[Considerations on cochleovestibular symptomatology of neurinoma of the 8th nerve in its initial phase].
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Cochlea↗
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[Auditory evoked potentials and cochlear pathology].
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Aging↗
Facioscapulohumeral muscular dystrophy.
A decade's progress in facioscapulohumeral muscular dystrophy genetics has been marked by the discovery of novel genetic phenomena such as crossover of subtelomeric DNA between chromosomes 4 and 10 in normal individuals and by the recognition that the facioscapulohumeral muscular dystrophy deletion-mutation may cause a position variegation effect on more proximal DNA. The mutated DNA itself is probably not transcribed. Larger deletions tend to cause more severe disease. Antenatal diagnosis, based on detection of the short fragment of mutated DNA, is possible in between 95 and 100% of cases, depending on the precise nature of the parental facioscapulohumeral muscular dystrophy mutation. Yet remarkably, the nature of the gene product(s) of the affected proximal gene(s), as well as of the molecular pathogenesis of facioscapulohumeral muscular dystrophy muscle, retinal and cochlear disease, is completely unknown. Marked perivascular inflammation is often present in facioscapulohumeral muscular dystrophy muscle biopsies. The expression of facioscapulohumeral muscular dystrophy within reported monozygotic twinships differs greatly. This raises the question of whether variations in expression of the T-cell receptor gene repertoire or of other immune genes play an important modifying role in determining the severity of facioscapulohumeral muscular dystrophy. A focus on traditional scientific disciplines may now be appropriate. Symptomatic treatments, for instance of scapular winging and of lagophthalmos, are important, and timely photocoagulation of the retinal exudates which are a very rare, but real, complication of retinal telangiectasis can curtail visual loss. The results of collobarative trials of pharmacological agents such as albuterol which affect muscle mass and development are awaited.
Diagnosis, Differential↗
Incidence of Ménière's disease.
The incidence of Ménière's disease in Sweden for the year 1973 has been calculated as one case in a population of 2,163. This gives an overall incidence of 46/100,000. Extrapolating the Swedish incidence data to the population of the United States, there should have been 97,000 cases of Ménière's disease treated as inpatients or outpatients during the year 1973. The incidence in the United States of Ménière's disease, cochlear type, is considered to be even higher. In addition, the Swedish statistic for some other disorders, including otosclerosis, are reported. For otosclerosis, the yearly incidence in Sweden is 12/100,000 or one case in a population of 8,414. This could be extrapolated to 25,000 patients with clinical otosclerosis in the United States for the year 1973. By comparison, Ménière's disease, by stringent diagnostic criteria, is approximately four times as common as clinical otosclerosis. It is also more common than all laryngeal carcinomas, all salivary gland tumors, both benign and malignant, as well as acute epiglottitis and acute nephritis.
Adolescent↗
CT of postmeningitic deafness: observations and predictive value for cochlear implants in children.
PURPOSE: To demonstrate CT abnormalities encountered in children with postmeningitic deafness and to assess the value of CT in the prediction of cochlear implantation difficulties. METHODS: Thirteen children with postmeningitic deafness were evaluated with high-resolution, thin-section CT. CT findings were correlated with surgical anatomy at the time of cochlear implantation, with particular regard to the prediction of implant success. RESULTS: CT findings included normal scans (3 of 13, 23.1%), cochlear stenosis (5 of 13, 37.7%), cochlear fibroossific change (1 of 13, 7.7%), cochlear ossification (4 of 13, 30.8%), and osseous hypertrophy at the round window niche (4 of 13, 30.8%). Nine of 10 patients with abnormal findings had incomplete or difficult implantations (90%); 7 (88.8%) of these 9 received limited electrode insertions. CONCLUSION: Attention to subtle otological abnormalities on thin-section CT is helpful in the prediction of early success or failure of implantation in children with postmeningitic deafness. Those with CT abnormalities had a 90% risk of incomplete or difficult insertions with a 70% chance of limited electrode insertion.
Adolescent↗
Two types of afferent terminals innervate cochlear inner hair cells in C57BL/6J mice.
Afferent synapses on inner hair cells (IHC) transfer auditory information to the central nervous system (CNS). Despite the importance of these synapses for normal hearing, their response to cochlear disease and dysfunction is not well understood. The C57BL/6J mouse is a model for presbycusis and noise-induced hearing loss because of its age-related hearing loss and susceptibility to acoustic over-exposure. In this context, we sought to establish normal synaptic structure in order to better evaluate synaptic changes due to presbycusis and noise exposure. Ultrastructural analysis of IHCs and afferent terminals was performed in a normal hearing 3-month-old C57BL/6J mouse at cochlear sites corresponding to 8, 16 and 32 kHz using semi-serial sections. A stereologic survey of random sections was conducted of IHCs in 11 additional mice. Two morphologically distinct groups of afferent terminals were identified at all 3 frequency locations in 11 out of 12 animals. "Simple" endings demonstrated classic features of bouton terminals, whereas "folded" endings were larger in size and exhibited a novel morphologic feature that consisted of a fully internalized double membrane that partially divided the terminal into two compartments. In many cases, the double membrane was continuous with the outer terminal membrane as if produced by an invagination. We still must determine the generality of these observations with respect to other mouse strains.
Afferent Pathways↗
Endolymphatic sac obstruction. Biochemical studies.
Inner ear fluids were studied biochemically in guinea pigs from 1 to 16 weeks after producing endolymphatic hydrops by obstructing the endolymphatic duct. Fluid collected from beneath the footplate showed changes of 50% of the animals indicating distension of the saccule. There was an increase in potassium concentration and decrease in sodium concentration of the collected fluid, indicating a traumatic mixing of endolymph and perilymph produced by rupture of the saccule during collection of the fluid. The smallest changes occurred at one week, and the greatest changes were found four months after endolymphatic sac obstruction. Similar findings were observed in studying inner ear fluids obtained from patients with Ménière's disease. Cochlear endolymph showed biochemical alterations after endolymphatic duct blockage. There was a two- to three-fold increase in sodium concentration and a decrease in potassium concentration with the total ionic concentration remaining approximately the same. Some guinea pigs showed similar changes in vestibular endolymph. This study indicates that in the guinea pig, endolymph obtained in the distended endolymph compartment has a slightly different sodium-potassium ratio as compared to the normal ear. In patients with Ménière's disease there may also be an elevation of endolymph sodium concentration. The significance of this change and hearing loss observed in experimental endolymphatic hydrops and Ménière's disease is open to speculation at the present time.
Animals↗
Cochlear implantation and Cogan syndrome.
OBJECTIVE: To evaluate outcomes and issues pertaining to cochlear implantation in a group of subjects affected by Cogan syndrome. STUDY DESIGN: Prospective cohort. SETTING: Department of Ophthalmology and Otorhinolaryngology, University of Parma. PATIENTS: Five postlingually deafened adults suffering from a typical form of Cogan syndrome who underwent cochlear implantation. MAIN OUTCOME MEASURES: Benefit from cochlear implantation as measured by word and everyday sentence recognition tests. Surgical issues and postoperative complications were also evaluated. RESULTS: In two cases, intracochlear electrodes were inserted into the scala vestibuli because of the ossification of the scala tympani. Two patients experienced a recurrence of keratitis the day after surgery. To date, with a follow-up of 1 to 4 years, no patient has experienced flap complications or other local or systemic complications. At the 12-month postoperative evaluation, all patients had gained useful open-set speech perception, achieving a mean score of 91% and 95% on word and everyday sentence recognition tests, respectively. CONCLUSIONS: Patients deafened by Cogan syndrome demonstrated high levels of speech understanding after undergoing cochlear implantation. Obliteration of the cochlea may complicate electrode implantation, requiring modifications of the surgical technique. Stress consequent to the surgical procedure may instigate an acute phase of the basic illness.
Adult↗
Usher's syndrome and cochlear implant.
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Cochlear Diseases↗
Clinical trial of a multi-channel cochlear prosthesis: results on 10 postlingually deaf patients.
The clinical trial of a multi-channel cochlear prosthesis has been carried out on 10 profoundly-totally deaf adult patients. Speech perception tests have shown that all the patients received significant benefit from the device. They obtained improvements in understanding running speech from 47% to 550% when using the device in conjunction with lipreading compared to lipreading alone. With an open-set CID sentence test, three patients obtained scores showing an ability to understand speech without the need to lipread, and a further three patients had scores indicating they could also receive useful information without lipreading. In two patients, very limited open-set scores for electrical stimulation alone were obtained. This was most probably due to the fact that only a few channels of stimulation were possible due to cochlear disease, and they were therefore receiving information more like a single-channel device. The prosthesis has also been found to provide considerable help in hearing and recognizing everyday sounds.
Adult↗
Auditory brainstem implant in posttraumatic cochlear nerve avulsion.
Patients aged over 12 years with neurofibromatosis type 2 are considered candidates for an auditory brainstem implant (ABI). This study extends the indication criteria of ABI to subjects with profound hearing loss due to damaged cochleas and/or cochlear nerves (CNs) following head injuries. In our department, over the period from April 1997 to November 2002, 32 patients, 23 adults and 9 children, were fitted with ABIs. Their ages ranged from 14 months to 70 years. These patients were suffering from a variety of tumor (13 subjects) and nontumor CN or cochlear diseases (19 subjects). Six patients, 5 adults and 1 child, had profound hearing loss following head injury. Their mean age was 25 years (range: 16-48 years). Five were male and 1 female. The retrosigmoid approach was used in all 6 patients. The electrode array was inserted into the lateral recess of the fourth ventricle and correct electrode positioning was monitored with the aid of electrically evoked auditory brainstem responses and neural response telemetry. Correct implantation was achieved in all patients. No complications were observed due to implantation surgery or related to ABI activation and stimulation of the cochlear nuclei. At activation, an average of 9.8 electrodes (range 5-13) were switched on without side effects. One to 6 electrodes were activated in the following sessions after time periods ranging from 2 to 16 months. All patients achieved auditory-alone-mode closed-set word recognition scores ranging from 40 to 100%; 3 had auditory-alone-mode open-set sentence recognition scores of 60-100%; 2 of these even had speech-tracking performance scores of 38 and 43 words, respectively, showing an ability to engage in normal conversation and converse over the phone. The present study demonstrates that the ABI is a useful rehabilitation instrument in subjects with damaged cochleas and/or CN avulsion following head injury who are unamenable or poorly responsive to auditory rehabilitation using cochlear implants.
Adolescent↗
Testing the vestibulo-ocular reflex.
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Caloric Tests↗
Preoperative high resolution CT and MR imaging in cochlear implantation.
INTRODUCTION: Accurate preoperative imaging of the temporal bone in patients receiving cochlear implants is important. High resolution computed tomography (HRCT) and magnetic resonance (MR) imaging are the 2 preoperative imaging modalities that provide critical information on abnormalities of the otic capsule, pneumatisation of the mastoid, middle ear abnormalities, cochlear ducts patency and presence of cochlear nerve. MATERIALS AND METHODS: The HRCT and MR imaging in 46 cochlear implant patients in our department were reviewed. RESULTS: Majority of our patients [34 patients (73.9%)] showed normal HRCT of the temporal bone; 5 (10.9%) patients had labyrinthitis ossificans, 2 (4.3%) had Mondini's abnormality and 2 (4.3%) had middle ear effusion. One patient each had high jugular bulb, hypoplasia of the internal auditory canal and single cochlear cavity, respectively. CONCLUSION: The above findings contribute significantly to our surgical decisions regarding candidacy for surgery, side selection and surgical technique in cochlear implantation.
Cochlear Diseases↗
Cochlear implants: indications in groups of patients with borderline indications. A review.
Cochlear implants (CI) represent the current treatment for patients affected by profound sensorineural hearing loss (SNHL). Initially only deaf adult patients were considered to be candidates for a CI; however, the development of technology and matured experience have expanded the indications for cochlear implantation. Today, CIs are implanted in adults and children and broader indications are followed. There are, however, a number of patients who do not completely fulfill the current indications and who are potential candidates for CI. The duration of deafness and residual hearing represent prognostic indicators for CI performance; however, the candidacy of children with residual hearing and prelingually deafened adults are still under debate. Anatomical variants such as cochlear ossification, cochlear malformation and chronic otitis media represented and still represent for some surgeons a contraindication to CI. The otological experience of CI surgeons and the advent of auditory brainstem implants have changed the approach to these patients, who may still benefit from hearing rehabilitation. This paper briefly analyses and reviews the results obtained in these groups of patients, who were not, at least initially, considered to be candidates for cochlear implantation.
Cochlea↗
Cochleovestibular afferent pathways of trapezius muscle responses to clicks in human.
Brief intense clicks cause short-latency cervical muscles microcontractions which are supposed to be of vestibular origin. Averaging these microcontractions allows myogenic vestibular evoked potentials (MVEP) to be obtained. MVEP from the trapezius muscles were investigated in normal subjects, cochleovestibular nerve-damaged patients and patients with a vestibular or a cochlear lesion. Muscular responses were recorded on right and left trapezius by averaging from surface electrodes following right and left monaural 100 dB hearing level click stimulation. In normal subjects, responses to monaural stimuli were bilateral, of equal amplitude and latency in left and right trapezia. Normal response consisted of four consecutive waves, labelled p13, n23, p32 and n40 according to their polarity (p, positive; n, negative) and mean peak latency in msec. In total unilateral cochleovestibular damaged patients, auditory stimulation of the affected side gave no MVEP either ipsilateral or contralateral to the stimulation. In the case of selective cochlear lesion, stimulation of the affected side gave MVEP which was present on ipsilateral and contralateral trapezius muscles. The four successive waves were present with a normal latency; however, amplitude was lower than that obtained after stimulation of the healthy ear. In the case of selective vestibular lesion, the four waves of MVEP were again present with normal latency but with reduced amplitude. Responses were present on both the ipsilateral and contralateral trapezius muscle. It is concluded that normal MVEP recorded on the trapezius muscles are bilateral and consist of four waves, the amplitude of which could depend on the simultaneous stimulation of both cochlear and vestibular afferents. In the case of unilateral cochlear and/or vestibular impairments responses were present on both ipsilateral and contralateral trapezius muscles. Latencies had normal values but amplitudes were reduced. MEVP recorded on trapezius muscles were absent in the case of total cochleovestibular damage.
Acoustic Stimulation↗
Incidence of cochlear involvement in hyperbilirubinemic deafness.
Neonatal hyperbilirubinemia remains an important cause of childhood deafness, especially in developing countries. After neonatal hyperbilirubinemia, the auditory neural pathways, cochlea, or both may be affected. In this study, we aimed to determine the incidence of cochlear impairment and the appropriate means of hearing screening in hyperbilirubinemic neonates. A retrospective review of 1,032 pediatric patients with hearing loss revealed 67 cases (6.5%) of severe hyperbilirubinemia in the neonatal period. Thirty of these patients had neonatal hyperbilirubinemia as the single identifiable risk factor for hearing loss. In 26 of 30 cases (87%), otoacoustic emissions (OAEs) were absent, whereas in the remaining 4 cases (13%), robust emissions were detected despite an absent auditory brain stem response (ABR). Auditory screening of newborns with jaundice by OAEs possesses a significant risk of undiagnosed deafness. On the other hand, if the ABR is used as the single means of screening, auditory neuropathic conditions will probably be underlooked. Therefore, we recommend dual screening of hearing by ABR and OAEs in hyperbilirubinemic newborns.
Child, Preschool↗
Electrically evoked auditory brain-stem response in pediatric patients with cochlear implants.
OBJECTIVE: To study the feasibility and clinical applicability of preoperative, transtympanic electrically evoked auditory brain-stem response (EABR) in a pediatric patient population with cochlear implants. DESIGN: A descriptive study using repeated measures analyses of variance to determine if EABR measures were affected by response configuration or cochlear status. SETTING: The operating room before cochlear implant surgery. PATIENTS: A population-based sample of 43 patients aged 2.5 to 14.5 years who were candidates for cochlear implantation. INTERVENTION: Stimuli consisting of brief balanced biphasic current pulses were provided by a transtympanically placed promontory needle electrode; EABR was recorded with subdermal needle electrodes on the forehead and contralateral mastoid. MAIN OUTCOME MEASURE: Presence or absence of postoperative electrical excitability with a cochlear implant. RESULTS: Electrically evoked auditory brain-stem responses were available from 41 of the 43 patients tested. Mean EABR threshold was 406.5 microA (SD = 118.1) for 31 patients with patent cochleas and 472 microA (SD = 91) for 10 patients with cochlear ossification. Mean wave V latency at threshold was 4.69 milliseconds (SD = 0.57). CONCLUSION: Preoperative EABR is an integral component of the preoperative selection process for pediatric patients with cochlear implants.
Adolescent↗
The scala vestibuli for cochlear implantation. An anatomic study.
BACKGROUND: Traditionally, cochlear implantation has used the scala tympani (ST) for electrode insertion. When faced with ST ossification, the surgeon may elect to drill out the cochlea to accomplish partial electrode insertion. Theoretically, another option in this situation is to insert the electrode into the scala vestibuli (SV). OBJECTIVE: To determine whether or not the dimensions of the SV are sufficient to accommodate an electrode array so as to assess the feasibility of SV cochlear implantation. METHODS: The study of 20 normal human temporal bones, comparing the maximum diameter and surface area of the ST with those of the combined SV and scala media. RESULTS: The dimensions of the SV and scala media were comparable to those of the ST and appeared sufficient to accommodate a cochlear implant electrode array. CONCLUSION: It appears that the combination of SV and scala media is a viable alternative route for electrode insertion, at least on the basis of anatomic dimensions, in those cases in which the ST is obliterated.
Cochlea↗