Age predicts the absence of caloric-induced vertigo.

INTRODUCTION: The absence of vertigo during the caloric test, despite a robust response, has been suggested to represent a central vestibular system phenomenon. The purpose of this investigation was to determine the prevalence of absent caloric-induced vertigo perception in an unselected group of patients and to assess possible predicting variables. METHODS: Prospective investigation of 92 unselected patients who underwent caloric testing. Inclusion criteria were that each patient generate a maximum slow phase velocity (maxSPV) ≥ 15 deg/sec and a caloric asymmetry of ≤10%. Following the caloric, patients were asked, "Did you have any sensation of motion?" RESULTS: Results showed 75% of patients reported motion with a mean age of 56.51 years compared to a mean age of 66.55 in the 25% of patients reporting an absence of motion. A logistic regression was performed and the overall model was statistically significant accounting for 29% of the variance in caloric perception. The significant predictor variables were patient age and maxSPV of the caloric response. The effect size for both variables was small with an odds ratio of .9 for maxSPV and 1.06 for age. CONCLUSIONS: The current investigation showed that both age and maxSPV of the caloric response were significant predictors of vertigo perception during the caloric exam. However, the association between age and caloric perception is not conclusive. Although there is evidence to suggest that these findings represent age-related changes in the central processing of vestibular system stimulation, there are additional unmeasured factors that influence the perception of caloric-induced vertigo.

Patterns of abnormality in cVEMP, oVEMP, and caloric tests may provide topological information about vestibular impairment.

BACKGROUND: The cervical vestibular evoked myogenic potential (cVEMP) is recorded from the sternocleidomastoid muscle (SCM) and represents a stimulus-evoked attenuation of electromyographic (EMG) activity following activation of the saccule and inferior vestibular nerve. In addition to the cVEMP, it is possible to record a biphasic response from the infraorbital region following stimulation that is identical to that used to record the cVEMP. This response is known as the ocular VEMP (oVEMP). The peripheral vestibular origins of the oVEMP elicited with air conduction remain controversial as some investigators argue the response originates from the saccule and others argue that the response emanates from the utricle. We review several lines of evidence and present several case studies supporting the contention that the oVEMP to air conduction stimulation derives its peripheral origins predominantly from the utricle and superior vestibular nerve. PURPOSE: To review the current evidence regarding the peripheral origins of the oVEMP. Further, a purpose of this report is to present case studies illustrating that the cVEMP and oVEMP to air conduction stimulation may vary independently of one another in patients with peripheral vestibular system impairments. RESEARCH DESIGN: A collection of case studies illustrating three common patterns of abnormality observed in patients complaining of vertigo seen in a tertiary care referral center. STUDY SAMPLE: Retrospective analysis of data from three patients complaining of dizziness and/or vertigo who have undergone vestibular function tests. RESULTS: Each case report illustrates a different pattern of abnormality of caloric, cVEMP, and oVEMP tests results from three patients with a vestibular nerve section, superior vestibular neuritis, and Ménière's disease, respectively. CONCLUSIONS: We have shown that the cVEMP and oVEMP can vary independent of one another, and in that way, provide topological information about the sites of impairment. We feel that, with caloric, oVEMP, and cVEMP tests, it is possible to augment the diagnostic information we are able to provide regarding the location, or locations, of vestibular system impairment. These findings suggest that air conduction oVEMPs measure a part of the peripheral vestibular system different from that measured by cVEMPs, perhaps the utricle, and similar to that measured by caloric testing, the superior portion of the vestibular nerve.

The influence of unilateral saccular impairment on functional balance performance and self-report dizziness.

BACKGROUND: Postural stability in humans is largely maintained by vestibular, visual, and somatosensory inputs to the central nervous system. Recent clinical advances in the assessment of otolith function (e.g., cervical and ocular vestibular evoked myogenic potentials [cVEMPs and oVEMPs], subjective visual vertical [SVV] during eccentric rotation) have enabled investigators to identify patients with unilateral otolith impairments. This research has suggested that patients with unilateral otolith impairments perform worse than normal healthy controls on measures of postural stability. It is not yet known if patients with unilateral impairments of the saccule and/or inferior vestibular nerve (i.e., unilaterally abnormal cVEMP) perform differently on measures of postural stability than patients with unilateral impairments of the horizontal SCC (semicircular canal) and/or superior vestibular nerve (i.e., unilateral caloric weakness). Further, it is not known what relationship exists, if any, between otolith system impairment and self-report dizziness handicap. PURPOSE: The purpose of this investigation was to determine the extent to which saccular impairments (defined by a unilaterally absent cVEMP) and impairments of the horizontal semicircular canal (as measured by the results of caloric testing) affect vestibulospinal function as measured through the Sensory Organization Test (SOT) of the computerized dynamic posturography (CDP). A secondary objective of this investigation was to measure the effects, if any, that saccular impairment has on a modality-specific measure of health-related quality of life. RESEARCH DESIGN: A retrospective cohort study. Subjects were assigned to one of four groups based on results from balance function testing: Group 1 (abnormal cVEMP response only), Group 2 (abnormal caloric response only), Group 3 (abnormal cVEMP and abnormal caloric response), and Group 4 (normal control group). STUDY SAMPLE: Subjects were 92 adult patients: 62 were seen for balance function testing due to complaints of dizziness, vertigo, or unsteadiness, and 30 served as controls. INTERVENTION: All subjects underwent videonystagmography or electronystagmography (VNG/ENG), vestibular evoked myogenic potentials (VEMPs), self-report measures of self-perceived dizziness disability/handicap (Dizziness Handicap Inventory), and tests of postural control (Neurocom Equitest). DATA COLLECTION AND ANALYSIS: Subjects were categorized into one of four groups based on balance function test results. All variables were subjected to a multifactor analysis of variance (ANOVA). The Dizziness Handicap Inventory (DHI) total scores and equilibrium scores served as the dependent variables. RESULTS: Results showed that patients with abnormal unilateral saccular or inferior vestibular nerve function (i.e., abnormal cVEMP) demonstrated significantly impaired postural control when compared to normal participants. However, this group demonstrated significantly better postural stability when compared to the group with abnormal caloric responses alone and the group with abnormal caloric responses and abnormal cVEMP results. Patients with an abnormal cVEMP did not differ significantly on the DHI compared to the other two impaired groups. CONCLUSIONS: We interpret these findings as evidence that a significantly asymmetrical cVEMP in isolation negatively impacts performance on measures of postural control compared to normal subjects but not compared to patients with significant caloric weaknesses. However, patients with a unilaterally abnormal cVEMP do not differ from patients with significant caloric weaknesses in regard to self-perceived dizziness handicap.

Psychological comorbidities and their relationship to self-reported handicap in samples of dizzy patients.

Factors such as anxiety, depression, somatic awareness, autonomic symptoms, and differences in coping strategies are known to affect dizziness handicap. We studied these factors in 63 consecutive "dizzy" patients. This sample was subgrouped into normals and patients with benign paroxysmal positional vertigo, compensated and uncompensated unilateral peripheral vestibular system impairment, or abnormal vestibular evoked myogenic potential as a single significant diagnostic finding. Results showed that (1) anxiety and depression occur with greater frequency in dizzy patients than in the normal population; (2) the magnitude of anxiety, depression, somatization, and autonomic symptoms does not differ significantly in subgroups of patients; (3) women tended to report greater handicap and somatic/autonomic symptoms; and (4) Dizziness Handicap Inventory total scores were correlated with patients' complaints of somatic/autonomic symptoms, anxiety, depression, and coping strategies. These findings suggest that self-reported measures represent unique pieces of information important for the management of dizzy patients.

Significant vestibular system impairment is common in a cohort of elderly patients referred for assessment of falls risk.

BACKGROUND: Falls in elderly patients are associated with morbidity, mortality, and cost to the healthcare system. The development of falls risk assessment programs have represented a method of responding to what is known about injurious falls. The multidimensional assessments involve the comparison against normative data of a patient's performance on metrics known to influence the likelihood of future falls. The factors assessed usually include falls and medication history, measures of mentation, depression, orthostatic hypotension, simple or choice reaction time, gait stability, postural stability, and the integrity of the patient's vision, somesthetic, and vestibular senses. PURPOSE: This investigation was conducted to measure the proportion of patients referred for falls risk assessment who have evidence of vestibular system impairment. RESEARCH DESIGN: Qualitative, retrospective review of data collected from 2003 to 2007. STUDY SAMPLE: The cohort was 185 consecutive patients referred for multidimensional assessments of falls risk. DATA COLLECTION AND ANALYSIS: Patients underwent quantitative assessments of peripheral and central vestibular system function consisting of electro- or videonystagmography (i.e., ENG/VNG), and sinusoidal harmonic acceleration testing. Results of these tests were compared to normative data. RESULTS: We found that 73% of the sample who underwent vestibular system assessment had quantitative evidence of either peripheral or central vestibular system impairment. CONCLUSIONS: Our results suggest that quantitative assessments of the vestibulo-ocular reflex should be conducted on patients who are evaluated for falls risk. These examinations should include at least caloric testing and, where available, rotational testing.