The head impulse test as a predictor of videonystagmography caloric test lateralization according to the level of examiner experience: A prospective open-label study.

We conducted a study to compare how well the head impulse test (HIT), without and with eye-movement recordings, would predict videonystagmographic (VNG) caloric test lateralization when performed by a resident and an experienced otoneurologist. This prospective, open-label, blinded study was conducted in an ambulatory tertiary care referral center. Our study population was made up of 60 patients-29 men and 31 women, aged 20 to 82 years (mean: 56.4 ± 11.4)-with peripheral vestibulopathy who underwent HIT and VNG caloric testing. The HIT was conducted in two protocols: HIT0 and HIT1. The HIT0 was performed with passive brisk movements of the patient's head from the 0° null position to 20° sideways, and the HIT1 was performed toward the center while the null position was a 20° head rotation to the right and to the left. Each protocol was carried out without video eye-movement recordings (HIT0 and HIT1) and with such recordings (rHIT0 and rHIT1). The primary outcome measures were (1) a comparison of the HIT's sensitivity and specificity when performed by the resident and by the experienced otoneurologist and (2) the ability of video-recorded HIT to predict VNG caloric test lateralization. The sensitivity and specificity obtained by the resident were 41 and 81%, respectively, for HIT0 and 41 and 90% for HIT1. The sensitivity and specificity obtained by the experienced otoneurologist were 18 and 89% for HIT0 and 32 and 85% for HIT1. Analysis of the recorded eye-movement clips of the HIT0 and HIT1 obtained by a second experienced otoneurologist found a sensitivity and specificity of 32 and 63% for rHIT0 and 33 and 82% for rHIT1. We conclude that the HIT yields high false-negative rates in predicting significant caloric lateralization. Analysis of the eye-movement recordings was no better than normal testing alone for detecting saccades. The experience of the examining physician had no impact on test performance characteristics.

A cohort study of patients with tinnitus and sensorineural hearing loss in a Swedish population.

OBJECTIVE: We aimed to describe a large cohort of patients with tinnitus and sensorineural hearing loss (SNHL) in Sweden, and also to explore the possibility of finding potential possible differences between various diagnoses within SNHL. It is also of great interest to see how a multidisciplinary team was used in the different subgroups and the frequency of hearing aids use in patients with tinnitus. METHODS: Medical records of all patients who had received the diagnosis SNHL in Östergötland County, Sweden between 2004 and 2007 were reviewed. Patients between 20 and 80 years with tinnitus and a pure tone average (PTA) lower than 70dB HL were included in the study. Patients were excluded from the analyses if they had a cochlear implantation, middle ear disorders or had a hearing loss since birth or childhood. The investigators completed a form for each included patient, covering background facts, and audiograms taken at the yearly check up. RESULTS: Of a total 1672 patients' medical record review, 714 patients were included. The majority of patients (79%) were in the age group over 50 years. In male patients with bilateral tinnitus, the PTA for the left ear was significantly higher than for the right ear. The results regarding the configuration of hearing loss revealed that 555 patients (78%) had symmetric and 159 (22%) asymmetric hearing loss. Retrocochlear examinations were done in 372 patients and MRI was the most common examination. In all patients, 400 had no hearing aids and out of those 220 had unilateral tinnitus and 180 patients had bilateral tinnitus. 219 patients had a PTA>20dB HL and did not have any hearing aid. Results demonstrated that the Stepped Care model was not used widely in the daily practice. In our study, patients with bilateral-, unilateral hearing loss or Mb Ménière were the most common patients included in the Stepped Care model. CONCLUSION: In a large cohort of patients with SNHL and tinnitus, despite their hearing loss only 39% had hearing aids. It was observed that the medical record review often showed a lack of information about many background factors, such as; patients' general health condition, which could be a quality factor that needs improvement. Our results show that the Stepped Care model could be an effective option for providing a better access for tinnitus-focused treatment, although the number of patients in this study who were included in the Stepped Care model was low.

Ocular counterrolling: an indicator of bilateral vestibulopathy.

The ocular counterrolling can be static or dynamic. The purpose of this work is to connect the clinical absence of dynamic ocular counterrolling with bilateral caloric paresis. A prospective study on 216 patients in whom the absence of dynamic ocular counterrolling was tested and standard caloric test was performed. The cut-off value for bilateral caloric paresis is an absolute reflectivity of 10 in nystagmic frequency and 8 in slow phase velocity. The adequate contingency tables were constructed and tests of Chi-squared calculated. Sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, and area under receiver operating characteristic (ROC) curve were also calculated. Using the reflectivity according to the nystagmic frequency, we obtained P = 0.000 for Chi-squared, area under ROC curve was 0.832 and positive likelihood ratio 11.47. For slow-phase velocity, the results were P = 0.000, area ROC of 0.735 and positive likelihood ratio 9.43. There is a statistically significant connection between the clinical absence of dynamic ocular counterrolling and bilateral caloric paresis, with a strong diagnostic power. The mechanisms by which this phenomenon can be attributed to canalicular damage instead of otolithic damage are discussed.

A comparison of water and air caloric responses and their ability to distinguish between patients with normal and impaired ears.

OBJECTIVES: The caloric test is a mainstay of modern vestibular assessment. Yet caloric test methods have not been well standardized, and normal response values have not been universally agreed upon. The air caloric test has been particularly problematic. In this article, we present our efforts to establish a population-based description of the caloric response evoked by water and air stimuli at both cool and warm temperatures. DESIGN: Data were collected from a retrospective record review of patients who underwent caloric testing at Mayo Clinic Jacksonville between 2002 and 2006. Two subgroups were identified. One group was found to have no vestibulopathy after comprehensive medical investigation. The second group was found to have severe bilateral vestibular weakness; this diagnosis was based on medical evaluation and objective test results. Caloric response distributions and associated probability estimates were developed from each group. RESULTS: A total of 2587 medical records were found to contain caloric response data. Of these, 693 patients met the criteria to be classified as having no identifiable vestibulopathy (otologically normal patients with normal caloric responses). Sixty-eight patients met the criteria for bilateral vestibular weakness (reduced or absent rotatory chair responses). Our analysis yielded the following results: (1) there were differences between nystagmus distributions across stimuli. On average, the magnitude of cool water (30 degrees C) maximum slow-phase velocities was smaller than those from warm water (44 degrees C). Maximum slow-phase velocity distributions from cool (21 degrees C) and warm (51 degrees C) air stimuli were more similar to each other than were responses to water stimuli and fell between the water distributions. (2) Combined metrics (combined eye speed and total eye speed) were comparable for water and air stimuli. (3) Response distributions from otologically normal patients were different from those of patients with bilateral vestibular weakness. (4) Derived probability estimates allowed for quantification of caloric response normal limits, sensitivity, specificity, and error rates. CONCLUSIONS: Current bithermal test methods assume an equivalence of caloric response strength from warm and cool stimuli. Our results show standard cool and warm water stimuli provoke substantially different response magnitudes, with warm stimuli provoking stronger responses. When calibrated as described herein, air stimuli perform comparably with water stimuli for bithermal caloric test purposes, with more uniform and less variable response distributions. Both air- and water-based tests were able to distinguish between normal and abnormally weak ears with sensitivity and specificity values between 0.82 and 0.84. We advocate for the calibration of all caloric stimuli based on the test's statistical performance and not arbitrary assumptions about stimulus equivalence.

Is electronystagmography of diagnostic value in the elderly?

We aimed to determine the diagnostic value of electronystagmography (ENG) in a community-based sample of dizzy subjects over 65 years old. A total of 96 asymptomatic controls and 149 dizzy subjects underwent ENG. Clinical diagnoses were made on standardized criteria. ENG results were classed as normal or abnormal, according to reference ranges derived from the controls. Rates of ENG abnormality in different diagnostic categories, sensitivities, specificities and predictive values were calculated. Central vascular disease was common (105 out of 149 subjects); peripheral vestibular disease was not (14). Spontaneous nystagmus had a positive predictive value of 95% for central vascular disease, but was only 18%-sensitive, and was usually detectable clinically. ENG had no other significant diagnostic value. ENG failed to discriminate dizzy subjects from controls and failed to differentiate various dizziness syndromes. ENG was of no practical value in this community-derived sample of dizzy elderly subjects.

Electronystagmography: how helpful is it?

Two hundred and sixty patients tested with electronystagmography (ENG) for evaluation of complaints of disequilibrium were the representative sample for this study. As all new dizzy patients currently receive an ENG, the goal of this project was to determine how much an ENG adds to the diagnostic acumen, and which patients really needed an ENG in order to maximize efficiency and minimize patient cost. Results indicate the suspected diagnosis prior to ENG is assisted by its use only when the cause is thought to be central or is uncertain. The percentage of unknown causes of disequilibrium decreased from 34.2 to 13.8 per cent and the percentage of central causes increased from 13.1 to 23.1 per cent. Electronystagmography does not significantly aid in the diagnosis of peripheral lesions except as confirmation. Specific findings and recommendations are discussed.

[Normal vertical vestibulo-ocular reflexes in man]. / Vertikal'nye vestibulookuliarnte refleksy u cheloveka v norme.

The vertical vestibular-ocular reflexes (VVOR) were evaluated in 22 human test subjects aged 18-47 years. The VVOR were evoked by active head movements in the sagittal plane with the frequencies of 0.04 Hz (stimulus 1), 0.12 Hz (stimulus 2), and 0.24 Hz (stimulus 3). Records were made either with eyes closed (Program I) or fixed at an object (Program II). In the norm, the interocular asymmetry was absent and there was an insignificant prevalence of upward VVOR. As was noted, VVOR were largely subdued in the condition of gaze fixation; this was particularly true with the downward vertical vestibular-ocular reflexes.

Oculomotor dysfunction in rheumatoid patients with upper cervical dislocation.

Several studies of patients with chronic cervical pain and chronic whiplash syndrome report a high frequency of oculomotor function derangements pointing towards brainstem involvement and/or default sensory input from neck afferents. In light of these reports, it seems important to investigate other patient groups with similar upper cervical spine disorders. In this study, voluntary eye motor performance was evaluated in 11 rheumatoid patients (RA) with upper cervical dislocation and a clearly noticed joint affection of the cervical spine. The results were compared with 6 RA patients without cervical engagement and normal individuals. Nine of the 11 patients with atlanto-axial dislocation showed pronounced oculomotor disturbances of smooth pursuits compared with only minor changes in the control group. The pattern of oculomotor dysfunction in patients with rheumatoid cervical dislocation indicates brainstem involvement, which may be an early sign of brainstem affection/myelopathy.

[What is the role of contact lenses within the scope of electronystagmography?]. / Welche Bedeutung haben Kontaktlinsen im Rahmen der Elektronystagmographie?

BACKGROUND: During electronystagmography it is necessary to correct detective vision for calibration, smooth pursuit, and saccadic eye movements. Therefore more and more people use contact lenses instead of normal glasses. Given the lack of detailed information about this phenomenon, in the current literature we decided to investigate the influence of soft contact lenses on electronystagmography. The aim of this study was to find out differences in the results of electronystagmography between using glasses or contact lenses. METHODS: Our investigation involved 20 vestibular healthy human subjects with myopia. In the first part of the examination they used their contact lenses and in the second part they were wearing normal glasses. After measuring the calibration potential we wanted to see if contact lenses would increase the rate of artifacts in the electronystagmogram. Then we attempted to determine whether contact lenses would an influence on the registration of the optokinetic nystagmus. Induced saccadic eye movements were recorded and analysed. RESULTS: Contact lenses had a negative influence neither on the calibration potential nor on the rate of artifacts. The latency of the saccadic eye movements also showed no differences between both parts of this investigation. Only the velocity of the saccades and the gain value during the optokinetic test were reduced when glasses were used. CONCLUSIONS: Contact lenses may stimulate the secretory function of the lacrimal gland and thus decrease friction forces. It is also possible that the reduced image size produced or the reduction-effect of minus by glasses in near sighted persons negatively influences eyeball velocity. In summary, our study demonstrates that contact lenses do not have a negative influence on electronystagmography. Therefore electronystagmographic studies of patients with contact lenses are permissible for purposes of documenting a medical opinion.

Positional nystagmus in asymptomatic human subjects.

Nystagmus produced by static placement of the head in different orientations is termed positional nystagmus and is known to occur in human subjects who are free of vestibular symptoms. This study provides quantitative data for horizontal positional nystagmus occurrence in 49 normal human subjects, in whom the number of nystagmus beats, the slow-phase velocity of each beat, and distribution statistics were determined. A metric for the possible differentiation of physiologic positional nystagmus from pathologic nystagmus is described.

Can posturography contribute to the diagnosis of vertigo in patients where other tests fail to do so?

In this study, patients showing abnormal posturographic results in a test-configuration upon examination of the visuo-proprioceptive-vestibular interaction (Static Posturography type III, SPGIII) are reviewed. Group I (n = 81) comprised patients for whom no clear diagnosis could be obtained (neither central nor peripheral) and with rather atypical complaints. Group II (n = 77) comprised patients in whom a well-defined peripheral disorder could be found (typical provoked vertigo as BPPV (n = 30) and Meniere's disease (n = 30)). Group I consisted of s subgroup Ia, including patients with a complete negative classical examination (n = 32), a subgroup Ib with patients showing minor central signs (n = 28), and subgroup Ic comprising patients with slight peripheral indications (n = 21). The findings in SPGIII were compared between these two groups and are discussed in the light of earlier experience with such data in typical peripheral vestibular disorders. Similar sensory interaction patterns were found in both groups, with only small differences between them, suggesting that in some of these cases, especially in subgroups Ia and Ic, vestibular disturbance might be present, which would not have been sufficiently and clearly revealed by the classical tests. Especially the negative effects, i.e. when the withdrawal of a sensory input improved stability instead of aggravating it, which is the opposite to what should be expected, suggest that the other sensory inputs, vision and proprioception, play a role in the definition of the posturographic results in typical vestibular disorders as well as in diagnosis.

Chaos theory applied to the caloric response of the vestibular system.

Developments in the field of nonlinear dynamics has given us a new conceptual framework for understanding the mechanisms involved in the regulation of complex nonlinear systems. This concept, called "chaos" or "deterministic chaos," has been applied to EKG, EEG, and other physiological signals, but not yet to the ENG signal. The underlying geometrical structure in chaotic dynamics is fractal (noninteger dimension), and calculating the fractal dimension of the electronystagmographic recording from caloric testing gave a dimension ranging from 3.3 to 7.7. This result demonstrates that the multidimensional vestibular system, with its numerous neurological pathways, can somehow reduce the degrees of freedom and give rise to an irregular dynamic low-dimensional behavior, which is associated with deterministic chaos.

Double-blind, placebo-controlled trial of rehabilitation for bilateral vestibular hypofunction: preliminary report.

Vestibular rehabilitation (VR) is increasingly popular, but few data exist to support enthusiasts' claims of efficacy in improving functional abilities of patients with bilateral vestibular hypofunction (BVH). A double-blind, controlled study of eight subjects (mean, 64 +/- 12 years; seven females, one male) with bilateral vestibular hypofunction was conducted. Subjects in group A received 8 weeks of VR followed by 8 weeks of home VR exercises, whereas those in group B received 8 weeks of control treatment (isometric strengthening exercises) followed by 8 weeks of VR. At the end of 8 weeks, group A walked 8% faster and, during paced gait and stair-climbing, with greater stability, evidenced by a 10% larger maximum moment arm and a 17% decreased double-support duration during gait and stair stance. Group B improved less than 1% during the control treatment. Self-reported Dizziness Handicap Inventory scores did not differ significantly between control and active VR. All subjects improved compared with baseline tests at the 16-week post-test on both functional testing and on the Self-reported Dizziness Handicap Inventory scale. We conclude that in this small sample, VR effectively improved functional, dynamic stability during locomotion, but even strengthening exercises result in self-reported symptomatic improvement.

Electronystagmographic features in some peripheral and central vestibular disorders: application of multiple discriminant analysis of electronystagmographic parameters.

In routine clinical electronystagmographic (ENG) tests (postrotatory, optokinetic, caloric and tracking tests), eye movement signals were analyzed and a multiple discriminant analysis was carried out with the aid of a microcomputer. Six parameters were selected and, based on these, two functions for discriminating between peripheral and central disorders were established. Discrimination between 35 patients with peripheral lesions and 15 patients with central lesions was made with a correct classification rate of 97.1 and 86.7%, respectively. These rates are significantly higher than that of any single ENG test analysis. Our results indicate that the clinical application of ENG can be improved by searching for more sensitive ENG parameters and adopting the comprehensive analysis approach.

Classification of peripheral and central (pontine infarction) vestibular deficits. Selection of a neuro-otological test battery using discriminant analysis.

The results obtained from a complete neuro-otological test battery were examined statistically in order to select measurement variables which would optimally indicate significant differences between four groups: normal patients, patients with partially compensated unilateral peripheral vestibular deficit, patients with an acoustic neurinoma and patients with central (brainstem) vestibular deficit. A stepwise-discriminant analysis was performed on measurements of slow-phase velocity obtained from each test. The primary measurements selected to assign a subject optimally to one population were the canal paresis (CP) of the caloric test, the eye-tracking gain contralateral to the deficit for a 15 deg/s stimulus, the gain asymmetry for optokinetic nystagmus with a 30 deg/s stimulus, and the level of spontaneous nystagmus. The resulting classifications were 100% correct for normal and central deficit patients. However, the division between peripheral deficit and acoustic neurinoma patients overlapped causing about 30% false classifications of neurinoma patients: some 20% of the peripheral deficit patients were classified as normal. If the CP was not available the discriminant analysis substituted the rotating chair response for 5 deg/s2, in place of CP. This substitution caused a 10 to 20% decrease in classification accuracy.