Acoustic, mechanical and galvanic stimulation modes elicit ocular vestibular-evoked myogenic potentials

ObjectiveThis study compared the characteristic parameters of ocular vestibular-evoked myogenic potentials (oVEMPs) elicited by the air-conducted sound (ACS) and bone-conducted vibration (BCV) stimulation modes as well as the galvanic vestibular stimulation (GVS) mode.DesignFifteen healthy subjects underwent oVEMP tests using ACS (127 dBSPL), BCV (142 dB force level), and GVS (5 mA) modes. The response rate, latencies of nI and pI, nI–pI interval and amplitude were measured for each mode and compared among modes.ResultsAll 15 healthy subjects (30 ears) had 100% response rates in both BCV- and GVS–oVEMPs, exhibiting a response rate significantly higher than 80% in ACS–oVEMPs. The mean nI latency was the shortest in the GVS mode, followed by BCV and then ACS modes. The variation among the latencies of the three modes was significant. Likewise, the mean nI–pI amplitudes in ACS-, BCV- and GVS modes varied significantly. However, the mean nI–pI interval did not differ significantly among the three modes.ConclusionsAmong the ACS (127 dBSPL), BCV (142 dB force level), and GVS (5 mA) modes, the BCV mode yields a 100% response rate and the largest nI–pI amplitude of oVEMPs.SignificanceThe oVEMPs in ACS and GVS modes may help to differentiate the saccular from the retro-saccular lesions. If ACS–oVEMPs are normal, then oVEMPs in BCV and GVS modes can distinguish between utricular and retro-utricular disorders. Restated, oVEMPs in ACS, BCV, and GVS modes may promote the topographical delineation of the lesion site of the otolithic–ocular reflex pathway.     

Ocular vestibular evoked myogenic potentials to head tap and cervical vestibular evoked myogenic potentials to air-conducted sounds in isolated internuclear ophthalmoplegia

ObjectiveThe central pathways responsible for ocular vestibular evoked myogenic potentials (VEMPs) to forehead tapping remain to be determined. This study aimed to determine whether the medial longitudinal fasciculus (MLF) carries the signals for ocular VEMPs (oVEMPs) in response to this mode of stimulation.MethodsTwelve patients with isolated unilateral internuclear ophthalmoplegia (INO) due to brainstem infarction underwent evaluation of the ocular tilt reaction (ocular torsion and skew deviation), tilt of the subjective visual vertical (SVV), cervical VEMPs (cVEMPs) in response to tone burst sound, and oVEMPs induced by tapping the forehead.ResultsEight (67%) patients showed abnormal oVEMPs that included no wave formation (n = 4) and decreased amplitude (n = 3) in the lesion side, and bilaterally absent responses in the remaining patient. Furthermore, the patients showed diminished oVEMPs responses in the lesion side compared with normal side (6.0 ± 5.6 vs. 11.7 ± 5.5 μV, paired t-test, p = 0.001) and increased IAD_amp(%) of the oVEMPs compared with normal controls (43.6 ± 41.2 vs. 9.1 ± 6.2, t-test, p = 0.018). In contrast, cVEMPs were abnormal in only three (25%) patients, decreased (n = 2) or no response in the lesion side. Eleven (92%) patients showed contraversive ocular tilt reaction or SVV tilt.ConclusionPatients with INO frequently show impaired formation of ipsilesional oVEMPs in response to forehead tapping. The occasional abnormality and decreased amplitude of ipsilesional cVEMPs also suggest a modulatory pathway for the inhibitory sacculocollic reflex descending in the MLF.SignificanceThis study suggests that the MLF contains the fibers for the otolith-ocular reflex from the contralateral ear.     

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

ObjectiveBy 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.MethodsTwenty 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.ResultsAll 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.ConclusionBy 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.SignificanceCompared 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.     

Differing response properties of cervical and ocular vestibular evoked myogenic potentials evoked by air-conducted stimulation

ObjectiveTo determine the amplitude changes of vestibular evoked myogenic potentials (VEMPs) recorded simultaneously from the neck (cVEMPs) and eyes (oVEMPs) in response to 500 Hz, 2 ms air-conducted sound pips over a 30 dB range.MethodsFifteen healthy volunteers (mean age 29, range 18–57 years old) and one patient with unilateral superior canal dehiscence (SCD) were studied. The stimulus was reduced in increments to 105 dB pSPL for the normals (81 dB pSPL for the SCD patient). A statistical criterion was used to detect responses.ResultsIpsilateral (i-p13/n23) and contralateral (c-n12/p24/n30) peaks for the cVEMP montage and contralateral (c-n10/p16/n21) and ipsilateral (i-n13) peaks for the oVEMP montage were present for the baseline intensity. For the lowest intensity, 6/15 subjects had responses for the i-p13 cVEMP potential and 4/15 had c-n10 oVEMP responses. The SCD patient showed larger responses for nearly all intensities. The cVEMP potentials were generally well fitted by a power law relationship, but the oVEMP c-n10, p16 and n21 potentials showed a significant increase in gradient for the higher intensities.ConclusionMost oVEMP and cVEMP responses follow a power law relationship but crossed oVEMP responses showed a change in gradient above a threshold.SignificanceThe pattern of response to AC stimulation may be a property of the pathways underlying the potentials.     

Mastoid and vertex low-frequency vibration-induced oVEMP in relation to medially directed acceleration of the labyrinth

ObjectiveTo explore the stimulus site and stimulus configuration dependency for bone-conducted low-frequency vibration-induced ocular vestibular evoked myogenic potentials (oVEMPs).MethodsoVEMPs were tested in response to 125 Hz single cycle bone-conducted vibration in healthy subjects (n = 12) and in patients with severe unilateral vestibular lesions (n = 10). The stimulus sites were the mastoids and vertex. Both directions of initial stimulus motion were used.ResultsAt mastoid stimulation, the oVEMP to initial laterally directed acceleration of the labyrinth was delayed approximately the length of time of a stimulus half-cycle, as compared with the response to initial medially directed acceleration. At vertex stimulation, the oVEMP to positive initial acceleration was similar to the oVEMP to mastoid stimulation causing lateral initial acceleration. Likewise, the oVEMP to vertex negative initial acceleration was similar to mastoid stimulation causing initial medial acceleration. Further, patients with unilateral vestibular loss had, compared to healthy subjects, similar oVEMP from the healthy labyrinth.ConclusionsA fundamental dependency on medially directed accelerations of the labyrinth, based on the latency differences revealed, may theoretically account for oVEMP in response to low-frequency stimulation.SignificanceLow-frequency bone vibration stimulation at vertex might serve for simultaneous oVEMP testing of both ears.     

Ocular vestibular-evoked myogenic potentials in children using air conducted sound stimulation

ObjectiveThis study compared ocular vestibular-evoked myogenic potentials (oVEMPs) in children and adults using air conducted sound stimulation to determine when oVEMP characteristic parameters in children reach adult levels. The relationships between oVEMP characteristics and structural factors were also investigated.MethodsIn total, 15 healthy children (aged 3–13 years) and 15 healthy adults (aged 24–33 years) underwent a combined oVEMP and cVEMP test under 105 dBnHL acoustic stimulation.ResultsMean nI latency, pI latency, nI–pI interval and amplitude of oVEMPs of children did not differ significantly from those of adults. In contrast to oVEMPs, a significant difference in p13 cVEMP latency existed between children and adults. Correlating the structural factors with the characteristic parameters of oVEMPs did not show significant relationship. However, p13 and n23 latencies of cVEMPs in children were significantly related to the age, head girth, body height and body weight.ConclusionsThe non-invasive oVEMP test can quantitatively measure the vestibulo-ocular reflex (VOR) system, which has similar characteristic parameters in children aged >3 years and adults. For children aged <3 years, modified methodologies for testing oVEMPs are warranted.SignificanceThe oVEMP test may serve as an effective diagnostic tool for evaluating the integrity of the VOR system for those >3 years old.     

The effect of electrode positioning on the ocular vestibular evoked myogenic potential to air-conducted sound

ObjectiveTo assess the effect of electrode position on the amplitude and latency of ocular vestibular evoked myogenic potentials (oVEMPs) produced by air-conducted (AC) sound with a view to optimisation of the recording paradigm.MethodsEight otologically normal subjects (16 ears) were stimulated by 500 Hz AC tone bursts at 95 dBnHL; oVEMP traces were recorded below the eye contralateral to the acoustic stimulation. Five independent oVEMP measurements were recorded with the active electrode in equally spaced positions in the infra-orbital plane relative to a reference electrode positioned 2 cm below the lower lid in the orbital midline. These measurements included the accepted standard-montage in which the electrodes were positioned vertically above and below each other in the orbital midline. A further recording was made using a belly-tendon montage with reference to the inferior oblique muscle.ResultsOf the six recording paradigms tested the largest amplitude oVEMP response was found using the belly-tendon montage with an n₁₀ average of 5.67 ± 3.42 μV (sd). This was significantly larger than the amplitude recorded using the standard-montage (p < 0.01). With the reference electrode in the orbital midline, the position of the active electrode in the infra-orbital plane was found to significantly alter the response magnitude. As the active electrode was moved laterally the response reduced in amplitude, however when moved medially the response polarity reversed indicating the existence of a null-point at which no response was present.ConclusionsThe location of oVEMP recording electrodes significantly alters the response amplitude. Whilst the standard-montage provides a reasonable method for recording oVEMPs, the belly-tendon montage results in a significantly larger amplitude response. Furthermore medial and lateral variations in the position of the active electrode using the standard-montage significantly affect the magnitude and polarity of the response.SignificanceThe standard-montage used for recording oVEMPs is sensitive to the placement of the active electrode. Small variations in position result in significant changes in the n₁₀ amplitude and this may account for the variability reported in the literature. Using the belly-tendon montage, larger amplitude responses can be elicited which may improve the robustness with which oVEMPs can be collected. However this enhancement in response amplitude must be balanced against the increased possibility of signal contamination from neighbouring extraocular muscles.     

Ocular vestibular evoked myogenic potentials: The effect of head and body tilt in the roll plane

ObjectiveTo explore effects of whole-head/body tilt in the roll plane on ocular-vestibular evoked myogenic potentials (oVEMP).MethodsTwenty healthy subjects were randomly tilted in an Eply Omniax rotator across a series of eight angles from 0° to 360° (at 45° separations) in the roll plane. At each position, oVEMPs to air-conducted (AC) and bone-conducted (BC) stimulation were recorded from unrectified infra-orbital surface electromyography during upward gaze. oVEMP amplitudes, latencies and amplitude asymmetry were compared across each angle of orientation.ResultsHead orientation had a significant effect on oVEMP reflex amplitudes for both AC and BC stimulation (p < 0.001). For both stimuli there was a trend for lower amplitudes with increasing angular departure from the upright position. Mean amplitudes decreased by 42.6–56.8% (AC) and 23.2–25.5% (BC) when tilted 180°. Roll-plane tilt had a significant effect on amplitude asymmetry ratios recorded in response to AC stimuli (p < 0.001), indicating a trend for lower amplitudes from the dependent (down) ear. Amplitude asymmetry ratios for BC stimuli were unaffected by head and body orientation.ConclusionsThe results confirm an effect of head and body orientation on oVEMP reflexes recorded in response to air- and bone-conducted stimuli.SignificanceThe upright position yields an optimal oVEMP response.     

Why do oVEMPs become larger when you look up? Explaining the effect of gaze elevation on the ocular vestibular evoked myogenic potential

ObjectivesThe ocular vestibular evoked myogenic potential (oVEMP) is a vestibular reflex recorded from the inferior oblique (IO) muscles, which increases in amplitude during eye elevation. We investigated whether this effect of gaze elevation could be explained by movement of the IO closer to the recording electrode.MethodsWe compared oVEMPs recorded with different gaze elevations to those recorded with constant gaze position but electrodes placed at increasing distance from the eyes. oVEMPs were recorded in ten healthy subjects using bursts of skull vibration.ResultsoVEMP amplitude decreased more with decreasing gaze elevation (9 μV from 24° up to neutral) than with increasing electrode distance (2.7 μV from baseline to 6.4 mm; P < 0.005). The oVEMP recorded with gaze 24° down had delayed latency (by 4.5 ms).ConclusionThe effect of gaze elevation on the oVEMP cannot be explained by changes in position of the muscle alone and is likely mainly due to increased tonic contraction of the IO muscle in up-gaze. The oVEMP recorded in down-gaze (when the IO is inactivated, but the IR activated) likely originates in the adjacent IR muscle.SignificanceOur results suggest that oVEMP amplitudes in extraocular muscles scale in response to changing tonic muscle activity.     

The effect of alcohol on cervical and ocular vestibular evoked myogenic potentials in healthy volunteers

ObjectiveWe investigated the effect of alcohol on the cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs). As alcohol produces gaze-evoked nystagmus (GEN), we also tested the effect of nystagmus independent of alcohol by recording oVEMPs during optokinetic stimulation (OKS).MethodsThe effect of alcohol was tested in 14 subjects over multiple rounds of alcohol consumption up to a maximum breath alcohol concentration (BrAC) of 1.5‰ (mean 0.97‰). The effect of OKS was tested in 11 subjects at 5, 10 and 15 deg/sec.ResultsoVEMP amplitude decreased from baseline to the highest BrAC level by 27% (range 5–50%, P < 0.001), but there was no significant effect on oVEMP latency or cVEMP amplitude or latency. There was a significant negative effect of OKS on oVEMP amplitude (16%, P = 0.006).ConclusionsWe found a selective effect of alcohol on oVEMP amplitude, but no effect on the cVEMP. Vertical nystagmus elicited by OKS reduced oVEMP amplitude.SignificanceAlcohol selectively affects oVEMP amplitude. Despite the effects of alcohol and nystagmus, both reflexes were reliably recorded in all subjects and conditions. An absent response in a patient affected by alcohol or nystagmus indicates a vestibular deficit.     

Feasibility of ocular vestibular-evoked myogenic potentials (oVEMPs) recorded with eyes closed

ObjectiveThis study compared the characteristic parameters of ocular vestibular-evoked myogenic potential (oVEMP) test between eyes gazing up and eyes closed to evaluate the feasibility of oVEMP test with eyes closed.MethodsTwenty-three healthy adults underwent oVEMP testing with upward gaze and with eyes closed in a randomized order. For each condition, the thickness of the inferior oblique and inferior rectus muscles, and the distance from the electrode on the skin to each muscle were measured via ultrasonography. Two patients with pathological ears were also included in this study for comparison.ResultsTwenty of the 23 subjects showed clear oVEMPs regardless of whether eyes were gazing up or eyes were closed. Mean latencies of nI and pI, and nI–pI interval with eyes closed were significantly prolonged when compared with those measured with eyes up. The mean nI–pI amplitude with eyes closed was significantly smaller than that with eyes up. However, no significant difference existed in the mean asymmetry ratio of amplitude between the two conditions. With eyes closed, the mean distances from the skin to the inferior oblique and inferior rectus muscles are 0.17 ± 0.03 and 0.40 ± 0.09 cm, respectively. In contrast with eyes gazing up, the mean distance from the skin to the inferior rectus muscle reduces significantly to 0.23 ± 0.09 cm, whereas the inferior oblique muscle slips out of ultrasonographic view.ConclusionsOcular VEMP can also be recorded with eyes closed in those who cannot perform upward gaze. However, the characteristic parameters of oVEMP are different between the eyes up and eyes closed conditions, probably because various extraocular muscles are involved in the generation of oVEMPs.SignificanceIn those who cannot gaze upward such as small children, oVEMPs can be recorded by eyes closed.     

Ocular vestibular-evoked myogenic potentials elicited from monaural versus binaural acoustic stimulations

ObjectiveThis study compared the ocular vestibular-evoked myogenic potentials (oVEMPs) that are elicited (recorded) in response to monaural and separately, simultaneous binaural acoustic stimulations. The optimal stimulation mode for oVEMPs was also determined.MethodsTwenty healthy volunteers (14 men and 6 women, aged from 22 to 33 years, mean 28 years) without any previous ear disorders were enrolled in this study. Each subject underwent oVEMP testing using monaural acoustic stimulation (Mon-oVEMP) with different stimulus intensities, and with bilateral recording. On another day, the same volunteers underwent oVEMP testing using simultaneous binaural acoustic stimulation and bilateral recording (Bin-oVEMP).ResultsWith 95 dB nHL tone burst stimulation, the biphasic nI–pI waveforms were recorded with maximal amplitudes from the electrodes located below the eyes contralateral to the side of acoustic stimulation while the subject was gazing upward. Significant correlations were identified between Mon-oVEMPs and Bin-oVEMPs with respect to threshold, latencies and amplitude. However, no significant difference existed between Mon-oVEMPs and Bin-oVEMPs in terms of the response rate, threshold, latency or amplitude.ConclusionsThe Bin-oVEMP test yields the same information as the Mon-oVEMP test, but the duration of recording in the former is shorter than the latter.SignificanceThe Bin-oVEMP test may be a more convenient screening tool for evaluating the crossed vestibulo-ocular reflex.     

Ocular and cervical vestibular-evoked myogenic potentials to bone conducted vibration in Ménière’s disease during quiescence vs during acute attacks

ObjectiveTwo indicators of otolithic function were used to measure dynamic otolith function in the same patients both during an acute attack of Ménière’s disease (MD) and in the quiescent period between attacks.MethodsThe early negative component (n10) of the ocular vestibular-evoked myogenic potential (the oVEMP) to brief 500 Hz bone conducted vibration (BCV) stimulation of the forehead, in the midline at the hairline (Fz) was recorded by surface EMG electrodes just beneath both eyes while the patient looked up. It has been proposed that the n10 component of the oVEMP to 500 Hz Fz BCV indicates utricular function. It has been proposed that the early positive component (p13) of the cervical vestibular-evoked myogenic potential (the cVEMP) recorded by surface electrodes on both tensed SCM neck muscles to 500 Hz Fz BCV indicates saccular function.ResultsSixteen healthy control subjects tested on two occasions showed no detectable change in the symmetry of oVEMPs or cVEMPs to 500 Hz Fz BCV. In response to 500 Hz Fz BCV 15 early MD patients tested at both attack and quiescent phases showed a dissociation: there was a significant increase in contralesional of n10 of the oVEMP during the attack compared to quiescence but a significant decrease in the ipsilesional p13 of the cVEMP during the attack compared to quiescence.ConclusionsDuring an MD attack, dynamic utricular function in the affected ear as measured by the n10 of the oVEMP to 500 Hz Fz BCV is enhanced, whereas dynamic saccular function in the affected ear as measured by the p13 of the cVEMP to 500 Hz Fz BCV is not similarly affected.SignificanceThe MD attack appears to affect different otolithic regions differentially.     

Cervical and ocular vestibular-evoked myogenic potentials in acute vestibular neuritis

ObjectivesTo clarify the origin and afferent pathways of short-latency ocular vestibular-evoked myogenic potential (oVEMP) in response to air-conducted sound (ACS), we evaluated cervical (cVEMP) and ocular VEMPs in patients with vestibular neuritis (VN).MethodsIn response to air-conducted tone burst, the oVEMP and cVEMP were measured in 60 healthy controls and in 41 patients with acute VN. The VN selectively involved the superior vestibular nerve (superior VN) in 30 patients, affected the inferior vestibular nerve only (inferior VN) in three and damaged both superior and inferior vestibular nerve branches in eight.ResultsAll 30 patients with superior VN presented normal cVEMPs, indicating preservation of the saccular receptors and their afferents in the inferior vestibular nerve. However, the oVEMP was abnormal in all patients with superior VN. By contrast, the patients with inferior VN showed normal oVEMP and abnormal cVEMP.ConclusionThese dissociations in the abnormalities of cVEMP and oVEMP in patients with VN selectively involving the superior or inferior vestibular nerve suggest that the origin of the vestibular nerve afferents of oVEMP differ from those of cVEMP.SignificanceThe oVEMP in response to ACS may be mediated by the superior vestibular nerve, probably due to an activation of the utricular receptors.     

‘Standard’ versus ‘nose reference’ electrode placement for measuring oVEMPs with air-conducted sound: Test–retest reliability and preliminary patient results

Objectives

This study compared two electrode placements (‘standard’ versus ‘nose reference’ placement) for measuring oVEMPs, elicited by air-conducted 500 Hz tone bursts. The test–retest reliability of both positions was evaluated and additionally both electrode placements were applied on a group of vestibular patients.

Effects of the stimulus phase on the air-conducted ocular vestibular evoked myogenic potential in healthy subjects

Objective

The study aimed to examine the effect of the stimulus phase of air-conducted sound on ocular vestibular evoked myogenic potentials (oVEMPs).

Feasibility of the simultaneous ocular and cervical vestibular-evoked myogenic potentials in unilateral vestibular hypofunction

ObjectiveThis study compared the results of combined and individual ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in healthy subjects and patients with unilateral vestibular hypofunction to confirm the effectiveness of the combined oVEMP and cVEMP test.MethodsTwenty healthy volunteers and 12 patients with unilateral vestibular hypofunction underwent individual oVEMP and cVEMP tests in a random order, and combined oVEMP and cVEMP test on another day.ResultsTwenty healthy subjects had 100% response rates for oVEMPs and cVEMPs in both individual and combined stimulation modes. Significant positive correlations exist between individual and combined oVEMPs/cVEMPs in terms of latencies and amplitudes. In 12 patients with unilateral vestibular hypofunction, differences in abnormal percentages of oVEMPs or cVEMPs were non-significant. Additionally, the characteristic parameters of oVEMP/cVEMP among ears of healthy subjects, good and pathological ears of patients with unilateral vestibular hypofunction did not differ significantly, regardless of whether the individual or combined mode was used.ConclusionsThe combined oVEMP and cVEMP test generates similar information to that obtained by individual mode, regardless of whether subjects are healthy or have unilateral vestibular hypofunction.SignificanceSimultaneous oVEMP and cVEMP tests may be a convenient screening tool for assessing crossed vestibulo-ocular reflex and ipsilateral sacculo-collic reflex, which definitely shortens the diagnostic test time. Thus, it may favor the large diffusion of these techniques.     

Ocular vestibular-evoked myogenic potentials (oVEMPs) require extraocular muscles but not facial or cochlear nerve activity

ObjectivesCervical vestibular evoked myogenic potentials (cVEMPs) have been found to be useful for clinical testing of vestibular function. Recently, investigators showed that short-latency, initially negative surface EMG potentials can be recorded around the extraocular muscles (oVEMPs) in response to air-conducted sound (ACS), bone-conducted vibration (BCV), and head taps. Although these evoked potentials, which are located around the eyes, most likely originate primarily from the otolith-ocular pathway, the possibility of contamination by other nerve activities cannot be completely eliminated. The purpose of the present study was to clarify the origin of oVEMPs by examining these possibilities using clinical findings.MethodsTwelve healthy subjects and 15 patients were enrolled. Of the 15 patients, 3 patients had undergone exenteration of the unilateral intraorbital contents, one had undergone exenteration of the right eyeball with preservation of extraocular muscles, 5 had facial palsy, and 6 had profound hearing loss. ACS and/or BCV were used in these subjects.ResultsExenteration of the unilateral intraorbital contents resulted in absence of myogenic potentials on the affected side. On the other hand, exenteration of the eyeball with preservation of extraocular muscles did not have a major impact on the responses. There were no significant differences in the waveforms between healthy subjects and patients with facial palsy or profound hearing loss.ConclusionsThe results suggested that short-latency, initially negative evoked potentials recorded below the eyes are not affected by cochlear or facial nerve activities and are dependent on the presence of extraocular muscles.SignificanceThis study provides the evidence that oVEMPs originate from exraocular muscles activated through the vestibulo-ocular pathway.     

Clinico-radiological spectrum in enterovirus 71 infection involving the central nervous system in children

Enterovirus 71 infection causes hand, foot and mouth disease in children, and can produce diverse neurologic complications. Epidemics occurring in Korea between 2009 and 2012 resulted in the death of some patients. The present study aimed to clarify the correlation between clinical features and MRI findings in patients presenting with acute neurologic manifestations related to enterovirus 71 infection. Based on their clinical features, the patients were classified into four clinical groups: (1) brainstem encephalitis (n = 17), characterized by myoclonus, tremor, ataxia, and autonomic dysregulation such as pulmonary hemorrhage; (2) aseptic meningitis (n = 2); (3) encephalitis (n = 2), characterized by decreased consciousness, seizure, and fever without myoclonus, tremor, ataxia, and autonomic dysregulation; and (4) acute flaccid paralysis (n = 1). Thirteen of the 17 patients with brainstem encephalitis showed characteristic lesions in the dorsal brainstem and bilateral cerebellar dentate nuclei on brain MRI, whereas three had no abnormality. One of the two patients with meningitis had a small lesion in the left dorsal pons. Two patients with encephalitis had no apparent MRI abnormality. One patient with acute flaccid paralysis of the right leg had contrast-enhancement of the bilateral ventral nerve roots at the lumbar spine level on MRI. Five of 13 patients with lesions in the bilateral dentate nuclei of the cerebellum exhibited no cerebellar symptoms, while two with no cerebellar lesions developed ataxia. Although most patients presenting with neurologic manifestations of enterovirus 71 infection had characteristic clinical features together with typical MRI findings, the clinical features were not necessarily consistent with MRI findings.     

Treatment rates for PTSD and depression in recently hospitalized cardiac patients

ObjectivePosttraumatic stress disorder (PTSD) and depression are common after evaluation for suspected acute coronary syndrome (ACS), and are associated with poor prognosis. However, it is unclear whether patients discharged after suspected ACS access treatments for subsequent psychological distress. We examined self-reported rates of receiving psychotherapy and/or medication for psychological distress in patients one month after a suspected ACS event.MethodsA sample of 448 adults (age 60.4 ± 12.5; 47.8% female; 52.7% Hispanic, 32.1% Black) presenting to the emergency department with suspected ACS were recruited for the REactions to Acute Care and Hospitalization (REACH) study, an ongoing cohort study of medical and psychological outcomes after ACS evaluation. Socio-demographics and depressive symptoms were assessed in-hospital, and PTSD symptoms related to the suspected ACS event were queried via phone one month after enrollment. Participants also indicated whether they received either medication or counseling to deal with their emotions and coping after their heart problem.ResultsApproximately 15% (n = 68) of the sample reported receiving some form of treatment. Treatment rate did not differ significantly as a function of demographics, ACS status, or insurance coverage, ps > 0.1. Over a quarter of participants (25.3%) who screened positive for PTSD and/or depression reported receiving treatment. Participants with PTSD and depression had a higher treatment rate (47.6%) vs. those with only depression (12.8%) or PTSD (30%) or no psychopathology (10.3%).ConclusionFindings suggest that 1 in 4 patients who screened positive for PTSD and/or depression reported receiving counseling or medication in the first month after a suspected ACS event.