Deafness in cochlear and auditory nerve disorders

Sensorineural hearing loss is the most common type of hearing impairment worldwide. It arises as a consequence of damage to the cochlea or auditory nerve, and several structures are often affected simultaneously. There are many causes, including genetic mutations affecting the structures of the inner ear, and environmental insults such as noise, ototoxic substances, and hypoxia. The prevalence increases dramatically with age. Clinical diagnosis is most commonly accomplished by measuring detection thresholds and comparing these to normative values to determine the degree of hearing loss. In addition to causing insensitivity to weak sounds, sensorineural hearing loss has a number of adverse perceptual consequences, including loudness recruitment, poor perception of pitch and auditory space, and difficulty understanding speech, particularly in the presence of background noise. The condition is usually incurable; treatment focuses on restoring the audibility of sounds made inaudible by hearing loss using either hearing aids or cochlear implants.

Cochlear-facial dehiscence--a newly described entity

Dehiscence of the cochlear otic capsule has recently been described as a pathologic entity. We describe two cases of cochlear-facial dehiscence, which are the first reported: a 69-year-old male who complained of hearing loss, autophony, and pulsatile tinnitus and a 41-year-old female who complained of left-sided hearing loss, pulsatile tinnitus, and vertigo. In both, computed tomography (CT) showed bony dehiscence between the facial nerve and cochlea. Cochlear-facial dehiscence is another example of otic capsule dehiscence that produces symptoms of third-window lesions. When patients present with symptoms of third-window lesions and CT does not show superior canal dehiscence, cochlear-facial dehiscence should be considered.

Underlying mechanisms of tinnitus: review and clinical implications

BACKGROUND

The study of tinnitus mechanisms has increased tenfold in the last decade. The common denominator for all of these studies is the goal of elucidating the underlying neural mechanisms of tinnitus with the ultimate purpose of finding a cure. While these basic science findings may not be immediately applicable to the clinician who works directly with patients to assist them in managing their reactions to tinnitus, a clear understanding of these findings is needed to develop the most effective procedures for alleviating tinnitus.

PURPOSE

The goal of this review is to provide audiologists and other health-care professionals with a basic understanding of the neurophysiological changes in the auditory system likely to be responsible for tinnitus.

RESULTS

It is increasingly clear that tinnitus is a pathology involving neuroplastic changes in central auditory structures that take place when the brain is deprived of its normal input by pathology in the cochlea. Cochlear pathology is not always expressed in the audiogram but may be detected by more sensitive measures. Neural changes can occur at the level of synapses between inner hair cells and the auditory nerve and within multiple levels of the central auditory pathway. Long-term maintenance of tinnitus is likely a function of a complex network of structures involving central auditory and nonauditory systems.

CONCLUSIONS

Patients often have expectations that a treatment exists to cure their tinnitus. They should be made aware that research is increasing to discover such a cure and that their reactions to tinnitus can be mitigated through the use of evidence-based behavioral interventions.

Cochlear implant in a patient with mondini's deformity of the cochlea: pilot patient in Pakistan

Autosomal-recessive genes account for about 80% of the patients of non-syndromic deafness, and a major portion of those lead to cochlear pathology. Given the strong cultural practice of consanguineous marriages and the lack of awareness regarding screening modalities, a high prevalence of hereditary pre-lingual deafness is seen in Pakistan. Considering the situation, cochlear implant surgery was introduced by Aga Khan University Hospital (AKUH), Karachi, Pakistan, in 2003. Recently we decided to expand the profile and services available and conducted the first ever cochlear implant on an anatomically-challenged cochlea. The case report relates to the experience of our pilot patient who was suffering from Mondini's deformity.

Late pneumolabyrinth after undiagnosed post-traumatic perilymphatic fistula. Case report illustrating the importance of systematic emergency management

INTRODUCTION

Temporal bone fracture is a common complication of high-energy cranial trauma. Labyrinth involvement is rare, but there is a risk of perilymphatic rupture that is often underestimated on initial clinical examination due to the predominance of neurological and/or somatic symptoms.

CASE REPORT

A patient presented with overlooked perilymphatic fistula, decompensated by hyperpressure effort due to poorly adapted management.

DISCUSSION

Following a review of the literature on post-traumatic pneumolabyrinth, overall management (from diagnosis to treatment, via prevention advice) was analyzed. A constructive critique of the patient's treatment was thus made.

CONCLUSION

We argue for a systematic management protocol in cranial trauma with temporal bone fracture, comprising ENT examination, millimetric-scale cross-sectional imaging of the fracture site, and standardized counseling to prevent late complications.

[The estimation of the efficacy of manual therapy included in the combined treatment of cochlear-vestibular disorders based on the results of computed stabilography]

The objective of the present study was to estimate the efficacy of the combined treatment of spondylogenic cochlear-vestibular disorders with the use of both medicamental and non-medicamental modalities. Computed static stabilometry was applied for diagnostics of postural disbalance and evaluation of the treatment outcomes. It was shown that the application of manual therapy for the management of 56 patients presenting with spondylogenic cochlear-vestibular disorders resulted in the decrease of tinnitus and the improvement of vestibular and cochlear functions.

Computed Tomography measurements of the normal and the pathologic cochlea in children

BACKGROUND

Radiological investigation is frequently undertaken to assess the aetiology of sensorineural hearing loss (SNHL).

OBJECTIVE

To establish the CT measurements of the normal cochlea in children and to determine radiological criteria correlated with SNHL.

MATERIALS AND METHODS

A retrospective study of temporal bone CT performed in 159 children, age range from 3 days to 16 years between February 1999 and July 2004. A control group (n = 88) comprised children without SNHL; the SNHL group comprised 71 children. The width of the second turn of the cochlea (CW), the cochlear height (CH), and the width of the bony canal for the cochlear nerve (WCN) were measured on a reference plane containing the modiolus, the posterior semicircular canal, the footplate, and the stapes arch.

RESULTS

Width of the canal measurements <or=1.7 mm or >or=2.5 mm supported the diagnosis of SNHL with a specificity of 97% and 91%, respectively. Cochlear width was found to be significantly smaller in the SNHL group (5.61 +/- 0.51 mm) than in the control group (5.75 +/- 0.31 mm, P < 0.02), a size <5.4 mm being highly suggestive of SNHL with a specificity of 90%. No significant variations of all measurements were found with age.

CONCLUSION

Appropriate measurements of WCN and CW are highly correlated with SNHL.

Causation of permanent unilateral and mild bilateral hearing loss in children

Children with permanent unilateral or mild bilateral hearing loss have been a focus of concern by audiologists, educators, and physicians for at least 2 decades. These children are known to be at risk for psychoeducational difficulties. However, despite this concern, little has been learned about the causative factors of these hearing losses and how those factors might be contributing to child development. This review of known causes of permanent unilateral and mild bilateral hearing loss in children is meant to draw attention to the importance of the search for etiologic factors. That is, the identification of the hearing loss should not signal the end of the diagnostic process but, rather, the beginning of a search for causation. With the combined efforts of audiologists, otolaryngologists, pediatricians, geneticists, and other medical professionals, we may enhance our understanding of the primary causes of unilateral and mild bilateral hearing loss and, perhaps, create links between causative factors and psychosocial and psychoeducational outcomes.

Recurrent meningitis and cerebrospinal fluid leak-two sides of the same vestibulocochlear defect: report of three cases

Cochlear dysplasia is a rare congenital anomaly. However, early detection of this anomaly can prevent serious consequences. We describe three cases of cochlear dysplasia that presented with recurrent meningitis and cerebro-spinal fluid (CSF) leak in children in which early diagnosis prevented further complications.

Hematopoietic stem cells prevent hair cell death after transient cochlear ischemia through paracrine effects

Transplantation of hematopoietic stem cells (HSCs) is regarded to be a potential approach for promoting repair of damaged organs. Here, we investigated the influence of hematopoietic stem cells on progressive hair cell degeneration after transient cochlear ischemia in gerbils. Transient cochlear ischemia was produced by extracranial occlusion of the bilateral vertebral arteries just before their entry into the transverse foramen of the cervical vertebra. Intrascalar injection of HSCs prevented ischemia-induced hair cell degeneration and ameliorated hearing impairment. We also showed that the protein level of glial cell line-derived neurotrophic factor (GDNF) in the organ of Corti was upregulated after cochlear ischemia and that treatment with HSCs augmented this ischemia-induced upregulation of GDNF. A tracking study revealed that HSCs injected into the cochlea were retained in the perilymphatic space of the cochlea, although they neither transdifferentiated into cochlear cell types nor fused with the injured hair cells after ischemia, suggesting that HSCs had therapeutic potential possibly through paracrine effects. Thus, we propose HSCs as a potential new therapeutic strategy for hearing loss.

[Distortion product otoacoustic emissions in newborns treated by ototoxic drugs]

OBJECTIVE

The aim of this prospective longitudinal study is to research the amplitude of distortion product otoacoustic emissions caused by the ototoxic drugs used, between the end of the administration and from 15 to 40 days after its use.

METHODS

It was a prospective longitudinal study composed by term and preterm newborns from the Santo André city hospital, in the period from July 2003 to September 2004. The first evaluation occurred on the hospital discharge day. Three groups were evaluated: control group with 33 term and healthy newborns; term study group with 19 term newborns with more than 37 weeks exposed to amikacin and/or vancomycin; and preterm study group with 15 preterm newborns from 32 to 37 weeks exposed to the same ototoxic. The newborns did not present risk factors for hearing loss according to the JCIH, 2000 concomitant to the neonatal infection. All newborns were evaluated at a corrected gestational age greater than 37 weeks. The otoacoustic emissions amplitudes obtained at the hospital discharge were compared to the ones obtained from 15 to 40 days after the discharge.

RESULTS

The otoacoustic emissions amplitudes of the preterm study group were smaller than the amplitudes of the control group and the term study group in both moments of the test. The amplitude of the newborns' otoacoustic emissions increased in the second moment of the test. The otoacoustic emissions amplitudes of the control group in the second moment of the test were similar to the term study group in the first moment of the research.

CONCLUSION

There are the increase of the distortion product otoacoustic emissions amplitude from the discharge moment until 15 to 40 days after in the post-natal period. The exposure to amikacin and vancomycin on the recommended dose by Neofax, 2003/2004 did not alter the amplitude of the emissions in the newborns without risk indicators concomitant with neonatal infection.

Intrakochleäres Schwannom als Ursache für eine Surditas

Inner ear extension caused by schwannomas, which can cause hearing loss, tinnitus and vertigo, is an extremely rare finding. We report a male patient who presented with progressive hearing loss as well as tinnitus in the right ear. Despite rheologic infusion therapy with glucocorticosteroids at another hospital, the patient showed an explicit hearing loss and vertigo related to the right ear. In the pure tone audiogram, we found complete deafness of the right ear, the equilibriometry with caloric testing showed complete loss of the labyrinth. In the HR-MRI, a structure appeared in ranges of the basal and middle cochlea with enhancement of the contrast medium. From the MRI aspect, this appeared to be a small intracochlear schwannoma. As a differential diagnosis, a chronic granulation is also possible. In agreement with the patient, we decided to control the structure clinically every 6 months using MRI; no further growth of the structure appeared. A precise imaging via HR-MRI is required to detect intracochlear schwannomas. Observation is an appropriate option for patients who have serviceable hearing. Surgical exploration can be recommended in cases of progressive diseases and growth into the inner ear with recurrent vertigo attacks. The option of radiotherapy for the treatment of intrameatal acoustic neurinomas should be considered.

Benzodiazepines and GABAergics in treating severe disabling tinnitus of predominantly cochlear origin

Severe disabling tinnitus (SDT) refers to a symptom severe enough to disrupt affected patients' routine and keep them from performing their daily activities. SDT of a predominantly central origin has been treated successfully with benzodiazepines and GABAergic drugs. Our aim was to test the control of SDT of predominantly cochlear origin by benzodiazepines and GABAergic drugs. We followed the format of a prospective, randomized, single-blind clinical trial at an academic tertiary-care hospital. We studied 30 patients, all with SDT of clear cochlear origin. We treated 10 patients with placebo (group 1), 10 with benzodiazepine drugs (group 2), and 10 with benzodiazepine and GABAergic drugs (group 3). We recorded a decrease in the annoyance and intensity of SDT as measured by a visual analog scale ranging from 1 (negligible) to 10 (unbearable). We found statistically significant improvement in comparing groups 2 and 3 with group 1 but found no significant difference when groups 2 and 3 were compared. Addition of GABAergic to benzodiazepine drugs does not modify the treatment results in SDT of a predominantly cochlear origin.

Auditory brainstem implant (ABI): new frontiers in adults and children

Previous studies have considered only patients with neurofibromatosis type 2 (NF2) older than 12 years as candidates for an auditory brainstem implant (ABI). Our study expands the potential criteria to include both children and adult subjects with other cochlear or cochlear nerve malfunctions who either would not benefit at all from a cochlear implant (eg, cochlear nerve aplasia or avulsion) or whose benefit was or would be severely compromised (eg, cochlear ossification, cochlear fracture).

STUDY DESIGN

In our department, over the period from April 1997 to September 2002, 29 patients, 20 adults and 9 children, were fitted with ABIs. Their ages ranged from 14 months to 70 years. Thirteen subjects had tumors, 10 NF2 and 3 solitary vestibular schwannoma, and 16 patients had a variety of nontumor (NT) cochlear or cochlear nerve diseases. A retrosigmoid-transmeatal approach was used in T and a retrosigmoid approach in NT 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 (EABRs).

RESULTS

Correct implantation was achieved in all patients. No complications were observed due to implantation surgery or related to ABI activation or long-term use. Auditory sensations were induced in all patients with various numbers of electrodes (from 5 to 15). Different pitch sensations were identifiable with different electrode stimulation. Closed-set word recognition, open-set sentence recognition, and speech tracking scores achieved by the patients are reported in detail. The auditory performance of the patients showed significantly better outcomes than controls (Multicentric European clinical investigations on ABI with NF2).

CONCLUSION

We have shown that the indications for the ABI can be extended to include NT patients with severe cochlear and/or cochlear nerve abnormalities. The degree of auditory benefit varies as a function of the underlying pathological conditions, with NT subjects exhibiting significantly better outcomes than the T patients.

Auditory Neuropathy or Endocochlear Hearing Loss?

AIMS

The purpose of the study was to define boundaries between endocochlear hearing loss and auditory neuropathy in children with congenital profound hearing loss and positive otoacoustic emissions.

PATIENT

A child presented with bilateral profound hearing loss, which was confirmed by the absence of evoked auditory potentials at 110 dB and with conserved otoacoustic emissions. The lack of any relevant medical history, a normal neurologic pediatric examination, and the improvement obtained with powerful hearing aids suggested an endocochlear cause. Genetic testing identified mutations in OTOF, responsible for the DFNB9 recessive form of hearing loss.

RESULTS

In recent years, cases of children with hearing loss associated with positive otoacoustic emissions have been labeled as "auditory neuropathy." Classically, this form of hearing loss is refractory to the use of hearing aids and cochlear implants. Mutations in OTOF lead to inner hair cells dysfunction, whereas the outer hair cells are initially functionally preserved. As this form of endocochlear hearing loss can be detected at a molecular level, genetic testing can be proposed for cases of nonsyndromic auditory neuropathy, as those children could benefit from cochlear implantation.

CONCLUSION

It is advisable to reserve the term "auditory neuropathy" for patients who present hearing loss and conserved otoacoustic emissions in the context of a neurologic syndrome or for children with suggestive perinatal history. In other cases, genetic testing for mutations in OTOF should be carried out.

[Psychosomatic status of patients with cochleovestibular disorders. Correction methods]

Psychosomatic status was studied in 106 patients aged 18-65 years with acute and chronic cochleovestibular disorders. Hearing problems, noise in the ears and vestibular disorders have a negative psychogenic effect in patients with cochleovestibulopathy. The majority of the patients need psychological and psychopharmacological care to relieve anxiety and form adequate attitude to the disease. Correction of psychosomatic disorders raises efficacy of the treatment of cochleovestibular diseases.

Management of the draining ear in children

There are a variety of causes of otorrhea in children. The most important factor in reaching the proper diagnosis and providing relief of the problem is aural toilet. Once adequate debridement has been performed, the diagnosis is usually clearer, and treatment with ototopicals is significantly more effective. Most cases of otorrhea are due to infection or granulation tissue and can be managed initially with appropriately selected ototopical medication, thereby avoiding the risks and side effects of systemic therapy and the need for referral to a specialist. However, otorrhea in children that is refractory to medical therapy may be due to retained tympanostomy tubes or insidious pathology such as cholesteatoma or malignancy. In such cases, prompt referral to the otolaryngologist can facilitate accurate diagnosis and successful management.

Dizziness

BACKGROUND

The article gives an overview of the most frequent forms of vertigo, that are of peripheral-labyrinthine, central-vestibular, psychogenic, or physiologic origin. Dizziness or vertigo is a result of a mismatch between 3 sensory systems: the vestibular, the visual, and the somatosensory systems. These systems are mutually interactive and redundant in that orientation and balance are guided by simultaneous reafferent cues. The functional ranges of the systems overlap, thus permitting them to compensate in part for each other's deficiencies.

SUMMARY

Vertigo is not a well-defined disease entity, but rather a multisensory syndrome induced either by stimulation of the intact sensorimotor system by motion (eg, physiologic vertigo as in motion sickness or height vertigo), or by pathologic dysfunction of any of the stabilizing sensory systems (eg, peripheral vestibular as in vestibular neuritis, or central vestibular as in vertebro-basilar ischemia). The core region in vestibular vertigo syndromes is the vestibulo-ocular reflex, a 3-neuron arc that mediates the information of the semicircular canals and otoliths via the vestibular nerve and vestibular nucleus to the ocular motor nuclei (VI, IV, III) and the supranuclear integration centers in the ponto-mesencephalic brain stem.

CONCLUSIONS

Clinical phenomena characteristic for physiological and pathologic vertigo syndromes include postural, perceptual, oculomotor, and vegetative syndromes, which manifest with ataxia, nystagmus, vertigo, and nausea. Thus, the clinical testing must include examinations of postural, perceptual, oculomotor, and vegetative dysfunctions.

Recurrent acute otitis media associated meningitis in a patient with a contralateral cochlear implant and bilateral cochleovestibular dysplasia

OBJECTIVE

To illustrate that a patient with a cochlear implant may be at increased risk of meningitis secondary to developmental anatomic abnormality associated with the underlying sensorineural hearing loss, as opposed to the implant itself.

METHODS

Case report.

RESULTS

Our 12-year-old patient has bilateral cochlear dysplasia, profound sensorineural hearing loss and no prior history of recurrent acute otitis media or meningitis. He underwent a left cochlear implant at 8 years of age and subsequently experienced three episodes of right acute otitis media and meningitis over the next 4 years. Middle ear exploration revealed a cerebrospinal fluid leak. A right radical mastoidectomy with closure of the external auditory canal, removal of the tympanic membrane, malleus, and incus, closure of the Eustachian tube, and obliteration of the mastoid and middle ear with abdominal fat has prevented further episodes.

CONCLUSION

Meningitis in a patient with a cochlear implant is not necessarily related to the implant.

Questioning the Relationship between Cochlear Otosclerosis and Sensorineural Hearing Loss: A Quantitative Evaluation of Cochlear Structures in Cases of Otosclerosis and Review of the Literature

BACKGROUND

The literature provides conflicting information regarding the prevalence and cause of sensorineural hearing loss (HL) in individuals with otosclerosis.

OBJECTIVE

The purpose of this study was to further evaluate the association between involvement of the cochlear endosteal layer with otosclerosis and sensorineural HL.

STUDY DESIGN

Retrospective case review.

METHODS

Temporal bones and audiograms from five individuals with otosclerosis were evaluated. The cochlear elements were quantified. The location and extent of the cochlear element loss was correlated with the location and extent of endosteal involvement with otosclerosis.

RESULTS

A reduction in the population of cochlear elements was observed in most individuals; however, the reduction was not proportional to the extent of endosteal involvement with otosclerosis. The cochlear elements remained normal adjacent to some areas of endosteal involvement with otosclerosis. One individual with extensive cochlear otosclerosis had normal hearing and predominantly normal cochlear elements.

CONCLUSION

This study demonstrates a variable amount of degeneration of the cochlear elements in individuals with otosclerotic involvement of the endosteum. The reduction in the population of cochlear elements was not related to the extent and location of endosteal involvement with otosclerosis. These findings suggest that factors that limit the effect of otosclerotic endosteal involvement on the cochlear elements or processes that effect the cochlear elements directly and are independent of bone involvement may be present.

Cochlear implant failure: is an auditory brainstem implant the answer?

OBJECTIVE

To investigate the auditory rehabilitative results achieved in five patients with cochlear implants (CIs) who subsequently received, due to poor results, auditory brainstem implants (ABIs).

MATERIAL AND METHODS

Between April 1997 and March 2003, 37 patients (age range 14 months to 70 years) were fitted with ABIs in our ENT Department. Fourteen subjects had neurofibromatosis type 2 and 23 were non-tumor patients who had cochlea or cochlear nerve disease. Five subjects had previously been treated with a CI and received an ABI owing to the poor results achieved. One child had bilateral undiagnosed cochlear nerve aplasia and one was suffering from auditory neuropathy; three adults had total cochlear ossification.

RESULTS

The open-set sentence recognition score (auditory-only mode) 6-8 months after ABI activation ranged from 0% to 100% in adults. In 1 subject the speech-tracking score was 56 words/min with the ABI. The two children who had achieved no hearing ability with their CI were able to detect sounds and words as early as 3 months after activation of the ABI.

CONCLUSION

CI failure as a result of anatomical abnormalities can be remedied by an ABI.

Free radical scavenger protects against inner hair cell loss after cochlear ischemia

We investigated the protective effects of edaravone, a free radical scavenger, against ischemic damage of inner hair cells (IHCs) in gerbils. Cochlear ischemia was induced in the animals by occluding the vertebral arteries bilaterally for 15 min. Edaravone (1 mg/kg, i.v.) or saline was administered 1 h after ischemia. Hearing was assessed by auditory brain response (ABR). In animals treated with saline, the ABR threshold shift was 24.1 dB and there was a 26.5% decrease in the number of IHCs. By contrast, in animals treated with edaravone, the threshold shift was 7.5 dB and only 8.8% of IHCs was lost. These results suggest that edaravone protects against damage to the inner ear following transient ischemia.

Hyperbaric compression in the guinea pig with perilymph fistula

OBJECTIVE

The study goal was to evaluate the effects of hyperbaric therapy on the auditory and vestibular function of guinea pigs compromised by perilymph fistula (PLF).

METHODS

Twenty-four pigmented guinea pigs underwent induction of bilateral eustachian tube dysfunction before the creation of a unilateral PLF. Half of the animals were randomly assigned to receive immediate hyperbaric compression treatment of 4 "dives" each. Hearing was tested electrocochleographically, and signs of vestibulopathy were recorded before and after compression.

RESULTS

After accounting for the effects of PLF, compression was not associated with significant hearing loss (P = 0.5411). Vestibulopathy was seen only in ears with PLF, and its incidence was similar for compression and noncompression groups.

CONCLUSION

Hyperbaric compression does not compromise auditory or vestibular function in guinea pig ears with experimental PLF.

SIGNIFICANCE

Our observations support the relative safety of recompression in patients with PLF.

Transmeatal cochlear laser (TCL) treatment of cochlear dysfunction: A feasibility study for chronic tinnitus

Low-level-laser-therapy (LLLT) targeting the inner ear has been discussed as a therapeutic procedure for cochlear dysfunction such as chronic cochlear tinnitus or sensorineural hearing loss. Former studies demonstrate dose-dependent biological and physiological effects of LLLT such as enhanced recovery of peripheral nerve injuries, which could be of therapeutic interest in cochlear dysfunction. To date, in patients with chronic tinnitus mastoidal and transmeatal irradiation has been performed without systematic dosimetric assessment. However, light-dosimetric studies on human temporal bones demonstrated that controlled application of laserlight to the human cochlea depends on defined radiator position within the external auditory meatus. This feasibility study first presents a laser application system enabling dose-controlled transmeatal cochlear laser-irradiation (TCL), as well as preliminary clinical results in patients with chronic cochlear tinnitus. The novel laser TCL-system, consisting of four diode lasers (lambda=635 nm-830 nm) and a new specific head-set applicator, was developed on the basis of dosimetric data from a former light-dosimetric study. In a preliminary clinical study, the TCL-system was applied to 35 patients with chronic tinnitus and sensorineural hearing loss. The chronic symptoms persisted after standard therapeutic procedures for at least six months, while retrocochlear or middle-ear pathologies have been ruled out. The patients were randomised and received five single diode laser treatments (lambda=635 nm, 7.8 mW cw, n=17 and lambda=830 nm, 20 mW cw, n=18) with a space irradiation of 4 J/cm2 site of maximal cochlear injury. For evaluation of laser-induced effects complete otolaryngologic examinations with audiometry, tinnitus masking and matching, and a tinnitus-self-assessment were performed before, during and after the laser-irradiation. The first clinical use of the TCL-system has been well tolerated without side-effects and produced no observable damage to the external, middle or inner ear. Changes of tinnitus loudness and tinnitus matching have been described. After a follow-up period of six months tinnitus loudness was attenuated in 13 of 35 irradiated patients, while two of 35 patients reported their tinnitus as totally absent. Hearing threshold levels and middle ear function remained unchanged. Further investigations by large double-blind placebo-controlled studies are mandatory for clinical evaluation of the presented TCL-system and its therapeutic effectiveness in acute and chronic cochlear dysfunction.

Cochlear implantation in prelingually deaf children with ossified cochleae

OBJECTIVE

To evaluate the effects that degree of cochlear ossification has on performance of prelingually deafened children who receive cochlear implants.

STUDY DESIGN

A matched-pairs analysis comparing speech perception results obtained 6 and 24 months after implant by children with ossified and nonossified cochleae. Additionally, long-term performance was evaluated in patients with follow-up periods longer than 24 months. Comparisons were also performed within the ossified cochleae group to determine if degree of cochlear ossification and surgical technique affected outcome with the cochlear implant. SETTING Large cochlear implant program in an academic tertiary care medical center.

PATIENTS

Twenty-one pairs of prelingually deaf children with and without cochlear ossification. Meningitis was the etiology of hearing loss in children with ossified cochleae. The control group had nonmeningitic etiology for the hearing loss.

INTERVENTIONS

Multichannel cochlear implantation and routine postoperative auditory rehabilitation and performance evaluation.

MAIN OUTCOME MEASURES

Speech perception category ratings based on scores obtained on a battery of closed- and open-set speech recognition tests 6 and 24 months after implant. Longer follow-up period is also reported.

RESULTS

As a group, children with cochlear ossification showed significant improvement in their speech perception abilities 6 and 24 months after implant. Children with cochlear ossification performed at a significantly lower speech perception category than a group of matched controls with nonossified cochleae at both the 6- and 24-month postimplant intervals. With longer implant use, open-set speech recognition was possible in some children with ossification. Within-group analysis of the children with ossified cochleae revealed that degree of ossification and surgical procedure used for implantation did not significantly affect outcome.

CONCLUSIONS

Prelingually deafened children with postmeningitic hearing loss and ossified cochleae receive significant benefit from cochlear implants. Their performance is frequently poorer, however, than children with nonossified cochleae.

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.

Effect of cochlear damage on the detection of complex temporal envelopes

Recent studies have demonstrated that the detection of complex temporal envelopes relies - at least partially - on the perception of a distortion component generated by a peripheral (cochlear) and/or central (post-cochlear) non-linearity. In the present study, first- and second-order amplitude modulation (AM) detection thresholds were obtained in normally hearing (NH) and hearing-impaired (HI) listeners using a 2-kHz pure-tone carrier. In both groups of listeners, first-order AM detection thresholds were measured for AM rates fm ranging between 4 and 87 Hz, and second-order AM detection thresholds were measured for second-order AM rates fm' ranging between 4 and 23 Hz, using a fixed first-order 'carrier' AM rate fm of 64 Hz. When the sound pressure level was adjusted in order to yield equal detectability in both groups for the 64-Hz first-order carrier modulation, (i) first-order AM detection thresholds for the HI listeners were normal at fm=87 Hz, and better-than-normal at fm=4 and 16 Hz, and (ii) second-order AM detection thresholds were identical at all modulation rates in NH and HI listeners. Similar results were obtained when the audibility of the 2-kHz pure-tone carrier was equated for both groups, i.e. when listeners were tested at the same sensation level. These results demonstrate clearly that cochlear damage has no effect on the detection of complex temporal envelopes, and indicate that the distortion component must be generated by a more central non-linearity than cochlear compression, transduction, or short-term adaptation.

Prediction of progression from atypical to definite Ménière's disease using electrocochleography and glycerol and furosemide tests

OBJECTIVE

To investigate whether electrocochleography (ECochG) and glycerol and furosemide tests could predict progression from atypical to definite Ménière's disease (MD).

MATERIAL AND METHODS

ECochG and glycerol and furosemide tests were performed in 1569 patients with various cochleovestibular diseases, including definite MD, atypical MD, syphilitic labyrinthitis, delayed endolymphatic hydrops, sudden hearing loss, cochleovestibulopathy and sensorineural hearing loss. Patients with atypical MD were divided into five categories based on their symptoms.

RESULTS

A total of 115/118 patients (97%) with definite MD who underwent all 3 tests showed a positive result in at least 1 test. Ninety-nine patients who did not satisfy the diagnostic criteria of definite MD but had vertigo and/or hearing loss at the first visit subsequently progressed to definite MD. It was retrospectively found that 92% of patients showed at least 1 positive finding in these 3 tests at the initial stage. In those patients who showed a negative test result in either ECochG or the glycerol test, the possibility of progression to definite MD was low.

CONCLUSION

The combination of ECochG and the glycerol and furosemide tests was helpful in diagnosing endolymphatic hydrops (ELH). ECochG and the glycerol test were effective tools for predicting the progression to definite MD in patients with atypical MD, sudden hearing loss and other cochleovestibular diseases. Our test results also indicated that the pathological state of atypical MD included both non-ELH and ELH.

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.

Cochlear implantation in the obliterated cochlea

We present three cases of acquired deafness, associated with obliterated cochleas, in which the apparently radiologically more favourable side was chosen for implantation. In the first case, because of unexpected obliteration, only a partial insertion was possible. Deteriorating performance and non-auditory stimulation of the facial nerve led to removal of the implant and a contralateral implantation with full insertion under the same anaesthetic gave a good postoperative result. In the second case, CT scanning indicated minimal obliteration, but extensive obliteration was encountered at surgery, which required double-array insertion with a delayed but satisfactory outcome. In the third case, extensive unexpected obliteration was noted at surgery and, in light of the experience gained with the first two cases, it was decided not to proceed but to explore the contralateral side. At surgery on the contralateral side, a patent cochlea was noted with full electrode insertion and an excellent outcome. These cases demonstrate a learning curve for this department and our philosophy now is to explore the contralateral ear rather than accept a partial insertion.

[Cochlear hemorrhage. Unusual cause of sudden sensorineural deafness]

Sudden sensorineural hearing loss (SNHL) caused by intralabyrinthine hemorrhage is a rare entity usually associated to patients with previous pathological factors, such as blood dyscrasias, anticoagulant therapy and local hemorrhagic pathologies. We report the first-published case of sudden-onset deafness due to cochlear hemorrhage in a patient with no previous pathologies. We describe the history, diagnosis and follow-up of this patient in comparison to others previously published.

The otolithic organ as a receptor of vestibular hearing revealed by vestibular-evoked myogenic potentials in patients with inner ear anomalies

The human vestibule has preserved an ancestral sound sensitivity and it has been suggested that a reflex could originate from this property underlying cervical muscle micro-contractions secondary to strong acoustic stimulation. Previous studies have established that an early component of loud sound-evoked myogenic potentials from the sternocleidomastoid muscle originate in the vestibule. This is based on findings that the response can still be obtained from patients with complete loss of cochlear and vestibular (semi-circular canal) function. Our data confirm, in a more direct way, a saccular origin of this short-latency acoustic response and verifies that a saccular acoustic response persists in the human ear. The contribution of this response to the perception of loud sounds is discussed. It is concluded that vestibular response to sound might be used to assist in the rehabilitation of deafness.

Hereditary cochleovestibular dysfunction due to a COCH gene mutation (DFNA9): a follow-up study of a family

Cochleovestibular impairment was evaluated, in relation to age, in a longitudinal follow-up study on a Dutch family with a DFNA9 trait caused by a Pro51Ser mutation in the COCH gene on chromosome 14q12-q13. Fourteen cases were genotyped. The onset age of progressive impairment reported by the mutation carriers was between age 35 and 45 years. Pure-tone thresholds deteriorated by about 2-7 dB per year (mean 3.8 dB per year) in a variable, often asymmetrical, fashion. One mutation carrier developed recurrent episodes of vertigo accompanied by nausea and vomiting, resembling Ménière's disease. Two others developed special susceptibility for motion sickness and appeared to have a hyperactive vestibulo-ocular reflex. More advanced stages of vestibular impairment, i.e. vestibular hyporeflexia and complete vestibular areflexia, were eventually found in a number of cases. DFNA9/COCH should be considered as a possible cause in patients developing combined progressive cochlear and vestibular impairment, or suspected hereditary Ménière-like disease, from around middle age.

Etanercept therapy for immune-mediated cochleovestibular disorders: preliminary results in a pilot study

OBJECTIVE

Immune-mediated cochleovestibular disorders (IMCVDs) continue to present a management challenge to the otolaryngologist. Antirheumatic agents, commonly used for IMCVDs, are associated with variable efficacy and sometimes with serious side effects. The authors describe the preliminary result of their experience in patients with IMCVDs who have been treated with etanercept, a tumor necrosis factor alpha receptor blocker, recently approved by the United States Food and Drug Administration for the treatment of rheumatoid arthritis.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary care hospital.

PATIENTS

Twelve patients suspected of having IMCVD who did not respond to conventional therapies or experienced side effects of the conventional therapies.

INTERVENTION

Etanercept 25 mg by subcutaneous injection twice per week.

MAIN OUTCOME MEASURES

The main outcome measurement was assessment of hearing change by air conduction pure tone audiograms and/or word discrimination. When present, vertigo, tinnitus, and aural fullness were assessed as well.

RESULTS

Follow-up of more than 5 months was available for all patients (range, 5-12 months). Eleven (92%) of 12 patients had improvement or stabilization of hearing and tinnitus, seven (88%) of eight patients who had vertigo and eight (89%) of nine patients who had aural fullness had resolution or significant improvement of their symptoms. The benefit persisted until the last visit (5-12 months after etanercept was begun). The condition of one patient improved dramatically at first but deteriorated after 5 months. The patient's hearing was rescued and stabilized with the addition of leflunomide to etanercept. Similarly, three other patients required a second antirheumatic agent to stabilize their hearing. There were no significant side effects from the etanercept therapy.

CONCLUSIONS

Our limited data suggest that etanercept therapy is safe and may be efficacious in carefully selected patients with IMCVDs, at least on a short-term basis. These preliminary efficacy and safety results appear encouraging enough to warrant further follow-up and studies for better determination of the potential clinical utility of etanercept for IMCVDs.

Electrical stimulation of the auditory nerve: single neuron strength-duration functions in deafened animals

Destruction of cochlear hair cells initiates degenerative changes within auditory nerve fibres (ANFs), including loss of peripheral processes and demyelination of the cell body. These changes are likely to affect the biophysical processes involved in action potential generation to an electrical stimulus. We measured the strength-duration relationship in acutely deafened (100% ANF survival) versus long-term deafened cochleae (approximately 15% ANF survival) by recording from single neurons in the central nucleus of the inferior colliculus (ICC). Input/output functions were constructed for 22 ICC neurons in response to stimulation of the auditory nerve using biphasic current pulses of 20-1000 micros/phase. Strength-duration curves were derived and found to be of the same general form for both acute and long-term deafened cochleae. While there was an increase in rheobase for neurons from long-term versus acute deafened cochleae, this increase was not statistically significant (p=0.097). In contrast, chronaxie--which is related to the membrane time constant--was significantly shorter in the long-term deafened cochleae (p = 0.004). This presumably reflects a shift in the site of action potential initiation to the larger diameter, heavily myelinated central axon as a result of the pathology. These changes in the site of action potential generation have implications for the delivery of charge to ANFs via cochlear implants.