Effect of different head impulse procedures on vestibulo-ocular reflex gain

Objectiveto study the effects on vestibulo-ocular reflex (VOR) gain using both video head impulse test (vHIT) and Suppression Head impulse test (SHIMP) either using the outward or the inwards head impulse.MethodsTwenty healthy subjects were enrolled in the study. They were examined using otometric vHIT and SHIMP test lateral plane using the lateral outwards head impulse ten impulses for each side and the inwards head impulse ten impulses for each side. The VOR gain resulting from the outwards versus inwards head impulse during the vHIT and SHIMP were statistically compared.ResultsTwenty healthy subjects, 10 Males and 10 females with a mean age 35 ± 11.7. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (1.1 ± .12) using outwards versus (1.03 ± .22) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (1.1 ± .22) using outwards head impulse (1.1 ± .3) for inwards head impulse in vHIT. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (0.96 ± 0.2)using outwards versus (1.04 ± 0.2) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (0.98 ± 0.25) using outwards head impulse (1.1 ± 0.28) for inwards head impulse in SHIMP test. No statistical significant difference was found between the VOR gain resulting from the right versus the left semicircular canal.ConclusionThe starting head position does not affect the VOR gain using both vHIT and SHIMP tests.     

The skull vibration-induced nystagmus test: A useful vestibular screening test in children with hearing loss

IntroductionSkull-Vibration-Induced-Nystagmus Test (SVINT), a non-invasive first line examination test, stimulates both otolith and canal structures and shows instantaneously a vestibular asymmetry. This study aimed to analyze the SVINT results observed in children with hearing loss (HL) amplified with hearing aids (HA) or unilateral cochlear implant (uCI) and healthy children.Material and methodsThis case-control study compared the results of SVINT, caloric test (CaT) and video head-impulse-test (VHIT) in 120 controls to 30 children with HA and 30 with uCI, aged 5-18 years old. SVINT was recorded with videonystagmography after very high frequency (VHF) stimulation of mastoids and vertex.ResultsSVINT results were non-pathological in 98% of the control group but modified in the HL group (P-value = 0.04). In uCI participants, 13.3% had a bilateral weakness (BW) and 16.7% had a unilateral weakness (UW). In the HA group, 26.7% had BW, 10% had UW. SVINT was efficient to show a UW (6 out of 7 confirmed cases) but not efficient to show BW (1/12 confirmed cases).ConclusionSVINT can detect unilateral vestibular deficit in the VHF with a sensitivity of 86% and specificity of 96%. The positive predictive value is 75% and negative predictive value is 98%. In the case of bilateral deficit, the SVINT is inoperant. In amplified participants, a UW was equally detected whether using SVINT, CaT or VHIT. SVINT is a well-tolerated and useful test to screen vestibular asymmetry in children with HL when combined with other vestibular tests and shows its complementary at very high frequencies.     

Computer-assisted versus traditional technique in fibular free-flap mandibular reconstruction: A CT symmetry study

ObjectivesIn the past few years, virtual planning has been increasingly used for mandibular reconstruction. The objective of our study was to evaluate and compare symmetry and the accuracy of morphologic reconstruction in patients undergoing mandibular reconstruction by fibular free flap between traditional freehand technique and computer-aided surgical cutting guides.Material and methodsA single-center retrospective study included all cases of mandibular reconstruction using fibular free flap. In the three-dimensional (3D) group, virtual surgery planning with cut guides was used (Materialise ®), while the Control group underwent traditional freehand reconstruction. Morphometric comparisons were made to evaluate reconstruction accuracy between pre- and post-operative CT scans (mean deviations of 3 angles and 3 lengths). Mandible symmetry was calculated by comparing each angle and length in the affected and non-affected sides of the mandible.ResultsThirty-three patients treated between January 2015 and June 2018 were included: 25 patients in the 3D group and 8 in the control group. The average number of mandibular segments was 2.16 ± 0.55 in the 3D group and 1.75 ± 1.16 in the control group (p = 0.005). Mean deviations between pre- and post-operative values of the coronal mandibular angle (angle formed by the line through the two condyles and the ramus), mandibular body height and mandibular ramus length on the affected side were significantly lower in the 3D group than in the control group. Sagittal mandibular angle symmetry was better in the 3D group than, in the control group (ratios of affected over non-affected sides: 1.07 ± 0.04 vs 1.12 ± 0.1; p = 0.034).ConclusionVirtual surgical planning for fibula free-flap reconstruction helps to improve reconstruction accuracy and maintains a significantly greater symmetry than the traditional freehand technique, and should improve functional and esthetic outcome in mandibular reconstruction.     

The role of vertical semicircular canal function in the vertical component of skull vibration-induced nystagmus

Abstract

Background: Generally, vertical component of the skull vibratory nystagmus (VCN) is ignored in the clinical practise. Thus, the relative contribution of the vestibular organs in the presence of VCN remains unknown.

Objectives: To determine the association between vertical semicircular canal (vSCC) function and the presence of VCN.

Material and methods: Comparisons were made between Video Head Impulse Test and SVINT (100?Hz) results at the time of the acute peripheral vestibular lesion (PVL) and at the post-acute phase in patients diagnosed PVL. Later on, a paired analysis was performed restricting the assessments to patients with vestibular explorations in both the acute and post-acute phases.

Results: In an univariable analysis, larger mean total gain differences (TGD) between vSCC VOR gains, significantly related with the appearance of VCN in nystagmography in the acute phase (p?=?.001), unlike the post-acute phase (p?=?.46). After a multivariate analysis, mean TGD was the only predictive factor of the VCN (p?=?.013). In the paired analysis, we found an increase in the post-acute phase mean TGD, approaching zero value.

Conclusions and significance: Global relation between all vertical canals has at least a contributory role in the presence of the vertical component of nystagmus in SVINT.     

Skull vibration induced nystagmus in patients with superior semicircular canal dehiscence

ObjectiveTo establish optimum stimulus frequency and location of bone conducted vibration provoking a skull vibration induced nystagmus (SVIN) in superior semi-circular canal dehiscences.MethodsSVIN 3D components in 40 patients with semi-circular canal dehiscence (27 unilateral and 13 bilateral) were compared with a group of 18 patients with severe unilateral vestibular loss and a control group of 11 volunteers.ResultsIn unilateral semi-circular canal dehiscences, SVIN torsional and horizontal components observed on vertex location in 88% beat toward the lesion side in 95%, and can be obtained up to 800 Hz (around 500 Hz being optimal). SVIN slow-phase-velocity was significantly higher on vertex stimulation at 100 and 300 Hz (P = 0.04) than on mastoids. SVIN vertical component is more often upbeating than downbeating. A SVIN was significantly more often observed in unilateral than bilateral semi-circular-canal dehiscences (P = 0.009) and with a higher slow phase velocity (P = 0.008). In severe unilateral vestibular lesions the optimal frequency was 100 Hz and SVIN beat toward the intact side. The mastoid stimulation was significantly more efficient than vertex stimulation at 60 and 100 Hz (P < 0.01).ConclusionSVIN reveals instantaneously in unilateral semi-circular canal dehiscences a characteristic nystagmus beating, for the torsional and horizontal components, toward the lesion side and with a greater sensitivity toward high frequencies on vertex stimulation. SVIN three components analysis suggests a stimulation of both superior semi-circular canal and utricle. SVIN acts as a vestibular Weber test, assessing a vestibular asymmetrical function and is a useful indicator for unilateral semi-circular canal dehiscence.     

Inferior nasal turbinate mucosa shrinkage prior to surgery under local anaesthesia

Introduction and ObjectivesChronic rhinitis-related complaints may result from isolated hypertrophy of the inferior nasal turbinates. If the symptoms persist despite conservative management, turbinoplasty is indicated. However, the nasal mucosa lining the inferior turbinates seems decongested immediately before the surgery performed under local anaesthesia, compared to the examination when the patients were entered for surgery. The study aimed to confirm this observation and to hypothesize as to the reasons for its occurrence.Patients and MethodsThe measurements of the longest distances between the medial rim of the inferior nasal turbinate mucosa and nasal septum and the shortest distances between the lower rim of the turbinate and floor of the nasal cavity in the inferior part of both common nasal meatus, were carried out on photos taken during endoscopic examinations: the one entering the patient for turbinoplasty, and the other immediately before the procedure. The results in this group were compared to those obtained from patients operated on under general anaesthesia.ResultsIn 130 patients aged 18-60 (mean = 40.7) years, operated on under local anaesthesia, the sum of the mean distances between the nasal septum and the medial rim of the lower turbinate in both nasal cavities, was 3.4 mm during the first examination, and 4.5 mm (p = .0008) during the second one. In the group of 42 participants aged 26-47, mean = 36.8 years operated on under general anaesthesia, the values were: 4.8 mm and 3.6 mm (p = .02), respectively. The differences were significantly smaller in the smokers (.3) compared to non-smokers (1.3; p = .04) mm.ConclusionsRecords of the entering examination must be considered before turbinoplasty under local anaesthesia.     

Anatomo-radiological study supporting the use of ipsilateral nasoseptal flap for the transpterygoid management of temporo-sphenoidal meningoceles. A review of 21 cases

ObjectivesSurgical treatment of temporo-sphenoidal meningoceles involves the reduction of the meningocele, watertight closure and defect coverage with a nasoseptal flap (NSF). It can be performed contralaterally or ipsilaterally: in the latter situation, the pedicle of the flap must be dissected into the pterygopalatine fossa. The objective of this study was to evaluate the benefit of using an ipsilateral NSF in transpterygoid approaches for the management of temporo-sphenoidal meningoceles, compared to a contralateral NSF, based on a radiological study.Material and methodsRetrospective monocentric study of 21 cases, between 2002 and 2018. Measurement of the NSF lengths, and lengths needed to cover the defect were evaluated on the preoperative scanner. Early and later failure and complication rates were evaluated.ResultsSeventeen cases of temporo-sphenoidal meningoceles with available CT scan were identified. The mean duration of follow up was 27.9 months [1–147]. Theoretical lengths of the ipsi and contralateral NSF were comparable: 71.4 ± 7.8 mm vs. 78.8 ± 8 mm, P = 0.729. In 8 cases/18 (42%), the theoretical length of the contralateral NSF was not long enough to cover the defect beyond the V2 (mean lack of 8.87 ± 6.6 mm). In all cases, the theoretical length of the ipsilateral NSF was sufficient to cover the defect. In the case series, failure and complication rates were similar.ConclusionThe use of an ipsilateral NSF for the transpterygoid management of temporo-sphenoidal meningoceles, although more complex, allows a better coverage of the defect, compared to the contralateral NSF, which is not long enough in 42% of cases.     

Nystagmus induced by high frequency vibrations of the skull in total unilateral peripheral vestibular lesions

CONCLUSION: The skull vibration-induced nystagmus test (SVINT) is a useful complementary test to the caloric test, which evaluates very low frequencies, and the head shaking test (HST), which explores medium range frequencies. These three tests are fully correlated in total unilateral vestibular lesions (tUVL) with a sensitivity of 98% and a specificity of 94% for the SVINT. The results of the interference of the SVINT with the cold caloric test on the intact ear suggest that different vestibular sensory cells are involved in these two tests. The stimulus location optimization suggests that vibrations directly stimulate the inner ear on the intact side. OBJECTIVES: The aim of this study was to establish the effectiveness of a rapid, non-invasive test used to detect vestibular asymmetry at 30, 60 and 100 Hz stimulation in tUVL. PATIENTS AND METHODS: The high frequency vibration test applied to the skull using the SVINT was compared to the results of HST and caloric test in 134 patients and 95 normal subjects: 131 patients had a total unilateral vestibular dysfunction and 3 had a bilateral total lesion (tBVL). The effects of stimulus frequency, topography and head position were studied using a video-nystagmograph. RESULTS: In tUVL, the SVINT always revealed a lesional nystagmus beating toward the healthy side at all frequencies. The mastoid site was more efficient than the cervical and vertex sites (p0.005). The mean skull vibratory nystagmus (SVN) slow phase velocity (SPV) is 10.7 degrees (SD =7.5; n=20). Mastoid stimulation efficiency was not correlated with the side of stimulation. SVN SPV was correlated with the total caloric efficiency on the healthy ear (p=0.03). The interference of the SVINT during the cold caloric test on the intact ear demonstrated a reversal of the caloric nystagmus at each application of the vibrator. In tBVL, SVINT revealed no nystagmus.     

Hearing rehabilitation with osseointegrated hearing implant in bilateral congenital external auditory canal atresia

Introduction and objectivesCongenital atresia of the external auditory canal (EAC) is a congenital defect present in one in every 10,000–20,000 births. It causes conductive hearing loss, with an air-bone gap of 50–60 dB. Early amplification is essential in bilateral cases to ensure normal language development. The aim of this study is to present the osseointegrated hearing implant as a treatment for bilateral EAC atresia, reviewing the audiometric results and the rate of complications.Material and methodsRetrospective analysis of patients diagnosed with bilateral congenital EAC atresia under follow-up in the pediatric ENT clinic of the ENT and Head and Neck Surgery department of a Portuguese Tertiary Hospital, between 2003 and 2019. We reviewed the medical records and collected information on the assessment of the initial audiometric status. In the cases submitted for implantation with an osseointegrated hearing implant, we analyzed the details of follow-up, including immediate and long-term post-operative complications, as well as the audiometric results.ResultsWe present 8 pediatric patients, 6 girls and 2 boys, with a diagnosis of bilateral congenital EAC atresia. The audiometric assessment revealed moderate to severe bilateral conductive hearing loss with a mean speech recognition threshold (SRT) of 51 dB. Six patients underwent osseointegrated hearing implantation. All 6 patients showed good audiometric results, with an average SRT of 20 dB and closure of the air-bone gap.ConclusionsThe osseointegrated hearing implant was an effective treatment option in these patients, without significant morbidity or complications. Osseointegrated hearing implantation should be considered first line treatment for children with bilateral congenital EAC atresia, as it presents good functional results and a high level of patient satisfaction.     

Aging effect and test-retest reliability of the sinusoidal harmonic acceleration test and velocity step test using nanotorque rotatory chair

IntroductionRotatory chair testing has been used to evaluate horizontal canal function. Frequently used tests include sinusoidal harmonic acceleration test (SHAT) and velocity step test (VST).ObjectivesAssessment of age effect on the SHAT and VST and assessment of test-retest reliability of the parameters of those two tests.MethodsA prospective study was performed on 100 subjects with no ear or vestibular complaints and normal vestibular evaluation. They were divided into two groups; Group A: below 50 years of age and Group B: 50 years of age or above. SHAT was presented at frequencies 0.02, 0.04, 0.08, 0.16, 0.32, 0.64 Hz with a peak velocity of 60°/s. VST was performed using a maximum velocity of 100°/s with acceleration and deceleration of 200°/s^2. Thirty subjects were tested twice to assess reliability.ResultsStudy participants ranged in age from 20 to 67 years. Regarding group A, the mean age was 30.92 ± 7.31 and 55.36 ± 4.61 for group B. No significant differences were found in SHAT parameters between the two groups. As well, there was no significant difference in VST per-rotatory time constant, however, post-rotatory time constant was significantly longer for Group B (P value < 0.05). Intraclass correlation coefficient (ICC) values showed moderate to good reliability (ICC 0.580–0.818) for SHAT parameters for the lower frequencies and indicated moderate reliability for VST time constant (ICC 0.509–0.652).ConclusionsAge has no significant effect on the parameters of SHAT and VST. Test-retest reliability is generally good for both tests.     

Neck stiffness after transoral pharyngolaryngeal surgery for squamous cell carcinoma

IntroductionPyogenic spondylodiscitis is a rare, destructive intervertebral disc infection.Case summaryWe describe a case of C2-C3 pyogenic spondylodiscitis after transoral surgery of the posterior pharyngeal wall in a 64-year-old man with a history of oropharyngeal squamous cell carcinoma (SCC) treated by neck irradiation (45 Gy). Ten years after initial treatment, he underwent total laryngectomy for laryngeal SCC, together with transoral resection of carcinoma in situ (CIS) of the posterior pharyngeal wall followed by BioDesign® tissue repair graft. Five months later, C2-C3 spondylodiscitis was diagnosed with the formation of a fistula between the posterior pharyngeal wall and the intervertebral disc. Antibiotic therapy was administered for a total duration of 3 months (multi-susceptible Escherichia coli). Eight months after the diagnosis of spondylodiscitis, the patient died from carotid artery rupture following another course of radiotherapy for lymph node recurrence.DiscussionLarger-scale studies are necessary to evaluate the prevalence and risk factors of radiation-induced spondylodiscitis that currently remain poorly elucidated. The best treatment strategy (choice and duration of antibiotic therapy) and the optimal frequency of follow-up must be determined and the value of preventive measures (biomaterial, flap repair) needs to be evaluated.     

Current trends and applications in endoscopy for otology and neurotology

There has been a rapid increase in endoscopic ear surgery for the management of middle ear and lateral skull base disease in children and adults over the last decade. In this review paper, we discuss the current trends and applications of the endoscope in the field of otology and neurotology. Advantages of the endoscope include excellent ergonomics, compatibility with pediatric anatomy, and improved access to the middle ear through the external auditory canal. Transcanal endoscopic ear surgery has demonstrated comparable outcomes in the management of cholesteatoma, tympanic membrane perforations, and otosclerosis as compared to microscopic approaches, while utilizing less invasive surgical corridors and reducing the need for postauricular incisions. When a postauricular approach is required, the endoscopic-assisted transmastoid approach can avoid a canal wall down mastoidectomy in cases of cholesteatoma. The endoscope also has utility in treatment of superior canal dehiscence and various skull base lesions including glomus tumors, meningiomas, and vestibular schwannomas. Outside of the operating room, the endoscope can be used during examination of the outer and middle ear and for debridement of complex mastoid cavities. For these reasons, the endoscope is currently poised to transform the field of otology and neurotology.     

Clinical characteristics of patients with multi-canal benign paroxysmal positional vertigo

IntroductionMulti-canal benign paroxysmal positional vertigo is considered to be a rare and controversial type in the new diagnostic guidelines of Bárány because the nystagmus is more complicated or atypical, which is worthy of further study.ObjectiveBased on the diagnostic criteria for multi-canal benign paroxysmal positional vertigo proposed by International Bárány Society, the study aimed to investigate the clinical characteristics, diagnosis and treatment of multi-canal benign paroxysmal positional vertigo.MethodsA total of 41 patients with multi-canal benign paroxysmal positional vertigo were included and diagnosed by Roll, Dix-Hallpike and straight head hanging tests. Manual reduction was performed according to the involvement of semicircular canals.ResultsAmong the 41 cases, 19 (46.3%) patients showed vertical up-beating nystagmus with or without torsional component and geotropic, apogeotropic horizontal nystagmus, and were diagnosed with posterior-horizontal canal. 11 (26.8%) patients showed vertical up-beating nystagmus with torsional component on one side and vertical down-beating nystagmus with or without torsional component on the other side during Dix-Hallpike test or straight head hanging test and were diagnosed with posterior-anterior canal benign paroxysmal positional vertigo 9 (26.8%) patients showed vertical down-beating nystagmus with or without torsional component and geotropic, apogeotropic horizontal nystagmus, and were diagnosed with anterior-horizontal canal 2 (4.9%) patients showed vertical geotropic torsional up-beating nystagmus on both sides and were diagnosed with bilateral posterior canal benign paroxysmal positional vertigo. High correlation between the sides with reduced vestibular function or hearing loss and the side affected by Multi-canal benign paroxysmal positional vertigo was revealed (contingency coefficient = 0.602, p = 0.010). During one-week follow up, nystagmus/vertigo has been significantly alleviated or disappeared in 87.8% (36/41) patients.ConclusionPosterior-horizontal canal benign paroxysmal positional vertigo was the most common type. Multi-canal benign paroxysmal positional vertigo involving anterior canal was also not uncommon. Caloric tests and pure tone audiometry may help in the determination of the affected side. Manual reduction was effective in most of Multi-canal benign paroxysmal positional vertigo patients.     

Implication of vibration induced nystagmus in Meniere's disease

CONCLUSION: The incidence of ipsilesional beating vibration induced nystagmus (VIN) is significantly higher in Meniere's disease (MD) with lower canal paresis (CP) group on caloric test and the intensity of VIN shows significant positive correlation with CP. Considering previous reports showing predominant loss of type II hair cells in MD and discrepancy of the results between caloric test and head thrust test in MD patients, VIN may provide valuable information regarding the functional reservoir of vestibular type II hair cells in MD. OBJECTIVES: Clinical presentation of MD is dynamic and nystagmus changes phase to phase, which is attributed to the recovery process in addition to central compensation after active vertigo attack of MD. VIN has been shown to reflect the side difference of peripheral vestibular excitability and is well correlated with the severity of caloric weakness in vestibular neuritis. Aim of this study was to compare the intensity and the direction of VIN with CP in unilateral MD. MATERIALS AND METHODS: 52 patients with unilateral definite MD on AAO-HNS guideline (1995) were included. Auditory and vestibular function tests including caloric test, post-head shaking nystagmus (HSN) and VIN were evaluated during symptom free period and cases with spontaneous nystagmus were excluded. Vibratory stimuli (100 Hz) were applied to either mastoid alternatively. Eye movement was recorded using video nystagmography system. The horizontal component of VIN was compared with HSN and caloric test. RESULTS: 37 patients (71%) showed VIN. VIN to ipsilesional side was in 10 and to contralesional side in 27. In patients with CP over 43% (N =23), 2 beated to ipsilesional side, 17 to contralesional side and 4 showed no VIN. In patients with CP of less than 43% (N =29), 8 beated to ipsilesional side, 10 to contralesional side and 11 showed no VIN (p<0.05). 33 patients (63%) showed HSN and 24 patients of them (72%) showed contralesional nystagmus. The intensity of VIN shows significant positive correlation with the degree of CP on caloric test (Spearman's rho =0.340, p<0.05).     

Functional significance of peripheral head-shaking nystagmus

OBJECTIVES/HYPOTHESIS: The objective was to determine the characteristics of horizontal head-shaking nystagmus of peripheral origin and its relationship to vestibular dysfunction. STUDY DESIGN: Retrospective case series. METHODS: Eighty-three patients met the inclusion criteria of having peripheral and unilateral vestibular disease. Patients were tested with video nystagmography. Head-shaking nystagmus was performed in the horizontal plane during 30 cycles at a frequency of approximately 3 Hz. Head-shaking nystagmus was classified as monophasic or biphasic and, based on the pathological ear, as ipsilateral or contralateral related to nystagmus fast phases. The two-tailed t test, ANOVA, Mann-Whitney and chi2 tests, and lineal and polynomial regression tests were used for statistical analysis. RESULTS: Twenty-three patients showed a positive head-shaking nystagmus. All cases of head-shaking nystagmus observed were horizontal. There were four biphasic and 19 monophasic cases of head-shaking nystagmus. First phases of biphasic head-shaking nystagmus beat toward the normal ear. Eleven of the monophasic cases of head-shaking nystagmus were ipsilateral, and nine were contralateral. There was a statistically significant correlation between caloric weakness and head-shaking nystagmus. Ipsilateral head-shaking nystagmus corresponded to lower caloric asymmetries, and contralateral and biphasic head-shaking nystagmus corresponded to greater caloric weakness (P <.001). As the caloric asymmetry increased, the maximal slow-phase eye velocity of head-shaking nystagmus was greater (P =.01) and its duration shortened (P =.008). Ipsilateral responses could be distinguished from contralateral responses based on their latency (P =.03), maximal slow-phase eye velocity (P <.05), and duration (P =.02). The frequency of head-shaking nystagmus was significantly higher among older patients. There was no correlation between head-shaking nystagmus and clinical patterns. CONCLUSION: Head-shaking nystagmus of peripheral vestibular origin is a response both qualitatively and quantitatively associated with the degree of the vestibular loss.     

震动眼震在单侧前庭外周疾病中的临床意义

目的研究震动眼震（vibration—induced nystagmu，VIN）在前庭外周疾病诊断中的临床意义，并确定震动实验（vibration test，VT）的灵敏度和特异度。方法30例健康成人和眩晕门诊112例单侧外周前庭疾病患者纳入本研究，排除具有自发性眼震患者，采用置于乳突和前额的震动刺激（92Hz）进行震动实验，观察记录VIN的诱发情况，患者和正常受试者同时还进行摇头眼震（headshaking nystagmus，HSN）和前庭双温冷热试验检查，并进行比较。结果112例患者中，有91例（81％）出现VIN，主要是水平眼震，VIN在乳突比在前额更常诱发出，其中76例VIN的方向朝向健侧，然而15例梅尼埃病患者VIN方向朝向患侧。30例健康受试者，均未出现VIN。随着前庭双温冷热试验中半规管轻瘫（canal paresis，CP）值的增加，VIN出现率增加。分别有70例（63％）单侧外周前庭疾病患者和9例健康受试者（30％）出现HSN。前庭双温检查，112例患者中CP值〈25％有10例，25％≤CP值≤40％有32例，40％〈CP值〈70％有48例，cP值≥70％有22例，30例健康受试者CP值均〈25％，VIN出现率随着cP值的增加而增加。结论VIN检查是一项简单、非侵入性的、患者能很好耐受的检测单侧外周前庭功能障碍的临床测试方法，具有比HSN检查更高的灵敏度和特异度。     

Dynamics of canal response to head-shaking test in benign paroxysmal positional vertigo

Conclusions. Time constant and maximum slow phase velocity (SPV) of head-shaking nystagmus (HSN) demonstrated a differential canal response to head shaking in 24% of patients with posterior canal benign paroxysmal positional vertigo (BPPV). We suggest that vestibular lithiasis has a limited contribution to the mechanism that generates HSN. Objective. To determine the canal response to head shaking in BPPV. Patients and methods. This was a case-control study including 104 individuals with BPPV. The diagnosis was based on the presence of vertigo and nystagmus during the positional test. Subjects were examined by the horizontal and vertical head-shaking test. Eye movements were recorded on a video camera to analyze the nystagmus. The head was shaken passively in the horizontal and sagittal planes, respectively, for horizontal and vertical HSN at a frequency of 2 Hz. HSN was considered when six consecutive beats of nystagmus with an SPV of at least 2°/s were detected. Main outcome measures were the presence of horizontal and vertical HSN, maximum SPV of HSN, time constant of HSN, and canal paresis. Results. Maximum SPV of vertical HSN was higher in BPPV patients with posterior canal BPPV (n=10) than in controls (p=0.04). Moreover, the time constant of vertical HSN was significantly lower for posterior canal BPPV when compared with controls (p<0.02).     

Head-Shaking Nystagmus Depends on Gravity

In acute unilateral peripheral vestibular deficit, horizontal spontaneous nystagmus (SN) increases when patients lie on their affected ear. This phenomenon indicates an ipsilesional reduction of otolith function that normally suppresses asymmetric semicircular canal signals. We asked whether head-shaking nystagmus (HSN) in patients with chronic unilateral vestibular deficit following vestibular neuritis is influenced by gravity in the same way as SN in acute patients. Using a three-dimensional (3-D) turntable, patients (N = 7) were placed in different whole-body positions along the roll plane and oscillated (1 Hz, ±10°) about their head-fixed vertical axis. Eye movements were recorded with 3-D magnetic search coils. HSN was modulated by gravity: When patients lay on their affected ear, slow-phase eye velocity significantly increased upon head shaking and consisted of a horizontal drift toward the affected ear (average: 1.2°/s ±0.5 SD), which was added to the gravity-independent and directionally nonspecific SN. In conclusion, HSN in patients with chronic unilateral peripheral vestibular deficit is best elicited when they are lying on their affected ear. This suggests a gravity-dependent mechanism similar to the one observed for SN in acute patients, i.e., an asymmetric suppression of vestibular nystagmus by the unilaterally impaired otolith organs.     

Three-Dimensional Vibration-Induced Vestibulo-ocular Reflex Identifies Vertical Semicircular Canal Dehiscence

Vertical semicircular canal dehiscence (VSCD) due to superior canal dehiscence (SCD) or posterior canal dehiscence (PCD) of the temporal bone causes vestibular and cochlear hypersensitivity to sound. This study aimed to characterize the vibration-induced vestibulo-ocular reflex (ViVOR) in VSCD. ViVORs in one PCD and 17 SCD patients, confirmed by CT imaging reformatted in semicircular canal planes, were measured with dual-search coils as binocular three-dimensional eye rotations induced by skull vibrations from a bone oscillator (B71—10 ohms) at 7 ms, 500 Hz, 135-dB peak-force level (re: 1 μN). The ViVOR eye rotation axes were computed by vector analysis and referenced to known semicircular canal planes. Onset latency of the ViVOR was 11 ms. ViVOR from VSCD was up to nine times greater than normal. The ViVOR’s torsional rotation was always contraversive-torsional (the eye’s upper pole rotated away from the stimulated ear), i.e. its direction was clockwise from a left and counterclockwise from a right VSCD, thereby lateralizing the side of the VSCD. The ViVORs vertical component distinguishes PCD from SCD, being downwards in PCD and upwards in SCD. In unilateral VSCD, the ViVOR eye rotation axis aligned closest to the dehiscent vertical semicircular canal axis from either ipsilateral or contralateral mastoid vibrations. However, in bilateral VSCDs, the ViVOR eye rotation axis lateralized to the ipsilateral dehiscent vertical semicircular canal axis. ViVOR was evoked in ossicular chain dysfunction, even when air-conducted click vestibulo-ocular reflex (VOR) was absent or markedly reduced. Hence, ViVOR could be a useful measurement to identify unilateral or bilateral VSCD even in the presence of ossicular chain dysfunction.     

'Bow and lean test' to determine the affected ear of horizontal canal benign paroxysmal positional vertigo

OBJECTIVE: One of the problems in the management of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) is the difficulty in determining the affected ear using Ewald's second law. The purpose of this study is to develop the new "bow and lean test (BLT)" to easily determine the affected ear of HSC-BPPV and evaluate its efficiency. METHODS: We compared the efficiency between the classic method and BLT in 26 patients with HSC-BPPV. The classic method is based on Ewald's second law comparing the intensity of nystagmus or symptoms in the head roll test. BLT is based on the direction of both "bowing nystagmus" and "leaning nystagmus" at the head's bowing and leaning state in a sitting position. The affected ear is the same direction of bowing nystagmus in canalolithiasis and the same direction of leaning nystagmus in cupulolithiasis. RESULTS: In 26 patents (15 canalolithiasis, 11 cupulolithiasis), 3 (11.5%) patients did not show a prominent affected ear in the classic method, and 7 (26.9%) patients showed the different affected ear between the two methods. All 10 patients were successfully treated with just one trial of barbecue rotation based on the affected ear in BLT. Three patients did not show any bowing or leaning nystagmus. The side with canal paresis in all four patients, who showed significant canal paresis in bithermal caloric tests, was equal to the affected ear based on BLT. CONCLUSIONS: The "bow and lean test" (also called "Choung's test") is a new method that can easily determine the affected ear of HC-BPPV.