Simultaneous recording of ultrasound and polysomnography during natural sleep in patients with obstructive sleep apnea: a pilot study.

Tongue base deformation may play a critical role in the phenomenon of obstructive sleep apnea, but polysomnography provides limited information regarding the effect of tongue motion during natural sleep. We reported on preliminary results of combining a novel ultrasound system and polysomnography for simultaneous recordings during natural sleep in volunteers and patients with obstructive sleep apnea. All participants underwent time-synchronized polysomnography and submental transcutaneous ultrasound examinations. The wearable ultrasound device detected the air-mucosal interface of the tongue surface and automatically determined the maximum tongue base thickness in real time. All participants reported no sensation of heat, no sign of skin allergy, and an average of mild disturbance after the ultrasound recordings. In the individual patient with obstructive sleep apnea, we demonstrated a significant difference (P < 0.001) between the ultrasonic tongue base thickness measured during eupnea and that measured during snoring, hypopnea and apnea. The ultrasonic tongue base thickness increased and remained before the occurrence of obstructive apnea. On average, increased tongue base thicknesses of 2.5 (4.1%), 6.0 (9.8%) and 7.7 mm (12.5%) are associated with snoring, hypopnea and apnea, respectively. Our present data demonstrate that simultaneous examination of ultrasonic tongue base thickness and polysomnography is feasible for prolonged recording during natural sleep. The proposed method also enables the detection of significant differences in ultrasonic tongue base thickness between eupnea and obstructive respiratory events evaluated using polysomnography. This novel technique can be used to generate hypotheses for subsequent investigations of the underlying mechanisms and individualized combined therapy for obstructive sleep apnea. CLINICAL TRIAL REGISTRATION: This study has been registered at the Chinese Clinical Trial Registry website with the registration number of ChiCTR-DDT-13003313. The date of registration was 13 July 2013.

Correlating vestibular schwannoma size with vestibular-evoked myogenic potential results.

OBJECTIVES: The maximum size of the vestibular schwannoma (VS) that is compatible with preservation of the function of the vestibular nerve in performing stereotactic radiosurgery remains unclear. This study utilized ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) test results to correlate with the size of VS. DESIGN: Fifty patients with unilateral VS underwent audiometry, and caloric, oVEMP and cVEMP tests. Tumor size from magnetic resonance imaging was measured on the axial plane, and the relationships between tumor size and each test result were analyzed. RESULTS: The pure-tone average from four frequencies did not significantly predict tumor size. Alternatively, oVEMP and cVEMP responses remained significant predictors for tumor size in the regression model, namely, tumor size (cm) = 0.62 × (oVEMP response) + 1.39 × (cVEMP response), where oVEMP and cVEMP responses were regarded as binary variables, in which 1 and 0 reflect abnormal and normal responses, respectively. This model explained 76% of the variance. Accordingly, the estimated VS size exhibiting abnormal oVEMPs and cVEMPs is >2.01 (0.62 +1.39) cm. CONCLUSIONS: When VS size is <2.0 cm, preservation of the function of superior/inferior vestibular nerve indicated by the oVEMP/cVEMP test is achievable. Therefore, both oVEMP and cVEMP tests may serve as supplementary tools for determining treatment option in VS patients.

Registering grades of sudden deafness to predict the hearing outcome via an inner-ear test battery.

OBJECTIVES: An inner ear test battery comprising audiometry and ocular vestibular-evoked myogenic potential (oVEMP), cervical VEMP (cVEMP), and caloric tests was applied to patients with sudden deafness to map their lesions and predict hearing outcome. DESIGN: Retrospective study. STUDY SAMPLE: Seventy-five patients with unilateral sudden deafness underwent an inner-ear test battery. Registering the grades of sudden deafness was based on the number of abnormal test results in the inner ear test battery. RESULTS: After treatment for three consecutive months, mean hearing gain declined significantly from Grade I (one abnormal test) to Grade IV (four abnormal tests). Significant relations existed between hearing outcome and oVEMP test results (p < 0.05), caloric test results (p < 0.05), but not cVEMP test results and pre-treatment mean hearing level. Combined caloric and oVEMP test results demonstrated a stronger predictor with a c statistic of 0.722 than either test alone, indicating that this regression model fits the whole set of observations well and is effective in predicting the hearing outcome. CONCLUSION: Abnormal caloric and oVEMP test results in sudden deafness patients may indicate poor prognosis for hearing improvement, whereas hearing recovery can be anticipated when both tests reveal normal responses.

Creating an autoencoder single summary metric to assess gait quality to compare surgical outcomes in children with cerebral palsy: The Shriners Gait Index (SGI).

Gait for individuals with movement disorders varies widely and the variability makes it difficult to assess outcomes of surgical and therapeutic interventions. Although specific joints can be assessed by fewer individual measures, gait depends on multiple parameters making an overall assessment metric difficult to determine. A holistic, summary measure can permit a standard comparison of progress throughout treatments and interventions, and permit more straightforward comparison across varied subjects. We propose a single summary metric (the Shriners Gait Index (SGI)) to represent the quality of gait using a deep learning autoencoder model, which helps to capture the nonlinear statistical relationships among a number of disparate gait metrics. We utilized gait data of 412 individuals under the age of 18 collected from the Motion Analysis Center (MAC) at the Shriners Children's - Chicago. The gait data includes a total of 114 features: temporo-spatial parameters (7), lower extremity kinematics (64), and lower extremity kinetics (43) which were min-max normalized. The developed SGI score captured more than 89% variance of all 144 features using subject-wise cross-validation. Such summary metrics holistically quantify an individual's gait which can then be used to assess the impact of therapeutic interventions. The machine learning approach utilized can be leveraged to create such metrics in a variety of contexts depending on the data available. We also utilized the SGI to compare overall changes to gait after surgery with the goal of improving mobility for individuals with gait disabilities such as Cerebral Palsy.

Correlations between foam posturography and vestibular-evoked myogenic potential tests in Ménière's disease.

OBJECTIVES: This study adopted foam posturography coupled with inner ear test battery including audiometry, and cervical Vestibular-Evoked Myogenic Potential (cVEMP), ocular Vestibular-Evoked Myogenic Potential (oVEMP) and Caloric tests in patients with Ménière's disease to investigate the relations between them. DESIGN: Fifty patients with unilateral definite Ménière's disease were enrolled. All patients underwent Audiometry, and Caloric, oVEMP, and cVEMP tests. In addition, posturography was also performed under 4 conditions: A (firm surface, eyes open), B (firm surface, eyes closed), C (foam pad, eyes open), and D (foam pad, eyes closed). Romberg quotient (RQ) was measured as the value from eyes closed divided by that from eyes open. RESULTS: No correlation existed between Ménière stage and RQ measured with foam pad. Mean RQ of the sway area on foam pad in Ménière's patients with abnormal oVEMPs (1.75 ± 0.95) was significantly larger than 1.20 ± 0.70 in those with normal oVEMPs. However, neither cVEMP nor Caloric test results were associated with RQ on foam pad (p > 0.05). Further, the area under the receiver operating characteristic curve of the RQ of sway area on foam pad in discrimination between normal and abnormal oVEMP test was 0.65 (95% CI, 0.51 to 0.79; p < 0.05), implying that RQ of the sway area on foam pad may serve as a significant predictor for abnormal oVEMP test. CONCLUSIONS: By removing or reducing both visual and somatosensory inputs from foam posturography, the remaining vestibular cue, represented as RQ of sway area on foam pad, may reflect utricular function.

Comparison of head elevation versus rotation methods for eliciting cervical vestibular-evoked myogenic potentials via bone-conducted vibration.

OBJECTIVES: This study investigated the feasibility of the cervical vestibular-evoked myogenic potential (cVEMP) test using bone-conducted vibration (BCV) tapping. DESIGN: Prospective study. STUDY SAMPLE: Initially, 20 healthy volunteers aged 23-38 years underwent cVEMP tests in supine position using head elevation method by BCV tapping at the Fz and inion. On another day, the same subjects underwent cVEMP tests in seated position with head rotation method by BCV tapping at the Fz and inion. Another 20 healthy subjects aged 41-60 years undergoing cVEMP tests by BCV tapping at the inion were also included for comparison. RESULTS: Tapping at the inion (100%) had significantly higher response rate of cVEMPs than tapping at Fz (65-70%), regardless of whether the head was elevated or rotated. Except for mean latencies of p13 and n23, the mean p13-n23 amplitude, corrected amplitude, and asymmetry ratio did not differ significantly between the elevation and rotation methods when cVEMPs were elicited by inion tapping; both methods showed excellent test-retest reliability. CONCLUSIONS: The BCV at the inion is the optimal method for eliciting BCV cVEMPs. These responses can be recorded using either the seated/head rotation method or supine/head elevation method.

Vestibular-evoked myogenic potential tests in orthostatic dizziness.

OBJECTIVE: As otolithic control of blood pressure has been the focus of recent interest, this study investigated the ocular and cervical vestibular-evoked myogenic potential (oVEMP and cVEMP) tests in patients with orthostatic dizziness. METHODS: Sixty patients with orthostatic dizziness and 20 normal controls were consecutively enrolled. All subjects received a battery of tests including audiometry, and caloric, oVEMP and cVEMP tests. RESULTS: Audiometry revealed normal hearing in all 60 patients. Caloric test identified hyperactive and normal responses in 35 and 65 % of patients, respectively. The oVEMP test showed normal responses in 36 patients, and abnormal (absent and reduced) responses in 24 patients (40 %). Most patients (22/24) with abnormal oVEMPs revealed asymmetrical responses. For the cVEMP test, 30 patients (50 %) had normal responses, and 23 and 7 patients showed delayed and absent cVEMPs, respectively. Significant differences existed in the abnormal percentage of oVEMP and cVEMP tests between the patient and control groups. When the oVEMP and cVEMP test results were combined, the abnormal rate increased to 70 % of the patients, resulting in stronger association as an elevated odds ratio of 13.2, greater than 12.7 and 5.7 in the corresponding individual oVEMP and cVEMP tests. INTERPRETATION: Patients with orthostatic dizziness may show asymmetric oVEMPs and abnormal (delayed) cVEMPs. If both test results were combined together, a high abnormality (70 %) was obtained, indicating that in addition to conventional autonomic test battery, the two VEMP tests may serve as a supplementary tool for evaluating orthostatic dizziness.

Influence of head acceleration on ocular vestibular-evoked myogenic potentials via skull vibration at Fz versus Fpz sites.

OBJECTIVE: This study applied bone vibration (BV) stimulation to the Fz and Fpz sites to investigate the influence of head acceleration on the ocular vestibular-evoked myogenic potentials (oVEMPs). DESIGN: Prospective study. STUDY SAMPLE: Fourteen healthy subjects underwent oVEMP tests combined with real-time triaxial accelerometry. RESULTS: Under BV stimulation from a vibrator to the Fz and Fpz sites, acceleration magnitudes along x-, y- or z-axis did not significantly differ between the two sites. The mean nI and pI latencies of the oVEMPs stimulated at Fz were significantly earlier than those at Fpz. However, no statistical differences existed in the nI-pI interval and amplitude between the two sites. A blunt or double peak nI configuration was noted in three subjects (22%) when tapping at Fpz, but not at Fz, likely because different muscles contributing to the oVEMPs. CONCLUSION: While both Fz and Fpz are effective sites for generating an oVEMP, the variation in human skull shapes and properties will lead to different acceleration profiles being transmitted to the vestibular apparatus. These differing stimuli may lead to different oVEMP profiles, so if one site does not produce the expected response, the clinician should try the other site.

Localization and prevalence of hydrops formation in Ménière's disease using a test battery.

This study investigated the localization and prevalence of hydrops formation in 20 patients with unilateral Ménière's disease using a battery of tests, including audiometry, caloric, ocular vestibular evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests. The latter two tests used air-conducted sound (ACS) and bone-conducted vibration (BCV) as stimuli. Thirteen patients (65%) had abnormal hearing with a 4-tone average >26 dBHL. In the caloric test, 4 patients (20%) had abnormal responses, including canal paresis in 3 and caloric areflexia in 1 patient. The percentages of patients with abnormal ACS-oVEMP, BCV-oVEMP, ACS-cVEMP, and BCV-cVEMP tests were 65, 25, 45, and 25% in affected ears, and 40, 0, 15, and 0% in unaffected ears, respectively. Although ACS- and BCV-oVEMP results differed significantly, ACS- and BCV-cVEMP results did not, regardless of the affected or unaffected ears. Thus, the abnormal rates for hearing, ACS-cVEMP, BCV-oVEMP, and caloric tests in affected ears were 65, 45, 25, and 20%, respectively. This decreasing order of abnormal percentages in function of the cochlea, saccule, utricle, and semicircular canals mimics the declining sequence of hydrops formation in temporal bone studies. In conclusion, an inner ear test battery comprising audiometry, caloric, oVEMP, and cVEMP tests may provide further insight into the localization and prevalence of hydrops formation in Ménière's disease.

An animal model of ocular vestibular-evoked myogenic potential in guinea pigs.

This study aimed to establish an animal model of ocular vestibular-evoked myogenic potential (oVEMP) in guinea pigs. Ten healthy and 10 gentamicin-treated guinea pigs underwent oVEMP test using a hand-held bone-conducted vibrator placed on the animal's forehead. All 10 healthy animals exhibited bilateral oVEMPs at the stimulus intensity of 139 dB force level (FL), with a mean threshold and latencies of peak nI and pI of 130 +/- 4 dBFL, 3.17 +/- 0.37 ms and 4.72 +/- 0.38 ms, respectively. Similar to response rate, the nI-pI amplitude decreased markedly in magnitude as stimulus intensity decreased. Another 10 animals administered with gentamicin (2 mg) on the left ear 1 week after surgery had 100% clear oVEMPs beneath the left eye (ipsilateral to the lesion side), whereas oVEMPs were absent and reduced beneath the right eye (opposite to the lesion side) in 7 and 3 animals, respectively. Morphological study of animals with absent oVEMPs identified substantial damage to the hair cells of the utricular macula. Quantitative analysis revealed that histological density of intact hair cells of the utricular macula from control and lesion ears were 194 +/- 15 and 66 +/- 9 per 130 x 130 microm(2) field, respectively, showing a 68% reduction in the latter. Further, the stereocilia of the residual hair cells were either fused or deformed, and pointed outward randomly. In conclusion, this study establishes the animal model of oVEMP in guinea pigs using bone-conducted vibration stimuli, which sets the stage for investigating the pathophysiology of the utricular disorders.

Ocular and cervical vestibular-evoked myogenic potentials: a study to determine whether air- or bone-conducted stimuli are optimal.

OBJECTIVES: The aim of this study was to determine whether bone-conducted vibration (BCV) or air-conducted sound (ACS) is the optimal mode for eliciting both ocular vestibular-evoked myogenic potentials (oVEMPs) and cervical VEMPs (cVEMPs). DESIGN: Twelve healthy volunteers, five patients with unilateral chronic otitis media, and 10 patients with unilateral Meniere disease underwent oVEMP and cVEMP tests using ACS and BCV stimulation modes in a random order. RESULTS: In healthy controls, BCV mode at Fz had a significantly higher response rate and larger nI-pI amplitude of oVEMPs than that of the ACS mode. In cVEMPs, a significantly higher response rate was noted in BCV mode at inion, when compared with ACS mode. However, no significant difference was noted in the p13-n23 amplitude between these two modes. In five chronic otitis media ears, absence of oVEMPs and cVEMPs in ACS mode and presence of oVEMPs and cVEMPs in BCV mode were shown. In 10 patients with Meniere disease, BCV mode elicited higher response rates of oVEMPs and cVEMPs in the pathological ears than ACS mode did. CONCLUSIONS: Using BCV mode, Fz and inion may be the optimal sites for eliciting oVEMPs and cVEMPs, respectively. Thus, BCV mode can be substituted for ACS mode to elicit oVEMPs and cVEMPs in the future, especially in "mass detection." In contrast, ACS mode provides an essential clinical merit of site selectivity.

Development of vestibular evoked myogenic potentials in preterm neonates.

Our recent study successfully recorded vestibular evoked myogenic potential (VEMP) responses in full-term newborns. However, when VEMP responses are elicited in preterm neonates remains unclear. This study employed the VEMP test in 27 low-risk preterm and 25 healthy full-term neonates without sedation to investigate the development of VEMP response after birth. Fourteen (26%) of 54 ears in preterm neonates exhibited VEMP responses, a response rate significantly lower than that of full-term neonates (72%). The mean latencies of peaks p13 and n23 in the preterm group were significantly longer than those in the full-term group. Analysis of variable parameters for present VEMPs in pre- and full-term neonates revealed that the cutoff values of body weight were 2.26 and 2.82 kg, and that those of postmenstrual age were 37.1 and 38.4 weeks, respectively. Both body weight and postmenstrual age were significantly negatively correlated with p13 and n23 latencies but not with p13-n23 amplitude. In conclusion, present VEMPs can be anticipated when the body weight of pre- and full-term neonates reaches >2.26 and 2.82 kg, respectively. It indicates that the sacculocollic reflex develops in the same manner, but the difference in response rate between full- and pre-term neonates may, at least in part, correlate with muscle bulk and strength, relative to the body weight adequate for the VEMP response.

Consistent latencies of vestibular evoked myogenic potentials.

OBJECTIVES: This study investigated the association between neck length and vestibular evoked myogenic potential (VEMP) latencies in healthy children, adolescents, and adults to elucidate when VEMP latencies reach consistent levels. DESIGN: Findings of VEMP tests in 14 healthy children, seven healthy adolescents, and 14 healthy adults were analyzed for correlations with neck length, which was measured as the distance of a line dropping vertically from the mastoid tip to the horizontal plane passing through the clavicle. RESULTS: All healthy children, adolescents, and adults exhibited present VEMP responses. Children, adolescents, and adults significantly differed in p13 latency, n23 latency, and p13-n23 interval. According to receiver operating characteristic curve analysis, the optimal cutoff values of p13 and n23 latencies between children and adults were 12.6 and 19.8 msec, respectively. Because the odds ratio of p13 latency was less than that of n23 latency, n23 latency was used to discriminate VEMP latencies between children and adults. Accordingly, a cutoff value of 15.3 cm for neck length was proposed as a criterion for predicting VEMP latency within the adult range. Consequently, a positive correlation between neck length and VEMP latency was observed when neck length was <15.3 cm, while above which level one need not account for neck length in evaluating VEMP latency. CONCLUSIONS: The intra-subject variability of norms can be enhanced if the normative data for VEMP characteristic parameters take structural variance into account. This study suggests that the adult range of VEMP latencies can be anticipated if neck length is >15.3 cm.

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.

Vestibular evoked myogenic potentials using simultaneous binaural acoustic stimulation.

The aim of this study is to investigate the feasibility of recording vestibular evoked myogenic potential (VEMP) using simultaneous binaural acoustic stimulation (B-VEMP), and compare it with that using monaural acoustic stimulation (M-VEMP). Seven healthy volunteers were evoked by initial B-VEMP test and subsequent M-VEMP test, whereas vice versa in another 7 volunteers. All 14 subjects demonstrated both B-VEMPs and M-VEMPs, without significant difference in the latencies of p13 and n23. When using interaural amplitude difference (IAD) ratio for interpreting amplitude, B-VEMPs did not differ significantly from that of M-VEMPs. Hence, B-VEMPs can produce information equivalent to M-VEMPs in terms of response rate, latencies, and IAD ratio in healthy subjects. Likewise, similar results were also shown in the patients with unilateral Meniere's disease. In conclusion, B-VEMPs provide neither different information nor less variability, as compared with M-VEMPs. In addition, B-VEMPs can offer information on unilateral inner ear (saccular) pathology similar to that by M-VEMPs. Furthermore, recording from binaural stimulation can be used as a possibly more convenient mode compared with two monaural recordings, especially when testing young or old or disabled patients, since a continuous muscular effort is required during recording.

Selective effects of head posture on ocular vestibular-evoked myogenic potential (oVEMP) by bone-conducted vibration.

OBJECTIVE: By altering head postures from sitting, supine to head hanging, this study investigated the effects of gravitational force on ocular vestibular-evoked myogenic potential (oVEMP) via either air-conducted sound (ACS) or bone-conducted vibration (BCV) stimuli. METHODS: Twenty healthy volunteers underwent the oVEMP test via ACS or BCV stimuli with the sitting, supine, and head hanging positions on the same day in a randomized order. RESULTS: All subjects had clear BCV oVEMPs in the three head postures. No significant differences existed in terms of mean nI and pI latencies, the nI-pI interval, and asymmetry ratio regardless of various positions. However, the mean nI-pI amplitude with the head hanging position (15.9 ± 6.4 µV) was significantly larger than that with the sitting position (13.8 ± 6.0 µV), but not significantly larger than that with the supine position (14.7 ± 6.1 µV). Nevertheless, such a difference in reflex amplitude does not exist in oVEMPs elicited by ACS stimuli. With the sitting position, mean linear acceleration at the mastoids in response to BCV stimuli was -0.06 ± 0.02, 0.20 ± 0.04 and -0.04 ± 0.02 g along the x-, y-, and z-axis, respectively, which did not differ significantly from those with the head hanging position. CONCLUSION: By altering head postures from sitting to head hanging, gravitational force can exert a selective effect on the reflex amplitude of oVEMPs elicited by BCV stimuli, but not by ACS stimuli. SIGNIFICANCE: Compared to ACS mode, BCV mode can provoke higher response rate, generate earlier and larger waveforms, and be influenced by both dynamic shearing force and static gravitational force to enlarge the reflex amplitude of oVEMPs.

Submental ultrasound measurement of dynamic tongue base thickness in patients with obstructive sleep apnea.

Dynamic tongue base thickness (TBT) may be an important anatomic factor in airway narrowing in patients with obstructive sleep apnea (OSA). The development of an accurate clinical assessment of the retroglossal airway in patients with OSA is still evolving. Submental ultrasound was used to investigate the association between measurements of TBT in response to negative airway pressure and the existence of OSA. Twenty OSA patients and 20 control participants underwent ultrasound measurement of TBT on eupneic breathing and with the Mueller maneuver, as well as clinical and polysomnographic assessments. Logistic regression analyses indicated that after adjustment for confounding factors, independent predictors of OSA included TBT in response to negative airway pressure, as measured by submental ultrasound with the Mueller maneuver (odds ratio: 2.11, 95% confidence interval: 1.15-3.87, p < 0.05), and the difference between TBT with the Muller maneuver and that without the Mueller maneuver (odds ratio: 2.47, 95% confidence interval: 1.09-5.58, p < 0.05). Ultrasound measurement of TBT during the Mueller maneuver provides a quantitative assessment of the retroglossal airway in OSA patients with minimal invasiveness and easy accessibility.

Optimizing the bandpass filter for acoustic stimuli in recording ocular vestibular-evoked myogenic potentials.

This study aimed to determine the optimal bandpass filter (BPF) setting for acoustic stimuli in recording the ocular vestibular-evoked myogenic potential (oVEMP). Twelve healthy volunteers underwent oVEMP tests using acoustic stimuli with various high-pass filters (1, 10 and 100Hz) and low-pass filters (500, 1000 and 2000Hz). Initially, various effects of high-pass filter on the oVEMPs were examined under Conditions A (BPF of 1-1000Hz), B (BPF of 10-1000Hz) and C (BPF of 100-1000Hz). Of these conditions, Condition A showed 100% response rate and had larger nI-pI amplitude than Conditions B and C. Thus, Condition A was selected for subsequent analysis of the various effects of low-pass filter on the oVEMPs. However, Condition A (BPF of 1-1000Hz) did not significantly differ from Conditions D (BPF of 1-500Hz) and E (BPF of 1-2000Hz) in terms of the latencies and amplitudes of oVEMPs. Condition A thus is supposed to be the optimal recording condition for oVEMPs. In conclusion, the optimal BPF setting for acoustic stimuli in recording oVEMPs is suggested to be between 1 and 1000Hz.

Development of ocular vestibular-evoked myogenic potentials in small children.

OBJECTIVES/HYPOTHESIS: This study investigated the development of otolithic-ocular reflex in small children (<3 years old) via the ocular vestibular-evoked myogenic potential (oVEMP) test. STUDY DESIGN: Prospective study. METHODS: Twenty full-term newborns (group A), 15 children aged 1 to 3 years (group B), and 15 children aged 4 to 13 years (group C) were enrolled in this study. All children underwent auditory brainstem response testing or audiometry, and the oVEMP test. RESULTS: All subjects had normal hearing. Typical biphasic oVEMP waveforms were not observed in the 20 newborns, but were present in six (40%) of 15 children aged 1 to 3 years and all (100%) children aged 4 to 13 years, exhibiting a significant difference. In group B, except for the nine children aged 12 to 24 months, the remaining six children, aged 25 to 47 months, had clear oVEMPs, with the mean nI latency and nI-pI amplitude resembling those in children aged 4 to 13 years, indicating that the otolithic-ocular reflex is mature in children aged >2 years. CONCLUSIONS: Despite the well-developed caloric and cervical VEMP responses in early life, oVEMPs are not present in newborns, but are present in children aged >2 years who can walk with a gait resembling an adult. Maturation of the otolithic-ocular reflex is important to balance control, which is necessary in small children for independent gait.

Correlation between acceleration magnitude and ocular vestibular-evoked myogenic potential.

This study combined bone-conducted vibration (BCV) stimulation with triaxial accelerometry to correlate the acceleration magnitudes of BCV stimuli with ocular vestibular-evoked myogenic potential (oVEMP) test results. Fourteen healthy volunteers underwent oVEMP test using BCV stimuli with simultaneous monitoring the triaxial acceleration. All (100%) subjects exhibited clear oVEMPs in response to BCV stimuli from a vibrator. The lowest acceleration magnitudes for eliciting oVEMPs along the x-, y- and z-axes were 0.05±0.01 g, 0.16±0.08 g, and 0.04±0.01 g, respectively, exhibiting significantly higher acceleration magnitude along the y-axis than those along the x- and z-axes. In addition, significantly positive correlations were noted between the acceleration magnitude along each axis and the oVEMP amplitude. In conclusion, measuring the acceleration magnitude throughout oVEMP testing revealed a significant correlation between linear acceleration and oVEMP responses. Restated, increasing acceleration magnitude may have more synchronization of firing of vestibular afferents, resulting in more synchronized evoked potentials and greater oVEMP amplitude.