within 30 days. Advantages of inwardly applied HITs are discussed and must be balanced against the risk of a false-negative HIT interpretation.