Transtympanic versus tympanic membrane electrocochleography in examining cochleovestibular disorders

The use of electrocochleography (EcoG) is considered to be of clinical value in otological diagnosis. Non-invasive ear canal (EC) and tympanic membrane (TM) EcoG recording techniques, and invasive transtympanic (TT) technique are the methods used for objective assessment of cochlear function. In this study, eight adults (16 ears) with suspected Meniere's disease were examined using a newly designed, disposable tympanic electrode and a traditional, thin transtympanic needle. The amplitudes of the TT electrode responses were 4-6-fold larger than those produced by the TM electrode. The morphology of the waveforms for the two recording techniques was nearly identical. The mean amplitudes of the action potential (AP) obtained with the TM electrode were 2.39-3.73 microV, and with the TT electrode 14.08-19.60 microV, depending on the stimulus intensity. For the summating potential (SP), the TM and TT electrodes had mean amplitudes of 0.82-1.60 microV and 3.53-5.81 microV respectively. The SP/AP ratios were larger with the TM electrode than with the TT electrode. They were inconsistent in four ears (25%) when measured with the TM and TT electrodes. All patients were more satisfied with the TT examination, since it was quite painless, unlike the TM examination. The authors recommend the use of the TT recording technique as a painless examination in which the electrode is close to the inner ear, allowing a good signal-to-noise ratio and large amplitudes. Diagnostic interpretations are easier and more reliable with the TT electrode than with the TM electrode.

[Cochlear hypoxia and mtDNA deletion: possible correlated factors to cause presbycusis]

OBJECTIVE

To find the relationship among the most common mitochondrial DNA (mtDNA) 4,977 bp deletion, aging and deterioration of acoustic organ and determine the pathologic factors causing mtDNA 4,977 bp deletion.

METHODS

Sixty-seven temporal bones from a presbycusis group, an age-matched control group and a young control group were evaluated. The nested PCR and tri-nested PCR techniques were used to test the presence of mtDNA 4,977 deletion. Computer imaging processing was used to measure the parameters of blood vessels in the internal acoustic meatus.

RESULTS

Temporal bones from patients aged 50 years or over frequently showed mtDNA 4,977 deletions. In presbycusis patients, 17 of 34 ears showed mtDNA 4,977 deletion, whereas only 4 of 19 ears from the age-matched control group showed mtDNA 4,977 deletions. mtDNA 4,977 deletions were often seen in the spiral ganglion and vestibular ganglion neurons. In the presbycusis group, the lumen of the vasa nervosum of the internal auditory meatus showed a more severe reduction in patients with mtDNA 4,977 deletion than in those without deletion.

CONCLUSION

There is a strong correlation between presbycusis and mtDNA 4,977 deletion. We hypothesize that cochlear hypoxia may cause mtDNA 4,977 deletions and other mtDNA mutants which in turn may cause a reduction of mitochondrial oxidative phosphorylation and decreased auditory nerve function. The symptoms of neural presbycusis, however, may appear only after mtDNA metabolism decreases below a specific threshold.

Hearing loss in Sjögren's syndrome patients. A comparative study

OBJECTIVE

In an attempt to investigate the presence of hearing loss in primary Sjögren's syndrome (SS) patients and to determine the factors that might be involved in its pathogenesis, we prospectively evaluated 45 female SS patients with a mean age of 56.8 +/- 9.23 years and a mean disease duration of 8.32 +/- 5.39 years.

METHODS

Forty patients underwent a complete ear-nose-throat physical examination and audiological evaluation with: (a) pure tone audiometry thresholds at octave frequencies of 250 to 8000 Hz; (b) impedance audiometry (tympanogram, static compliance, acoustic reflexes, reflex decay; and (c) speech audiometry and auditory brainstem response where indicated. In addition, glandular and extraglandular manifestations of the disease and drug therapy were recorded. Finally, all patients were tested for the presence of autoantibodies, including: rheumatoid factor, antinuclear antibodies, antibodies to Ro(SSA), La(SSB) nuclear antigens, anticardiolipin antibodies and antineutrophil cytoplasmatic antibodies. The results were compared with those of 40 healthy, age-matched women.

RESULTS

We found sensorineural hearing loss (SNHL) in 9 patients (22.5%): 4 patients bilaterally, 4 patients in the left ear only and one in the right ear only. In all cases the site of the ear damage was cochlear. A correlation between SNHL and the duration of the disease was found, while there was no correlation with age, systemic manifestations of the disease or the presence of autoantibodies. In addition, no correlation was found between SNHL and drug therapy.

CONCLUSION

Approximately one-fourth of our SS patients presented SNHL of cochlear origin affecting mainly the high frequencies. This prevalence was lower than that reported by other investigators. SNHL was associated only with disease duration. Further investigation is needed to attain a better understanding of the mechanism of inner ear involvement in SS patients.

[Susac syndrome: clinical and diagnostic approach. A new case report]

INTRODUCTION

The Susac syndrome is made up of the clinical triad: encephalopathy, visual and hearing defects. It is caused by microangiopathy of unknown origin affecting the small arteries of the brain, retina and cochlea. It is very uncommon. It mainly affects young women. The course of the illness is usually monophasic and self-limiting. The deficit of visual acuity is caused by occlusion of tributaries of the retinal artery. The auditory defect is bilateral and symmetrical, and particularly affects medium and low frequencies. NMR is of great diagnostic value, showing multiple lesions in the grey and white matter. Our case gives more data regarding the evolution of this condition and the contribution of cerebral SPECT to diagnosis, the results of systemic treatment, use of hyperbaric oxygen and reflections on the physiopathology of the process.

CLINICAL CASE

We present the clinical case of a young woman who presented with psychiatric symptoms and migraine followed by clinical encephalopathy and acute/subacute coma. There were also visual and auditory deficits. Other types of systemic disease were ruled out.

CONCLUSIONS

Findings on SPECT suggested the presence of a microangiopathic disorder of the brain. The patient responded to systemic treatment with cortico-steroids. The encephalopathy resolved in a few days and two months later she had resumed her former daily activities. Treatment with hyperbaric oxygen definitely reduced visual sequelae.

Cochlear implantation in auditory neuropathy

OBJECTIVE

Auditory neuropathy is a recently described clinical entity characterized by sensorineural hearing loss in which the auditory evoked potential (ABR) is absent but otoacoustic emissions are present. This suggests a central locus for the associated hearing loss. In this study the results observed in a child with auditory neuropathy who received a cochlear implant are presented and compared with those of a matched group of children who were recipients of implants.

METHODS

A single-subject, repeated-measures design, evaluating closed-set and open-set word recognition abilities was used to assess the subject and a control group of matched children with implants who had also experienced a progressive sensorineural hearing loss.

RESULTS

The subject demonstrated improvements in vowel recognition (82% correct) by 1 year after implantation, which were only slightly lower than the control group. Consonant recognition and open-set word recognition scores were significantly lower.

CONCLUSION

Caution should be exercised when considering cochlear implantation in children with auditory neuropathy. As with conventional hearing aids, less than optimal results may be seen.

Lesion site in sudden deafness: study with electrocochleography and transiently evoked otoacoustic emission

We examined electrocochleogram (ECochG) and transiently evoked otoacoustic emission (TEOAE) on five cases of sudden sensorineural hearing loss which had no abnormalities detected on diagnostic imagings and showed complete recovery of hearing. At the initial examination, three cases showed a broadened wave 1 with prolonged latency in the auditory brainstem response (ABR) at 90 dB HL. The ECochG AP showed a broad waveform, low amplitude, and high threshold. CM threshold, although increased, was relatively well preserved compared with hearing threshold measured with conventional pure-tone audiometry. The thresholds in TEOAE examination were similar to those for CM and preserved better when compared with pure-tone audiometric thresholds. These findings suggest that the location of the disorder in these three cases involved not only the cochlea but also the retrocochlear auditory pathway. The other two cases showed normal ABR waveforms at 90 dB HL at the initial examinations. ECochG examination showed that a normal AP in one case and a smaller amplitude AP, an elevated threshold, and normal waveform of AP in the other ear. CM thresholds coincided with the conventional audiometry thresholds. These findings suggest that hearing loss in these two cases involved primarily the sensory hair cells.

Tone burst auditory brain stem response latency estimates of cochlear travel time in Meniere's disease, cochlear hearing loss, and normal ears

OBJECTIVE

The current study sought to determine whether tone burst auditory brain stem response (ABR) latencies could be used to detect an increase in the cochlear traveling wave velocity in patients with Meniere's disease.

BACKGROUND

It has been proposed that the derived band ABR technique can be used to show an increase in cochlear traveling wave velocity in patients with Meniere's disease. The current study sought to replicate these findings using tone burst ABR at frequencies of 0.5, 1, 2, 4, and 8 kHz and intensities from 40-100 dB hearing loss (HL) in 10-dB steps.

METHODS

Wave V latency differences between adjacent frequencies were taken to represent the time it takes the traveling wave to travel between the "place" on the basilar membrane where these two frequencies are represented. Thirty-two subjects participated in the project consisting of 10 with normal hearing, 10 with cochlear HL (not caused by Meniere's disease), and 12 with Meniere's disease.

RESULTS

There were no significant differences in absolute wave V latencies or in wave V latency differences (travel time estimates) between the groups (repeated measures analysis of variance, p > 0.05).

CONCLUSION

These results suggest that wave V latencies and estimates of cochlear travel time cannot be used to distinguish Meniere's disease from other forms of cochlear HL or from normal-hearing ears. The results of this study differ from those using the derived band ABR technique. This difference may be because of the disease state of the authors' subjects or differences in stimulus paradigm.

Age-related changes in cochlear blood flow response to occlusion of anterior inferior cerebellar artery in mice

Previous studies suggest that autoregulation of cochlear blood flow (CBF) may be impaired by aging. In this study, we quantified the capacity of CBF autoregulation in young adult (6-month-old) and aged (21-month-old) CBA mice, to examine the effect of aging on CBF autoregulation. The technique of anterior inferior cerebellar artery (AICA) occlusion was employed to manipulate cochlear perfusion pressure. The CBF was measured by laser Doppler flowmetry during intermittent occlusion of the AICA with a microvascular clamp, which causes an initial decrease in CBF. The autoregulation of CBF was evaluated by quantifying the CBF increase (compensatory dilatory response in the cochlear vessels) during AICA occlusion. Our results demonstrated that autoregulation of CBF was significantly reduced and that collateral vascular function supplying CBF was significantly lower in the aged group. These findings suggest that the aged ear has less capacity to maintain stable blood flow and thus may be more vulnerable to stress factors that affect cochlear function.

Interaction between hypertension and diabetes mellitus in the pathogenesis of sensorineural hearing loss

The purpose of this study is to support the hypothesis that diabetic end-organ damage of the cochlea is augmented in the setting of hypertension. A historical perspective reviewing the effects of diabetes and hypertension as causative factors in the development of sensorineural hearing loss, as well as the basic epidemiology and pathophysiology of the renal and vascular effects of diabetes and hypertension, is presented. The results of audiologic findings in insulin-dependent diabetic patients, both normotensive and hypertensive, were analyzed and correlated with the results of animal studies to support the hypothesis that sensorineural hearing loss in patients and cochlear hair cell loss in animal studies result from the effects of hypertension in conjunction with insulin-dependent diabetes mellitus.

Cochlear implants in children: what constitutes a complication?

The surgeon must ultimately accept the responsibility for any complications that occur as the result of a cochlear implant. Listening to the cochlear implant team members and responding to their needs may enhance the child's progress. Surgical complications, (i.e., skinflap problems, infection, and facial paralysis) are indeed infrequent, but nonsurgical problems are not. Surgical and nonsurgical experiences were reviewed in 55 children. Ages ranged from 23 months to 18 years at the time of cochlear implantation, which occurred from 1984 to 1995. There were no surgical complications. However, the most common surgical obstacle was ossification, which was present in 40% and undetected by computed tomographic scanning in 16.3% of children. Ossification occurred at the round window and scala tympani in 32.7% and involved the cochlea more extensively in 7.3% of children. In only one child was the cochlea entirely ossified. There were, however, many nonsurgical problems that were viewed as complications in patient management. The single most important complication was device failure. This occurred in 10.9% (5/46) of children with the Cochlear Corporation multichannel implant. Head banging and other temper tantrums, parental interference with rehabilitation, socioeconomic factors, poor compliance by the family unit, equipment problems, educational deficiencies, and impatience with habilitative training were some of the other problems.

Assessment of cochlear damage after pneumococcal meningitis using otoacoustic emissions

Three cases are reported of children in Ghana with pneumococcal meningitis and differing degrees of hearing loss. The children were examined up to 12 d after admission by means of otoacoustic emissions. The technique is objective, non-invasive, quick (< 5 min per ear) and suitable for use in paediatric wards.

Effectiveness of hyperbaric oxygen therapy in patients with acute and chronic cochlear disorders

Over the course of 18 months 359 patients with defined acute and chronic inner ear disorders who had not responded to treatment with medication were given hyperbaric oxygen (HBO) therapy. The inner ear diseases of the patients were divided, based on the duration of their conditions, into four symptomatic groups. Of the patients who had had hearing loss for less than 3 months, noticeable improvement or complete recovery was seen in 13% (20 dB in at least three test frequencies); 25.2% showed an improvement between 10 and 20 dB. Changes up to 10 dB or less were not considered to be positive. Patients with a pretreated hearing loss for more than 3 months had markedly less benefit from HBO therapy. Two percent regained normal hearing function. In 30% an improvement of more than 10 dB was achieved. For patients who had suffered from tinnitus for less than 3 months excellent improvement was seen in 6.7% and noticeable improvement in 44.3% expressed by means of a visual analog scale. In 44.3% the tinnitus was described as unchanged. Patients who had had tinnitus for more than 3 months before HBO therapy showed a less favorable response to HBO. In none of the patients did the tinnitus disappear; 34.4% of the patients described a noticeable improvement in their complaints.

Azathioprine with cortisone in treatment of hearing loss in only hearing ear

A sudden or progressive hearing loss in the only hearing ear is an otologic emergency, in which therapeutic possibilities are limited. We describe results of immunosuppressive therapy in 10 patients with one deafened ear either due to cochlear hydrops or Meniere's disease, who developed progressive or fluctuant hearing loss in the only hearing ear. The perilymphatic fistula was excluded with tympanoscopy. Azathioprine (25 mg t.i.d.) with prednisone (initial dose 20-40 mg with daily dose of 5-15 mg/day) was used. The hearing of 6 subjects responded to treatment. The initial pure tone audiogram (PTA) at speech frequencies of the "only hearing ear" was 57.3 dB HL with speech discrimination score (SDS) of 85%. The hearing improvement occurred successively within days or weeks. The average improvement of PTA was 22.4 dB HL after the mean treatment period of 5 weeks. In contralateral ear (the average PTA and SDS were 72.5 dB HL and 28%, respectively) the mean improvement in PTA was insignificant (4.4 dB). In 5 patients with vertigo it was improved in 3 cases. Cortisone alone or with combination of cyclophosphamide or ciclosporine was not effective in our hands.

Late sequelae of cochlear infection

Inflammatory reactions within the inner ear are deleterious to cochlear function and can result in server hearing loss that does not recover. This study investigated a guinea pig model of long-term cytomegalovirus infection. At high doses active inflammation was still present after 35 days. At lower doses some ears showed partial resolution while others were still inflamed. Hearing was totally lost in all cases of persistent inflammation. There was some residual hearing in the cases that had resolved. Cochlear structures including the organ of Corti, stria vascularis, and spiral ganglion were partially degenerated. Fibrotic matrix within scala tympani was ossified in many cases. These changes are consistent with those described for human cochleas following putative viral infections.

Unilateral mimicking bilateral benign paroxysmal positioning vertigo

BACKGROUND

Unilateral benign paroxysmal positioning vertigo (BPPV) may mimic bilateral BPPV if the diagnostic positioning maneuver is executed without appropriate alignment of the head and neck with the trunk.

OBSERVATIONS

Appropriate alignment is achieved by adjusting the plane of the affected posterior semicircular canal so that it is parallel to the plane of diagnostic head tilt, ie, 45 degrees horizontal head rotation to the left before a head tilt to the right in suspected right-sided BPPV. With inappropriate head alignment and head tilt to the side of the unaffected ear, a free-floating clot within the long arm of the uppermost posterior canal may gravitate toward the cupula and become settled on it. This causes ampullopetal cupulolithiasis, evoking geotropic nystagmus, which may mimic BPPV of the unaffected ear.

CONCLUSION

This hypothesis explains the seemingly paradoxical observation of immediate relief from "bilateral BPPV" following unilateral surgical canal occlusion on the "more symptomatic" side.

[The radiological pattern of cochlear otosclerosis. A CT study of 14 patients]

In this review of cochlear otosclerosis 14 cases were studied by CT scan aiming to establish a densitometric pattern of the capsular foci and relating it to the hearing and vestibule dysfunctions. Severe demineralization with characteristics of probable activity (increased lucency of 30-40%) was demonstrated in the capsular foci. These were mainly cochlear with endosteal involvement (93%): large (64%) or discrete (29%). Cochlear otosclerosis was widespread in 64% of the patients, with coexisting foci in the semicircular canals (38%), vestibule aqueduct (43%) and internal auditory canal (43%). The antefenestral component with stapes involvement was 85%, mostly of the anterior polar and crural varieties (64%) and signs of activity. In 2 patients there was a conductive hearing loss in the tonal audiometry, pure or combined; in 2 others there was only a pure perceptive hypoacusis of type IV. A direct relationship was noted (64% of cases) between the most serious hypoacusis (type III and IV) and the endosteal extension of the cochlear foci. Vertigo occurred in 36% of the patients and was attributed to the posterior labyrinth foci.

Frequency selectivity in patients with acoustic neuroma

Frequency selectivity was compared in subjects with hearing loss due to acoustic neuroma and cochlear pathology, and normal listeners. A particular interest was the role of probe tone parameters on the shape of the tuning curve. Psychophysical tuning curves (PTCs) were measured for each of two equal energy 2000-Hz probe tones (10 dB SL/300 msec and 17 dB SL/60 msec), using simultaneous 1/3-octave narrow-band noise maskers centered at 1, 1.25, 1.6, 2.5, 3.15, and 4 kHz. The results showed that the critical masker levels obtained for impaired listeners were significantly greater than those from normal subjects. The slope of the low-frequency limb of the PTC was steeper for normal compared to hearing-impaired listeners but there was no difference due to site of lesion. In all three groups, the critical masker levels obtained with the short probe were significantly greater than those for the long probe, negating the hypothesis that equal energy probes would yield the same outcomes. Tuning in listeners with hearing loss was highly correlated with audiometric threshold but not with tumor size, width of the internal auditory canal, or tumor location within the cerebellopontine angle. The main conclusion was that cochlear and retrocochlear hearing loss are similar with respect to their effect on frequency selectivity.

[Autonomic nervous system in patients with cochleovestibular diseases]

Clinical, electrophysiological investigations, evaluation of autonomic nervous system reactivity with estimation of Kerdo vegetative and stability indices were carried out in 58 patients with cochleovestibulopathy (CVP) and 10 normal controls. CVP patients with compensated disease had sympathicotonia, those with decompensated CVP exhibited parasympathicotonia. Functional loading tests and the stability index values revealed compensatory nature of sympathicotonia. Quantitative and qualitative characteristics of the compensation were related to age (under 40, over 41) and pathogenesis of the disease (central or peripheral). In CVP decompensation poor tolerance of mental work load was reported.

Perilymphatic fistula--the value of diagnostic tests

Perilymphatic fistula (PLF) remains one of the most challenging problems in otological practice. Fifty-two consecutive patients (53 ears) who underwent explorative tympanotomy for suspected PLF between 1985-1992 were included in this study. The clinical picture, history, patients' complaints and laboratory tests were analysed and compared with the operative findings. The conclusions of our work are that the diagnosis of PLF is based mostly on the clinical picture and a battery of laboratory diagnostic tests, but no one test is truly diagnostic for PLF.

Acute simultaneous bilateral vestibulocochlear impairment in neuro-Behçet's disease: a case report

The central nervous system (CNS) is often a preferential target of Behçet's disease and diverse neurological manifestations have been described. Isolated hearing impairment or disequilibrium is also known to occur, but the simultaneous bilateral impairment of both vestibular and cochlear functions has been only rarely documented in Behçet's disease. A 52-year-old Japanese woman with neuro-Behçet's disease had meningoencephalitis, a profound thrombocytopenia, and bilateral vestibulocochlear impairment during the acute exacerbation. Although the CNS involvement was apparent, the clinical history and neuro-otological findings pointed to bilateral inner ear involvement rather than the brainstem or the 8th nerve lesions. She has made an excellent clinical response to pulse-dose methylprednisolone therapy with improvement in her neurological symptoms and in arresting the acute deterioration of hearing loss, but repeated audiograms failed to maintain the improvement with a modest dose of oral prednisolone. Since the bilateral vestibulocochleopathy can be as incapacitating as oculopathy in Behçet's disease, an early detection and prompt instillation of adequate corticosteroid therapy may be mandatory, although not curative.