Role of conventional MD staging in modern era of hydrops MR imaging

Objective/Hypothesis

This study correlated stage of Meniere's disease (MD) with MR imaging of endolymphatic hydrops (EH) to assess the role of MD staging in modern era.

Study Design

Retrospective study.

Methods

Fifty-four MD patients (60 ears) underwent an inner ear test battery and were further confirmed by MR imaging. Sixty MD ears were divided into stages I-IV, and hydrops MR images at each stage were compared.

Results

Hydrops MRI demonstrated that EH at the cochlea with respective Grades 0/I/II were 3/7/1 ears for stage I, 0/5/3 ears for stage II, 1/6/26 ears for stage III and 0/2/6 ears for stage IV. Significant relationship was not identified between MD stage and grades of cochlear hydrops. Similarly, no significant relationship was shown between MD stage and grades of vestibular (saccular/utricular) hydrops. The optimal cutoff value of four-tone average for predicting severe type (Grade II-III) cochlear/vestibular EH was 48 dB, which was within the stage III. Hence, prevalence of severe type (Grade II) cochlear EH in stages III (79%) and IV (75%) was significantly higher than stages I (9%) and II (38%). Similarly, severe type saccular/utricular EH in stages III (64%) and IV (75%) also showed significantly higher than stages I (18%) and II (25%).

Conclusion

Although conventional MD staging fails to correlate with the grades of EH on hydrops MRI, late-stage MD may indicate heightened EH severity in the cochlea and vestibule.

Level of Evidence

4.

Magnitude, variability and symmetry in head acceleration and jerk and their relationship to cervical and ocular vestibular evoked myogenic potentials

BACKGROUND

Acceleration and changes in acceleration (jerk) stimulate vestibular otolith afferents. Bone-conducted (BC) vibration applied to the skull accelerates the head and produces short latency reflexes termed vestibular evoked myogenic potentials (VEMPs).

OBJECTIVE

To determine the magnitude, variability and symmetry in head acceleration/jerk during VEMP recordings and investigate the relationship between head acceleration/jerk and VEMP properties.

METHODS

3D head accelerometery (sagittal, interaural and vertical axes) was recorded bilaterally in thirty-two healthy subjects during cervical (cVEMP) and ocular (oVEMP) recordings. BC 500 Hz sinusoidal tones were applied to the midline forehead using a positive polarity stimulus.

RESULTS

The direction of induced acceleration/jerk was predominately backward, outward and downward on either side of the head during cVEMP and oVEMP recordings.Overall, acceleration/jerk was larger in the sagittal and interaural axes and peaked earlier in the interaural axis bilaterally. Acceleration was more symmetric in the sagittal and interaural axes whereas jerk symmetry did not differ between axes. Regression models did not show a systematic relationship between acceleration/jerk and either VEMP reflex.

CONCLUSIONS

The pattern of skull acceleration/jerk was relatively consistent between the two sides of the head and across subjects, but there were differences in magnitude, leading to inter-side and inter-subject variability.

Effect of Video Games on the Otolithic Reflex System

BACKGROUND

Video gaming (VG) has since the 1980s become increasingly ubiquitous entertainment among the adolescents and young adults. Many young people expe-rienced dizzy spells, but not vertiginous episodes, after playing VG.

OBJECTIVES

This study performed ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in subjects before and after engaging on VG to investigate the effect of VG on the otolithic reflex system.

METHODS

Twenty subjects who frequently played VG (>3 days per week) for more than 10 years were assigned to the long-term group. Another 20 subjects with engaging on VG <3 days per week or <10 years were assigned to the short-term group. Each subject underwent baseline oVEMP and cVEMP tests first, followed by playing VG for 1 h. Then, all subjects underwent the same paradigm. The "VG-year" is defined as frequency of VG playing within 1 week (day/week) multiplied by total length of VG engagement (year).

RESULTS

Engagement on VG rarely affected the oVEMP responses for either short- or long-term players. In contrast, the response rates of cVEMP significantly declined from pre-VG period (80%) to post-VG period (58%) in the short-term group, but not in the long-term group. The cutoff value for predicting absent cVEMP in VG engagement is 21 VG-year.

CONCLUSION

Short-term engagement on VG may result in temporary cVEMP loss, while permanent cVEMP loss could be identified in long-term VG players. The cutoff value for predicting absent cVEMP in VG engagement is 21 VG-year, indicating that damage to the sacculo-collic reflex system could be anticipated in a subject who has played VG at least 1 h per session, 7 days weekly for 3 years.

Sudden deafness: a comparison between age groups

OBJECTIVES

This study compared sudden deafness (SD) cases in 20-year age bands to investigate their causes and treatment outcome.

DESIGN

Retrospective study.

STUDY SAMPLES

178 unilateral SD patients were divided into four 20-year age-groups, namely Groups I (aged 0-19 years, n = 6), II (aged 20-39 years, n = 33), III (aged 40-59 years, n = 63), and IV (aged 60-79 years, n = 76).

METHODS

An inner ear test battery and/or serology assay were performed.

RESULTS

Incidence of SD in relation to overall neurotological cases did not significantly differ among the four groups. Groups I and II showed two or three audiographic patterns, while Groups III and IV had six audiographic patterns indicating that the aetiology of Groups I and II may be of the same origin, while Groups III and IV had multiple aetiologies. The hearing improvement rate was significantly higher in Groups III (62%) and IV (62%) than in Groups I (16%) and II (33%).

CONCLUSION

SD inevitably affects individuals of all ages. Significant differences in the audiographic patterns and speculative causes may account for various outcomes of treatment in each 20-year age band. Those SD patients aged 40-59 and 60-79 years showed significantly better treatment outcomes than those aged 0-19 and 20-39 years.

Resonance Effect of the Frontal Sinus on Ocular Vestibular-Evoked Myogenic Potential Recordings

OBJECTIVE

This study performed ocular vestibular-evoked myogenic potential (oVEMP) test via Fpz bone vibration (termed Fpz-oVEMP) and Fz bone vibration (termed Fz-oVEMP) using a minishaker. The aim of this study was to evaluate the resonance effect of the frontal sinus on the oVEMP recordings, so as to establish an optimal clinical protocol for eliciting oVEMPs by bone vibration.

DESIGN

Thirty healthy volunteers (15 children and 15 adults) and 15 adults with frontal sinusitis were enrolled in this study. All subjects underwent oVEMP test via Fpz and Fz bone vibration stimuli, and volume of the frontal sinus was measured by CT scan.

RESULTS

Because healthy adults (3.20 ± 1.08 mL) had significantly larger frontal sinus volume than healthy children (2.04±1.87 mL), the former (100%) showed higher response rates of Fpz-oVEMP than the latter (30%), but not Fz-oVEMP. When the frontal sinus volume is >1.91 mL (approximately at the age of 14 years), Fpz-oVEMP displayed larger reflex amplitude than Fz-oVEMP did. In contrast, Fpz-oVEMP (30%) displayed lower response rate than Fz-oVEMP (73%) in patients with frontal sinusitis.

CONCLUSIONS

Both developmental (frontal sinus volume) and pathological (frontal sinus inflammation) factors may affect the oVEMP responses via altering resonance function. For the developmental factor, frontal sinus volume >1.91 mL may initiate the resonance effect on oVEMPs, as evidenced by higher response rate with larger reflex amplitude of Fpz-oVEMP than Fz-oVEMP. For the pathological factor, frontal sinusitis may hamper the resonance effect on oVEMPs, as shown by the lower response rate of Fpz-oVEMP than Fz-oVEMP. Hence, oVEMP test may be performed via Fpz bone vibration first in healthy adults, while via Fz bone vibration first in children aged under 14 years or subjects with frontal sinusitis.

Assessing the cervico-ocular reflex system via modifying the ocular vestibular-evoked myogenic potential test

PURPOSE

The aim of this study was to devise a novel test for assessing the cervico-ocular reflex (COR) system via head vibration (termed h-COR) or neck vibration (termed n-COR) method.

MATERIALS AND METHODS

Thirteen patients with complete loss of bilateral vestibulo-ocular reflex (VOR) showing oscillopsia were assigned to Group A, while 13 patients with bilateral VOR loss but no oscillopsia were Group B. Another 13 healthy elderly served as a control. The COR test was performed via modifying the ocular vestibular-evoked myogenic potential (oVEMP) test by tapping at the forehead with head rotation (h-COR) or at mid-dorsal neck with head straight (n-COR).

RESULTS

Both h-COR and n-COR tests displayed similar cI-cII waveforms. None of the Group A or healthy elderly showed present h-COR, while 8% of Group A and 31% of the healthy elderly revealed present n-COR. In contrast, present h-COR and n-COR were elicited in 85 and 77% of Group B, respectively. Restated, significantly higher response rate of COR in Group B (without oscillopsia) than Group A (with oscillopsia) indicates that present COR is related to the alleviation of oscillopsia.

CONCLUSIONS

Head vibration method (h-COR test) is superior to neck vibration method (n-COR test) for assessing the COR system.

Bone Conduction Vibration Vestibular Evoked Myogenic Potential (VEMP) Testing: Reliability in Children, Adolescents, and Young Adults

OBJECTIVES

Bone conduction vibration (BCV) vestibular evoked myogenic potentials (VEMP) are clinically desirable in children for multiple reasons. However, no accepted standard exists for stimulus type and the reliability of BCV devices has not been investigated in children. The objective of the current study was to determine which BCV VEMP method (B-71, impulse hammer, or Mini-shaker) yields the highest response rates and reliability in a group of adults, adolescents, and children. It was hypothesized that the Mini-shaker would yield the highest response rates and reliability because it provides frequency specificity, higher output levels without distortion, and the most consistent force output as compared to the impulse hammer and B-71.

DESIGN

Participants included 10 child (ages 5 to 10), 11 adolescent (ages 11 to 18), and 11 young adult (ages 23 to 39) normal controls. Cervical VEMP (cVEMP) and ocular VEMP (oVEMP) were measured in response to suprathreshold air-conducted, 500 Hz tone bursts and 3 types of BCV (B-71, impulse hammer, and Mini-shaker) across 2 test sessions to assess reliability.

RESULTS

For cVEMP, response rates were 100% for all methods in all groups with the exception of the adult group in response to the impulse hammer (95%). For oVEMP, response rates varied by group and BCV method. For cVEMP, reliability was highest in adults using the Mini-shaker, in adolescents using the impulse hammer, and in children using the B-71. For oVEMP, reliability was highest in adults using the Mini-shaker, in adolescents using the Mini-shaker or impulse hammer, and in children using the impulse hammer. Age positively correlated with air-conducted oVEMP amplitude, but not cVEMP amplitude or cVEMP corrected amplitude. Age negatively correlated with all BCV VEMP amplitudes with the exception of cVEMP corrected amplitude in response to the Mini-shaker.

CONCLUSIONS

All BCV methods resulted in consistent cVEMP responses (response rates 95 to 100%) with at least moderate reliability (intraclass correlation coefficient ≥ 0.5) for all groups. Similarly, all BCV methods resulted in consistent oVEMP responses (89 to 100%) with at least moderate reliability (intraclass correlation coefficient ≥ 0.5) except for the B-71 in adults.

Pediatric Meniere's disease

OBJECTIVE

This study adopted an inner ear test battery comprising audiometry, and ocular vestibular evoked myogenic potential (oVEMP), cervical VEMP (cVEMP), and caloric tests to investigate the sequence of inner ear deficits in pediatric Meniere's disease (MD).

METHODS

From 2005 to 2016, a total of 24 MD children aged <15 years old underwent otoscopy, CT scan, blood test, and an inner ear test battery. Nine subjects were males and 15 were females, with mean age of 12 years. Right ear was affected in 3 patients, left ear in 5 patients, and both ears in 16 patients (67%). Eight (33%) of the 24 MD children had positive family history.

RESULTS

Inner ear deficits in MD children ran from abnormal hearing (25%) to abnormal cVEMP (20%), oVEMP (13%), and caloric (12%) tests, exhibiting a significantly declining sequence from the cochlea, to the saccule, utricle and semicircular canals. Analysis between the laterality and family history revealed a significantly positive correlation.

CONCLUSION

Pediatric MD is rare, accounting for 2.3% prevalence in MD patients. The inner ear deficits in pediatric MD showed a significantly declining sequence from the cochlea, to the saccule, utricle and semicircular canals, mimicking the sequence in adult MD. One-third MD children had positive family history, which may explain the high rate of bilateral affliction and symmetrical hearing levels on both ears.

Role of the Frontal Sinus in Mediating Ocular Vestibular-Evoked Myogenic Potentials by Bone Vibration Stimuli Applied to the Forehead

This study investigated ocular vestibular-evoked myogenic potential (oVEMP) tests via Fpz and Fz taps to assess the role of the frontal sinus in mediating oVEMP elicitation. Forty healthy subjects and 80 patients with Ménière disease (MD) underwent a series of oVEMP tests via a minishaker tapping at the Fpz and Fz sites in a randomized order. Response rates of oVEMP test via various tapping sites were compared. Dimensions of the frontal sinus were measured via CT scan. A significantly negative correlation between the age and height of the frontal sinus was noted, and the cutoff age for discriminating present and absent Fpz oVEMPs in MD patients was 52 years. Additionally, oVEMPs by Fpz tapping were more efficiently presented in males than females, likely because of the greater resonance by the larger height of the frontal sinus in males (3.88 ± 0.68 cm) than females (3.42 ± 0.67 cm). In conclusion, the height of the frontal sinus plays a role in mediating the elicitation of oVEMPs. The oVEMPs could be easily elicited by the first-order bone vibration (Fpz/Fz tapping) coupled with the second-order resonance effect (with a high extent of the frontal sinus). Thus, initial tapping at the Fpz site is suggested. If it fails, try the Fz site for screening the oVEMPs.

Pathological eye movements influence on the recordings of ocular vestibular-evoked myogenic potential

OBJECTIVE

This study investigated the influence of pathological eye movements on the recordings of ocular vestibulo-evoked myogenic potential (oVEMP).

METHODS

Ten patients with pathological eye movements of non-vestibular origin (nine congenital nystagmus and one opsoclonus) who had negative MRI result were assigned to Group A. Another 20 vestibular neuritis (VN) patients with spontaneous nystagmus were assigned to Group B. Both groups underwent audiometry, and caloric, oVEMP and cervical VEMP (cVEMP) tests.

RESULTS

In Group A, the caloric, oVEMP and cVEMP tests showed 40%, 55% and 50% abnormalities, respectively. In Group B (VN), caloric, oVEMP and cVEMP tests revealed 100%, 80% and 45% abnormalities on the lesion ears, and 0%, 40% and 0% abnormalities on the healthy (opposite) ears, respectively. The 40% oVEMP abnormality on the healthy ears may be due to recording failure from the presence of spontaneous nystagmus, since five of five VN patients showed normal oVEMPs on the healthy ears, one year after presentation.

CONCLUSIONS

Presence of pathological eye movements may affect the recordings of oVEMP. Thus, the oVEMP test is recommended to perform after acute vertiginous episode to exclude the influence of pathological eye movements on the oVEMP recordings.

N-acetylcysteine as a single therapy for sudden deafness

CONCLUSION

Like NAC ameliorates hearing loss from acoustic trauma in the inner ear, NAC may also rescue hearing loss from sudden deafness confined to the inner ear.

OBJECTIVE

This study assesses the effect of N-acetyl-L-cysteine (NAC) as a single therapy for sudden deafness.

METHODS

Thirty-five sudden deafness patients with neither systemic disorders nor central signs in electronystagmography were treated with NAC alone and assigned to Group A. For comparison, another 35 sudden deafness patients treated by corticosteroids and plasma expander were assigned to Group B. There were no significant differences between the two groups in terms of age, sex, laterality, and pre-treatment mean hearing level. All patients underwent an inner ear test battery comprising audiometry, and ocular vestibular-evoked myogenic potential (oVEMP), cervical VEMP (cVEMP), and caloric tests.

RESULTS

Groups A and B did not significantly differ in the pre-treatment mean hearing level, and percentages of abnormal oVEMP, cVEMP, and caloric tests, indicating that the involvement severity of sudden deafness between the two groups was similar. However, Group A (43 ± 27 dB) showed significantly greater mean hearing gain than Group B (21 ± 28 dB), and Group A (91%) revealed better improved rate of hearing than Group B (57%).

Eliciting Cervical Vestibular-Evoked Myogenic Potentials by Bone-Conducted Vibration via Various Tapping Sites

OBJECTIVES

This study compared bone-conducted vibration (BCV) cervical vestibular-evoked myogenic potentials (cVEMPs) via tapping at various skull sites in healthy subjects and patients with vestibular migraine (VM) to optimize stimulation conditions.

DESIGN

Twenty healthy subjects underwent a series of cVEMP tests by BCV tapping via a minishaker at the Fz (forehead), Cz (vertex), and inion (occiput) sites in a randomized order of tapping sites. Another 20 VM patients were also enrolled in this study for comparison.

RESULTS

All 20 healthy subjects had clear BCV cVEMPs when tapping at the inion (100%) or Cz (100%), but not at the Fz (75%). Mean p13 and n23 latencies from the Cz tapping were significantly longer than those from the Fz tapping, but not longer than those from the inion tapping. Unlike healthy subjects, tapping at the Cz (95%) elicited a significantly higher response rate of present cVEMPs than tapping at the inion (78%) in 20 VM patients (40 ears), because seven of nine VM ears with absent cVEMPs by inion tapping turned out to be present cVEMPs by Cz tapping.

CONCLUSIONS

While both inion and Cz tapping elicited 100% response rate of cVEMPs for healthy individuals, Cz tapping had a higher response rate of cVEMPs than inion tapping for the VM group. In cases of total loss of saccular function, cVEMPs could not be activated by either inion or Cz tapping. However, if residual saccular function remains, Cz tapping may activate saccular afferents more efficiently than inion tapping.

Vestibular function disorders and potential mechanisms in irradiation nasopharyngeal carcinoma patients

CONCLUSIONS

Vestibular function disorders were widespread among nasopharyngeal carcinoma (NPC) patients. The radiation doses to the inner ears were associated with the incidence of vestibular function disorders, but the correlations were mild. The inflammatory responses and possible resolution obstacles of inflammation participated in persistent vestibular function disorders after irradiation.

OBJECTIVES

To investigate the incidence of vestibular function disorders in NPC patients after irradiation and potential mechanisms.

METHODS

Patients who received radical intensity-modulated radiotherapy for their NPC were recruited. The serum levels of IL-6 and IL-17 were detected by ELISA method. Vestibular evoked myogenic potential (VEMP) tests were used to evaluate vestibular function and correlation analyses were used to analyze the potential mechanisms of vestibular function disorders.

RESULTS

Thirty-eight patients were included. The incidences of abnormal ocular VEMP (oVEMP) and cervical VEMP (cVEMP) were 65.79% and 80.26% at the time of completion of radiotherapy, and 61.84% and 71.05% at 3 months after radiotherapy. The mean and maximum radiation doses to the inner ears were both significantly associated with abnormal oVEMP and cVEMP (p < 0.05, all), but the correlations were all mild. The serum levels of IL-6 and IL-17 were both significantly associated with abnormal oVEMP and cVEMP after irradiation (p < 0.05, all).

Acute hearing loss in patients with hematological disorders

OBJECTIVE

This study adopted an inner ear test battery to investigate the causes of acute sensorineural hearing loss in patients with hematological disorders.

METHODS

During the past 20 years, the authors have experienced 14 patients with hematological disorders, i.e. leukemia or aplastic anemia, having acute sensorineural hearing loss. An inner ear test battery comprising audiometry and cervical vestibular-evoked myogenic potential (cVEMP), ocular VEMP (oVEMP), and caloric tests was performed.

RESULTS

Diagnoses comprised of sudden sensorineural hearing loss in 12 patients and endolymphatic hydrops in four patients (two patients had one ear with sudden sensorineural hearing loss while the other ear had endolymphatic hydrops). Percentages of recruitment phenomenon showed a significant difference between endolymphatic hydrops and sudden sensorineural hearing loss. Abnormal percentages for mean hearing level (86%), cVEMP test (71%), oVEMP test (25%), and caloric test (14%) exhibited a significant sequential decline in these patients.

CONCLUSION

Acute sensorineural hearing loss in a patient with leukemia or aplastic anemia may be related to either sudden sensorineural hearing loss or endolymphatic hydrops. A significant sequential decline in the function of the cochlea, saccule, utricle, and semicircular canals indicates that the pars inferior is more vulnerable to blood insult than the pars superior.

Assessment of functional development of the otolithic system in growing children: a review

OBJECTIVES

Although the caloric test, rotational test, and posturography have been used to investigate balance function conventionally, and they are older than tests of otolithic organs, yet it seems that most clinicians are less familiar with the development of otolithic (saccular and utricular) function in children. This study reviewed the electrophysiological testing used to assess the functional development of the otolithic system in growing children.

METHODS

Based on the literature, studies of cervical vestibular-evoked myogenic potential (cVEMP) and ocular VEMP (oVEMP) tests in children ranging from newborns, small children to adolescents were reviewed. Papers concerning foam posturography in children were also included.

RESULTS

The cVEMPs can be elicited in newborns at day 5, whereas the oVEMPs are absent in neonatal period. When children grow to 2 years old, the oVEMPs can be induced with eyes closed condition, while the oVEMPs with eyes up condition can be elicited in children aged >3 years old, with the characteristic parameters similar to adult levels. In contrast with cVEMPs, it is until the neck length >15.3cm (aldolesence), one need not account for neck length in evaluating cVEMP latency. Additionally, foam posturography indicated by the Romberg quotient of the sway velocity/area on foam pad is considered to reflect the otolithic function, which reached adult levels when the children at 12 years old.

CONCLUSIONS

For the functional development of the otolithic system in growing children to approach adult levels, the earliest occurrence is the oVEMP test, followed by the foam posturography, and cVEMP test.

Bilateral Meniere's disease assessed by an inner ear test battery

CONCLUSION

An inner ear test battery may suggest bilateral involvement and aid in 'grading' of potential disease in a patient with actively symptomatic Meniere's disease (MD).

OBJECTIVES

This study applied an inner ear test battery in patients with bilateral MD to map the inner ear deficits in each ear.

METHODS

From 2009 to 2012, 100 (20%) of 498 MD patients were diagnosed with bilateral involvement, which was defined as established MD in one ear, and the opposite ear had inner ear symptoms combined with documented hearing loss. Each patient underwent audiometry, and ocular vestibular-evoked myogenic potential (oVEMP), cervical VEMP (cVEMP), and caloric tests.

RESULTS

Grading of inner ear deficits was based on the number of abnormal results in the inner ear test battery. Of 100 patients with bilateral MD, 54% had the same grade and 46% had different grades in their 2 ears. On the other hand, based on four-tone average, 79% had the same Meniere stage and 21% had different stages in their two ears. The difference between ears with asymmetric grades (46%) and ears with asymmetric stages (21%) accounts for 25% of bilateral MD patients, which may be caused by the saccular hydrops in the opposite ear.

Test battery of cranial nerves VII and VIII for assessing herpes zoster oticus

OBJECTIVE

This study adopted a test battery of cranial nerves (CNs) VII and VIII comprising a facial nerve function test, audiometry, a caloric test, and ocular and cervical vestibular-evoked myogenic potential (oVEMP and cVEMP, respectively) tests to assess the function of CNs VII and VIII comprehensively so as to predict facial nerve recovery in patients with herpes zoster oticus (HZO).

STUDY DESIGN

Case series with chart review.

SETTING

University hospital.

METHODS

A total of 20 patients with HZO underwent a test battery of CNs VII and VIII. Registering the unaffected nerve bundles in the internal auditory canal was based on the number of normal results in the test battery of CNs VII and VIII. Fair facial nerve recovery is defined as the improvement of facial paresis to facial nerve grades I to II/VI.

RESULTS

In 20 patients with HZO, 6, 7, 3, and 4 patients had 0, 1, 2, and 3 unaffected nerve bundles, respectively. A significantly positive correlation was identified between the number of unaffected nerve bundles and fair facial nerve recovery. Similarly, a statistically significant predictor of fair facial nerve recovery was noted for unaffected nerve bundles (odds ratio, 15.42) but not for grading of the facial nerve (odds ratio, 0.49).

CONCLUSION

Grading of the facial nerve alone fails to predict the outcome of facial paresis in patients with HZO mainly because it overlooks the involvement of CN VIII. Alternatively, a combined test battery of CNs VII and VIII may serve as a strong predictor for facial nerve recovery.

The role of cervical and ocular vestibular evoked myogenic potentials in the assessment of patients with vestibular schwannomas

OBJECTIVES

To investigate the clinical utility of VEMPs in patients suffering from unilateral vestibular schwannoma (VS) and to determine the optimal stimulation parameter (air conducted sound, bone conducted vibration) for evaluating the function of the vestibular nerve.

METHODS

Data were obtained in 63 patients with non-operated VS, and 20 patients operated on VS. Vestibular function was assessed by caloric, cervical and ocular VEMP testing. 37/63 patients with conclusive ACS ocular VEMPs responses were studied separately.

RESULTS

In the 63 non-operated VS patients, cVEMPs were abnormal in 65.1% of patients in response to AC STB and in 49.2% of patients to AC clicks. In the 37/63 patients with positive responses from the unaffected side, oVEMPs were abnormal in 75.7% of patients with ACS, in 67.6% with AFz and in 56.8% with mastoid BCV stimulation. In 16% of the patients, VEMPs were the only abnormal test (normal caloric and normal hearing). Among the 26 patients who did not show oVEMP responses on either side with ACS, oVEMPs responses could be obtained with AFz (50%) and with mastoid stimulation (89%).

CONCLUSIONS

The VEMP test demonstrated significant clinical value as it yielded the only abnormal test results in some patients suffering from a unilateral vestibular schwannoma. For oVEMPs, we suggest that ACS stimulation should be the initial test. In patients who responded to ACS and who had normal responses, BCV was not required. In patients with abnormal responses on the affected side using ACS, BCV at AFz should be used to confirm abnormal function of the superior vestibular nerve. In patients who exhibited no responses on either side to ACS, BCV was the only approach allowing assessment of the function of the superior vestibular nerve. We favor using AFz stimulation first because it is easier to perform in clinical practice than mastoid stimulation.

Ocular vestibular-evoked myogenic potentials (oVEMPs) in response to bone-conducted vertex vibration

OBJECTIVE

To investigate low-frequency vertex bone-conducted (BC) vibration for evoking ocular vestibular myogenic potentials (oVEMPs) and its ability to discriminate between lesioned and healthy ears.

METHODS

oVEMPs were analysed in response to 125-Hz single cycle vertex BC vibration in healthy subjects (n=50) and in patients with severe unilateral vestibular loss (n=10). Both positive and negative initial stimulus motions were used.

RESULTS

In most healthy subjects, vertex BC vibration oVEMPs was successfully and symmetrically evoked from both ears. The response was dependent on the direction of the stimulus motion. The latency was shorter with negative initial stimulus motion; however, a positive initial stimulus motion generated somewhat larger amplitudes. Furthermore, there was no significant response from lesioned ears, whereas oVEMPs from the patients' healthy ears were similar to the responses in healthy subjects.

CONCLUSION

The oVEMP low-frequency BC response was dependent on the direction of the initial stimulus motion. Testing oVEMPs in response to low-frequency vertex vibration can discriminate patients with unilateral vestibular function loss from healthy controls.

SIGNIFICANCE

Low-frequency vertex BC vibration oVEMPs should be considered a possible clinical screening test to evaluate vestibular function.

Mapping affected territory of anterior/posterior inferior cerebellar artery infarction using a vestibular test battery

CONCLUSION

Although the affected territory in the posterior/anterior inferior cerebellar artery (PICA/AICA) infarction could not be meticulously demonstrated by magnetic resonance imaging (MRI), it could be picked up by the results of a vestibular test battery comprising caloric, ocular vestibular evoked myogenic potential (oVEMP), and cervical VEMP (cVEMP) tests.

OBJECTIVES

This study applied audiometry and caloric, oVEMP, and cVEMP tests to map affected territory in patients with PICA/AICA infarction.

METHODS

Fourteen patients, including 11 with PICA infarction and 3 with AICA infarction, were enrolled in this study during the last 8 years. Each patient underwent audiometry, caloric test, oVEMP test, and cVEMP test.

RESULTS

In the PICA group, 8 (36%) of 22 ears had a mean hearing level >25 dB. All six ears (100%) in the AICA group had abnormal hearing, and thus both groups revealed a significant difference. Conversely, significant differences were not observed in the vestibular test battery between the PICA and AICA groups. MRI demonstrated infarction at the brainstem for six patients, while one patient also had cerebellar involvement, indicated by loss of visual suppression on caloric nystagmus. Six patients showed infarction at the cerebellum, and four of them had brainstem affliction based on abnormal oVEMP/cVEMP test results.

Secondary endolymphatic hydrops after sudden deafness

CONCLUSION

Patients with sudden deafness who had abnormal ocular vestibular-evoked myogenic potential (oVEMP)/cervical VEMP (cVEMP) responses but retained caloric function may subsequently develop secondary hydrops with a mean interval of 8 years.

OBJECTIVE

This study applied the inner ear test battery in patients who had sudden deafness previously to elucidate how secondary endolymphatic hydrops occurs years after sudden deafness.

METHODS

Twenty patients who had experienced recent vertiginous attacks several years after sudden deafness (group A) and 20 patients without rotational vertiginous episode for at least 5 years following sudden deafness (group B) were enrolled. All patients underwent an inner ear test battery comprising audiometry, caloric test, and oVEMP and cVEMP tests.

RESULTS

The mean interval from initial sudden deafness to vertiginous attack in group A was 8 years, with a mean hearing level of 66 ± 20 dB, which did not significantly differ from 61 ± 20 dB in group B. For the vestibular test results, the percentages of abnormal cVEMP, oVEMP, and caloric tests in group A were 65%, 70%, and 25%, respectively. Compared to the respective 70%, 60%, and 75% abnormalities in group B, only the caloric test differed significantly.

Inner ear deficits after chronic otitis media

Investigation of the causes of vestibular symptoms in patients with chronic otitis media (COM) faces frustration, mainly because the bithermal caloric test using tap water is generally contraindicated in perforated ears. This study utilized audiometry, ocular vestibular-evoked myogenic potential (oVEMP) test, and cervical VEMP (cVEMP) test to evaluate inner ear deficits after COM. A total of 85 COM patients (117 ears) underwent otoscopy, image study, audiometry, oVEMP test, and cVEMP test. Mean bone-conducted (BC) hearing threshold ≤25 dB was observed in 74 ears, 26-40 dB in 30 ears, and >40 dB in 13 ears. Restated, abnormal BC hearing threshold was identified in 43 ears (37 %). Percentages of abnormal cVEMP test, oVEMP test, and BC hearing threshold in 117 COM ears were 65, 62, and 37 %, respectively, exhibiting a significantly declining sequence in inner ear function. Furthermore, cVEMP/oVEMP test results were significantly correlated with BC hearing threshold, whereas no correlation existed between the cVEMP and oVEMP test results. In conclusion, the sequence of inner ear deficits after COM runs from the saccule/utricle to the cochlea and semicircular canals. Restated, in addition to BC hearing test, the cVEMP/oVEMP test may serve as a supplementary tool for early detection of inner ear involvement in COM patients.

Characteristics and clinical applications of ocular vestibular evoked myogenic potentials

Recently, ocular vestibular evoked myogenic potentials (oVEMPs) have been described and added to the neuro-otologic test battery as a new measure for the vestibulo-ocular reflex. oVEMPs represent extraocular muscle activity in response to otolith stimulation e.g. by air-conducted sound or bone-conducted vibration. In response to vestibular stimulation, electromyographic activity of the extraocular muscles can be recorded by means of surface electrodes placed beneath the contralateral eye. oVEMPs are likely to reflect predominantly utricular function, while the widely established cervical vestibular evoked myogenic potentials (cVEMPs) assess saccular function. Thus, measuring oVEMPs and cVEMPs in addition to caloric and head impulse testing provides further evaluation of the vestibular system and enables quick and cost-effective assessment of otolith function. This review summarizes the neurophysiological properties of oVEMPs, gives recommendations for recording conditions and discusses oVEMP alterations in various disorders of the vestibular system. With increasing insight into oVEMP characteristics in vestibular disorders, e.g. Menière's disease and superior semicircular canal dehiscence syndrome, oVEMPs are becoming a promising new diagnostic tool for evaluating utricular function.