The pathology of sudden deafness

Transtympanic perfusion: indications and limitations

PURPOSE OF REVIEW

To review the most recent literature regarding the application of transtympanic inner ear perfusion in the treatment of inner ear disorders including Meniere disease, sudden sensorineural hearing loss, and autoimmune inner ear disease.

RECENT FINDINGS

The use of gentamicin perfusion in the management of Meniere disease with intractable vertigo has been demonstrated to have a very high rate of success, and is much less invasive than alternative surgical procedures such as vestibular nerve section or labyrinthectomy. The technique for achieving the highest rate of success while still minimizing the risk of cochleotoxicity continues to be investigated. Sustained delivery techniques such as the Silverstein MicroWick appear to achieve the best pharmacokinetic profile within the inner ear fluids. The end point of treatment does not necessarily require complete vestibular ablation to cure the patient, and shorter courses of treatment may help to reduce the risk of hearing loss. Cochlear Meniere disease can be treated with dexamethasone 4 mg/cc perfusion of the inner ear, which may improve the hearing, tinnitus, and pressure in the ear. Sudden sensorineural hearing loss has been managed with transtympanic steroid delivery, and this appears to be beneficial for some patients who have failed to respond to oral steroids, or have medical contraindications to systemic steroids.

SUMMARY

Inner ear perfusion via transtympanic delivery is an emerging technique in the management of inner ear disease. Improved results are expected over time as research in this area answers questions about dosage and delivery techniques, as well as identifying new applications and pharmaceuticals.

Platelet GPIaC807T polymorphism is associated with negative outcome of sudden hearing loss

To determine the relevance of inherited prothrombotic risk factors in sudden hearing loss, we investigated 85 patients with sudden hearing loss of >/= 60 dB for the presence of inherited prothrombotic risk factors. The FV G1691A, FII G20210A, GPIa C807T, GPIIIa PIA1/A2, PAI-1 4G/5G, t-PA Alu repeat ID, MTHFR C677T and CBS 844ins68 genotypes were investigated. Allele frequencies found in patients were compared to those of 85 healthy control subjects of the same ethnic background using Chi-squared and odds-ratio analysis. The frequency of the GPIa807T allele was significantly elevated in patients compared to controls. In addition, allele frequency and genotype distribution of GPIa was significantly elevated in the patient group without recovery after 3 months of sudden hearing loss onset. Allele frequencies of all other prothrombotic risk factors investigated here did not differ from those of the control subjects. The single-nucleotide polymorphism of GPIa C807T seems to play a role as a prognostic factor in recovery from sudden hearing loss.

Oral steroid treatment of sudden sensorineural hearing loss: a ten year retrospective analysis

OBJECTIVE

To describe ten years of experience with Sudden Sensorineural Hearing Loss and compare the outcomes with and without treatment with oral corticosteroids.

STUDY DESIGN

Retrospective review of medical records.

SETTING

Large specialty hospital, Department of Otolaryngology.

PATIENTS

Patients presenting with sudden onset (72 hours) unilateral sensorineural hearing loss, with no evidence of Ménière's Disease, acoustic injury, retrocochlear disease, and other specifiable disorders.

INTERVENTIONS

The majority of patients received a standard course of oral corticosteroids (Prednisone 60 mg and taper). A smaller group declined treatment.

MAIN OUTCOME MEASURES

Recovery of hearing sensitivity was measured using standard audiometry and reported as change in Pure Tone Average. Word recognition scores were also analyzed.

RESULTS

When severe-to-profound cases are analyzed, a significant improvement (p <.01) in Pure Tone Average is seen in cases treated with steroids versus those untreated. When milder cases are included, a statistical floor effect prevents differentiation of these groups. Word recognition scores were significantly improved (p <.05) in the treated group.

CONCLUSIONS

Application of steroid medication significantly improves the recovery outcomes in cases of Severe Sudden Sensorineural Hearing Loss.

Treatment of idiopathic sudden sensorineural hearing loss with antiviral therapy: a prospective, randomized, double-blind clinical trial

A subclinical viral labyrinthitis has been postulated in the literature to elicit idiopathic sudden sensorineural hearing loss (ISSHL). An etiologic role for the herpes family is assumed. Corticosteroids possess a limited beneficial effect on hearing recovery in ISSHL. In this study, we evaluated the therapeutic value of the antiherpetic drug acyclovir (Zovirax) on hearing recovery in 91 patients with ISSHL who received prednisolone in a prospective, randomized, double-blind, placebo-controlled, multicenter trial. The audiometric parameters included pure tone and speech audiometry. Subjective parameters studied included hearing recovery, a pressure sensation in the affected ear, vertigo, and tinnitus. A 1-year follow-up was obtained. Hearing recovery for the whole group averaged about 35 dB and was independent of the severity of the initial hearing loss or vestibular involvement. Speech audiometry improved from 49% to 75%. After 12 months, pressure sensation and vertigo decreased to 15.6% (acyclovir) and 10.3% (placebo) and 12.5% (acyclovir) and 10.7% (placebo), respectively. Tinnitus decreased slightly, to 46.9% (acyclovir) and 55.2% (placebo), in the same period (p > .05 for all parameters). We conclude that no beneficial effect from combining acyclovir with prednisolone can be established in patients with ISSHL.

Oscillucusis and sudden deafness in a migraine patient

Migraine is a complex disease that includes neurologic, gastrointestinal and autonomic symptoms, although headache is most common feature. In a portion of cases headache is preceded by focal neurologic symptoms termed auras. Auditory symptoms only rarely occur as part of an aura. We describe a patient whose 13-year migraine history that included the abnormal perception an oscillation of the intensity of ambient sounds (oscillucusis). During a migraine attack immediately after oscillucusis, the patient developed acute and permanent sudden deafness. Clinical and neurologic examinations revealed only profound hearing loss in her left ear. Audiometric testing confirmed the sensorineural nature of the hearing loss. The clinical aspects and physiopathology of auditory symptoms in this case and in patients with migraine is reviewed.

Prognosis is predicted by early hearing improvement in patients with idiopathic sudden sensorineural hearing loss

The time-course of the recovery of the hearing level after treatment in 90 patients with idiopathic sudden sensorineural hearing loss was examined. The improvement rate calculated relative to the hearing level of the opposite ear was investigated to estimate the hearing recovery. Follow-up audiograms were performed once per week for 1 month after treatment and once per month thereafter. There were two groups that differed with respect to the characteristics of hearing recovery. One group showed an improvement rate of over 50% at 1-2 weeks and a good improvement rate at 3 months after treatment. In the other group, the improvement rate did not reach 50% at 1-2 weeks, and the improvement rate was poor at 3 months after treatment. The patients with improvement rates of over 50% at 1-2 weeks had earlier initial visits and had mild hearing loss, whereas the patients with profound hearing loss had improvement rates under 50% and poor long-term prognosis. We conclude that the improvement rate at 1-2 weeks after treatment predicts the long-term prognosis for recovery of hearing level in patients with sudden sensorineural hearing loss.

[Idiopathic sudden deafness]

PURPOSE

Sudden idiopathic deafness is a sensorineural hearing loss with no recognized causes at the time of onset. The impairment site is usually localized in the cochlea, but some cases of retrocochlear lesions (e.g., cerebellopontine angle tumors, degenerative neural diseases, neuraxial ischemic lesions) can induce sensorineural deafness. The medical management of patients presenting with sudden deafness aims at detecting a causal mechanism, and at administering emergency therapeutic drugs. The diagnosis of idiopathic sudden deafness can be definitely made when no causes are found. Usually, the impairing mechanism involves the cochlea. The pathophysiology of this sensorineural alteration is still unknown. It is most likely that several mechanisms are associated together, their common point being an impairment to the feedback loop of the organ of Corti.

CURRENT KNOWLEDGE AND KEY POINTS

It is very likely that reactivation of neurotropic viruses and/or cochlear ischemia are frequent etiologies. Whatever the cause, the treatment is to be administered urgently, and consists of a high-dose corticotherapy at the least. Other treatments have never really proven to be effective. It is secondarily checked that no retrocochlear pathological processes, such as a cerebellopontine angle tumor, is present, in particular in young people.

FUTURE PROSPECTS AND PROJECTS

One of the current objectives is to determine when cochlear ischemia is involved, in a mini-invasive manner, such as with laser Doppler flowmetry, so that the treatment can be optimized. From a therapeutic point of view, early acoustic protection has been proven to be effective in cases of cochlear ischemia in small laboratory animals. Its efficacy in case of sudden deafness, non-exclusive of other causes than ischemia, is being assessed in a multicentric project.

Long-term changes in off-lesion endocochlear potential after induction of localized lesions in the lateral wall

Localized lesions were produced in various turns of the guinea pig cochlea by means of a photochemical reaction between systemically administered rose bengal dye and green light illumination. The endocochlear potential (EP) was measured at various off-lesion sites, and a morphological examination was performed. In a previous study, this same investigation was done at 3 days, at which time all sites apical to the lesion showed significant EP depression, and damage to the stria vascularis at the lesion was ongoing. In the present 2-week study, the apical EP values were not different from the basal values, and all experimental values were essentially the same as the EP values found in control animals. Morphological examination revealed that the previously damaged structures were greatly repaired. Localized damage and early apical EP depression followed by damage repair and eventual EP recovery could account for the clinical course of certain cases of idiopathic sudden hearing loss involving low-tone deafness.

Magnetic resonance imaging of the membranous labyrinth during in vivo gadolinium (Gd-DTPA-BMA) uptake in the normal and lesioned cochlea

MRI with a T1 contrast agent was used to investigate the normal and noise-damaged cochlea. The time course and distribution of the in vivo uptake of the gadodiamide chelate bound paramagnetic Gd ion (GdDTPA-BMA) throughout the membranous labyrinth of normal and impulse noise-damaged guinea pig cochleae were measured by MRI at 4.7T. Simultaneous signal enhancement of the basal, medial and apical scala tympani (ST) and scala vestibuli (SV) was observed within 10 min following i.v. injection, reaching maximum levels at around 100 min. ANOVA and post hoc paired t-tests showed statistically significant differences in the levels and rates of Gd uptake-enhancement between the scalae. The ST revealed the most rapid and extensive enhancement throughout the period of active Gd uptake, while the SV showed comparatively slower and less enhancement, and the intact scala media (SM) indicated insignificant enhancement. The in vivo Gd penetration and enhancement of the membranous SM increased significantly in the noise-damaged cochlea, suggesting lesioning of the cochlear membranes.

Auditory dysfunction in stroke

The auditory and vestibular systems share the same end organ and cranial nerve, yet vestibular signs and symptoms are common with stroke, whereas hearing disturbances are much less frequent. Several reasons would appear to account for this striking dissimilarity. One is that the auditory pathway is less ubiquitous than the vestibular pathways. The likelihood that a stroke involves the auditory pathway is, therefore, less on this basis alone. A second difference, to our knowledge not previously reported, is that the auditory pathway is often spared by the most common strokes. This is because major parts of the auditory pathway, such as the cochlear nucleus, inferior colliculus and medial geniculate body, have multiple sources of blood supply. A third well-recognized factor is the redundancy of the central auditory system and its strong bilateral representation above the level of the cochlear nuclei. Consequently, rostral to the cochlear nuclei gross deficits in hearing, such as those measured by standard pure-tone audiometry and speech discrimination, only occur if lesions are bilateral. Furthermore, widespread bilateral lesions of the auditory system typically render the patient unable to respond or are incompatible with life. In contrast, language disorders are more frequent because language is usually unilaterally represented in the cortex. Certainly, cerebral stroke often includes the auditory system, resulting in various types of auditory disorders, but most hemispherical lesions produce subtle hearing dysfunctions that can only be detected with sophisticated psychoacoustic and electrophysiological testing. The purpose of this review is to provide an overview of the auditory system and its blood supply and to review how auditory processing can be affected by stroke. Psychoacoustic and electrophysiological test procedures for identifying lesions in the central auditory system are described. The literature of hearing disorders due to stroke is reviewed and illustrative cases are presented.

Idiopathic sudden sensorineural hearing loss: temporal bone histopathologic study

We microscopically examined the temporal bones of 12 ears with idiopathic sudden sensorineural hearing loss (iSSNHL), 10 ears with presbycusis, 11 ears with normal hearing, and 8 unaffected contralateral ears of patients with iSSNHL. The degeneration of the spiral ligament, vascular stria, hair cells, dendrites, and apical spiral ganglion cells was greater in ears with iSSNHL than in the other groups. The apical ganglion cells were significantly more affected than the basal ganglion cells, and the spiral ganglion cell loss increased as a function of duration of iSSNHL. Cochlear ossification was found in 1 ear with iSSNHL, and hydrops in 2. These findings suggest a viral rather than a vascular or ruptured inner ear membrane origin for iSSNHL.

Changes in off-lesion endocochlear potential following localized lesion in the lateral wall

Endocochlear potential (EP) was measured at various off-lesion sites after a small focal lesion was made in the lateral wall of the guinea pig cochlea. Lesions were produced by a photochemical reaction between systemically administered rose bengal and focused green light illumination. In 21 ears, continuous measurement for 30 min after onset of the reaction at turns apical or basal to the site of illumination revealed no significant changes in EP compared with the control value (p < 0.01). In another group of 43 ears, EP was measured at 3 days post-illumination. A significant decline was seen at every site located apical to the lesion (p < 0.001). Conversely, no significant change was measured at any site located basal to the lesion. These findings suggest that the decrease in EP assumes the form of a gradient from the lower to upper turns in the guinea pig cochlea.

Value of Gd-DTPA-enhanced MR imaging of the labyrinth in patients with sudden hearing loss

Recent reports describe labyrinthine enhancement on MRI as a highly specific sign of labyrinthine disease. This paper reports 44 patients with unilateral sensorineural hearing loss (SNHL) and laboratory evidence of cochlear damage investigated with Gd-enhanced MR imaging. Enhancement of the cochlea was observed in only one patient with a lesion at the fundus of the internal auditory canal (IAC) that extended into the cochlea after Gd-DTPA administration. In one more patient, MR imaging demonstrated large vestibular aqueducts as underlying cause for his hearing loss, but no enhancement of the labyrinth was observed. No abnormal signal intensity on precontrast MR scans nor pathologic enhancement of the membranous labyrinth were identified in the other 42 patients. Gd-enhanced MR imaging appears to be insensitive in demonstrating labyrinthine disease and normal examination findings in a patient with sudden SNHL cannot exclude damage at the cochlear level.

Temporal bone pathology in patients without caloric response

Pathologies of serial sections of 9 temporal bones from 6 patients without caloric response were studied. The patients died of epipharyngeal cancer, middle ear cancer, chronic renal failure with DIC, pancreatic cancer with DIC, multiple brain metastasis of pancreatic cancer, and leukemia. Under light microscopy, 8 ears showed pathologies in the vestibular end organs and the nerves. Possible causes of the lack of caloric responses in the 8 ears were endolymphatic hemorrhage, labyrinthitis, leukemic infiltration in the labyrinth, degeneration or disappearance of the vestibular sensory cells, reduction in the number of vestibular nerve fibers, and/or brainstem lesions. The remaining one ear did not show abnormal findings in the vestibular end organs or the nerves, but the patient had brainstem lesions. Four types of temporal bone pathologies were observed according to the lesion site responsible for the lack of caloric response; i) sensory type, ii) neural type, iii) mixed type and iv) central type.

Multiple sclerosis as the cause of sudden 'pontine' deafness

Sudden deafness is rarely ascribed to multiple sclerosis (MS). Sudden deafness and tinnitus were the initial symptoms of MS for the two patients described in this paper. A sensorineural hearing loss was present in one ear in both patients. Brainstem responses (BSRs) showed only the first three waves for the first patient, and only wave I for the second. Magnetic resonance imaging showed focuses of demyelination in the pons (case 1) and on the borderline between medulla and pons (case 2). The placement of plaques and the involvement of the BSR-generating acoustic afferent pathways are discussed. The hearing level measured by tonal audiometry recovered after 1 month in both patients and remained stable during 1 year. BSRs remained pathological after 1 month as well as after 1 year. Sudden hearing loss and tinnitus might be the initial symptoms of MS.

Aplastic anemia and sudden sensorineural hearing loss

In the present study, the clinical and audiological features of 3 patients with aplastic anemia who subsequently developed sudden sensorineural hearing loss are reported. These patients, for whom a diagnosis of aplastic anemia had previously been confirmed, suddenly developed profound or complete hearing loss accompanied by tinnitus and severe vertigo. In addition to erythrocytopenia and thrombocytopenia, serial hematological examinations revealed a marked drop in the platelet count prior to or just at the time of the acute episode of hearing loss. The prognosis for hearing recovery was poor in each patient. These findings suggest that intracochlear hemorrhage could be a mechanism underlying the sudden sensorineural hearing loss in these patients.

Clinical Correlates of Sudden Auditory-Vestibular Loss in a Cochlear Implant Patient

The precise electrophysiologic mechanism for sudden sensorineural auditory-vestibular loss has yet to be defined. No human models exist for this idiopathic phenomenon. A 67-year-old cochlear implant (CI) patient experienced what could be termed a “typical” acute sudden auditory-vestibular loss. Vestibular and CI electrical psychophysical changes were monitored over a 22-month period. Once the acute vestibular problems diminished, CI electrical parameters returned to near pre-episode levels. Some improvement occurred in rotational chair phase lag and asymmetry. While improving, platform posturography continued to show difficulty performing sensory organization tests V and VI. These clinical findings may imply that ganglion cell and neuronal population are responsible for the auditory findings in sudden auditory-vestibular loss. Secondly, a CI patient may serve as an ideal human model for further study of this phenomenon, should it occur.

Vestibular neuritis: an overview using a classical case

Although acute unilateral and/or bilateral vestibular paralysis, known as vestibular neuronitis, is the second most common cause of vertigo (the most common is benign paroxysmal positional vertigo (BPPV), it is fraught with controversies. The clinical symptoms and methods of treatment of vestibular neuronitis are well defined; however, the etiology and pathophysiology of this disorder are still sketchy. Furthermore, there are no specific diagnostic tests available, and unfortunately, there are no animal models for this disorder. The purpose of this paper is to present an overview of those controversies using a classical case of vestibular neuronitis.

Vestibular pathology of totally deaf ears

The temporal bone vestibular pathologies of 23 totally deaf ears (16 patients) were studied. Abnormal findings in the saccule were seen more often than in the other vestibular sensory organs. Abnormal findings in the vestibular ganglion cells were found in 7 ears. There were fewer ears with main damage in the hair cells than with main damage in the nerves.

Measurement of anaphylatoxin activity during surgery

We studied whether or not anaphylatoxins (ATs) are related to stress-related surgery by examining AT measurement in 51 patients undergoing operation. C3a plasma levels in patients who underwent the Caldwell-Luc operation increased from a pre-surgery concentration of 129 +/- 19 (mean +/- SD) ng/ml to 293 +/- 91 ng/ml during surgery under local anesthesia. However, pre- and post-surgery values were almost the same. No significant change occurred in the C5a plasma concentration at any time in patients undergoing the Caldwell-Luc operation, tonsillectomy or partial glossectomy. The mechanism underlying elevation in C3a during surgery is discussed.

The effect of anaphylatoxin component on inner ear damage

It has already been reported that anaphylatoxin (AT) is closely related to inner ear lesions. In this study the pathology of inner ear damage caused by AT was investigated in Hartley strain and C4 deficient guinea pigs (C4D-GP). Although the biological activity of C3a and C5a is strong, it is of short duration, and the resulting ear damage is considered to be reversible. Because of the cellular degeneration caused by this slight damage, the damage owing to continuously activated C4a is thought to be irreversible, that is, atrophy in the stria vascularis, degeneration and sloughing of the cochlear neurons, and stretching of Reissner's membrane, and C4a is therefore considered to be requisite for the manifestation of inner ear damage.

Investigations into the cause of vertigo in sudden sensorineural hearing loss

In this light microscopic study of the temporal bone, an attempt has been made to find a morphologic correlate of vertigo associated with idiopathic sudden sensori-neural hearing loss (ISSHL). Hair cell densities of the three cristae and both maculae, as well as vestibular ganglion cell (neuronal) count estimation, was done in nine ears that had documented histories of ISSHL. There were five ears with vertigo and four without. These quantitative data--i.e., hair cell densities and neuronal counts, of the vertiginous ears (group I) and nonvertiginous ears (group II)--was compared by histograms and statistically. Additionally, in each of the two groups, the data from three opposite normal hearing ears were taken as a control and used for comparison with the ISSHL ears. The differences between the vertiginous, nonvertiginous, and control ears were not significant at the 0.01 level, indicating that the vertigo was not caused by hair cell or neuronal degeneration. Gross morphologic alterations in the vestibular system, such as membrane ruptures, endolymphatic hydrops, etc., were also assessed, but no clear-cut pathology was identified in the vertiginous and nonvertiginous ears. The absence of a light microscopic morphologic correlate for vestibular disturbances associated with ISSHL suggests that the symptoms could result from ultrastructural changes in the hair cells and their synapses or from biochemical alterations in their environment.

Red blood cell deformability in sudden sensorineural deafness: another aetiology?

Red blood cell deformability (RCD) was measured by a filtration technique in 12 patients with sudden sensorineural deafness. Five patients had reduced deformability, including 3 out of 4 patients with a recent upper respiratory tract infection. This may be an important factor in sudden deafness, more likely as a complicating factor of other disorders rather than as a truly primary aetiology. Factors and diseases which alter RCD are discussed and a possible link between the viral and vascular causes of idiopathic sudden deafness is suggested. While several lines of therapy seem promising there is still no clinically proved method for improving RCD. With the development of an acceptable therapeutic regimen, we feel that the possibility of reduced RCD should be considered and that a deformability test be included in the work-up of patients with a sudden sensorineural hearing loss.

The efficacy of Lasix-vitamin therapy (L-V therapy) for sudden deafness and other sensorineural hearing loss

The efficacy of Lasix-vitamin therapy (L-V therapy) for sudden deafness (SD) was compared with that of conventional therapeutic regimens. There was no significant difference in efficacy between the two therapies. However, in fresh cases (within 7 days from onset of SD), L-V therapy gave a cure rate of 42.3% and an effectiveness rate of 88.4%, these rates being higher than those obtained with conventional therapy; and in cases treated within 4 weeks, L-V therapy was significantly more effective than conventional therapy. Besides, in cases with severe hearing loss (more than 70 dB hearing level) or vestibular symptoms, which were important factors of prognosis, L-V therapy proved more efficient. The efficacy of L-V therapy for other sensorineural hearing loss was also evaluated. In Meniere's disease, L-V therapy proved effective in 45.9% of cases, but with only a 20-30% effectiveness rate in other cases, e.g. idiopathic hearing loss, head and neck injury, noise-induced hearing loss and chronic otitis media.

Probational treatment of sudden deafness with prostacyclin: a pilot study

Sudden idiopathic hearing loss has occasionally been supposed to be caused by a disturbed microcirculation in the inner ear of unknown origin. Little is known about the regulation of cochlear blood flow and the effectiveness of drugs in cochlear microcirculation. Because animal experiments gave evidence that prostacyclin (PGI2) might be one biochemical substratum of local regulators in the flow of blood in the stria vascularis, 11 patients with sudden idiopathic hearing loss were treated once for 6 h with prostacyclin (10 ng/kg body weight/min) in a first open clinical trial. In most cases prostacyclin increased hearing level (mean value: 7.4 dB/frequency/day) more than a standard therapy with pentoxifylline. The substitution of PGI2 could be another indication of a rheologic disorder--whether per se or within a larger context of inflammation-like interaction--in the inner ear of patients with sudden hearing impairment.

Idiopathic sudden sensorineural hearing loss and postnatal viral labyrinthitis: a statistical comparison of temporal bone findings

Although the cause of idiopathic sudden sensorineural hearing loss remains uncertain, a viral origin has been suggested in many cases on the basis of anamnestic microbiologic and pathologic data. Twenty-two temporal bone specimens from 18 patients who during life suffered a sudden partial or complete sensorineural hearing loss were studied. On the basis of clinical data, these cases were assigned to one of three diagnostic categories, and the temporal bones were studied by light microscopy and serial section analysis. The implications of the histopathologic findings for the pathogenesis of idiopathic sudden sensorineural hearing loss are discussed.

The vessels of the stria vascularis: quantitative comparison of three rodent species

The stria vascularis (SV) was quantitatively compared in three species commonly used in auditory research: guinea pig, mouse and gerbil. Measurements were obtained for surface area, cross-sectional area, length, width and thickness of SV. Surface area and length were proportional to the overall size of the cochlea in each species, but there was no significant difference between species in mean cross-sectional area. In guinea pig and mouse, there was no significant difference in thickness (endolymphatic surface to spiral ligament) and a similar pattern was observed for width (Reissner's membrane to spiral prominence): the width of SV increased from the apical end to a point 80% of the distance from the apex, then decreased to the basal end of SV. The thickness of gerbil SV was significantly less (P less than 0.001) and there was less of a gradient in width as compared to guinea pig and mouse. The vessels of SV were compared in terms of vascular density (vessels per unit area), rbc density (red blood cells per unit area), R/V (rbc density/vascular density), inter-vessel spacing and vessel diameter. Highly significant (P less than 0.001) differences between species were found in vascular density, RBC density and vessel diameter, but there were no differences between species for R/V or inter-vessel spacing. The results of this study may reflect differences in the metabolic requirements of SV among different species.

Hypaque and steroids in the treatment of sudden sensorineural hearing loss

While the origins of sudden sensorineural hearing loss remain unproven and treatment empirical, the most appropriate therapy remains a matter of controversy. In this paper we have analysed the current forms of treatment, i.e. diatrizoate meglumine, steroids and a vasodilator. The results suggest that although several related factors were shown to indicate a good prognosis regardless of the therapy, none of the currently available regimens produces consistently better results than the spontaneous recovery rate of 65% reported by Mattox & Simmons.

Clinical treatment of vascular inner ear diseases

A multitude of general disorders of the vascular system may also affect the blood circulation of the cochlea and cause symptoms such as fluctuating or permanent hearing loss. Such is the case for arteriosclerosis combined with hypertension or hypotension, collagenosis, and diabetes. Blood disorders, like leukemia, sickle cell anemia, and polycythemia, and infectious diseases involving the blood vessels, such as lues, may also present their primary symptoms in the ear. The otorhinolaryngologist must be able to establish the correct diagnosis and refer patients requiring more general treatment to other specialists. The use of specific vasoactive treatment should be continued to those patients with symptoms of acute or fluctuating hearing loss, vertigo, or tinnitus who exhibit no other signs. Modern techniques for cochlear blood flow measurements have verified that several of the treatment protocols in use, which have a sound theoretical background, do indeed increase cochlear blood flow.

Total bilateral hearing loss as a complication of myeloma

A 58-year-old lady relapsed from longterm remission of multiple myeloma and developed a sudden and complete hearing loss in the left ear followed two weeks later by the right ear. This permanent loss was almost certainly due to inner ear haemorrhages.

Acute profound deafness in Ramsay Hunt syndrome. Two case reports

Two patients with sudden progressive profound hearing loss resulting from Ramsay Hunt syndrome are reported. Case 1: A 63-year-old woman was admitted to Jichi Medical School Hospital with sudden, progressing deafness of the left ear, vertigo, sore throat, and hoarseness. An otoscopic examination revealed the external ear and the tympanic membrane to be normal. Pure-tone audiometry revealed profound deafness in the left ear. A horizontal nystagmus in the non-affected direction was observed by gaze nystagmus test. An endoscopic examination revealed herpetic vesicles and shallow ulcers on the left side of the pharynx and the larynx. There was complete paralysis of the left recurrent nerve. Hearing acuity of the left ear did not recover at all with steroid hormone therapy. Case 2: A 75-year-old man was referred to the ENT Clinic by a dermatologist for hearing evaluation in Ramsay Hunt syndrome. The man had noticed severe otalgia and sudden progressive deafness of the right ear approximately 2 weeks prior to admission. Physical examination revealed herpetic vesicles and ulcers in the right external ear and lateral neck. Complete paralysis of the right facial nerve was noted. Profound hearing loss in the affected ear was observed by pure-tone audiometry. A gaze nystagmus test revealed a horizontal nystagmus in the non-affected direction. No recovery of the cochlear function was noted following administration of antiviral drug. The pertinent literature is briefly reviewed.

Serological and clinical study of herpes simplex virus infection in patients with sudden deafness

A serosurvey for antibodies against type 1 and type 2 herpes simplex virus (HSV) was performed in consecutive sera collected from 61 patients with sudden deafness. A positive test for neutralizing antibody to type 1 HSV was found in 80% of patients and 77% of controls, a non-significant value. Almost all the patients possessing neutralizing antibody had complement-fixing antibody too, which some controls would have lost in the course of time. The kinetic survey of the antibody titers during the clinical course demonstrated constant levels of these antibodies. It is suggested that there may be some relationship of HSV to sudden deafness and that reactivation of a latent infection may play an important role in the etiology of this disease. We found some relationship between the serological data and the clinical findings with respect to hearing recovery.

Effect of upper respiratory infection on hearing in the ferret model

In an effort to develop an adult animal model for acquired viral-induced hearing loss, three groups of mature ferrets were inoculated intranasally with respiratory viruses (influenza A/Port Chalmers, influenza B/Mass, and parainfluenza I), which have been implicated as causative agents in idiopathic sudden hearing loss (ISHL). All ferrets challenged with influenza A/Port Chalmers (A/PC) exhibited clinical signs of infection, but neither of the other two groups exhibited such signs. Conductive and/or sensorineural hearing losses were demonstrated in eight of 15 ferrets challenged with influenza A/PC and four of 10 ferrets in the group challenged with influenza B/Mass by brainstem auditory-evoked responses (BAERs) and acoustic immittance. None of the four ferrets infected with parainfluenza I demonstrated auditory dysfunction. When auditory changes were observed, nasal washes were performed, and tissues of the middle and inner ears were collected for viral assay and morphologic examination. All ferrets demonstrating auditory changes were shown to be infected by isolation of virus from nasal tissues. Virus was isolated from eustachian tube tissue in six of the eight ferrets infected with influenza A/PC, which also demonstrated altered BAERs and one of the four infected with influenza B/Mass, which also had auditory changes. Virus was isolated from the middle ear of two ferrets infected with influenza A/PC and from the inner ear of another two ferrets from the same group. These data suggest that influenza A/PC has a greater effect on auditory function in the ferret model than either influenza B/Mass or parainfluenza I and that the ferret may be an appropriate adult model to examine the etiologic role of viral upper respiratory tract infections in some acquired hearing impairments.

Methodological aspects of quantitative study of spiral ganglion cells

The literature contains little numerical information on the population of spiral ganglion cells from normal-hearing adults. We present a method for quantitative analysis of spiral ganglion cells. We used not only the total counts of the neurons but also divided the spiral ganglion into four segments as described by Otte et al. Nine perilymphatic perfused temporal bones from 5 adult patients with normal hearing for age were examined. The largest population of spiral ganglion cells was always in segment II and fewest in segment I. There is no correlation between the total count and the length of the cochlea.

Effect of hemodilution on cochlear blood flow measured by laser-Doppler flowmetry

The effect of hemodilution on cochlear blood flow was studied in guinea pigs. Hypervolemic hemodilution was accomplished by infusion of 10 mg/kg of body weight of dextran 40 (as a 10% solution in normal saline), which resulted in an average hematocrit decrease from 43 to 32%. Normovolemic hemodilution was accomplished by repeated exchange of 3 ml of whole blood with 3 ml of dextran 75 (6% solution in normal saline) every 5 minutes until the hematocrit reached approximately 5%. The cochlear blood flow was measured by laser-Doppler flowmetry. Irrespective of the dilutional technique, the cochlear blood flow increased as hematocrit decreased to a maximum of approximately 200% of original value at a hematocrit near 20%. The blood pressure was not significantly influenced by the hemodilution until hematocrit values below 15% were reached. The enhancement of cochlear blood flow is consistent with the expected reduction of blood viscosity and increase of cardiac output. Normovolemic hemodilution with dextran 75 causes a smaller disturbance of systemic circulation physiology and has a more lasting effect than dextran 40 infusion.

The relationship of the herpesvirus family to sudden hearing loss: a prospective clinical study and literature review

The herpesvirus family is associated with sudden hearing loss syndrome and the evidence includes clinical findings (HV-Z), temporal bone studies (CMV and HV-Z), and serologic studies. The data presented demonstrate that herpes infections, in association with sudden viral hearing loss, occur as part of a multiple viral infection in 70% of instances. This feature is unique to the herpesvirus infections when compared to other neurotropic viral agents. The study also demonstrates that the variables of viral hearing loss, such as degree of hearing loss, percentage of recovery, or the incidence of vertigo are unaffected by the presence of herpesvirus infection. Mechanisms for inner ear injury may be influenced by temporary alterations in cellular immunity secondary to simultaneous viral infections as well as the native virulence of the infecting herpesvirus.

Animal models of inner ear vascular disturbances

Animal models of vascular disorders are identified or developed for the evaluation of functional deficits and morphologic alterations. This information will serve a useful purpose for a better understanding of sudden deafness, Meniere's disease, and presbycusis. The study of microcirculation of the inner ear vessels reveals that their responses to various stimuli, such as anoxia, sympathetic nerve stimulation, hypothermia, and drugs, are different from those of the middle ear vessels. In sudden occlusion of the major vascular supply to the inner ear, the cochlea is found to be more vulnerable than the vestibular labyrinth; outer and inner hair cells and stria vascularis are most often affected. Animal models for Meniere's disease are also described, and the importance of vascularity at the endolymphatic duct and sac is discussed from an etiologic viewpoint. In presbycusis, animal models show sensory cell and spiral ganglion cell atrophies in different locations than in human cochleas, and the relationship between these atrophies and vascular impairments is not clear at the present time.

The pathology of idiopathic sudden sensorineural hearing loss

We examined the temporal bone pathologies in 12 ears with idiopathic sudden sensorineural hearing loss, and found that the lesions present in these specimens and in 10 others reported in the literature are similar to lesions occurring in known cases of viral cochleitis. These lesions are unlike those resulting from known vascular causes.

Acoustic neuroma presenting as sudden hearing loss with recovery

In our series of patients operated on for acoustic neuromas at New York University Medical Center between 1974 and 1983, 13% (17 of 133) had sudden hearing loss. Of these, approximately 23% (four of 17) had recovered auditory function before acoustic neuroma extirpation. Three patients spontaneously recovered, while one improved with steroid therapy. Contrast computerized tomography demonstrated a widened internal auditory canal and evidence of cerebellopontine angle tumor, respectively, in 88% and 59% of patients with sudden hearing loss and acoustic neuroma. Clinical characteristics suggesting acoustic neuroma as the cause of sudden hearing loss with or without auditory recovery could not be identified in our series. Our data support the rationale that patients with unilateral sudden hearing loss, even with recovery, must be evaluated for a possible cerebellopontine lesion.

Vestibular findings in sensorineural hearing disorders. Results of caloric, oculomotor and hearing tests in 205 patients with unilateral hearing dysfunction

In 205 patients with unilateral hearing loss, 117 of cochlear and 88 of retrocochlear origin, thorough audiovestibular examinations were performed to establish the occurrence and severity of vestibular dysfunction. The results were also analysed with the aim of determining the relationships between the severity of the hearing loss, the etiology and the topical location of the hearing disorder, on the one hand, and vestibular dysfunction, recorded as reduced caloric sensitivity and occurrence of oculomotor disturbances, on the other. No correlation was found between severity of hearing loss and recordable vestibular dysfunction, in either the cochlear or retrocochlear group of patients, or in the etiological subgroups of these main groups. With respect to the relations between the topic locations of the lesions and the results of vestibular tests, distinct characteristics were observed. In the affected ears, totally extinguished caloric reactions were more than six times as frequent in the retrocochlear group as in the cochlear group and appeared as a specific but rather insensitive sign of acoustic neurinoma. Oculomotor disturbances were only exceptionally observed in patients with cochlear lesions, but were noted in nearly half of the retrocochlear group; when only those patients with lesions of the brain stem or cerebellum were considered, all were found to exhibit such disturbances. The relations between audiometric hearing test pattern, caloric sensitivity and oculomotor disturbances seem to form interesting diagnostic paradigms of great value for the topical localization of audiovestibular disorders.

Histopathological features of the spiral ganglion and cochlear nerve in temporal bones from three patients with profound hearing loss

In the following study the condition of the spiral ganglion and the cochlear nerve of ears from patients suffering from profound hearing loss is described. The number of spiral ganglion cells has been related to the clinical diagnosis. The number of spiral ganglion cells in the two temporal bones of a patient with Neomycin ototoxicity was almost normal. A reduction of less than one-third of spiral ganglion cells has been observed in the temporal bones of a child who died after a bacterial labyrinthitis. The temporal bone with a Mondini dysplasia revealed a pronounced reduction of ganglion cells of more than two-thirds. The cochlear nerve trunk in the internal auditory canal appeared normal in all three cases. The present findings are discussed in respect to the degenerative behaviour of the cochlear neural elements in human being compared to animals.

Viral and epidemiologic studies of idiopathic sudden hearing loss

The relationship between viral seroconversions and idiopathic sudden hearing loss (ISHL) is studied. Compared with our control group, the incidence of viral seroconversions is greater among ISHL patients, both for single and multiple viral infections. There was a significantly greater number of patients with seroconversions to mumps, rubeola, varicella-zoster, cytomegalovirus, and influenza B. We were unable to find a relationship between viral seroconversion and type or degree of hearing loss, vertigo, or chance for recovery. The incidences of viral conversion and sudden hearing loss track one another closely, suggesting that viral infection is a major cause of ISHL. During this 3-year study in Boston, ISHL was most prevalent in the spring.

Cochlear aqueduct radiographic anatomy in temporal bone preparations and in sudden hearing loss

Sudden sensorineural hearing loss appears to have many possible etiologic factors. Shea has presented work indicating that a large cochlear aqueduct (CA) is frequently present on the side of an idiopathic sudden sensorineural hearing loss (ISHL). However, Valvassori, on performing temporal bone tomographic studies on several hundred patients complaining of ISHL, has not found enlargement of the CA in a statistically significant number of these cases. In an attempt to resolve this discrepancy, a single blind study was performed utilizing temporal bone polytomography to evaluate the presence or absence of the CA in 22 adult patients. One-half of these patients had a history of ISHL, while the remaining patients had other complaints as an indication for tomography. In all cases, the CA was identified. The CA was felt to be enlarged in 1 patient suffering from ISHL, in the nonaffected ear of 1 patient with unilateral ISHL, and in 2 control patients. There was, therefore, no positive correlation between CA enlargement and the occurrence of ISHL. In order to further elucidate the radiologic anatomy of the CA, 9 pairs of adult temporal bones removed at autopsy were studied by polytomography after cannulation and injection of radiopaque material. Measurements of the dimensions of the CA and its radiographic anatomy are discussed and compared to measurements obtained from histopathologic evaluation of the temporal bone.

Deafness in cryoglobulinemia

We present a histopathological study of 44-year-old female with essential cryoglobulinemia. She had suffered from purpura and ulcer in winter, bilateral tinnitus and progressive hearing loss. An audiogram taken a week before her death showed bilateral total deafness. In the cochlea of the left temporal bone, the organ of Corti was either missing or present as a mound. The stria vascularis was atrophic throughout the cochlea. The tectorial membrane showed drooping and encapsulation. Reissner membrane was in the normal position. Eosinophilic precipitate was noted in the scala media at the site where Reissner membrane bulged. The spiral ganglion cells were well preserved. In the lower basal turn, there was fibrosis and ossification intermingled in the scala tympani. Ossification was most marked near the basal end. The semicircular canals and vestibule were almost totally ossified and fused with surrounding bone. There was a small, cyst-like structure in the vestibule containing eosinophilic fluid. Our findings indicate that the deafness was the result of circulatory disturbance due to cryoglobulinemia. To our knowledge, this is the first cryoglobulinemia case in which temporal bone findings are reported.

Sudden deafness due to infection by Mycoplasma pneumoniae

A case is described of sudden unilateral deafness associated with Mycoplasma pneumoniae. The hearing function of the patient returned to normal on the third day of treatment with tetracycline. M pneumoniae is a common causative agent of protean respiratory disease and the true incidence of hearing loss in these cases may be higher than reflected by the occasional reports. Therefore, appropriate laboratory studies should be included in the evaluation of sensorineural loss associated with diverse infections of the respiratory tract. Prompt diagnosis facilitates the administration of specific treatment. However, the actual contribution of tetracyclines to restoration of hearing cannot be assessed.

Demyelinating disease as the assumed cause of hearing loss and vertigo. A case report with light- and electron-microscopic findings

A patient initially presenting typical symptoms of idiopathic sudden deafness later developed disabling episodic vertigo, which led to translabyrinthine eighth nerve transection. Morphological examination of the removed cochlear nerve specimen revealed a demyelinating process in the neuroglial portion of the nerve. The major part of the peripheral, neurolemmal portion of the cochlear nerve was normal. The inferior vestibular nerve was fibrotic. The major part of the superior vestibular nerve was normal. Some of its peripheral bundles showed increased endoneurial fibrosis. It is suggested that a demyelinating process was the cause of the patient's symptoms.

The implication of viruses in idiopathic sudden hearing loss: primary infection or reactivation of latent viruses?

Seventy-seven paired serum samples from patients with known idiopathic sudden hearing loss (ISHL) were surveyed using viral serologic methods. Fifteen different viruses and Mycoplasma pneumonia were the agents tested. We determined an incidence of 65% (49/77) of documented significant seroconversions to one or more of the agents surveyed. Multiple agents were involved in 24 of the 49 positive cases we studied. Influenza virus Group B in 14 (18%) and rubeola in 12 (16%) were the most prevalent, followed by Herpes simplex type 1 in 6 (8%), mumps in 6 (8%), influenza Group A3 in 6 (8%), rubella in 5 (7%), and cytomegalovirus (CMV) in 5 (7%).