Detection and valid measurements of distortion product otoacoustic emissions are not influenced by cochlear status alone, but also by middle-ear status. There is a need to understand the use of ultra-high frequency distortion product otoacoustic emissions in cases of abnormal distortion product otoacoustic emission findings for conventional frequencies related to the middle-ear condition.

The present study investigated distortion product otoacoustic emission input–output functions in conventional and ultra-high frequencies in: 37 adults with chronic suppurative otitis media (clinical group) and 37 adults with normal hearing sensitivity (control group).

There were significant reductions in distortion product otoacoustic emission amplitude and mean signal-to-noise ratio in the clinical group compared to the control group, especially for conventional frequencies.

There was a significant reduction in the rate of ears with measurable distortion product otoacoustic emissions in the clinical group, especially for conventional frequencies. The effect of chronic suppurative otitis media was more pronounced in the conventional frequency range compared to the smaller effect seen in the ultra-high frequency range.

Sensorineural hearing loss is a recognised complication of cryptococcal meningitis. The mechanism of hearing loss in patients with cryptococcal meningitis is different from that in bacterial meningitis.

An immune-competent man with cryptococcal meningitis presented with sudden onset, bilateral, severe to profound sensorineural hearing loss and vestibular dysfunction. He was initially evaluated for cochlear implantation. However, he had a significant recovery; he no longer required surgery and was able to cope without a hearing aid.

Typically, cochlear implantation is performed with some urgency in patients with hearing loss post-bacterial meningitis, because of the risk of labyrinthitis ossificans. However, this process has not been described in patients with cryptococcal meningitis. Furthermore, patients with hearing loss associated with cryptococcal meningitis have shown varying degrees of reversibility. In this case report, hearing loss from cryptococcal meningitis is compared with that from bacterial meningitis, and the need for cochlear implantation in patients with cryptococcal meningitis is discussed.

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.

Brown–Vialetto–Van Laere syndrome is a rare neurological disorder characterised by pontobulbar palsy and sensorineural hearing loss. Hearing rehabilitation continues to be a challenge because the exact lesion site is unknown.

We examined the clinical and audiological profiles of a case series comprising four siblings with Brown–Vialetto–Van Laere syndrome who had decreased hearing and poor speech discrimination. Audiological investigations revealed normal otoacoustic emissions with absent auditory brainstem responses and middle-ear reflexes in sensorineural hearing loss, suggestive of auditory neuropathy spectrum disorder.

The sensorineural hearing loss in Brown–Vialetto–Van Laere syndrome patients is a retrocochlear pathology resembling auditory neuropathy spectrum disorder, with the lesion being most probably of post-synaptic origin. Early cochlear implantation along with high-dose riboflavin represents a possible rehabilitation therapy. However, further research is needed to confirm this. This report emphasises the need for a thorough neurological evaluation of auditory neuropathy spectrum disorder patients.

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 investigate the effectiveness of pomegranate extract as protection against aminoglycoside ototoxicity.

Prospective, randomised, controlled, experimental study.

Eighteen Wistar albino rats were randomly allocated to 5 days of either: saline injections; gentamicin injections; or pomegranate extract (100 µl/day via gavage) plus gentamicin injections. Distortion product otoacoustic emissions were tested before treatment and on day 3. After treatment, reactive oxygen species levels were measured in each rat's right cochlea and right kidney via chemiluminescence.

Baseline emission amplitudes were similar. Post-treatment emissions differed significantly in the two treatment groups (p < 0.001). Cochlear reactive oxygen species levels were significantly higher in the gentamicin group (mean ± standard deviation, 316.6 ± 36.5 relative light units per mg) than the gentamicin plus pomegranate extract group (240 ± 24.6 relative light units per mg) (p = 0.004); control group levels were 119.1 ± 10.3 relative light units per mg. Renal reactive oxygen species levels were similar for the control and gentamicin plus pomegranate extract groups (p = 0.59) but much higher in the gentamicin group (p = 0.004).

Concurrent systemic pomegranate extract administration reduced reactive oxygen species level increases and otoacoustic emission changes, following aminoglycoside injection.