OBJECTIVE: Sound localization plays a crucial role in our daily lives, enabling us to recognize voices, respond to alarming situations, avoid dangers, and navigate towards specific signals. However, this ability is compromised in patients with Single-Sided Deafness (SSD) and Asymmetric Hearing Loss (AHL), negatively impacting their daily functioning. The main objective of the study was to quantify the degree of sound source localization in patients with single-sided deafness or asymmetric hearing loss using a Cochlear Implant (CI) and to compare between the two subgroups.
METHODS: This was a prospective, longitudinal, observational, single-center study involving adult patients diagnosed with profound unilateral or asymmetric sensorineural hearing loss who underwent cochlear implantation. Sound localization was assessed in a chamber equipped with seven speakers evenly distributed from -90º to 90º. Stimuli were presented at 1000 Hz and intensities of 65 dB, 70 dB, and 75 dB. Each stimulus was presented only once per speaker, totaling 21 presentations. The number of correct responses at different intensities was recorded, and angular error in degrees was calculated to determine the mean angular distance between the patient-indicated speaker and the speaker presenting the stimulus. Both assessments were conducted preoperatively without a cochlear implant and two years post-implantation.
RESULTS: The total sample comprised 20 patients, with 9 assigned to the SSD group and 11 to the AHL group. The Preoperative Pure Tone Average (PTA) in free field was 31.7 dB in the SSD group and 41.8 dB in the AHL group. There was a statistically significant improvement in sound localization ability and angular error with the use of the cochlear implant at all intensities in both SSD and AHL subgroups.
CONCLUSIONS: Cochlear implantation in patients with SSD and AHL enhances sound localization, reducing mean angular error and increasing the number of correct sound localization responses.

OBJECTIVE: To perform a systematic review with meta-analysis of the studies published on the efficacy of bone conduction devices and cochlear implantation in single-sided deafness, through the evaluation of speech discrimination in noise, sound localization and tinnitus suppression. As a secondary outcome, patient satisfaction is also assessed.
METHODS: A systematic search in PubMed, Embase and CENTRAL was conducted, including all articles written in English and published in the last 10 years. The outcomes selected were speech perception in noise, sound localization, tinnitus intensity and, secondarily, quality of life assessment. Studies that met prospectively defined criteria were subjected to random effects meta-analyses. The review protocol is registered on PROSPERO with number CRD42019121444.
RESULTS: Nineteen articles reporting a total of 210 patients (95 patients with bone conduction devices and 115 in the cochlear implantation group) were included. The meta-analysis identifies statistically significant benefits in cochlear implantation for sound localization, tinnitus suppression, in global quality of life assessment and in 2 of the 3 subscales of quality of life assessment (ease of communication and reverberation). Bone conduction devices are better regarding speech discrimination in noise and background noise quality of life assessment.
CONCLUSIONS: Cochlear implants effectively offer better results in 2 of the 3 evaluated parameters, being a very valid option. Bone conduction devices should continue to be considered in the treatment of these patients because, in addition to allowing better discrimination in noise, patient satisfaction is greater in environments with background noise.

The aim of this document is to improve the management and the treatment of unilateral or asymmetrical hearing loss in children. One in one thousand newborn infants has unilateral hearing loss and this prevalence increases with age, due to cases of acquired and delayed-onset hearing loss. Although the impact on the development and learning processes of children of these kinds of hearing loss have usually been minimized, if they are not treated they will impact on language and speech development, as well as overall development, affecting the quality of life of the child and his/her family. The outcomes of the review are expressed as recommendations aimed at clinical diagnosis and therapeutic improvement for unilateral or asymmetrical hearing loss.

BACKGROUND: The acoustic neuroma is a benign tumour that originates in the vestibular branch of the eighth cranial nerve. The main treatment is surgery, but many authors suggest that with elderly patients or in small neuromas we can opt for watchful waiting.
METHODS: This was a retrospective study from 2007 to 2013 that included 27 patients diagnosed of acoustic neuroma that had not been treated due to the size of the tumour, age and comorbidities, or by patient choice. We evaluated overall condition, hearing thresholds, degree of canal paresis and central disorders.
RESULTS: After 6 years of follow up, clinical manifestations of 18 patients remained unchanged, 5 patients underwent hearing loss and developed tinnitus, 2 cases had more intense tinnitus and 2 cases had dizziness. The radiological controls by magnetic resonance imaging showed that the initial maximum diameters (5-16mm) increased by 1.7mm on average, with annual growth rates below 0.5mm.
CONCLUSIONS: In selected cases, such as for small neuromas and in elderly patients, the conservative option of close monitoring with magnetic resonance imaging is an important alternative given that, in our cases, clinical features and radiological image did not suffer major changes. If there were any such changes, therapeutic options could be proposed.