There is no consensus in the literature regarding the relationship between high-resolution computed tomography findings and hearing thresholds in pure-tone audiometry in otosclerosis. This study evaluated the association between high-resolution computed tomography findings and pure-tone audiometry in otosclerosis in the spongiotic phase.

A cross-sectional study was conducted of 57 ears with surgically confirmed stapes fixation and tomographic findings. Air conduction and bone conduction thresholds on audiometry, and air–bone gap, were analysed.

There were no correlations between sites affected by otospongiosis and air conduction threshold, bone conduction threshold or air–bone gap in the analysed tomographic images, but the diameter of the otospongiotic focus was greater in the presence of extension of the otospongiotic foci to the cochlear endosteum.

There were no relevant associations between high-resolution computed tomography findings and pure-tone audiometric measurements. However, the diameter of the otospongiotic focus was greater in the presence of extension of the otospongiotic foci to the cochlear endosteum.

To determine the effect of cochlear dimensions on cochlear implant selection in cochlear hypoplasia patients.

Temporal bone computed tomography images of 36 patients diagnosed with cochlear hypoplasia between 2010 and 2016 were retrospectively reviewed and compared with those of 40 controls without sensorineural hearing loss.

Basal turn length and mid-modiolar height were significantly lower in the cochlear hypoplasia patients with subtypes I, II and III than in the control group (p < 0.001). Mid-scalar length was significantly shorter in subtype I–III patients as compared with the control group (p < 0.001). In addition, cochlear canal length (measured along the lateral wall) was significantly shorter in subtype I–IV patients than in the control group (subtypes I–III, p < 0.001; subtype IV, p = 0.002)

Cochlear hypoplasia should be considered if basal turn length is less than 7.5 mm and mid-modiolar height is less than 3.42 mm. The cochlear implant should be selected according to cochlear hypoplasia subgroup. It is critically important to differentiate subtype II from incomplete partition type I and subtype III from a normal cochlea, to ensure the most appropriate implant electrode selection so as to optimise cochlear implantation outcomes.

To determine the prevalence and distribution of inner-ear malformations in congenital single-sided deafness cases, as details of malformation type are crucial for disease prognosis and management.

A retrospective study was conducted of 90 patients aged under 16 years with congenital single-sided deafness. Radiological findings were evaluated using computed tomography and magnetic resonance imaging. Inner-ear malformations were identified and cochlear nerve status was determined in affected ears.

Out of 90 ears, 42 (46.7 per cent) were found to have inner-ear malformation. Isolated cochlear aperture stenosis was the most common anomaly (n = 18, 20 per cent), followed by isolated cochlear aperture atresia (n = 11, 12.2 per cent) and cochlear hypoplasia (n = 7, 7.8 per cent). Cochlear nerve deficiency was encountered in 41 ears (45.6 per cent). The internal auditory canal was also stenotic in 49 ears (54.4 per cent).

Inner-ear malformations, especially cochlear aperture anomalies, are involved in the aetiology of single-sided deafness more than expected. The cause of single-sided deafness differs greatly between congenital and adult-onset cases. All children with single-sided deafness should undergo radiological evaluation, as the prognosis and management, as well as the aetiology, may be significantly influenced by inner-ear malformation type.

To propose a new classification of inner-ear anomalies that is more clinically oriented and surgically relevant: the SMS (Sawai Man Singh) classification of cochleovestibular malformations.

A retrospective multicentric study was conducted of 436 cochlear implantations carried out in 3 Indian tertiary care institutes. Patients with anomalous anatomy were included and classified, as per the new SMS classification, into cochleovestibular malformation types I, II, III and IV, based on cochlear morphology, modiolus and lamina cribrosa.

There were 19, 23, 8 and 4 patients with cochleovestibular malformation types I, II, III and IV, respectively. Two-year post-operative Meaningful Auditory Integration Scale scores were statistically analysed.

This new classification for inner-ear anomalies is a simpler, more practical, outcome-oriented classification that can be used to better plan the surgery. These merits make it a more uniform classification for recording results.

To evaluate the presence of endolymphatic hydrops in patients with immune-mediated inner-ear disease.

The presence of endolymphatic hydrops was prospectively evaluated in 17 patients clinically diagnosed with secondary (n = 5) or primary (n = 12) immune-mediated inner-ear disease, who attended the ENT department of a tertiary care centre for evaluation or treatment over the previous year. All patients underwent magnetic resonance imaging of the temporal bone.

Intratympanic gadolinium three-dimensional magnetic resonance imaging diagnosed hydrops in 11 of 12 patients with primary immune-mediated inner-ear disease (92 per cent). Of these, seven patients (64 per cent) presented only cochlear (n = 5) or predominantly cochlear (n = 2) hydrops. A positive magnetic resonance imaging result was observed in only one of five patients with secondary immune-mediated inner-ear disease (20 per cent).

This study confirms the presence of endolymphatic hydrops in immune-mediated inner-ear disease patients. The virtual absence of hydrops in patients with secondary immune-mediated inner-ear disease is remarkable, although firm conclusions cannot be drawn; this should be explored in a multicentre study with a larger sample of patients. A different immune reaction without development of endolymphatic hydrops should not be ruled out in secondary immune-mediated inner-ear disease patients.

The bony cochlear nerve canal is the space between the fundus of the internal auditory canal and the base of the cochlear modiolus that carries cochlear nerve fibres. This study aimed to determine the distribution of bony labyrinth anomalies and cochlear nerve anomalies in patients with bony cochlear nerve canal and internal auditory canal atresia and stenosis, and then to compare the diameter of the bony cochlear nerve canal and internal auditory canal with cochlear nerve status.

The study included 38 sensorineural hearing loss patients (59 ears) in whom the bony cochlear nerve canal diameter at the mid-modiolus was 1.5 mm or less. Atretic and stenotic bony cochlear nerve canals were examined separately, and internal auditory canals with a mid-point diameter of less than 2 mm were considered stenotic. Temporal bone computed tomography and magnetic resonance imaging scans were reviewed to determine cochlear nerve status.

Cochlear hypoplasia was noted in 44 out of 59 ears (75 per cent) with a bony cochlear nerve canal diameter at the mid-modiolus of 1.5 mm or less. Approximately 33 per cent of ears with bony cochlear nerve canal stenosis also had a stenotic internal auditory canal and 84 per cent had a hypoplastic or aplastic cochlear nerve. All patients with bony cochlear nerve canal atresia had cochlear nerve deficiency. The cochlear nerve was hypoplastic or aplastic when the diameter of the bony cochlear nerve canal was less than 1.5 mm and the diameter of the internal auditory canal was less than 2 mm.

The cochlear nerve may be aplastic or hypoplastic even if temporal bone computed tomography findings indicate a normal cochlea. If possible, patients scheduled to receive a cochlear implant should undergo both computed tomography and magnetic resonance imaging of the temporal bone. The bony cochlear nerve canal and internal auditory canal are complementary structures, and both should be assessed to determine cochlear nerve status.

Electrode insertion during cochlear implantation causes cochlear damage and apoptosis. Insulin-like growth factor applied locally was investigated in 21 rats.

In the sham group, an intracochlear dummy electrode was inserted through the round window. In the control group, after the same insertion procedure, saline-soaked porcine skin gelatine was placed on the round window. In the study group, insulin-like growth factor 1 soaked gelatine was placed on the round window. Auditory brainstem response thresholds were measured and histopathological examination was performed.

In the study group, at 2–4 kHz, one rat had deterioration, one showed improvement and the rest had stable thresholds 14 days after intervention. At 6 kHz, four rats showed improvement and the rest remained stable. At 8 kHz, four showed improvement, one had deterioration and two remained stable. In the other groups, hearing loss deteriorated in about half of the rats and remained stable in the rest. The mean post-operative 6 kHz threshold was significantly lower than that immediately after the intervention in the study group, contrary to the other groups. The study group had significantly better mean histopathological grading than the other groups.

Local insulin-like growth factor 1 application may protect hearing after cochlear implantation.

This study aimed to define the characteristics and use of ocular and cervical vestibular evoked myogenic potentials for evaluating paediatric cochlear implant candidates.

Ocular and cervical vestibular evoked myogenic potentials of 34 paediatric cochlear implant candidates were analysed. All patients also underwent a routine audiological examination, including computed tomography.

In all, 27 patients with normal inner-ear structures had absent or impaired vestibular evoked myogenic potential responses. In paediatric candidates with inner-ear malformations, ocular and cervical vestibular evoked myogenic potentials had lower thresholds and higher amplitudes. Vestibular evoked myogenic potential responses in this cohort were classified into three groups. There was significant concordance between vestibular evoked myogenic potentials and temporal bone computed tomography findings.

Ocular and cervical vestibular evoked myogenic potential waveforms were different in paediatric candidates with normal and abnormal inner-ear structures. Therefore, vestibular evoked myogenic potential responses can indicate temporal bone structure.

Pre-operative radiological identification of facial nerve anomalies can help prevent intra-operative facial nerve injury during cochlear implantation. This study aimed to evaluate the incidence and configuration of facial nerve anomalies and their concurrence with inner-ear anomalies in cochlear implant candidates.

Inner-ear and concomitant facial nerve anomalies were evaluated by magnetic resonance imaging and temporal high-resolution computed tomography in 48 children with congenital sensorineural hearing loss who were cochlear implant candidates.

Inner-ear anomalies were present in 11 out of 48 patients (23 per cent) and concomitant facial nerve anomalies were present on 7 sides in 4 patients (7 per cent of the total). Facial nerve anomalies were accompanied by cochlear or vestibular malformation.

Potential facial nerve abnormalities should always be considered in patients with inner-ear anomalies. Pre-operative facial nerve imaging can increase the surgeon's confidence to plan and perform cochlear implantation. Magnetic resonance imaging should be used to detect inner-ear anomalies; if these are identified, temporal high-resolution computed tomography should be used to evaluate the facial nerve.

Since the development of intratympanic aminoglycoside in the 1950s, otologists have been able to chemically ablate the vestibule. We present the results of using low-dose intratympanic gentamicin to treat Ménière's disease.

A retrospective review was performed of all patients who underwent low-dose intratympanic gentamicin therapy over seven years. Data on gender, age, number of procedures, pure tone audiometry and symptom control were analysed.

In all, 38 patients underwent low-dose intratympanic gentamicin therapy. These comprised 25 females and 13 males, with an average age of 58.4 years. Hearing was preserved in 87.5 per cent of patients, with no significant difference before and after treatment (p = 0.744). In all, 85.7 per cent of patients had complete or substantial symptom control (classes A and B, respectively).

Low-dose intratympanic gentamicin therapy was effective in controlling the symptoms of Ménière's disease patients, while preserving hearing.

There has been no previous research to demonstrate the risk of noise-induced hearing loss in industry in Nepal. Limited research on occupational noise-induced hearing loss has been conducted within small-scale industry worldwide, despite it being a substantial and growing cause of deafness in the developing world.

The study involved a cross-sectional audiometric assessment, with questionnaire-based examinations of noise and occupational history, and workplace noise level assessment.

A total of 115 metal workers and 123 hotel workers (control subjects) were recruited. Noise-induced hearing loss prevalence was 30.4 per cent in metal workers and 4.1 per cent in hotel workers, with a significant odds ratio of 10.3. Except for age and time in occupation, none of the demographic factors were significant in predicting outcomes in regression analyses. When adjusted for this finding, and previous noise-exposed occupations, the odds ratio was 13.8. Workplace noise was significantly different between the groups, ranging from 65.3 to 84.7 dBA in metal worker sites, and from 51.4 to 68.6 dBA in the control sites.

Metal workers appear to have a greater risk of noise-induced hearing loss than controls. Additional research on occupational noise-induced hearing loss in Nepal and small-scale industry globally is needed.

This paper describes the first reported case of progressive sensorineural hearing loss caused by azathioprine, which was reversed on stoppage of the drug.

A female patient with previously normal hearing presented with progressive sensorineural hearing loss after being started on azathioprine. Otological and neurological examination findings were unremarkable. After stopping the drug, the patient reported an improvement in hearing, which was confirmed on pure tone audiometry.

This previously unreported side effect of azathioprine is highlighted in order to increase clinical awareness. Early recognition of this adverse effect is important to minimise the possibility of permanent sensorineural hearing loss.

This study aimed to determine the effect of radiofrequency radiation generated by 900 and 1800 MHz Global System for Mobile Communications sources on cochlear development in the rat model.

Eight pregnant albino Wistar rats were divided into three groups: control, 900 MHz and 1800 MHz. The latter two groups of pregnant rats were exposed to radiofrequency radiation for 1 hour per day starting on the 12th day of pregnancy until delivery. The rats in the control, 900 MHz and 1800 MHz groups gave birth to 24, 31 and 26 newborn rats respectively. Newborn rats in the 900 MHz and 1800 MHz groups were exposed to radiofrequency radiation for 1 hour per day for 21 days after delivery. Hearing evaluations of newborn rats were carried out using distortion product otoacoustic emissions testing. Eight newborn rats were randomly selected from each group for electron microscopic evaluation.

Distortion product otoacoustic emission tests revealed no significant difference among the groups, but electron microscopic evaluation revealed significant differences among the groups with regard to the number of normal, apoptotic and necrotic cells.

The findings indicated cellular structural damage in the cochlea caused by radiofrequency radiation exposure during cochlear development in the rat model.

Professor Pietro Tullio was a director at the Laboratory of Experimental Physiology in Bologna during the early twentieth century. His experimental studies resulted in the description of the Tullio phenomenon, which is characterised by sound-induced vertigo and/or eye movements.

The experimental studies behind his contribution to vestibular physiology are described within this paper, as are some of the further developments that have been made.

Hereditary sensorineural hearing loss is the most frequently occurring birth defect. It has profound effects for the individual and is a substantial burden on society. Insight into disease mechanisms can help to broaden therapeutic options and considerably lower lifetime social costs. In the past few decades, the identification of genes that can cause this type of hearing loss has developed rapidly.

This paper provides a concise overview of the currently known genes involved in non-syndromic hereditary hearing loss and their function in the inner ear.

Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging of the inner ear after intratympanic injection of gadolinium, together with magnetic resonance imaging scoring of the perilymphatic space, were used to investigate the positive identification rate of hydrops and determine the technique's diagnostic value for delayed endolymphatic hydrops.

Twenty-five patients with delayed endolymphatic hydrops underwent pure tone audiometry, bithermal caloric testing, vestibular-evoked myogenic potential testing and three-dimensional magnetic resonance imaging of the inner ear after bilateral intratympanic injection of gadolinium. The perilymphatic space of the scanned images was analysed to investigate the positive identification rate of endolymphatic hydrops.

According to the magnetic resonance imaging scoring of the perilymphatic space and the diagnostic standard, 84 per cent of the patients examined had endolymphatic hydrops. In comparison, the positive identification rates for vestibular-evoked myogenic potential and bithermal caloric testing were 52 per cent and 72 per cent respectively.

Three-dimensional magnetic resonance imaging after intratympanic injection of gadolinium is valuable in the diagnosis of delayed endolymphatic hydrops and its classification. The perilymphatic space scoring system improved the diagnostic accuracy of magnetic resonance imaging.

This study aimed to: understand the effect that high intensity noise associated with drilling (during otological surgery) has on hearing in the contralateral ear; determine the nature of hearing loss, if any, by establishing whether it is temporary or persistent; and examine the association between hearing loss and various drill parameters.

A prospective clinical study was carried out at a tertiary centre. Thirty patients with unilateral cholesteatoma and normal contralateral hearing were included. Patients were evaluated pre-operatively and for five days following surgery using high frequency pure tone audiometry, and low and high frequency transient evoked and distortion product otoacoustic emission testing.

The findings revealed statistically significant changes in distortion product otoacoustic emissions at high frequencies (p = 0.016), and in transient evoked otoacoustic emissions at both low and high frequencies (p = 0.035 and 0.021, respectively). There was a higher statistical association between otoacoustic emission changes and cutting burrs compared with diamond burrs.

Drilling during mastoid surgery poses a threat to hearing in the contralateral ear due to noise and vibration conducted transcranially.

To investigate the feasibility of postauricular hypodermic injection for treating inner ear disorders, we compared perilymph pharmacokinetics for postauricular versus intravenous injection, using magnetic resonance imaging, in an animal model.

Twelve albino guinea pigs were divided randomly into two groups and administered gadopentetate dimeglumine via either a postauricular or an intravenous bolus injection. A 7.0 Tesla magnetic resonance imaging system was used to assess the signal intensities of gadolinium-enhanced images of the cochlea, as a biomarker for changes in gadopentetate dimeglumine concentration in the perilymph. Pharmacokinetic parameters were calculated based on these signal intensity values.

Guinea pigs receiving postauricular injection showed longer times to peak signal intensity, longer elimination half-life, longer mean residence time and a greater area under the signal–time curve (from pre-injection to the last time point) (p < 0.05).

Postauricular injection shows potential as an efficient drug delivery route for the treatment of inner ear disorders.

We describe a rare case of sudden onset of unilateral sensorineural hearing loss occurring as the first symptom of moyamoya disease, which is characterised by progressive stenosis of the intracranial internal carotid arteries and their proximal anterior cerebral arteries and middle cerebral arteries.

Case report and review of the world literature regarding moyamoya disease with hearing loss.

The reported patient had moyamoya disease that initially presented as sudden, unilateral sensorineural hearing loss. Magnetic resonance imaging showed occlusion of the anterior cerebral, middle cerebral and distal internal carotid arteries bilaterally. The possible mechanism of this patient's sudden sensorineural hearing loss may have been vascular occlusion resulting from thrombotic narrowing or blockage by plaque.

The described patient represents the first reported case of sudden onset, unilateral sensorineural hearing loss occurring as the first symptom of moyamoya disease. The possibility of a vascular lesion such as moyamoya disease should be considered in patients with sudden sensorineural hearing loss, especially children, young adults and Asian patients. Due to this disease's poor outcome, early diagnosis and treatment are important to prevent stroke.

To evaluate the safety of low-dose transtympanic methotrexate in a rat model.

Experimental animal study.

Tertiary training and research hospital.

Twenty-four rats were randomly divided into three study groups. Diluted methotrexate solution was administered transtympanically to fill the middle-ear cavity, twice a week in group one and three times a week in group two. Ringer lactate solution was administered transtympanically three times a week in the control group.

Main outcome measures: Local and systemic effects of low-dose transtympanic methotrexate.

In the methotrexate groups, middle-ear mucosal oedema was present in all animals. Auditory brainstem response thresholds indicated no inner-ear dysfunction in any group. Liver function and serum haemoglobin levels showed no statistically significant difference in any group. However, liver biopsies from groups one and two showed mild portal hyperaemia.

These findings are encouraging, and support further investigation of the topical application of methotrexate in autoimmune hearing diseases, as an alternative or adjunct to transtympanic steroids.