Head Thrust Research Articles

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).

Congenital and Compensated Vestibular Dysfunction in Childhood: An Overlooked Entity

We report five children with previously unrecognized vestibular dysfunction detected by clinical examination and confirmed by quantitative vestibular testing. Patient 1 presented with fluctuating visual acuity and intermittent nystagmus. Patient 2 had congenital hearing loss associated with imbalance, delayed motor development, and cyclic vomiting. Patient 3 had neurotrophic keratitis with an intermittent head tilt, imbalance, and motor delays. Patient 4 showed ataxia and eye movement abnormalities following traumatic brain injury and had reading difficulties. Patient 5 had episodic vertigo and eye movement abnormalities from infancy. Clinical vestibular testing emphasized spontaneous nystagmus, rapid head thrust, and assessment of post-rotatory nystagmus. Quantitative vestibular testing included the sinusoidal chair rotation and velocity step tests, measurement of dynamic visual acuity, post-head-shake nystagmus, and computerized platform posturography. Pediatric neurologists encounter children with congenital and compensated vestibular dysfunction, which can be recognized on the basis of relevant history and clinical abnormalities of the ocular-ocular reflex.

Dynamic Visual Acuity during Passive Head Thrusts in Canal Planes

We sought to determine whether the dynamic visual acuity (DVA) test, which has been used to measure the function of the two horizontal semicircular canals (SCCs), could be adapted to measure the individual function of all six SCCs using transient, rapid, unpredictable head rotation stimuli (head thrusts) in the direction of maximum sensitivity of each SCC. We examined head-thrust DVA (htDVA) performance in 19 healthy control subjects, five patients before and six patients after plugging of one superior SCC for treatment of superior canal dehiscence, and two subjects with unilateral vestibular deafferentation (UVD) by vestibular neurectomy. We compared htDVA results for each SCC to vestibulo-ocular reflex gains measured using 3-D scleral coil recordings during a passive head-thrust-test paradigm. Individuals with normal vestibular function had similar htDVA scores for each of the six directions (canals) tested (mean 0.058 +/- 0.050 LogMAR). Individuals tested after surgical plugging of one superior SCC were similar to normal for all SCCs except the plugged SCC, which had significantly worse htDVA scores (mean 0.270 +/- 0.08 LogMAR). Individuals with UVD had significantly worse htDVA scores for head rotations maximally exciting any of the ipsilesional SCC (mean 0.317 +/- 0.129 LogMAR) and scores similar to normal subjects for contralesional rotations (0.063 +/- 0.051 LogMAR). These findings suggest that the htDVA test, which does not require scleral coil placement, magnetic field coils, or expensive oculography equipment, can provide a useful quantitative measure of individual SCC function.

G608 CFDによるポンプ軸スラストの予測(2)(GS-6-2 翼干渉,フィン,境界層,一般セッション)

One method to predict the axial thrust is to use the relationship between the total head and axial thrust, where the axial thrust is supposed to be in proportion with the total head. But such method has insufficient prediction accuracy because it can not properly predict the circumferential velocity according to the direction of the leakage. We developed a numerical simulation method to predict the circumferential velocity properly. First, the numerical domain of the fluid part, including the impeller and vaned diffuser, was calculated. Second, that of the rear part located on the back side of the hub was calculated. The leakage in the rear part is usually about 5% less than the discharge in the fluid part, therefore the influence from the rear part to the fluid part is neglected. Three pump types were calculated and we could predict the maximum axial thrust with a high accuracy of ±6%.

Transtympanic Gentamicin and Fibrin Tissue Adhesive for Treatment of Unilateral Menière’s Disease: Effects on Vestibular Function

To determine the effects of transtympanic injections, with a mixture composed of gentamicin and fibrin tissue adhesive (FTA), on vestibular function of patients with intractable unilateral Menière's disease. This was an open, prospective study. The study was performed at 2 tertiary referral centers. Twenty-six patients affected by "definite" unilateral Menière's disease, unresponsive to medical therapy for at least 6 months, were enrolled. A buffered gentamicin solution mixed with FTA was injected in the middle ear until the development of bedside vestibular hypofunction signs and/or caloric weakness in the treated ear. Vestibular function was evaluated by 3 bedside vestibular tests (observation of spontaneous nystagmus, head shaking test, and head thrust test) and by a caloric test. Tests were performed on days 10 and 30 after completion of treatment. Tests were also performed 3, 6, and 12 months from completion of the gentamicin-FTA protocol. The effects of treatment were also assessed in terms of hearing levels, control of vertigo, and disability status. In 22 of the 26 patients, only 1 gentamicin-FTA injection was necessary to obtain 1 or more signs indicating a reduction of the vestibular function in the treated ear. Four patients needed another treatment because of the persistence of their incapacitating symptoms during the follow-up. Four patients needed more than 1 injection to obtain a vestibular hypofunction. None of the patients who received 1 or 2 injections presented hearing loss in direct temporal relationship to the treatment. A mixture of gentamicin and fibrin glue makes it possible to considerably reduce the number of administrations in patients with intractable unilateral Menière's disease. Spontaneous nystagmus, post head shaking nystagmus, and a head thrust sign are the clinical signs that indicate onset or progression of unilateral vestibular hypofunction. These signs were obtained with only 1 injection in 81% of patients.

Angular Vestibulo-Ocular Reflex Gains Correlate with Vertigo Control after Intratympanic Gentamicin Treatment for Meniere's Disease

The objective of our study was to determine whether angular vestibulo-ocular reflex (aVOR) gains correlated with vertigo control after intratympanic gentamicin treatment for Meniere's disease. We conducted a prospective study of 18 subjects with unilateral Meniere's disease treated with intratympanic gentamicin injection and followed all subjects for 1 year. We measured the gain of the aVOR elicited by rapid rotary head thrusts in each of the canal planes for each subject before and after treatment with intratympanic gentamicin by using magnetic search coils to record eye movements. During the follow-up period, 11 subjects ("single-treatment group"; 61%) had control of their vertigo with a single gentamicin injection. The remaining 7 subjects ("multiple-treatment group"; 39%) experienced recurrent vertigo that required a second injection of gentamicin at a mean of 6 months after the first treatment. The 11 subjects in the single-treatment group had significantly greater reduction of labyrinthine function after the first treatment, as measured by change in ipsilateral horizontal canal gain, than did the 7 subjects with vertigo recurrence. Changes in caloric asymmetry did not correlate with vertigo control. Our results suggest that successful treatment of Meniere's disease is closely related to attenuation of semicircular canal function as measured by horizontal canal aVOR gains.

Acute Vestibular Neuritis: Prognosis Based upon Bedside Clinical Tests (Thrusts and Heaves)

We compared bedside tests of vestibulo-ocular function (head thrust and head heave signs) with caloric testing results in 68 patients with acute vestibular neuritis seen at onset and in follow-up for one year. The head thrust and head heave signs each were strong predictors of a decreased probability of recovery, and if both were present, there was a trend for a slower recovery and a further decrease in the probability of recovery. If the head thrust sign was absent, recovery was assured. Our results suggest that careful bedside testing of semicircular canal (head thrust maneuver) and otolith (head heave maneuver) function provides useful information for predicting prognosis in patients with acute vestibular neuritis.

Head-bobbing behavior in foraging whooping cranes favors visual fixation

Many species of birds move their heads forward through a series of successive, fixed positions when walking. This unique ‘head-bobbing’ behavior stabilizes visual fields during body movement, preventing motion blur of the retinal image [1–3]. Gaze stabilization could be required for successful visual search, particularly for moving objects [4], but the time available for stabilization varies with walking speed. No direct evidence has been published showing that birds favor the stabilization phase while foraging either for moving or immobile food.

Gaze Position Corrective Eye Movements in Normal Subjects and in Patients with Vestibular Deficits

Eye movements in response to high-acceleration head rotations (thrusts) in the horizontal plane from patients with unilateral (UVD) or bilateral vestibular loss (BVD) were recorded. The rapid, gaze-position corrections (GPCs) that appeared when vestibulo-ocular reflex (VOR) slow phases were undercompensatory were characterized. For comparison, eye movements from normal subjects who were asked to generate saccades in the direction opposite head rotation (in the same direction as slow phases) were recorded. This normal-subject model produced responses with spatial and temporal characteristics similar to those from GPCs in patients as follows: When head rotations were generated actively, compared with passively, gaze-position errors and corresponding GPCs were smaller and occurred earlier. During passively generated head thrusts, GPCs still occurred when head rotations were made in total darkness, though their accuracy decreased as the requirement for maintaining gaze on a specific location in space was relaxed. Time of onset of GPCs was not rigidly tied to head kinematics (peak velocity or peak acceleration). Speeds of GPCs, however, were lower than speeds of similar-sized, head-fixed saccades. Finally, during passive and active head thrusts in patients, sustained, high-frequency (20 to 30 Hz) oscillations that appeared as tiny saccades were occasionally observed, one immediately following the other, resembling a compensatory slow-phase response. Taken together, the results suggest that one strategy for overcoming a VOR deficit is to enlist the saccadic system to produce an oculomotor response that is required to compensate for head rotation. This response may come in the form of high-velocity GPCs or smaller-amplitude oscillations.

Symptomatic high frequency/acceleration vestibular loss: consideration of a new clinical syndrome of vestibular dysfunction

ConclusionSymptomatic high frequency/acceleration vestibular loss is a distinct clinical entity that can be missed on conventional ENG with caloric testing. Under certain circumstances, symptomatic patients with a high frequency/acceleration vestibular loss should undergo an MSSC study for confirmation, if required.ObjectiveTo document that normal electronystagmography (ENG) with conventional bithermal caloric testing is inadequate for diagnosing clinically significant high frequency/acceleration vestibular loss.Material and methodsPatients with clinical symptoms and signs of persistent peripheral vestibular dysfunction despite normal conventional bithermal caloric testing on ENG underwent high frequency/acceleration horizontal magnetic scleral search coil (MSSC) eye movement studies. The clinical findings and results from audiometric tests, conventional ENG with bithermal caloric tests and MSSC tests were reviewed.ResultsEleven patients were identified as having an abnormal MSSC study, indicating a high frequency/acceleration vestibular loss consistent with their clinical history despite normal or equivocal bithermal caloric responses on conventional ENG. Although valuable, ENG caloric testing evaluates lateral semicircular canal function and should be considered a non-physiological test primarily of low frequency vestibular function. High frequency/acceleration head thrust testing clinically detected a “high frequency/acceleration vestibular loss” in 8/11(72.7%) cases.

P0 antigen detection in sudden hearing loss and ménière's disease: A new diagnostic marker?

Objective—To evaluate the presence of IgG autoantibodies against the P0 antigen in patients affected by sudden hearing loss and Ménière's disease (MD).Material and Methods—All patients underwent a tonal audiometric evaluation, tympanometry, evaluation of the stapedial reflex threshold with decay time, determination of auditory brainstem responses and a complete vestibular assessment involving evaluation of spontaneous and positional nystagmus (Frenzel glasses), a head thrust test and a caloric test (Fitzgerald–Hallpike technique). Blood samples were drawn from all patients for the immunologic assessment of IgG antibodies against the P0 antigen (30-kDa protein) of guinea pig inner ear extracts using a Western blot assay.Results—Ten patients affected by sudden hearing loss showed specific IgG antibodies against the P0 protein. Specifically, the P0 positive band was detectable in 5/45 patients with unilateral auditory impairment and in 5/5 of those with bilateral forms of auditory impairment. Among MD patients, the P0 positive band was detectable only in those with bilateral audiovestibular impairment (n=10). Interestingly, in none of the 35 patients affected by monolateral MD were specific IgG antibodies against the P0 protein detectable.Conclusion—The positive reactions to P0 in all bilateral MD and bilateral sudden hearing loss patients found in this study strongly indicate that these pathologies are the result of an ongoing autoimmune process directed against specific antigens of the inner ear.

Basement-involved inversion at the Appalachian structural front, western Newfoundland: an interpretation of seismic reflection data with implications for petroleum prospectivity

Abstract Recent hydrocarbon exploration in western Newfoundland has resulted in six new wells in the Port au Port Peninsula area. Port au Port No.1, drilled in 1994/95, penetrated the Cambro-Ordovician platform and underlying Grenville basement in the hanging wall of the southeast-dipping Round Head Thrust, terminated in the platform succession in the footwall of this basement-involved inversion structure, and discovered the Garden Hill petroleum pool. The most recent well, Shoal Point K-39, was drilled in 1999 to test a model in which the Round Head Thrust loses reverse displacement to the northeast, eventually becoming a normal fault. This model hinged on an interpretation of a seismic reflection survey acquired in 1996 in Port au Port Bay. This survey is now in the public domain. In our interpretation of these data, the Round Head Thrust is associated with another basement-involved feature, the northwest-dipping Piccadilly Bay Fault, which is mapped on Port au Port Peninsula. Active as normal faults in the Taconian foreland, both these faults were later inverted during Acadian orogenesis. The present reverse offset on the Piccadilly Bay Fault was previously interpreted as normal offset on the southeast-dipping Round Head Thrust. Our new interpretation is consistent with mapping on Port au Port Peninsula and north of Stephenville, where all basement-involved faults are inverted and display reverse senses of motion. It also explains spatially restricted, enigmatic reflections adjacent to the faults as carbonate conglomerates of the Cape Cormorant Formation or Daniel’s Harbour Member, units associated with inverted thick-skinned faults. The K-39 well, which targeted the footwall of the Round Head Thrust, actually penetrated the hanging wall of the Piccadilly Bay Fault. This distinction is important because the reservoir model invoked for this play involved preferential karstification and subsequent dolomitization in the footwalls of inverted thick-skinned faults. The apparent magnitude of structural inversion across the Piccadilly Bay Fault suggests other possible structural plays to the northeast of K-39.

An Older Adult Undergoing Vestibular Rehabilitation: A Case Report

Background and Purpose: Deteriorating balance and recurrence of disequilibria have severe impact on the life of an older adult. The purpose of this case study is to describe the interventions and course of E.F., an 83-year-old male whose independence was threatened because of vestibular dysfunction.Case Description: On examination, significant findings included a positive head thrust to the left and abnormal Dynamic Visual Acuity, right gaze holding nystagmus, + sharpened Romberg, and a Berg Balance Score of 48. Reduced efficacy was noted on the Activities Balance Confidence Questionnaire.Intervention: A plan of care consisting of vestibular rehabilitation to address all components of impairments noted on evaluation.Results: All of the patient's goals were met. The patient was discharged and resumed all of his previous interests and activities.

Characterization of the vestibulo-ocular reflex evoked by high-velocity movements.

The horizontal angular vestibulo-ocular reflex (VOR) plays an important role in stabilizing images on the retina throughout head rotations. Current evidence suggests that the VOR behaves linearly at low velocities and nonlinearly at high velocities. The aim of the research was to evaluate and characterize the normal behavior of the reflex evoked by high-velocity head rotations. Case control study. Manually applied head-thrust movements with peak velocities in the range of 100degrees to 500degrees/s and peak accelerations up to 7,000degrees/s were performed on normal volunteers. These head thrusts were comparable with those described in detail by Halmagi and coworkers. Eye and head movements were recorded using the magnetic search coil method. The gain of the VOR is linear at low velocities and saturates at head velocities greater than 350degrees/s. The values for the normal gain of the reflex were approximated by means of the area between two nonlinear functions. The directional difference parameter, exploring the symmetry of the reflex, indicated that the VOR in normal subjects is symmetric. The gain of the VOR in individuals with intact vestibular function is nonlinear at high angular head velocities. We propose a quantitative means using two nonlinear functions to characterize the normal range of values for the gain of the VOR in individuals with normal vestibular function. A directional difference parameter used in conjunction with the normal range of gains can detect small differences in the symmetry of the VOR and, consequently, reveal unilateral vestibular loss.

An office procedure to detect vestibular loss in children with hearing impairment.

As coexisting vestibular and cochlear lesions are of etiological importance, evaluation of children with congenital or early acquired hearing impairment (HI) should include vestibular assessment. A rotation test requires specific equipment and allows only detection of bilateral vestibular impairment. An impulse or head thrust test allows assessment of one ear at a time, detects more pronounced caloric side differences and can be performed without any equipment. We report a consecutive series of children with profound sensorineural HI investigated at a tertiary hospital unit. Age at taking first steps without help, the results of temporal bone images (CT/MRT) and vestibular tests were collected retrospectively from patient files. The children were 12 to 90 months old at the time they attended both a rotation and an impulse test. All 14 children cooperated in the impulse test, and 12 completed the vestibular rotation test successfully. Three out of 14 children tested so far have been confirmed to have a bilaterally pathological vestibulo-ocular reflex confirmed both in the rotation test and the impulse test. Our results show that both the rotation test and the vestibular impulse test can be successfully performed on small children at a regular outpatient appointment.

Optimizing the Sensitivity of the Head Thrust Test for Identifying Vestibular Hypofunction

The head thrust test (HTT) is used to assess the vestibulo-ocular reflex. Sensitivity and specificity for diagnosing unilateral vestibular hypofunction (UVH) in patients following vestibular ablation is excellent (100%), although sensitivity is lower (35%-39%) for patients with nonsurgically induced UVH. The variability of the test results may be from moving the subject's head outside the plane of the lateral semicircular canals as well as using a head thrust of predictable timing and direction. The purpose of this study was to examine sensitivity and specificity of the horizontal HTT in identifying patients with UVH and bilateral vestibular hypofunction (BVH) when the head was flexed 30 degrees in attempt to induce acceleration primarily in the lateral semicircular canal and the head was moved unpredictably. The medical records of 176 people with and without vestibular dysfunction (n=79 with UVH, n=32 with BVH, and n=65 with nonvestibular dizziness) were studied. Data were retrospectively tabulated from a de-identified database (ie, with health information stripped of all identifiers). Sensitivity of the HTT for identifying vestibular hypofunction was 71% for UVH and 84% for BVH. Specificity was 82%. Ensuring the head is pitched 30 degrees down and thrust with an unpredictable timing and direction appears to improve sensitivity of the HTT.

An Older Adult Undergoing Vestibular Rehabilitation: A Case Report

Background and Purpose: Deteriorating balance and recurrence of disequilibria have severe impact on the life of an older adult. The purpose of this case study is to describe the interventions and course of E.F., an 83-year-old male whose independence was threatened because of vestibular dysfunction.Case Description: On examination, significant findings included a positive head thrust to the left and abnormal Dynamic Visual Acuity, right gaze holding nystagmus, + sharpened Romberg, and a Berg Balance Score of 48. Reduced efficacy was noted on the Activities Balance Confidence Questionnaire.Intervention: A plan of care consisting of vestibular rehabilitation to address all components of impairments noted on evaluation.Results: All of the patient's goals were met. The patient was discharged and resumed all of his previous interests and activities.

Vestibulo-ocular arreflexia in families with spinocerebellar ataxia type 3 (Machado-Joseph disease)

Objective: To identify the presence of vestibulo-ocular arreflexia in patients with Machado-Joseph disease (MJD), which can easily be diagnosed at the bedside. Methods: Seven patients with MJD from five unrelated...

Flowchart for evaluating dairy cow freestalls

A flow chart system has been developed to evaluate dairy freestalls. It details 4 critical points: adequate surface cushion, adequate body resting space, lunge room for head thrust and an unobstructed bob-zone, and adequate height below and behind the neck rail. Surface cushion is considered to be the most important factor in determining stall usage. If the stall allows a full forward lunge, the configuration of the stall divider has little importance. If side lunge is required, the exact height of the divider rails is critical. Several clinical problems that result from inadequate stalls are discussed.

54th annual meeting of the American Academy of Neurology, Denver, Colorado, April 13-20, 2002.

54th annual meeting of the American Academy of Neurology, Denver, Colorado, April 13-20, 2002.