Relation of video-head-impulse test and caloric irrigation: a study on the recovery in unilateral vestibular neuritis

The head-impulse test (HIT) is an important test for examining unilateral vestibular hypofunction. The new video-head-impulse test (vHIT) is more sensitive and specific than the clinical bedside-head-impulse test. Alternatively, one can test for vestibular hypofunction with the caloric irrigation test. Various studies have shown that both tests may not always identify vestibular hypofunction; instead, the results of the tests might be contradictory. To further explore the question, of whether vHIT and caloric irrigation test the same part of the angular horizontal vestibulo-ocular reflex (VOR), we examined patients with unilateral vestibular neuritis at different points in time. The tonic vestibular imbalance (e.g., subjective-visual-vertical, ocular torsion and spontaneous nystagmus) and dynamic dysfunction of VOR (vHIT and bithermal caloric irrigation) were measured and quantified. While parameters of the tonic vestibular imbalance were well described by single exponential decay functions, dynamic parameters were less well defined. Therefore, to better compare the time course of pairs of two different parameters, we used a linear regression analysis. No linear correlation was found in the group and individually for the gain asymmetry and the ipsilesional gain of the vHIT with the unilateral weakness of the bithermal caloric irrigation tests. Linear correlation was found for most parameters of tonic vestibular imbalance. These findings are further evidence that vHIT and caloric irrigation test different parts of the angular VOR.     

Caloric test and video-head-impulse: a study of vertigo/dizziness patients in a community hospital

The head-impulse test (HIT) is an important test for examining unilateral vestibular hypofunction. The new video-head-impulse test (vHIT) is more sensitive and specific than the clinical bedside-head-impulse test (bHIT). Alternatively, one can test for vestibular hypofunction with the caloric irrigation test. Various studies showed that both tests may not always identify vestibular hypofunction; instead, the results of the tests might be contradictory. To evaluate the diagnostic value of these tests, we routinely measured patients exhibiting vertigo or dizziness at our community hospital with bithermal caloric irrigation, the bHIT and the vHIT. Only those patients (n = 172) with a pathological caloric irrigation test of more than 25 % unilateral weakness in the Jongkee’s formula were included. Out of these patients, 41 % had a pathologic vHIT. Among the subgroup with acute symptoms (symptom onset within 5 days), 63 % had a pathological video-head-impulse, whereas only 33 % of the non-acute group (symptom onset more than 5 days) tested pathological. A pathological HIT depended on the disease stage, the amount of unilateral weakness in caloric examination and on the test itself.     

Comprehensive analysis of head-shaking nystagmus in patients with vestibular neuritis

Although biphasic head-shaking nystagmus (HSN) is a basic response to head shaking in patients with unilateral vestibular loss, monophasic HSN is commonly seen in patients with dizziness of undetermined etiology. Since the clinical significance of HSN remains unclear, we sought to characterize different types of HSN in patients with vestibular neuritis (VN) during the acute stage (within 7 days after the onset of vertigo) and at follow-up (about 2 months after the onset of vertigo), and to compare HSN and caloric responses. We analyzed HSN, spontaneous nystagmus and caloric tests in 66 patients with VN. Overall, HSN showed high abnormal rates (94 and 89%) during the acute and follow-up stages and could detect vestibular hypofunction even when canal paresis (CP) had normalized at follow-up. All patients in the acute stage and most patients at follow-up showed HSN with the slow phase to the lesioned side (paretic). Biphasic HSN was common at follow-up, and many patients with a monophasic paretic pattern during the acute stage had evolved to a biphasic paretic pattern at follow-up. Initial slow-phase eye velocities (SPVs) in biphasic HSN were larger than those in monophasic HSN at follow-up. Absence of HSN or reversal of its direction was closely related to normalized caloric responses, but SPVs of HSN did not correlate with the severity of CP. These findings indicate that the HSN test is a sensitive detector of vestibular hypofunction upon 2-Hz head rotation. HSN may reveal previous vestibular hypofunction in the 2-Hz frequency range even at follow-up, when caloric responses detecting vestibular hypofunction in the low-frequency range had normalized. The two tests utilize different mechanisms to assess vestibular hypofunction and are complementary. Biphasic paretic HSN is the most common pattern at follow-up and occurs when the initial SPVs induced by head rotation are large enough to induce the adaptation of primary vestibular afferent activity. Monophasic HSN, which is commonly found in dizzy patients, indicates less severe vestibular hypofunction than biphasic HSN in the 2-Hz frequency range, and the caloric tests can provide further information about the side and presence of vestibular hypofunction at lower frequencies.     

Effectiveness of careful bedside examination in assessment, diagnosis, and prognosis of vestibular neuritis

OBJECTIVE: To determine whether the use of 4 bedside tests (head-impulse, head-heave, head-shake, and vibration tests) can be as effective as the caloric test, a widely accepted standard, in the diagnosis and prediction of the time to recovery from vestibular neuritis. DESIGN: Inception cohort (1-year follow-up), criterion standard study. SETTING: Primary referral center. PATIENTS: All patients had acute vertigo, and those having a diagnosis of vestibular neuritis were eligible for inclusion in the study. Sixty-eight patients (43 men and 25 women; mean age, 54.9 years) met this criterion, and 53 of them (77.9%) completed the study. MAIN OUTCOME MEASURES: Spontaneous head-shaking and vibration-induced nystagmus elicited with a battery-powered device were tested wearing Frenzel goggles. The head-impulse and head-heave tests were performed manually. Caloric irrigation was administered with hot, cold, and ice water. RESULTS: At baseline, more than half of the patients exhibited positive signs with all 4 tests and all had caloric paralysis or paresis. Signs with the head-impulse and head-heave tests correlated highly (odds ratio, 24.9; P < .001), as did those with the head-shake and vibration tests (odds ratio, 22.8; P < .001). Patients with a positive sign with the head-impulse or vibration test were 70% less likely to recover than were those with a negative sign. Head-impulse (hazard ratio, 0.08; P = .002) and head-shake (hazard ratio, 0.23; P = .01) test results were associated with the outcome of the caloric test. CONCLUSION: Careful bedside examination of patients with vestibular neuritis has both diagnostic value in the short term and prognostic value in the long term.     

Time constant of nystagmus slow-phase velocity to yaw-axis rotation as a function of the severity of unilateral caloric paresis.

OBJECTIVE: Complete unilateral loss of vestibular function results in a phase advance (reduced time constant) of the horizontal slow-phase nystagmus response to yaw-axis rotation. The objective of this study was to determine whether partial losses of lateral semicircular canal function would result in proportional reductions in the time constant. SETTING AND STUDY DESIGN: This was a retrospective study of consecutive patients' records at two tertiary referral centers for vestibular disorders. PATIENTS: Four hundred fifty-four patients who presented for evaluation of vertigo or imbalance or both and who were found to have partial or complete unilateral canal paresis on caloric testing. MAIN OUTCOME MEASURES: In 372 patients, the gain and time constant of the horizontal nystagmus response was measured using a 5-second velocity ramp of constant yaw-axis acceleration. Caloric responses to standard bithermal irrigations at 30 degrees and 44 degrees were obtained using an open-loop irrigation system. In a second group of 82 patients, the gain and time constant of the horizontal vestibulo-ocular reflex were measured using a sum-of-sines (pseudorandom) yaw-axis acceleration. The caloric response was measured using a closed-loop system. Results: In both groups, the peak gain of the nystagmus response was independent of the level of the canal paresis. However, the time constant of the response both toward and away from the lesioned side decreased proportionally with increasing canal paresis. CONCLUSION: This result supports the hypothesis that bilateral symmetrical peripheral vestibular input is a necessary condition for the mechanisms or processes underlying normal horizontal slow-phase velocity storage.     

Search-coil head-thrust and caloric tests in Ménière's disease

CONCLUSIONS: Our findings suggest that canal function is substantially preserved in subjects with active vertigo attacks as a result of Ménière's disease (MD). In these subjects, the head-thrust test (HTT) may not be as sensitive to canal dysfunction as traditional caloric testing. MD may differentially affect the low-frequency sensitivity of the canals. OBJECTIVE: Caloric tests have traditionally been used to characterize semicircular canal function in vestibular disorders, including MD. The quantitative HTT provides an objective measurement of semicircular canal function in the frequency and velocity ranges of normal head movements. The aim of this study was to compare the findings of caloric and HTTs in subjects with unilateral MD. MATERIAL AND METHODS: The study population consisted of 38 candidates for gentamicin treatment due to a high frequency of vertiginous attacks (25 males, 13 females; mean age 52.9 years; range 30-70 years). The duration of symptoms was 1-30 years (mean 5.3 years). Horizontal canal function was characterized with bithermal aqueous caloric tests and recordings of the angular vestibulo-ocular reflexes (aVORs) using the scleral search-coil technique during HTTs. The main outcomes were unilateral weakness (UW) on caloric testing and aVOR gain asymmetry (GA) during HTTs. A caloric response asymmetry of >20% was considered to be indicative of pathologic UW. A difference in GA during HTTs of >5.8% was considered significant. RESULTS: Twenty subjects (52.6%) showed abnormal results on one or both tests. Pathologic UW was present in 16 subjects (42.1%). During HTTs, 11 subjects (28.9%) showed pathologic GA. Seven subjects (18.4%) showed abnormal results on both tests. A significant correlation was found between UW and GA. However, pathologic GA during HTTs in subjects with unilateral MD was less frequent and the values smaller than those published for vestibular neuritis patients. Two subjects with unilateral MD had 100% UW, but none had >30% asymmetry on HTTs.     

Horizontal vestibulo-ocular reflex dynamics in acute vestibular neuritis and viral labyrinthitis: evidence of otolith-canal interaction

OBJECTIVE: To evaluate the dynamic properties of the horizontal vestibulo-ocular reflex (h-VOR) in the acute stage of two common labyrinthine diseases that provoke severe attacks of vertigo with spontaneous nystagmus: vestibular neuritis (vestibular loss alone) and viral labyrinthitis (cochleovestibular loss). MATERIAL AND METHODS: Sixty-three patients were investigated: 42 were diagnosed with vestibular neuritis and 21 with viral labyrinthitis. The h-VOR function was evaluated by conventional caloric and impulsive testing. A simplified model of vestibular function was used to analyze the vestibulo-ocular response to rotational stimulation. RESULTS: The results showed a significant difference in h-VOR characteristics between the two pathologies. Patients with vestibular neuritis exhibited a strong horizontal semicircular canal deficit, but no h-VOR asymmetry between the two rotational directions. In contrast, patients with viral labyrinthitis demonstrated moderate canal paresis and a marked h-VOR deficit in rotation toward the affected ear. CONCLUSION: These findings support the hypothesis that the h-VOR dynamic asymmetry that occurs after an acute unilateral inner ear lesion is not due to canal dysfunction alone, but involves complex adaptive changes in the central VOR that may implicate the otolith system. Based on histopathologic and clinical differences in the two pathologies reported in the literature, we postulate that this otolith-canal interaction is mainly linked to the loss of saccular function.     

Search-coil head-thrust and caloric tests in Ménière's disease

Conclusions. Our findings suggest that canal function is substantially preserved in subjects with active vertigo attacks as a result of Ménière's disease (MD). In these subjects, the head-thrust test (HTT) may not be as sensitive to canal dysfunction as traditional caloric testing. MD may differentially affect the low-frequency sensitivity of the canals. Objective. Caloric tests have traditionally been used to characterize semicircular canal function in vestibular disorders, including MD. The quantitative HTT provides an objective measurement of semicircular canal function in the frequency and velocity ranges of normal head movements. The aim of this study was to compare the findings of caloric and HTTs in subjects with unilateral MD. Material and methods. The study population consisted of 38 candidates for gentamicin treatment due to a high frequency of vertiginous attacks (25 males, 13 females; mean age 52.9 years; range 30–70 years). The duration of symptoms was 1–30 years (mean 5.3 years). Horizontal canal function was characterized with bithermal aqueous caloric tests and recordings of the angular vestibulo-ocular reflexes (aVORs) using the scleral search-coil technique during HTTs. The main outcomes were unilateral weakness (UW) on caloric testing and aVOR gain asymmetry (GA) during HTTs. A caloric response asymmetry of >20% was considered to be indicative of pathologic UW. A difference in GA during HTTs of >5.8% was considered significant. Results. Twenty subjects (52.6%) showed abnormal results on one or both tests. Pathologic UW was present in 16 subjects (42.1%). During HTTs, 11 subjects (28.9%) showed pathologic GA. Seven subjects (18.4%) showed abnormal results on both tests. A significant correlation was found between UW and GA. However, pathologic GA during HTTs in subjects with unilateral MD was less frequent and the values smaller than those published for vestibular neuritis patients. Two subjects with unilateral MD had 100% UW, but none had >30% asymmetry on HTTs.     

Horizontal vestibulo-ocular reflex dynamics in acute vestibular neuritis and viral labyrinthitis: evidence of otolith-canal interaction

Objective To evaluate the dynamic properties of the horizontal vestibulo-ocular reflex (h-VOR) in the acute stage of two common labyrinthine diseases that provoke severe attacks of vertigo with spontaneous nystagmus: vestibular neuritis (vestibular loss alone) and viral labyrinthitis (cochleovestibular loss).

Material and Methods Sixty-three patients were investigated: 42 were diagnosed with vestibular neuritis and 21 with viral labyrinthitis. The h-VOR function was evaluated by conventional caloric and impulsive testing. A simplified model of vestibular function was used to analyze the vestibulo-ocular response to rotational stimulation.

Results The results showed a significant difference in h-VOR characteristics between the two pathologies. Patients with vestibular neuritis exhibited a strong horizontal semicircular canal deficit, but no h-VOR asymmetry between the two rotational directions. In contrast, patients with viral labyrinthitis demonstrated moderate canal paresis and a marked h-VOR deficit in rotation toward the affected ear.

Conclusions These findings support the hypothesis that the h-VOR dynamic asymmetry that occurs after an acute unilateral inner ear lesion is not due to canal dysfunction alone, but involves complex adaptive changes in the central VOR that may implicate the otolith system. Based on histopathologic and clinical differences in the two pathologies reported in the literature, we postulate that this otolith-canal interaction is mainly linked to the loss of saccular function.     

Video head impulse in comparison to caloric testing in unilateral vestibular schwannoma

Conclusions: Although there was a statistically significant relationship between the results of the vHIT and the caloric test, the limited strength of this relationship suggests that, for unilateral vestibular schwannoma (UVS), caloric testing and vHIT may provide complementary information on vestibular function.

Objective: There is limited information that can be used to determine which of the video head impulse test (vHIT) and caloric test might be better used in the diagnosis and management of UVS. In this study, a group of participants with un-operated UVS was studied using both methods.

Methods: The subjects’ vestibular function was assessed using the vHIT and caloric testing. Tumour size was quantified using MRI and their balance disturbance assessed using the Jacobsen Dizziness Handicap Inventory (DHI).

Results: Twenty of 30 subjects had an abnormal canal paresis according to the Jongkees’ criterion (>?0.25); however, only 10/30 had an ipsilesional vHIT gain of <0.79. Canal paresis could be predicted from the ipsilesional and contralesional vHIT gains. Tumour size could also be predicted from the ipsilesional vHIT gain and canal paresis. However, DHI scores could not be predicted from the degree of canal paresis, vHIT gain, or the MRI measures.     

Validity and limitation of detection of peripheral vestibular imbalance from analysis of manually rotated vestibulo-ocular reflex recorded in the routine vestibular clinic

We compared the results of analysis of vestibulo-ocular reflex (VOR) obtained by manual rotation in routine vestibular clinical practice with that of caloric testing, and examined the validity and limitations of VOR analysis as a test for the estimation of peripheral vestibular function and imbalance. VOR response was recorded in daily vestibular clinical examinations by manually rotating the standard clinical chair for approximately 30 s. VOR gain was slightly, but significantly, correlated with the peak slow phase velocity of caloric response (r = 0.50, p < 0.001). However, 8 out of 12 patients with no caloric response failed to exceed the range of two standard deviations of the mean value of age-matched normal subjects, indicating that it is clinically difficult to use VOR gain alone as a estimate of unilateral vestibular function. VOR directional preponderance (VOR DP%) correlated well with caloric canal paresis (CP) (CP%; r = 0.89, p < 0.001). VOR DP% was within the normal range in patients with caloric CP% < 40 and exceeded the normal range in most cases with caloric CP% > 80. VOR DP% varied widely when caloric CP% ranged between 40 and 80. The effect of vestibular compensation on VOR DP% was examined by plotting VOR DP% divided by caloric CP% (DP/CP) against the number of days since the onset of vertigo in patients with vestibular neuritis or sudden deafness with vertigo. DP/CP was large within 50 days of the onset of vestibular damage, especially when caloric CP% was < 80, and gradually decreased with time. These results indicate that determination of VOR DP% should contribute to the early diagnosis of fresh vestibular imbalance, especially in daily clinical practice, because this type of VOR recording can be performed in < 1 min in routine vestibular clinics. The decay time constant of DP/CP was larger when caloric CP% exceeded 80, indicating that vestibular compensation proceeds more slowly when the vestibular damage is severe.     

Discrepancies in the caloric testing and video Head Impulse Test results in a case with bilateral lateral semicircular canal malformations

Lateral semicircular canal (LSCC) malformations represent one of the most common types of inner ear malformation. As many cases of LSCC malformations are asymptomatic, detailed vestibular functions in such cases remain unclear. We present a case with bilateral LSCC malformations for whom the function of each vestibular organ was evaluated by caloric testing, video Head Impulse Test (vHIT) and vestibular evoked myogenic potentials (VEMP). Caloric testing showed canal paresis of the left side, whereas vHIT showed bilateral normal semicircular canal function. The results of VEMP indicated left saccular dysfunction. Discrepancies in caloric testing and vHIT results were observed and these discrepancies are thought to be due to endolymphatic hydrops rather than vestibular hypofunction, similar to that in Meniere disease.     

Validity and Limitation of Detection of Peripheral Vestibular Imbalance from Analysis of Manually Rotated Vestibulo-Ocular Reflex Recorded in the Routine Vestibular Clinic

We compared the results of analysis of vestibulo-ocular reflex (VOR) obtained by manual rotation in routine vestibular clinical practice with that of caloric testing, and examined the validity and limitations of VOR analysis as a test for the estimation of peripheral vestibular function and imbalance. VOR response was recorded in daily vestibular clinical examinations by manually rotating the standard clinical chair for &#44 30 s. VOR gain was slightly, but significantly, correlated with the peak slow phase velocity of caloric response ( r = 0.50, p < 0.001). However, 8 out of 12 patients with no caloric response failed to exceed the range of two standard deviations of the mean value of age-matched normal subjects, indicating that it is clinically difficult to use VOR gain alone as a estimate of unilateral vestibular function. VOR directional preponderance (VOR DP%) correlated well with caloric canal paresis (CP) (CP%; r = 0.89, p < 0.001). VOR DP% was within the normal range in patients with caloric CP% < 40 and exceeded the normal range in most cases with caloric CP% > 80. VOR DP% varied widely when caloric CP% ranged between 40 and 80. The effect of vestibular compensation on VOR DP% was examined by plotting VOR DP% divided by caloric CP% (DP CP) against the number of days since the onset of vertigo in patients with vestibular neuritis or sudden deafness with vertigo. DP CP was large within 50 days of the onset of vestibular damage, especially when caloric CP% was < 80, and gradually decreased with time. These results indicate that determination of VOR DP% should contribute to the early diagnosis of fresh vestibular imbalance, especially in daily clinical practice, because this type of VOR recording can be performed in < 1 min in routine vestibular clinics. The decay time constant of DP CP was larger when caloric CP% exceeded 80, indicating that vestibular compensation proceeds more slowly when the vestibular damage is severe.     

Clinical significance of vibration-induced nystagmus and head-shaking nystagmus through follow-up examinations in patients with vestibular neuritis.

OBJECTIVES: To verify if vibration-induced nystagmus (VIN) in patients with vestibular neuritis changes over time and to compare the results of VIN test to those of caloric test and head-shaking nystagmus (HSN) test. STUDY DESIGN: Retrospective study of a series of cases. METHODS: We compared VIN and HSN tests using caloric test results in 22 patients (male-to-female ratio, 11:11; age range, 15-67 yr) with acute vestibular neuritis seen at onset and in follow-up after 2 months. The eye movement recordings were made, and the maximum slow-phase eye velocities (SPVs) were calculated during vibration and after head shaking. If spontaneous nystagmus was present, it was subtracted from the SPVs of VIN and HSN. Positive value of the SPVs means slow-phase eye movement to the lesioned side. RESULTS: In acute stage, VIN of which SPV was directed toward the lesioned side was observed in 21 (95%); and HSN, in 22 (100%). In follow-up, VIN of which SPV was directed toward the lesioned side was observed in 19 (86%); and HSN, in 17 (77%). There was a significant decrease of the SPV of VIN and HSN over time. Significant correlations were observed in between canal paresis and SPV of VIN but not in between canal paresis/SPV of VIN and SPV of HSN. CONCLUSION: Although VIN test can predict the severity of vestibular asymmetry in acute and follow-up stages, HSN test could only probe vestibular asymmetry and could not predict the severity of the vestibular asymmetry. Our results suggest that VIN might represent the peripheral vestibular asymmetry; however, HSN might represent the stored vestibular asymmetry in velocity storage system, which is induced by peripheral asymmetry.     

Machine learning method intervention: Determine proper screening tests for vestibular disorders

ObjectiveTo evaluate the performance of different vestibular indicators in disease classification based on machine learning method.MethodsThis study use retrospective analysis of the vertigo outpatient database from a tertiary care general hospital. 1491 patients with definite clinical diagnoses were enrolled in this study. Spontaneous nystagmus, head-shaking nystagmus, positional nystagmus, unilateral weakness in caloric test, and gain and saccade in video head impulse test (vHIT) were recorded as variables. Diagnoses were mainly reorganized as acute vestibular syndrome, episodic vestibular syndrome, and chronic vestibular syndrome. The trained random forest model was applied based on exploratory data analysis results.ResultsRandom forest accuracies on acute, episodic, and chronic vestibular syndrome are 90%, 81.74%, and 91.3%, respectively. The most important features in acute vestibular syndrome are spontaneous nystagmus, and vHIT variables. In episodic vestibular syndrome, unilateral weakness in caloric test, gain and saccades on lateral semicircular canal are the top three parameters. Lateral vHIT gain, head-shaking nystagmus, and unilateral weakness in caloric test are the main parameters on chronic vestibular syndrome. In acute vestibular syndrome, spontaneous nystagmus and vHIT make major contributions in vestibular disorders distinction. When the disease course prolongation, unilateral weakness and head-shaking nystagmus become increasingly important.ConclusionFast clinical test sets including spontaneous nystagmus, head shaking nystagmus, and vHIT should be the first consideration in screening vestibular disorders.     

Acute vestibular asymmetry disorder: a new disease entity in acute vestibular syndrome?

Background: Acute vestibular syndrome (AVS) is characterized by the rapid onset of vertigo, nausea, vomiting and gait unsteadiness, which lasts for days.

Aims/objectives: We report cases as acute vestibular asymmetry disorder (AVAD), with presentations that mimic vestibular neuritis (VN) but without central lesions.

Materials and methods: We retrospectively reviewed records of patients presenting with acute spontaneous vertigo lasting more than 24?h from January 2011 to June 2016. Among 341 patients, five showed different findings that did not indicate either VN or stroke. We analyzed the clinical features and vestibular assessments of these patients.

Results: All five patients showed spontaneous nystagmus continuing for several days. However, head impulse tests (HITs) did not reveal a corrective saccade. Brain magnetic resonance imaging showed no abnormal lesions. The bithermal caloric test revealed directional preponderance without canal paresis. Finally, the slow harmonic test of the rotatory chair revealed unilateral high gain and phase within the normal range, but a significantly asymmetric response was observed. No patients showed recurrence during follow-up.

Conclusions and significance: Our study suggests that a normal HIT in AVS is not always a dangerous sign indicating an acute stroke. From our observations, we propose that AVAD would be a new disease entity within AVS.     

Vestibular neuronitis in pilots: follow-up results and implications for flight safety

OBJECTIVES To report our experience over the past 12 years with the evaluation and follow-up of pilots with vestibular neuronitis and to discuss points relevant to flight safety and the resumption of flying duties.STUDY DESIGN A retrospective, consecutive case series.METHODS Eighteen military pilots with vestibular neuronitis were examined and followed up. A complete otoneurological workup was performed, including both physical examination and laboratory evaluation. The latter included electro-oculography (EOG) and a rotatory chair test using the smooth harmonic acceleration protocol.RESULTS The mean patient age was 35 +/- 6 years (range, 23 to 42 y), and the average follow-up period was 20.5 +/- 12.8 months (mean +/- standard deviation [SD]; (range, 11 to 48 mo). Electro-oculography caloric test on presentation documented significant unilateral hypofunction in all patients. Thirteen of the 18 patients (72%) had abnormal smooth harmonic acceleration test results. None of the pilots reported any symptoms on follow-up. However, five (28%) had positive otoneurological examination findings, and eight (44%) still had significant caloric lateralization (>25%). The average caloric hypofunction was reduced from 67.8% +/- 29.3% at onset to 40% +/- 16% (mean +/- SD, <.05, paired test). Seven of the patients (39%) had additional electro-oculography findings beyond caloric hypofunction. These included spontaneous, positional, and positioning nystagmus. Smooth harmonic acceleration disease on follow-up was documented in eight patients (44%), five of whom had canal paresis. Eleven patients (61%) demonstrated residual vestibular damage on follow-up. In 6 of these 11 cases (55%), the laboratory evaluation revealed vestibular deficits otherwise undiagnosed by the bedside test battery.CONCLUSIONS The vestibular system plays a central role in orientation awareness and is often challenged by flying conditions. The finding that approximately 60% of pilots who have had vestibular neuronitis continue to show signs of vestibular malfunction, despite apparent clinical recovery, emphasizes the need for a complete vestibular evaluation, including specific bedside testing and laboratory examinations, before flying duties can be resumed.     

Caloric response and postural control in patients with nasopharyngeal carcinoma after radiotherapy

Since radiotherapy is the treatment of choice for nasopharyngeal carcinoma, the influence of irradiation on the temporal bone is of great concern for these patients. In this study, the caloric test and posturography were used to investigate vestibular function in 41 irradiated patients with nasopharyngeal carcinoma. Caloric testing showed a high incidence of canal paresis; five unilateral and 10 bilateral. Factors such as middle ear effusion had no significant effect on the occurrence of canal paresis. Posturography showed no difference from the control group. The authors conclude that the influence of irradiation on the vestibular apparatus of patients with nasopharyngeal carcinoma might result in a canal paresis, while postural control is preserved. Central compensation may play an important role in the postural control of these patients.     

The effect of severity of unilateral vestibular dysfunction on symptoms,disabilities ανδ handicap in vertiginous patients

This study compares the symptoms, disabilities and handicap, as assessed by means of a questionnaire, in two groups of patients with a unilateral peripheral vestibular disorder: those with a total canal paresis and those with a partial canal paresis, as judged by the duration parameter using the Fitzgerald Hallpike caloric test in the absence of optic fixation. The results of the study indicate that the severity of dizziness, the Dizziness Index (severity × frequency) and the overall level of disabilities related to visual vertigo are less severe in unilateral profound or total loss of vestibular function than in unilateral mild vestibular loss.     

Head-shaking nystagmus predicts greater disability in unilateral peripheral vestibulopathy

Objectives

The objective of this study was to determine the association of the bedside test of head-shaking nystagmus (HSN) with patients' self-perceived dizziness handicap as well as this test's sensitivity and specificity in unilateral peripheral vestibular hypofunction.

Study Design

A retrospective case-control study was performed.

Setting

The study was held at an academic, tertiary referral center.

Methods

Fifty-three adult patients with unilateral peripheral hypofunction defined by the caloric test of the videonystagmography with documented bedside HSN and who had completed questionnaires of self-perceived dizziness handicap were included. The sensitivity and specificity of the bedside HSN in patients and 10 healthy controls in diagnosing unilateral vestibular hypofunction defined by videonystagmographic caloric testing and by abnormal gain and symmetry of the vestibular-ocular reflex by rotary chair testing were determined. Scores of the screening test of the Dizziness Handicap Index and Functional Level Scale questionnaires were taken.

Results

When using the caloric irrigation test as the reference standard for unilateral vestibular hypofunction, the sensitivity, specificity, and positive predictive value of the bedside HSN were 31%, 96%, and 97%, respectively. When comparing with results of rotational chair testing (vestibular-ocular reflex gain and symmetry), the sensitivity of the HSN test increases to 71%. Patients with positive bedside HSN had higher scores (greater self-perceived dizziness handicap) of the Dizziness Handicap Index (P = .049) and higher (worse) scores of the Functional Level Scale (P = .0377) than those with negative bedside HSN (Wilcoxon rank test).

Conclusions

Greater perceived handicap was correlated with a positive bedside HSN in patients with unilateral peripheral vestibulopathy. The HSN has sufficient sensitivity to be used as screening test of uncompensated vestibulopathy in this series. However, a negative HSN alone does not rule out the diagnosis of peripheral vestibular dysfunction.