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Sensorineural hearing loss: more than meets the eye?

PURPOSE: To assess the value of MR in patients with sensorineural hearing loss (SNHL) caused by lesions other than acoustic neuromas. METHODS: MR studies of 51 patients with SNHL were retrospectively reviewed; patients with acoustic neuroma were excluded to focus on the more uncommon causes. RESULTS: Twenty patients had labyrinthine lesions. Six patients had viral labyrinthitis, one patient had bacterial labyrinthitis, and one patient had luetic labyrinthitis. Three patients had hemorrhage in the labyrinth, two posttraumatic and one spontaneous from an adjacent temporal bone tumor. Only one of the two patients with traumatic labyrinthine hemorrhage had evidence of a fracture on high-resolution CT. In one patient with CT-proved cochlear otosclerosis, peri-cochlear foci of enhancement were seen on contrast-enhanced MR. Four patients had presumed labyrinthine schwannomas. A middle ear cholesteatoma in one patient invaded the cochlea and resulted in marked cochlear enhancement due to granulation tissue. Thirteen patients had intracanalicular and cerebellopontine angle lesions. The lesions included arteriovenous malformations (three patients), sarcoidosis (three patients), metastasis (two patients), lymphoma (two patients), lipomas (two patients), and postshunt meningeal fibrosis (one patient). Eighteen patients had intra-axial lesions responsible for SNHL. The most common intra-axial lesions were brain stem infarcts and multiple sclerosis. Traumatic lesions in the inferior colliculi, sarcoidosis, lymphoma, and extrinsic compression of the colliculi from a pineal tumor were also noted. CONCLUSION: MR can demonstrate numerous lesions responsible for SNHL other than acoustic neuromas. The entire acoustic pathways, including the labyrinth, internal auditory canal, cerebellopontine angle, and brain stem should be carefully scrutinized for lesions in patients with SNHL. The use of contrast media markedly increases the yield of MR in this clinical situation by demonstrating inflammatory and neoplastic labyrinthine lesions and meningeal pathology (both neoplastic and inflammatory) in the internal auditory canal and cerebellopontine angle cistern.

Adolescent↗

Clinical relevance of magnetic resonance imaging and computed tomography in Cogan's syndrome.

The Pathologic changes in the inner ears of 5 patients with Cogan's syndrome were studied by a combined application of MR imaging and CT scanning. We used T1- and T2-weighted MR imaging sequences and a special three-dimensional MR imaging technique which allows a very detailed imaging of the inner ear structures. By the use of a CT scan simultaneously, calcified and noncalcified obliterations could be differentiated. The aim of the study was to visualize membranous labyrinth pathology in Cogan's syndrome and correlate them with the clinical findings. In one patient who recovered completely without hearing loss, the MR and CT investigations revealed no pathology. In the remaining 4 cases, narrowing or obliteration of parts of the vestibular labyrinth was seen. In 3 patients, we found aberrations in the cochlea consistent with the audiological data. The gadolinium-enhanced T1-images showed enhancement of the cochlea and vestibular labyrinth in one case, probably indicating an active process with interruption of the "blood-labyrinth barrier". The results are consistent with the hypothesis that the inner ear pathology in Cogan's syndrome is probably caused by obstructive vasculitis.

Adult↗

[Inner ear damage induced by bacteria (Mycobacterium chelonae)].

Mycobacterium chelonae has a pathogenicity for mouse inner ear, resulting in "spinning disease". The mice were subjected to intravenous injection of 1-1.2 x 10(7) organisms of strain ATCC19977 of M. chelonae subspecies abscessus. Morphological changes in the inner ear were investigated together with changes in behavior and auditory brainstem response (ABR). Three days after injection, the threshold of ABR rose in high frequency and the latency of the fifth wave prolonged. The behaviors of the mice such as "grooming" or "sniffing" were suppressed day by day. Fourteen days after injection, 35% of mice showed abnormal behavior, such as "spinning disease". The damage in the cochlear and vestibular sensory cells were observed using scanning electron microscopy and light microscopy. The inner ear showed serous or purulent labyrinthitis after injection. The most specific change found in purulent labyrinthitis was massive abscess of the cochlea with necrosis. Serous labyrinthitis which might have been induced by bacterial toxins was characterized by homogeneous and eosinophilic precipitates and slight cellular infiltrations in the perilymphatic and endolymphatic spaces. In the organ of Corti, the inner and outer hair cell cilia had degenerated and disappeared. In the vestibular end organs, the sensory cilia were fused, lost and sustained ballooning. The cross links and rough nature of the sensory hair membrane had disappeared in the early stage of serous labyrinthitis.

Animals↗

Histological considerations in implant patients.

The selection of patients for cochlear implantation requires consideration of a variety of anatomical and histological facts. Mechanical impediments to cochlear implantation, including the consequences of chronic otitis media, bony obliteration of the membranous labyrinth, or labyrinthitis ossificans, following bacterial labyrinthitis or vascular compromise of the inner ear, obliterative otosclerosis, and middle-ear dysplasias may present difficulties in access to the inner ear and placement of electrodes. Consideration of the histopathological features of known causes of profound deafness will help predict the presence or absence of inner ear structures essential for successful implantation. The identity of these critical structures and the histopathologic characteristics of bacterial labyrinthitis, fungal meningitis, syphilis of the inner ear, otosclerosis, presbycusis, genetically determined degenerations, trauma, intoxications, inflammatory, autoimmune and idiopathic disorders are presented in terms of their relevance for cochlear implantation.

Adult↗

Antibiotic prophylaxis in clean and clean-contaminated ear surgery.

BACKGROUND: Ear surgery may be performed in the treatment of chronic otitis media, ossicular chain disorders, tympanic membrane perforations and otitis media with effusion. Postoperative infection in ear surgery may result in: Wound infections Infection of the middle ear or mastoid resulting in discharge from the ear canal Failure of the tympanic membrane to close Labyrinthitis due to infection in, or adjacent to, the inner ear These complications may be associated with discomfort and inconvenience for the patient, an increase in morbidity and an increase in the costs of medical care. OBJECTIVES: The objective of this review was to assess the effects of local and/or systemic antibiotics for preventing complications such as postoperative discharge, graft failure and labyrinthitis in patients undergoing clean or clean-contaminated ear surgery. SEARCH STRATEGY: We searched MEDLINE (searched January 1966 to December 2002), EMBASE (searched January 1980 to December 2002), the Science Citation Index, The Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 4 2002); the Cochrane Acute Respiratory Infections Group and Cochrane Ear, Nose and Throat Group Specialised Registers and proceedings of scientific meetings. The date of the last search was December 2002. We also contacted investigators in the field (Govaerts, Antwerp). Bibliographies of identified articles were screened for further relevant trials. No language restriction was applied. SELECTION CRITERIA: Randomised or quasi-randomised trials involving: PARTICIPANTS: patients undergoing clean or clean-contaminated types of ear surgery. Skull base surgery was excluded. INTERVENTION: any regimen of local and/or systemic antibiotic prophylaxis administered at or around the time of surgery compared to placebo, no antibiotic, or an alternative intervention group. OUTCOME MEASURES: infection, discharge, graft failure, labyrinthitis, adverse effects of prophylaxis. DATA COLLECTION AND ANALYSIS: When possible, investigators were contacted for additional information on data and methodological issues. At least two reviewers independently extracted data and assessed trial quality. MAIN RESULTS: Eleven studies were included in the review. The methodological quality of the trials was fair to good. However, most studies presented insufficient detail on methodological data. Although definitions of outcome measures were heterogeneous, pooling of results was possible. There were no significant differences between antibiotic prophylaxis groups and control groups in terms of reduction of postoperative infections, graft failures, draining outer ear canals and adverse drug effects. REVIEWERS' CONCLUSIONS: There is no strong evidence that the large scale use of prophylactic of antibiotics in clean and clean-contaminated ear surgery is helpful in reducing postoperative complications such as wound infection, discharge from the outer ear canal, labyrinthitis and graft failure.

Adult↗

[Aspects of labyrinthectomy (author's transl)].

Since the introduction of Antibiotics labyrinth operations have become very seldom. In those days before the Antibiotic Era the indication to function-destructing radical surgery was justified in cases of suppurative labyrinthitis. Only in cases of mild serous (irritative) labyrinthitis were conservative treatments with drugs successful. Nowadays, labyrinthoperations are not necessary in most cases. Endocranial complications and high mortality rates of the disease are no longer feared today. All the same, there are cases were the labyrinth operation is justified despite high dosis of Antibiotica. Spceial problems and indications for labyrinthectomy are discussed with own examples.

Adult↗

[The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas].

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas will be described in this paper. The pre- and postoperative imaging of the temporal bone was performed with HRCT and MRI.HRCT and MRI were performed in the axial and coronal plane. MRI was done with T2 weighted and T1 weighted sequences both before and after the intravenous application of contrast material. All imaging findings were confirmed clinically or surgically. The preoperative cholesteatoma-caused complications depicted by HRCT included bony erosions of the ossicles, scutum, facial canal in the middle ear, tympanic walls including the tegmen tympani, and of the labyrinth. The preoperative cholesteatoma-caused complications depicted by MRI included signs indicative for labyrinthitis, and brain abscess. Postoperative HRCT depicted bony erosions caused by recurrent cholesteatoma,bony defects of the facial nerve and of the labyrinth, and a defect of the tegmen tympani with a soft tissue mass in the middle ear. Postoperative MRI delineated neuritis of the facial nerve, labyrinthitis, and a meningo-encephalocele protruding into the middle ear. HRCT and MRI are excellent imaging tools to depict either bony or soft tissue complications or both if caused by acquired cholesteatomas. According to our findings and to the literature HRCT and MRI are complementary imaging methods to depict pre- or postoperative complications of acquired cholesteatomas if these are suspected by clinical examination.

Brain Abscess↗

Responses of neurons in the rostral ventrolateral medulla of the cat to natural vestibular stimulation.

To investigate the neural substrate of vestibulo-sympathetic reflexes, we studied the responses of neurons in the rostral ventrolateral medulla (RVLM) of decerebrate cats to natural stimulation of the labyrinth in vertical and horizontal planes. The RVLM is a major source of excitatory inputs to sympathetic preganglionic neurons. The animals used in these studies were baroreceptor-denervated and vagotomized and had a cervical spinal transection so that inputs from tilt-sensitive receptors outside of the labyrinth did not influence the units we recorded. Of the 38 neurons whose type of vertical vestibular inputs could be classified, the majority (27) received signals mainly from otolith organs. Only 4 of the neurons received inputs predominantly from vertical semicircular canals, and 7 were classified as having convergent inputs from otoliths and canals that were spatially aligned (2 cells) or misaligned (5 cells). In addition, only 2 of 68 neurons tested responded to sinusoidal horizontal rotations in a manner typical of brainstem neurons that receive inputs from the horizontal semicircular canals. Thus, the vestibular inputs to the RVLM appear to come mainly from otolith receptors. In labyrinthectomized cats, we were unable to locate neurons with responses to tilt similar to those of cells recorded in labyrinth-intact cats, confirming that the responses attributed to vertical vestibular inputs were produced by signals from the labyrinth. In animals whose semicircular canals had been rendered dysfunctional by plugging, we only recorded responses similar to those of neurons classified as having mainly otolith inputs in canal-intact animals, indicating that the dynamic behavior of these cells does not depend upon canal inputs. The presence of otolith inputs to the RVLM is consistent with the hypothesis that this region mediates vestibulo-sympathetic reflexes involved in correcting posturally-related changes in blood pressure.

Animals↗

The value of enhanced magnetic resonance imaging in the evaluation of endocochlear disease.

BACKGROUND: Gadolinium-enhanced magnetic resonance imaging (GdMRI) is routinely used in the evaluation and management of suspected retrocochlear pathology such as vestibular schwannoma. However, its value in the evaluation and diagnosis of cochlear pathology associated with sensorineural hearing loss (SNHL) has been less clear. STUDY DESIGN: Retrospective review of case histories and imaging studies of patients with SNHL and cochlear enhancement on GdMRI diagnosed between 1998 and 2000. RESULTS: Five patients with SNHL who required gadolinium administration to establish the diagnosis of endocochlear disease were identified. Diagnosed lesions included an intralabyrinthine schwannoma, intracochlear hemorrhage, radiation-induced ischemic change, autoimmune labyrinthitis, and meningogenic labyrinthitis. In these illustrative cases, the GdMRI demonstrated intrinsic high signal or contrast enhancement within the cochlea and labyrinth in the absence of a retrocochlear mass. In one patient with meningogenic labyrinthitis, cochlear enhancement on MRI led to prompt cochlear implantation before the potential development of cochlear ossification. CONCLUSION: Our experience suggests that GdMRI plays a crucial role in the diagnosis of cochlear pathology associated with sensorineural hearing loss and may directly impact patient management.

Adult↗

Labyrinthine fistulae: pathobiology and management.

PURPOSE OF REVIEW: This article reviews literature on three manifestations of these pathologic mechanisms: leakage of perilymph from the inner ear into the middle ear, disruption of the bone of the labyrinth caused by cholesteatoma or other manifestations of chronic otitis media, and superior semicircular canal dehiscence syndrome. RECENT FINDINGS: Labyrinthine fistulae are caused by abnormal communications between the inner ear and surrounding structures. Under normal circumstances, the fluid-filled spaces of the membranous labyrinth are encased in the dense bone of the otic capsule with only two places of increased compliance: the oval window and the round window. Disruption of the labyrinthine bone can lead to areas of increased compliance, with symptoms and signs that can be understood based upon abnormal pressure transmission in the system. Communication between the endolymphatic and perilymphatic spaces of the labyrinth or passage of perilymph from the labyrinth into the middle ear or mastoid can lead to hearing loss and/or vestibular disturbances. SUMMARY: Findings on clinical examination as well as CT imaging of the temporal bone can be useful in making the diagnosis. Management is based upon the specific pathological factors and the impact of the symptoms and signs on the patient.

Cholesteatoma, Middle Ear↗

Sensorineural hearing deficit: a systematic approach based on imaging findings.

Sensorineural hearing loss (SNHL) can be classified audiometrically into two varieties: sensory (cochlear) and neural (retrocochlear). Individuals with sensory SNHL have damage to the "end organ" (the cochlea) at a macroscopic or microscopic level. When present, imaging manifestations may involve the bony labyrinth or membranous labyrinth. Abnormalities of the bony labyrinth are demonstrable primarily with computed tomography and include demineralization, congenital deformities, traumatic lesions, and erosive or destructive lesions. Abnormalities of the membranous labyrinth include enhancement and hemorrhage, which are demonstrable with magnetic resonance (MR) imaging, and obliteration, which may be diagnosed with either modality. Individuals with neural (retrocochlear) SNHL have involvement of the remainder of the auditory pathway exclusive of the cochlea. This type of SNHL requires study of the internal auditory canal, cerebellopontine angle, brain stem, thalamus, and temporal lobe. The entirety of this type of examination is best performed with high-resolution MR imaging in virtually all cases.

Cochlear Diseases↗

Tonic neck reflex of the decerebrate cat: response of spinal interneurons to natural stimulation of neck and vestibular receptors.

In order to investigate the neural basis of the tonic neck reflex, we studied the response of neurons in the cervical spinal cord of decerebrate, paralyzed cats to neck rotation about the longitudinal axis (roll), to vestibular stimulation produced by roll tilt, and to a combination of these stimuli. Most neurons were outside the motoneuron nuclei and were arbitrarily classified as interneurons. Three types of preparation were used--one with intact labyrinths, one acutely labyrinthectomized, and one with acute spinal transection. The activity of 115 neurons recorded extracellularly was modulated by sinusoidal neck rotation in the range 0.02-4 Hz; their behavior was sufficiently linear for sinusoidal analysis. The phase and gain of the responses of neurons in all three preparations were similar except that the absolute gain in cats with intact labyrinths was higher than that of the others. The location of neurons in segments C4-C8 was mainly in laminae 7-8. Some neurons were excited by rotation of the chin to the ipsilateral side (type I) and others by contralateral chin rotation (type II). The dynamic behavior of type I and type II neurons was the same; phase was flat over most of the frequency range and close to the phase of peak neck rotation, while gain enhancement occurred at higher frequencies. This behavior was similar to that of the neckforelimb reflex evoked in unparalyzed intact-labyrinth and labyrinthectomized cats. In cats with intact labyrinths, vestibular input to neurons whose activity was modulated by the neck stimulus was studied using whole-body roll tilt. Many neurons received otolith input; some received canal input. Neck and vestibular inputs to spinal neurons always had opposite polarities (complementary inputs). Thus, type I neurons were always excited by tilt to the ipsilateral side (ipsilateral ear down) while type II neurons were excited by tilt to the contralateral side. Combined neck and vestibular stimulation indicated that the dynamic behavior of neurons was determined by a linear summation of the responses to these stimuli. Interaction of neck and vestibular input at the neuron level was similar to that observed previously at the reflex level in forelimb extensor muscles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Bilateral otolith contribution to spatial coding in the vestibular system.

Recent work on the coding of spatial information in central otolith neurons has significantly advanced our knowledge of signal transformation from head-fixed otolith coordinates to space-centered coordinates during motion. In this review, emphasis is placed on the neural mechanisms by which signals generated at the bilateral labyrinths are recognized as gravity-dependent spatial information and in turn as substrate for otolithic reflexes. We first focus on the spatiotemporal neuronal response patterns (i.e. one- and two-dimensional neurons) to pure otolith stimulation, as assessed by single unit recording from the vestibular nucleus in labyrinth-intact animals. These spatiotemporal features are also analyzed in association with other electrophysiological properties to evaluate their role in the central construction of a spatial frame of reference in the otolith system. Data derived from animals with elimination of inputs from one labyrinth then provide evidence that during vestibular stimulation signals arising from a single utricle are operative at the level of both the ipsilateral and contralateral vestibular nuclei. Hemilabyrinthectomy also revealed neural asymmetries in spontaneous activity, response dynamics and spatial coding behavior between neuronal subpopulations on the two sides and as a result suggested a segregation of otolith signals reaching the ipsilateral and contralateral vestibular nuclei. Recent studies have confirmed and extended previous observations that the recovery of resting activity within the vestibular nuclear complex during vestibular compensation is related to changes in both intrinsic membrane properties and capacities to respond to extracellular factors. The bilateral imbalance provides the basis for deranged spatial coding and motor deficits accompanying hemilabyrinthectomy. Taken together, these experimental findings indicate that in the normal state converging inputs from bilateral vestibular labyrinths are essential to spatiotemporal signal transformation at the central otolith neurons during low-frequency head movements.

Animals↗

Effect of cisplatin on the basement membrane anionic sites in the ampulla, macula, and stria vascularis of guinea pigs.

Our objective was to compare changes in the basement membrane anionic sites (BMAs) in the ampulla, macula, and stria vascularis following the infusion of cisplatin (CDDP). After CDDP was administered to anesthetized Hartley guinea pigs, the bony labyrinth was immersed in a solution of polyethyleneimine (PEI). The size and distribution of PEI particles associated with BMAs in the stria vascularis and in the dark cell and sensory cell areas of the vestibular labyrinth were determined by electron microscopy. A significant reduction in the number and size of PEI particles was observed on CDDP-treated strial vessels. The number and size of PEI particles on the basement membranes of the vestibular labyrinth did not differ from those in the control. Our findings suggest that the BMAs of the vestibular labyrinth were not significantly affected by the administration of a single dose of CDDP.

Acoustic Maculae↗

Therapy of idiopathic sudden sensorineural hearing loss: antiviral treatment of experimental herpes simplex virus infection of the inner ear.

Experimental herpes simplex virus type 1 (HSV-1) labyrinthitis provides a model of idiopathic sudden sensorineural hearing loss (ISSHL). Corticosteroids improve the prognosis for hearing recovery in ISSHL, but the effects of acyclovir are unknown. To establish the therapeutic efficacy of acyclovir (Zovirax) and prednisolone in experimental HSV-1 viral labyrinthitis, we induced HSV-1 labyrinthitis in 12 guinea pigs. Three animals received no treatment, 3 received prednisolone, 3 received acyclovir, and 3 received both. Four other animals served as controls, receiving culture medium only. Hearing, HSV-1 antibody titers, and cochlear damage were evaluated. The HSV-1 labyrinthitis caused hearing loss within 24 hours. Combination treatment consisting of prednisolone and acyclovir resulted in earlier hearing recovery and less extensive cochlear destruction compared to prednisolone or acyclovir as a monotherapy. The beneficial effect of this treatment modality remains to be demonstrated in ISSHL.

Acyclovir↗

Vestibular compensation in lampreys: role of vision at different stages of recovery of equilibrium control.

The main motor disorder evoked by unilateral labyrinthectomy (UL) in the lamprey (Lampetra fluviatilis) is a complete loss of equilibrium and rolling (rotation about the longitudinal axis) during swimming. A previous study has shown that the recovery of equilibrium control in the lamprey takes, on average, 33 days. However, lampreys were able to maintain equilibrium if UL was combined with removal of the ipsilateral eye ('surgical compensation' of the vestibular deficit). It was suggested that tonic excitatory inflow, rather than specific information about the orientation of the animal in space delivered by the remaining eye, is important for the recovery of equilibrium control. In the present study, a number of experiments were designed to test this hypothesis. It was found that illumination of the eye contralateral to the UL or continuous electrical stimulation (10 Hz) of the corresponding optic nerve resulted in immediate restoration of equilibrium control. The same result was obtained when the vestibular nerve on the UL side was stimulated. Thus, the roll control system in the lamprey, driven by only one labyrinth, is able to maintain equilibrium provided that the lack of tonic inflow from the missing labyrinth is compensated for by tonic vestibular or visual input. The present study has also shown that the importance of visual input for maintaining equilibrium after UL decreases with time. In animals that achieved a high degree of compensation, removal of the eyes on day 23 after UL evoked decompensation, whereas removal on day 70 did not. A reduction of the significance of visual input was also observed in surgically compensated UL lampreys. In these animals, removal of the remaining eye on days 1-3 after the first surgery resulted in a complete loss of equilibrium, removal on day 7 resulted in a partial loss, whereas removal on days 48-55 did not affect the postural stability. Three lines of evidence suggest that asymmetrical visual input evokes plastic changes in the roll control system. (i) In one group of animals, initially one eye was removed, and then 50 days later the labyrinth ipsilateral to the missing eye and remaining eye were removed. These animals exhibited a mild impairment of equilibrium control, in contrast to the animals in which both surgeries were performed simultaneously. (ii) In another group of animals, initially one eye was removed, and then 50 days later the remaining eye and both labyrinths were removed. These animals exhibited rolling towards the eye that remained intact for longer. (iii) A short-term electrical stimulation (5-10 min daily for 3 days) of the optic nerve (contralateral to UL) in blinded animals considerably improved the equilibrium control compared with that of non-stimulated animals; the improvement was observed for 60 days after stimulation.

Animals↗

The interutricular distance determined from external landmarks.

Knowledge of the exact distance between the utricles is important in new vestibular tests, such as the unilateral centrifugation (UC) test for the unilateral examination of the utricles. During this test, subjects are rotated at constant velocity and simultaneously laterally displaced along an interaural axis so that one labyrinth becomes aligned with the axis of rotation. When the axis of rotation crosses precisely through one labyrinth, only the opposite labyrinth is stimulated. To achieve this setup, precise knowledge of the interutricular distance is needed. The purpose of this study is to investigate the correlation between the interutricular distance (IUD), measured on T2-weighted magnetic resonance images, and specific external measures of head dimensions such as distance nasion-inion, intermastoid distance (IMD), distances between the temporomandibular joints and between the lateral margins of the orbits. Data have been collected in a series of 50 subjects (25 men and 25 women). On MR images we found a mean IUD of 7.22 cm (SD = 0.42 cm). There was a strong correlation between the IUD measured on MR images and the intermastoid distance. A linear combination of the IMD, nasion-inion distance and height of the subjects could predict the IUD very satisfactory (R = 0.85, adjusted R2=0.723). We also determined a measure of eccentricity of the vestibular labyrinths. The 95% prediction interval for the asymmetry appeared to be less than 4.3%.

Adolescent↗

[Preoperative vestibular diagnosis in therapy of Menière's disease].

Surgical treatment of Meniere's disease is indicated in patients with severe attacks who have failed drug therapy. A decision between a conservative or destructive procedure demands firstly exclusion of patients with non-otogenic diseases, bilateral disease or complete unilateral loss of function, and secondly assessment of the laterality of the disease, of residual labyrinthic function and of vestibular compensation. A total of 185 patients with Meniere's disease were investigated. All of them had a history and clinical signs that indicated surgery. Canal function, otolith responses and vestibular compensation were examined, in addition to routine preoperative tests as recommended by the Committee on Hearing and Equilibrium of the American Academy of Ophthalmology and Otolaryngology. Of the 185 patients 22% had findings that contraindicated surgery, 4% suffered from Meniere's disease in the opposite ear, 6% showed no signs of vestibular compensation and 12% had dead labyrinths on the side of the cochlear disease. No caloric response was elicited from the labyrinth by thermal bilateral testing in 25% of the 185 patients. In patients who were thought to have dead labyrinths based on routine caloric tests, residual canal function was detected by means of 20 degrees C stimulation in the prone and supine position. Without extensive vestibular testing the indications for surgical treatment of Meniere's disease will be incorrect in 47% of patients.

Functional Laterality↗

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