Factors influencing results with streptomycin perfusion of the labyrinth

Streptomycin perfusion of the labyrinth is the logical choice of treatment for the third stage of Meniere's disease with intractable vertigo. The results of streptomycin perfusion of the labyrinth are comparable to those of other treatments, including endolymphatic shunt and vestibular nerve section. Refinements must be made in the process of selecting candidates for the operation. To study the factors influencing the results of streptomycin perfusion of the labyrinth, 144 patients who had streptomycin perfusion of the labyrinth and were followed for 1 year were studied using the 1972 AAOO classification of results. The findings of this study indicate that only a low dosage of streptomycin and a small volume of perfusate are required to obtain good results. Patients who have long lasting severe endolymphatic hydrops with poor hearing preoperatively are less likely to achieve good results.

An electrocochleographic study of acute low-tone sensorineural hearing loss

Twenty-four patients with acute low-tone sensorineural hearing loss (ALHL) were examined using electrocochleography. The negative summating potential (SP) amplitude and the summating potential/action potential (AP) ratio were significantly greater in the ALHL patients than in normals. The SP/AP ratio was smaller in the ALHL patients than in patients with known Meniere's disease and moderate hearing loss, although the SP amplitude was somewhat greater in the former. An abnormal increase in the SP amplitude following click stimuli was found in 54% of the ALHL patients, while the SP/AP ratio was increased abnormally in 63% of these patients. These findings suggest that the pathophysiology of ALHL may be similar to that for endolymphatic hydrops.

Sensory interaction platform posturography in patients with Ménière's syndrome

INTRODUCTION

The influence on balance by the peripheral vestibular disturbance in Ménière's disease is studied. The influence of visual and proprioceptive support in balance is evaluated.

MATERIALS AND METHODS

Patients with recurrent spontaneous vertigo attacks (n = 134) were studied, 90 with Ménière's disease and 44 with recurrent vestibulopathy. A post-urographic technique was applied with the patient standing on a force plate in four test conditions: (1) eyes open, (2) eyes closed on a stable platform, and the same two conditions on a foam rubber platform. Postural sway was measured for each test and the normality of the results were evaluated by a scoring system. Sensory interaction on balance was assessed by comparing the values of the test results obtained with and without interfering influences on the vestibular-visual-proprioceptive sensory input.

RESULTS

The results of the posturographic data were used to subdivide the patients into normal and abnormal groups. Comparison of the tests with and without visual input as well as of the tests with undisturbed and disturbed proprioceptive input were used to evaluate the effect of each sensory input and to determine which effects were dominant. In this way a "pattern" was defined. The interaction effect, thus defined, was most frequently positive, however, it could also be negative (negative patterns). Visual effects were most frequent. There was no significant difference for findings between patients who were stabilized and nonstabilized. Negative patterns suggest a complex interaction of the sensory inputs.

CONCLUSION

In these patients with spontaneous vertigo attacks, sensory interaction posturography showed an influence upon balance in the erect position. Different patterns of sensory interaction were found. There was no specific pattern for this category of patients. There was no significant difference related to the "stabilization" of the syndrome.

Electrocochleography with postural changes in perilymphatic fistula and Menière's disease: case reports

Perilymphatic fistula can be difficult to diagnose differentially prior to exploratory surgery. In this study, we investigated a new test technique in four case studies of subjects with perilymphatic fistula and compared our findings to results obtained in 20 normally hearing subjects with no history of vertigo and 10 subjects with Meniere's disease. Recordings from an eardrum electrode were obtained with the subject in an upright position, after the subject had been lying in a horizontal position for 30 minutes with the test ear up and after 15 minutes with the test ear down. Stimuli consisted of high level clicks and tonebursts. Neither the summating potential (SP) and action potential (AP) amplitudes nor the SP/AP amplitude ratio were significantly affected by postural change in either the normal or Meniere's disease group. The perilymphatic fistula subjects, in general, showed greater changes in the SP/AP, particularly for the 6000 Hz tonebursts, than did the other two groups. More data will be needed to determine if these findings are consistent in a large population of perilymphatic fistula patients.

[Transtympanic electrocochleography in Menière's disease]

In order to examine the usefulness of the electrocochleography (ECoG) in the diagnosis of Menière's disease and establish the diagnostic criteria in Chinese, transtympanic ECoG was performed on 18 normal ears, 22 Menière's ears and 14 ears with cochlear type sensorineural hearing loss other than Menière's disease. Although the Menière's ears had larger mean summating potential (SP) than the normal ears, the difference between both groups was not statistically significant. The mean amplitude and latency of the action potential (AP) in Menière's ears decreased and elongated significantly, but neither was sensitive enough in diagnosing Menière's disease. The SP/AP amplitude ratio not only made significant difference among 3 groups, but also had good diagnostic sensitivity (59.1%) and specificity (92%) in diagnosing Menière's disease while using the 95% upper confidence limit of the normative data (i.e., 34%). The SP/AP amplitude ratio of Menière's ears tended to increase while the mean hearing level of 4-8 KHz deteriorated. Also, abnormal enlargement of the SP/AP amplitude ratio in Menière's disease tended to be the result of decreased AP amplitude.

[Acoustic distortion products. Recordings from patients with normal hearing and those with sensorineural hearing loss]

Distortion product otoacoustic emissions (DPEs) are a subtype of evoked otoacoustic emissions that represent a class of cochlear response. Because of their frequency specificity and the wide range of frequencies explored DPEs have a great potential for clinical use. DPEs studies include DP-audiograms and input/output functions. We recorded 27 DPEs, 24 of them from normal ears and 3 from pathological ears. This report resumes methods and results.

Neuro-otology

New techniques for the assessment of vestibulospinal, neck-afferent, and viscerograviceptive function may show future clinical applications for a broader assessment of balance function in neuro-otological patients. Magnetic resonance imaging studies revealed that many intralabyrinthine disorders (labyrinthitis, hemorrhage, schwannomas) can be adequately visualized. Perceptual and oculomotor clinical studies improved our understanding of vestibular disordered function in the roll (coronal) plane. Therapeutic studies highlight the importance of a team approach, with individually tailored programs for the rehabilitation of patients with vestibular disorders. Reasonable agreement on the criteria for attempting hearing preservation during acoustic neuroma surgery seems to have been reached.

Vestibular evaluation--electronystagmography, rotational testing, and posturography

This report describes a battery of tests that is utilized by several clinical laboratories to investigate vestibular and balance function. The electronystagmogram evaluates eye movements, inner ear function, brainstem function and cerebellar function. Sinusoidal vertical axis rotation is a sensitive measure of horizontal semicircular canal function that is often complimentary to the caloric stimulation portion of the electronystagmogram. Visual-vestibular interaction rotation testing is designed to evaluate brainstem, cerebellar and oculomotor function. Dynamic posturography facilitates measurement of standing balance and permits a quantification of the role of proprioception, vision and the vestibular system in the maintenance of standing balance.

Autorotation test of the horizontal vestibulo-ocular reflex in Menière's disease

Sixty-four patients with the diagnosis of Menière's disease were tested at the House Ear Clinic with an active head-rotation test system, the Vestibular Autorotation Test (VAT). The VAT is a portable, computerized test that measures the horizontal vestibulo-ocular reflex (VOR) with the use of high-frequency (2 to 6 Hz) active head movements to obtain gain and phase. The purpose of this study was to characterize the horizontal VOR at high frequencies in patients with Menière's disease. At frequencies from 5 to 6 Hz, all patients demonstrated horizontal phase greater than 180 degrees and 85% showed abnormal VAT results. The most common patterns were decreased gain or increased phase values, or both, relative to normative data. No significant differences in the degree of abnormality in gain and phase were noted among groups of patients when the patients were clinically staged. We conclude that, in our test population of patients with Menière's disease, the VAT shows common gain and phase patterns and abnormalities of the horizontal VOR. This may contribute to high retinal image velocities, which render the patient unable to stabilize retinal images during locomotion (visual field image slip), in as many as 85% of the patients tested, regardless of clinical stage. Such high-frequency testing can reveal abnormalities of the horizontal VOR not apparent from conventional vestibular testing. Thus VAT provides additional information about the functioning VOR when combined with the present vestibular test battery.

Immunoperoxidase study of the endolymphatic sac in Menière's disease

A growing body of evidence suggests that some cases of Menière's disease may be mediated by immune mechanisms. Because endolymphatic sac dysfunction is believed to be an underlying cause of Menière's disease, this study used immunohistochemical techniques to demonstrate the presence of immune complex deposition in the sacs of patients with Menière's disease. Positive immunoglobulin G (IgG) staining was noted in 10 of 23 sac biopsies from Menière's patients, with 2 specimens showing perivascular deposition. Only 1 of 5 control specimens was only slightly positive for IgG. Clinical correlation showed a statistically significant increase in disease bilaterality (P < .05), larger summating potential/action potential (SP/AP) ratios with electrocochleography (ECoG), and a tendency toward worse hearing and more progressive disease among the immunopositive Menière's patients. The results provided histological evidence of immune injury in the endolymphatic sacs of patients with Menière's disease.

Cortical evoked potential criteria in the objective assessment of auditory threshold: a comparison of noise induced hearing loss with Ménière's disease

Amplitude of the N1 component of the cortical response was used to objectively determine threshold of hearing at 1 kHz and 4 kHz in a series of consecutively referred medicolegal cases with alleged occupational noise induced hearing loss and a control group of patients with Ménière's disease who were not seeking compensation for their hearing loss. The cortical response thresholds were compared with the subjective pure tone audiometric (PTA) thresholds at the same frequencies. The cortical and PTA thresholds were 'within 10 dB' for 84 and 92 per cent of the cases of noise induced hearing loss (NIHL) and Ménière's disease respectively, confirming the validity of CERA as a means of defining accurately the frequency specific thresholds and the audiometric configuration. Of the remaining 16 per cent of NIHL, 13 per cent exaggerated their PTA thresholds at 1 kHz and 10 per cent at 4 kHz whilst the error in cortical threshold estimation was beyond the 10 dB level for three and six per cent of cases at those frequencies respectively. The median exaggeration of threshold was 25 dB. For eight per cent of the Ménière's patients, thresholds exceeded 10 dB at both 1 and 4 kHz, four per cent of whom exaggerated their PTA thresholds and four per cent had a test error greater than 10 dB. A similar percentage (four per cent) of both groups revealed a cortical test error greater than 10 dB whereas three times as many cases of noise induced hearing loss (13 per cent) revealed exaggeration of their subjective audiometric thresholds compared with the Ménière's group (four per cent).(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental endolymphatic hydrops and glycerol. Electrophysiologic study

The object of the present study was to evaluate electrophysiologically the therapeutic effect of glycerol on the cochlear function of guinea pigs in which experimental hydrops had been surgically induced. Fifteen albino guinea pigs were used. Each animal was chronically implanted to follow the evolution of hearing. The experimental protocol considered 3 groups of guinea pigs (5 animals each). Group 1 received no drug treatment, while groups 2 and 3 were given glycerol orally at 0.75 and 0.50 g/kg of body weight once a day for 4 months. The audiograms of the animals treated with glycerol showed a statistically significant hearing improvement compared with the control group. Clinically, our results seem to support the view of those who favor the use of glycerol for the medical treatment of Meniere's disease at an early stage.

[Otorhinolaryngologic aspects of diving sports]

ENT disorders are the most common of all medical problems of diving. This review summarizes the specific conditions and ENT diseases in Scuba diving. During compression failure to equalize the pressure of air-filled cavities surrounded by bone deprives the middle ear or sinuses of aeration. Middle ear barotrauma is the most common barotrauma encountered in divers while sinus barotrauma and especially inner ear barotrauma (with rupture of the round or oval window) are less common. Decompression sickness in primarily the result of inert gas bubbles; deafness and vertigo may result if the inner ear is involved. The ENT examination necessary for assessment of diving fitness focuses on the middle and inner ear as well as the nose, sinuses and larynx. A list of ENT contra-indications is presented that mandate temporary or permanent disqualification from diving.

Long-term efficacy of endolymphatic sac surgery for vertigo in Menière's disease

The long-term efficacy of endolymphatic sac procedures for control of vertigo in Menière's disease has been controversial. We evaluated results of sac shunt surgery for 234 patients having at least 10 years followup (mean, 13.5 years). All patients had persistent vestibular symptoms despite medical therapy. All underwent endolymphatic subarachnoid shunt as their original operation. Data were collected by chart review and questionnaire regarding: (1) the number of additional surgical procedures to control vertigo, (2) remaining dizziness, and (3) level of disability. One hundred forty-seven of the patients (63%) did not undergo any further surgery to control vertigo, and an additional 17% had only revisions of the endolymphatic sac shunt. Thus, 80% never required a destructive procedure. Long-term effectiveness of surgery in regard to dizziness and disability was determined from the questionnaire. Of the 147 patients with only the original sac shunt surgery, 93% reported no dizziness or mild to no disability. Of the group who underwent only revisions of the original shunt, 96% stated they had no more dizziness or mild to no disability. We conclude that endolymphatic sac shunt operations are effective as initial surgical procedures for long-term control of disabling vertigo of Menière's disease.

Bilateral vestibular neurectomy for treatment of vertigo

The effects of bilateral vestibular neurectomy on equilibrium and vestibular function were clinically evaluated in two patients more than 15 years after surgery. Both patients had bilateral Menière's disease and their vertiginous spells were permanently resolved after the second vestibular neurectomy. Symptoms of disequilibrium were absent in one patient and mild in the other. Reflexive horizontal eye movements on whole body rotation in darkness were absent on low angular accelerations (2 degrees/s2), but could be elicited with angular accelerations of 20 degrees/s2 or higher. Extravestibular cues generating these eye movements seemed to be unlikely because a "control" patient with complete peripheral vestibular ablation after bilateral subtotal petrosectomy did not present reflexive eye movements under the same stimulus paradigms. An incomplete deafferentiation of the vestibular end organ (rather than regeneration of vestibular nerve fibers) and a consecutive impairment of the central velocity storage mechanism may explain the good functional outcome in our bilateral neurectomized patients.

Endoscopic transcutaneous mastoidoscopy for evaluation of residual epitympanic/mastoid cholesteatoma

It is generally agreed that patients subjected to an intact canal wall mastoidectomy to excise mastoid/epitympanic cholesteatoma should undergo a "second-look" operation to rule out residual cholesteatoma. The morbidity of this second operation can be significantly reduced with endoscopic mastoidoscopy, when compared to the traditional postauricular (open) incision approach. Details, benefits, and limitations of endoscopic mastoidoscopy are discussed.

[Clinical significance of cervico-ocular reactions]

Cervically induced eye movements consist of a nystagmus and a deviation of the mean eye position (shift). They show in relation to different neck torsion velocities maximum reactions at slow velocities. The clinical significance of these cervico-ocular reactions is discussed controversially. Therefore we investigated 40 healthy subjects without any neurootological findings, who, in addition, underwent a manual examination. The neck torsion test was performed automatically with quantifiable stimulus parameters and a complete head fixation by means of individual dental casts. It could be shown that at a constant chair velocity of 5 degrees/s every healthy subject exhibits cervical nystagmus and/or shift deviations. In comparison a group of 30 patients with an upper cervical spine syndrome also showed similar cervico-ocular reactions without significant difference. It can be concluded that a muscle hypertonus in the deep neck region does not lead to pathological, cervically induced eye movements and that the cervical nystagmus itself is not a pathognomonic sign for cervical, proprioceptive vertigo.

Functional changes associated with experimentally induced endolymphatic hydrops

A guinea pig model with surgically induced endolymphatic hydrops of the inner ear has been developed and studied over the past thirty years. The aim of such studies is to obtain insight into physiological processes associated with endolymphatic hydrops in man and in particular in Menière's disease where endolymphatic hydrops is systematically encountered at post-mortem examination of the temporal bones. The present review attempts to draw together the data pertaining to functional modifications of inner ear function in the animal model. For simplicity the data are categorised under five main titles: electrochemical modifications, electrophysiological modifications, pressure and hydrops, sensitivity to other insults and vestibular dysfunction. One of the most striking observations that can be made is that the data originating from different authors are very variable. There is, however, some evidence suggesting that the evolution of the auditory dysfunction could be considered as consisting of a series of different phases. This kind of information could serve as a basic framework for future research on the animal model.

Classification of Menière's disease

To create a rational treatment system for Meniere's disease, it is helpful to divide Meniere's disease into five stages according to the signs, symptoms, pathology, and natural history by recalling what is known for certain and what is probably true about Meniere's disease. It is known that Meniere's disease is attributable to endolymphatic hydrops, caused by a small, malfunctioning endolymphatic sac, abnormally placed since birth, and Meniere's disease is therefore a congenital disorder of the endolymphatic sac. It is probably true that there is often an immune, viral, metabolic, or other insult to the inner ear, that disturbs the balance between the cochlea, where endolymph is produced, and the endolymphatic sac, where most of it is absorbed. Using this five-stage classification, it is possible to separate Meniere's disease into the first three stages, for which different but reasonable treatments are possible, and the last two stages, for which no treatments are effective.

Transtympanic electrocochleography in Menière's disease using clicks and tone-bursts

Transtympanic electrocochleography (ECoG), using clicks and tone-bursts at 500, 1000, and 2000 Hz, was employed to study 80 patients with Meniere's disease and 25 non-Meniere's patients. The magnitude of the negative summating potential and the summating potential:action potential ratio (SP:AP) were examined in both groups. Groups were further divided based upon degree of hearing loss and audiometric configuration. An elevated SP:AP ratio was found in 83.7 percent of the Meniere's ears and 12 percent of the non-Meniere's. The likelihood of obtaining a positive ECoG in Meniere's patients was strongly related to degree of hearing loss but not audiometric configuration.

Otoneuroscience and space vestibulo-neuroscience in the new century

From a clinically oriented point of view, efforts of otoneuroscience should be directed toward an improvement of the management of dizzy and vertiginous patients. At present, the main obstacles in this field are: (1) the lack of specific therapies for many of the clinical diagnoses. This reduces the necessity of clinical vestibular diagnosis to a pragmatic exclusion of the few diseases with therapeutic consequences; (2) the lack of feedback to confirm or disprove clinical diagnoses; (3) poor knowledge of the pathophysiology of many of the otoneurological diseases; experiments in animal models may be helpful in this respect; (4) most progress in medicine originates from the results of numerous, poorly controlled 'unscientific' trial and error experiments obtained during treatment of patients; training clinicians in more scientific, critical thinking would help to increase the profits that can be realized from this important source of information; and (5) to date, information obtained during zero-gravity experiments in space have not yet led to important consequences in treatment of patients under 1-g conditions, but are important for a possible evolutionary step of mammals adapting to a new environment.

[Therapy of vestibular vertigo]

The non-surgical treatment of vestibular disorders must be based on current knowledge of vestibular pathophysiology. It is generally accepted that after vestibular lesions a self-repair mechanism exists that allows a more or less complete recovery. In cases of persisting vestibular complaints the physician's duty consists in stimulation of these pre-existing mechanisms. This can be done by physical exercises, as has been recommended since the work of Cawthorne and Cooksey in 1946. This concept is meanwhile supported by modern neurophysiological research. This article describes a short training program consisting of exercises for fixation during rotations, smooth pursuit, optokinetic nystagmus and motor learning mechanisms. Physical exercises can be reinforced by nootropic drugs.

Intratympanic gentamicin instillation as treatment of unilateral Menière's disease: update of an ongoing study

A prospective study using intratympanic gentamicin instillation as treatment for disabling unilateral Meniere's disease has been ongoing at our institution for 4 years. Treatment effectiveness is evaluated based on the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) 1985 guidelines. This report is based on 30 patients who have become eligible for assessment. We conclude that gentamicin intratympanic instillation as currently used in our protocol is an effective, safe, and easily administered method of achieving a predictable measure of vertigo control.

[Effects of a change in environmental pressure on spontaneous nystagmus in patients with cochleovestibular diseases]

Cochlear and vestibular effects of variation of middle ear pressure have been discussed for more than 50 years. In 1975, Densert reported on temporary improvement of hearing threshold in patients suffering from Ménière's disease after reduction of air pressure in a pressure chamber. One year later Ingelstedt observed reduction of spontaneous nystagmus under this condition. The transmission of relative overpressure from the middle ear to the labyrinth with consecutive decongestion of the hydropic endolymphatic system to the saccus was thought to be the cause of this phenomenon. Meanwhile a direct effect of labyrinthine pressure on the activity of the inner ear and labyrinth in healthy subjects and animals has been described. In order to gain further information on the phenomenon observed by Densert and Ingelstedt we performed investigations on patients suffering from several cochleovestibular diseases. Chamber pressure was altered and simultaneous electronystagmographic recording was performed. As a striking result, we observed a reduction of the pathological spontaneous nystagmus in a majority of patients with vestibular damage during and after the reduction of chamber pressure. Many of these subjects showed a partial restitution of nystagmus if the chamber pressure was increased again. This observation was made in patients with Méni ere's disease, vestibular neuritis and sudden hearing loss with vestibular involvement. Hence, we conclude that this phenomenon is not specific for Ménière's disease. A transmission of middle ear pressure to the labyrinth may be an explanation of our observations.

[Results of 100 consecutively operated patients with acoustic neuroma]

The results from 100 patients with 103 acoustic neurinomas who were operated on between February 1979 and April 1992 are presented. All patients were placed in the half-sitting position and operated on by the same surgeon using the suboccipital-trans-meatal approach. Postoperative facial nerve function was good in 56%, moderate in 20% and poor in 24% of our patients. Preservation of useful hearing was achieved in 21%: the smaller the tumor, the better the functional result. However, the early symptoms of acoustic neuromas (tinnitus, dizziness, feeling of unsteadiness) were only slightly improved by the operation. The result concerning tinnitus seemed to be better after sacrificing the cochlear nerve. The number of patients with ataxia increased postoperatively, although objective ataxia decreased. Dizziness improved regardless of the tumor size.