While the pathogenesis of sudden sensorineural hearing loss is thought to be localised to the cochlea, recent microRNA findings suggest a neuro-topic localisation in some patients. This study distinguishes if neural and non-neural groups differ in hearing recovery.

Neural-type hearing loss was defined as a presenting word recognition score less than 60 per cent, with a word recognition score reduction greater than 20 per cent than expected based on the averaged pure tone audiometry. Hearing recovery was defined as an improvement of greater than or equal to 10 decibels in pure tone audiometric thresholds.

Eight of 12 and 24 of 36 of neural and non-neural hearing loss patients demonstrated hearing recovery, respectively. The affected ear's word recognition score (per cent) change with treatment were different between the neural and non-neural groups (46.9 ± 29.8 vs 3.2 ± 25.8 (p < 0.0001)).

The hearing recovery rate in neural and non-neural hearing loss groups was similar. Patients with neural-type hearing loss demonstrated greater word recognition score recovery post treatment than those in the sensory group.

To highlight the close anatomical relationship between the middle turn of the cochlea and the labyrinthine segment of the facial nerve, which will be helpful to predict the probability of occurrence of facial nerve stimulation following cochlear implant surgery.

High-resolution computed tomography of 40 cadaveric temporal bones was performed, followed by microscopic dissection. Cochleo-facial distance was measured with the help of a Digital Imaging and Communications in Medicine (‘DICOM’) viewer on high-resolution computed tomography and by a millimetre scale in the dissected specimen.

The cochleo-facial distance on high-resolution computed tomography was 0.62 ± 0.09 mm, ranging from 0.41 to 0.81 mm, and on dissection it was 0.57 ± 0.10 mm, ranging from 0.35 to 0.74 mm.

The labyrinthine segment is the most likely area of stimulation in patients suffering from facial nerve stimulation following cochlear implantation. Pre-operative high-resolution computed tomography of the temporal bone can be used to examine the bone separating the labyrinthine segment of the facial nerve from the middle turn of the cochlea. This has clinical significance regarding implant side selection and pre-operative patient counselling.

This study aimed to evaluate the association between cochlear nerve canal dimensions and semicircular canal abnormalities and to determine the distribution of bony labyrinth anomalies in patients with cochlear nerve canal stenosis.

This was a retrospective study in which high-resolution computed tomography images of paediatric patients with severe-to-profound sensorineural hearing loss were reviewed. A cochlear nerve canal diameter of 1.5 mm or less in the axial plane was classified as stenotic. Semicircular canals and other bony labyrinth morphology and abnormality were evaluated.

Cochlear nerve canal stenosis was detected in 65 out of 265 ears (24 per cent). Of the 65 ears, 17 ears had abnormal semicircular canals (26 per cent). Significant correlation was demonstrated between cochlear nerve canal stenosis and semicircular canal abnormalities (p < 0.01). Incomplete partition type II was the most common accompanying abnormality of cochlear nerve canal stenosis (15 out of 65, 23 per cent).

Cochlear nerve canal stenosis is statistically associated with semicircular canal abnormalities. Whenever a cochlear nerve canal stenosis is present in a patient with sensorineural hearing loss, the semicircular canal should be scrutinised for presence of abnormalities.

To examine when cochlear fibrosis occurs following a translabyrinthine approach for vestibular schwannoma resection, and to determine the safest time window for potential cochlear implantation in cases with a preserved cochlear nerve.

This study retrospectively reviewed the post-operative magnetic resonance imaging scans of patients undergoing a translabyrinthine approach for vestibular schwannoma resection, assessing the fluid signal within the cochlea. Cochleae were graded based on the Isaacson et al. system (from grade 0 – no obstruction, to grade 4 – complete obliteration).

Thirty-nine patients fulfilled the inclusion criteria. The cochleae showed no evidence of obliteration in: 75 per cent of patients at six months, 38.5 per cent at one year and 27 per cent beyond one year. Most changes happened between 6 and 12 months after vestibular schwannoma resection, with cases of an unobstructed cochlear decreasing dramatically, from 75 per cent to 38.5 per cent, within this time.

The progress of cochlear obliteration that occurred between 6 and 12 months following vestibular schwannoma resection indicates that the first 6 months provides a safer time window for cochlear patency.

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.

Rheumatoid arthritis is thought to induce conductive hearing loss and/or sensorineural hearing loss. This study evaluated the function of the middle ear and cochlea, and the related factors.

Pure tone audiometry, speech reception thresholds, speech discrimination scores, tympanometry, acoustic reflexes, and distortion product otoacoustic emissions were assessed in rheumatoid arthritis patients and healthy volunteers.

Pure tone audiometry results revealed a higher bone conduction threshold in the rheumatoid arthritis group, but there was no significant difference when evaluated according to the sensorineural hearing loss definition. Distortion product otoacoustic emissions related prevalence of conductive or mixed hearing loss, tympanometry values, acoustic reflexes, and speech discrimination scores were not significantly different between the two groups. Sensorineural hearing loss was significantly more prevalent in patients who used azathioprine, cyclosporine and etanercept.

Higher bone conduction thresholds in some frequencies were detected in rheumatoid arthritis patients that were not clinically significant. Sensorineural hearing loss is significantly more prevalent in refractory rheumatoid arthritis 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.

To describe our finding of increased ossification of the modiolus in paediatric patients with auditory neuropathy who met criteria for cochlear implantation.

A retrospective case series with a comparison group at a tertiary referral centre is described. Seven paediatric patients with auditory neuropathy who met criteria for and underwent cochlear implantation were identified. Fifteen paediatric implantees with bilateral profound sensorineural hearing loss were included as the comparison group. All patients underwent pre-operative computed tomography. Attenuation at the modiolus was measured in all subjects by a neuroradiologist blinded to clinical information.

Attenuation values in the modiolus in the auditory neuropathy patients (mean ± standard deviation = 796.2 ± 53.0 HU) was statistically significantly higher than in the comparison sensorineural hearing loss patients (267.1 ± 45.6 HU; p < 0.05, t-test).

Patients with auditory neuropathy who meet criteria for cochlear implantation demonstrate significantly higher modiolar attenuation on computed tomography imaging, consistent with increased ossification at the modiolus.

To investigate whether cochlear involvement is an extraintestinal manifestation in patients with ulcerative colitis.

Forty-four ulcerative colitis patients and 44 age-matched healthy subjects were included in the study. Pure tone and speech audiometry, and distortion product otoacoustic emission tests were performed on all participants. The audiometric test results were compared between groups and their relationship with disease activity was investigated.

Pure tone threshold averages were significantly higher in ulcerative colitis patients compared to controls (p < 0.05). Speech discrimination scores were significantly lower in ulcerative colitis patients compared to controls (p < 0.05). Distortion product otoacoustic emission amplitude values were significantly lower for all of the tested frequencies (except for 6000 Hz in the right ear) in ulcerative colitis patients compared to controls (p < 0.05). No relationship was detected between audiometric test results and disease activity (p > 0.05).

Even though hearing thresholds may be within normal limits, decreased distortion product otoacoustic emission amplitude values indicate a cochlear involvement in ulcerative colitis patients.

This study aimed to characterise the geometry of the human bilateral spiral cochlea by measuring curvature and length.

Eight subjects were recruited in this study. Magnetic resonance imaging was used to visualise the right and left cochlea. Visualisation of the cochlear spiral was enhanced by T2 weighting and further processing of the raw images. The spirals were divided into three segments: the basal turn, the middle turn and the apex turn. The length and curvature of each segment were non-invasively measured.

The mean left and right cochlear lengths were 3.11 cm and 3.95 cm, respectively. The measured lengths of the cochlear spiral are consistent with data in the literature derived from anatomical dissections. Overall, the apex turn segment of the cochlea had the greatest degree of curvature (p < 0.05). The mean apex turn segment curvatures for left and right cochleae were 9.65 cm−1 and 10.09 cm−1, respectively.

A detailed description of the cochlear spiral is provided, using measurements of curvature and length. These data will provide a valuable reference in the development of cochlear implantation procedures for minimising the potential damage during implantation.

This paper reports five cases of aberrant cochlear implant electrode array insertion into the vestibular labyrinth. A review of the literature was conducted in order to clarify reasonable preventive and detection strategies and endorse the routine use of intra-operative plain skull X-ray.

The study entailed a clinical case series and literature review. The setting was a tertiary academic referral centre. The following data were evaluated: pre-operative temporal bone computed tomography, operative reports, intra-operative imaging, neural response telemetry/imaging and post-operative imaging.

There were no consistent pre-operative risk factors found on computed tomography scans and no reliable intra-operative signs of electrode array misdirection. All misdirections in our case series, and those in the literature, were easily detectable on intra-operative plain film X-ray.

These reported cases demonstrate implant misdirection without the surgeon's awareness. Aberrant insertion cannot be anticipated, and neural response telemetry/imaging is not a reliable indicator of misdirection. Routine intra-operative anteroposterior plain X-ray of the head is a reliable indicator of misdirection, and is fast and relatively inexpensive.

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.

To determine the effect of experimentally induced hypoxia, in the first 10 days of life, on physiological hearing in a Sprague–Dawley rat model.

A prospective, controlled animal study was carried out using 22 male rat pups. The rats in the hypoxic group (n = 12) were reared in hypoxia for the first 10 days of life, and subsequently reared in normoxia, while those in the control group (n = 10) were reared in normoxia for the duration of the experiment. Hearing was assessed using auditory brainstem response testing at approximately 72 days of age.

The hypoxia group had higher auditory brainstem response thresholds for all frequencies tested (more pronounced at 16 kHz), compared with controls. Wave I–V inter-peak latencies were more prolonged in the hypoxic rats, while both groups had similar wave I latencies.

Chronic postnatal hypoxia induced permanent hearing loss in this Sprague–Dawley rat model. Prolonged wave I–V inter-peak latencies suggested functional abnormality in the central auditory pathway.

Cisplatin is an effective chemotherapeutic agent commonly used in the treatment of malignant tumours, but ototoxicity is a significant side effect.

To discuss the mechanisms of cisplatin ototoxicity and subsequent cell death, and to present the results of experimental studies.

We conducted a systematic search for data published in national and international journals and books, using the Medline, SciELO, Bireme, LILACS and PubMed databases.

The nicotinamide adenine dinucleotide phosphate oxidase 3 isoform (also termed NOX3) seems to be the main source of reactive oxygen species in the cochlea. These reactive oxygen species react with other molecules and trigger processes such as lipid peroxidation of the plasma membrane and increases in expression of the transient vanilloid receptor potential 1 ion channel.

Cisplatin ototoxicity proceeds via the formation of reactive oxygen species in cochlear tissue, with apoptotic cell death as a consequence.

To establish a new magnetic resonance imaging scoring system for diagnosing endolymphatic hydrops.

A total of 214 ears of 107 patients were categorised into five groups: no symptoms, Ménière's disease, sudden deafness, delayed endolymphatic hydrops and other ear disorders. Gadolinium distribution within the labyrinth was scored separately and quantitatively by two radiologists. Multiple independent-sample non-parametric tests, Bayesian discriminant analysis, multivariate logistic regression and receiver operating characteristic curve analyses were performed.

The derived scoring model was highly accurate for diagnosing Ménière's disease and delayed endolymphatic hydrops. Two magnetic resonance imaging scoring methods for the perilymphatic space were proposed for the diagnosis of endolymphatic hydrops: a pre-1 value (a new variable that predicts individual probability) of more than 0.3982299, or a sum of all labyrinth component scores of less than 14.5.

A convenient method is proposed which offers reliable radiological diagnostic criteria for Ménière's disease and delayed endolymphatic hydrops.

The Bluetooth wireless headset has been promoted as a ‘hands-free’ device with a low emission of electromagnetic radiation.

To evaluate potential changes in hearing function as a consequence of using Bluetooth devices, by assessing changes in pure tone audiography and distortion production otoacoustic emissions.

Prospective study.

Thirty adult volunteers were exposed to a Bluetooth headset device (1) on ‘standby’ setting for 6 hours and (2) at full power for 10 minutes. Post-exposure hearing was evaluated using pure tone audiography and distortion production otoacoustic emission testing.

There were no statistically significant changes in hearing, as measured above, following either exposure type.

Exposure to the electromagnetic field emitted by a Bluetooth headset, as described above, did not decrease hearing thresholds or alter distortion product otoacoustic emissions.

To evaluate the effect of different lipid fractions on auditory brainstem evoked responses in hyperlipidaemia.

We conducted a single institution (medical college), prospective, cross-sectional study of 25 hyperlipidaemic patients and 25 normolipidaemic controls, all with a normal hearing threshold on pure tone audiometry. Brainstem evoked response audiometry results were recorded in both groups. The hyperlipidaemic group were further divided into two subgroups, based on the serum value of each lipid fraction: those with less than and those with greater than the mean serum value. These two subgroups were further compared with the control group.

The hyperlipidaemic and normolipidaemic groups had statistically significant differences for all audiometry waves apart from the wave I and the III–V interpeak latencies. The subgroups had a statistically significant difference in brainstem evoked responses. We found a statistically significant association between low-density lipoproteins and many waveforms in the hyperlipidaemic group.

We found that low-density lipoproteins were significantly associated with many waveforms in hyperlipidaemic patients. Thus, low-density lipoproteins may be important in auditory dysfunction.

Cochlear implantation has been used to rehabilitate profoundly deafened adults for more than 25 years. However, surgical labyrinthectomy is often considered a contraindication to cochlear implantation, especially if there is a significant delay between the two procedures. As the role of cochlear implantation continues to expand, this idea requires reconsideration.

A 59-year-old woman presented to our clinic after undergoing bilateral surgical labyrinthectomies for intractable Ménière's disease 21 years prior. Despite the significant time delay, she underwent cochlear implantation with a good audiological outcome and improved quality of life.

Changes to the cochlea and vestibule following surgical labyrinthectomy include cochlear ossification and obliteration of the vestibule. These issues have been thought to limit the potential for cochlear implantation, especially when there is a significant delay between the two procedures. However, delayed cochlear implantation, even decades after labyrinthectomy, remains a viable treatment option which can benefit selected patients.