Background/Objectives: Tinnitus is a complex auditory phenomenon with multifactorial origins, often involving both peripheral and central auditory pathways. Given the multifactorial nature of tinnitus, this review specifically focuses on the auditory brainstem as it represents the first central relay for auditory input and a key site of abnormal synchrony and central gain, which may generate or modulate tinnitus even when peripheral hearing appears normal. Several studies suggest a potential role of brainstem dysfunction in its pathogenesis, even among patients with normal hearing thresholds. Although the physiopathological data provide evidence for the role of brainstem in the generation and magnification of tinnitus, the diagnostic tools are still unclear. This systematic review aimed to investigate the diagnostic relevance of brainstem-level abnormalities in individuals with tinnitus. Methods: Following PRISMA guidelines, a literature search was conducted using PubMed, Scopus, and Web of Science from January 2000 to June 2025. Studies were included if they addressed the diagnostic relationship between tinnitus and brainstem involvement. Data on auditory brainstem response (ABR), otoacoustic emissions (used to differentiate peripheral from central auditory abnormalities), neuroimaging, and electrophysiological markers were extracted. Results: Twenty studies were included. Most used ABR as a diagnostic tool, revealing significant amplitude and latency alterations in tinnitus patients compared to controls, particularly in wave V and V/I amplitude ratios. Imaging studies supported altered brainstem–cortical connectivity and localized changes in inferior colliculus (IC) activity. Additional techniques, such as middle-latency evoked potentials and gap-in-noise detection, showed potential but lacked consistent clinical utility. Conclusions: Evidence suggests that brainstem dysfunction may contribute to tinnitus generation or persistence. ABR and advanced imaging represent specific diagnostic tools, though standardization and high-quality studies are still needed to improve clinical applicability.

Background/Objectives: Unilateral hearing loss (UHL) is a relatively common disability condition comprising around 20–50% of all congenital hearing loss (HL). The adverse effects of UHL affect the typical development of auditory function with implications for communication, speech and language acquisition, academic development and quality of life. Current literature suggests an early intervention treatment in order to avoid developmental delays, but there is a lack of evidence about the effectiveness and use of hearing devices. The purpose of the present study was to evaluate the benefits of rehabilitative strategies such as hearing aid (HA) and cochlear implant (CI) in UHL children by exploring audiological and parent-reported outcomes. Methods: A total of 18 UHL children, between the ages of 3 and 17, were enrolled in the study designed as a prospective longitudinal study from July 2023 to July 2024. All children were evaluated for speech perception in quiet and noise and subjective benefits before and after rehabilitative treatment with HA in 15 (83.3%) children and with CI in 3 (16.7%) children. Results: The evaluation of audiological outcomes in children with UHL, based on assessment of aided sound field thresholds and speech perception scores assessment versus unaided, shows improvements in audiometric thresholds and how the hearing devices adequately support listening and spoken language. Scores with hearing devices were significantly higher than baseline-only scores when averaging both SSQ and CHILD questionnaires, pointing to an overall rehabilitative benefit. Conclusions: Rehabilitative interventions, particularly HA and CI, offer notable benefits when introduced early, but achieving optimal outcomes requires a multidisciplinary and individualized approach.

Background/Objectives: Functional near-infrared spectroscopy (fNIRS) has emerged as a non-invasive, implant-compatible imaging modality capable of capturing cortical hemodynamics during ecologically valid auditory and linguistic tasks. Its silent operation and tolerance to electrical artifacts make it particularly well suited to the study of hearing-impaired individuals, including cochlear implant (CI) users. However, evidence on the application of fNIRS to investigate speech perception, cognitive performance, and proxy of cortical activation patterns in patients with hearing loss (HL) remains fragmented. This systematic review aims to provide a structured, population-stratified description of current fNIRS literature on auditory and cognitive processing in adults with age-related hearing loss (ARHL) and CI users. Methods: A systematic search on PubMed Central, Web of Science and Scopus, based on PRISMA (2020) guidelines, was conducted to identify original studies that evaluate speech perception by means of fNIRS to assess auditory and cognitive process in hearing-impaired populations. Results: Across studies, fNIRS consistently detected activation of superior temporal and frontal cortices during speech-related tasks. In ARHL, increased dorsolateral prefrontal cortex (DLPFC) recruitment during speech-in-noise indicated compensatory yet inefficient processing. Longitudinal auditory training led to reduced prefrontal overactivation and enhanced temporal–frontal connectivity. In CI users, cortical responses to phonological and comprehension tasks show partially overlapping activation patterns with normal hearing (NH) peers, although arising within different neurobiological contexts, and are modulated by device experience and residual hearing (AV) speech, and stimulus-level effects further shape cortical responses. When interpreted in light of developmental evidence, these findings may be contextualized as reflecting distinct trajectories of cortical reorganization, rather than a common mechanism. Conclusions: fNIRS provides a tool to investigate auditory and cognitive responses in distinct hearing-impaired populations under ecologically valid conditions. It detects maladaptive frontal inefficiency in ARHL, tracks neuroplastic changes after rehabilitation, and captures population-specific cortical recruitment patterns in CI users. These findings are descriptive and context-dependent, and do not support cross-population mechanistic generalizations. Standardized protocols and longitudinal pediatric studies are needed to clarify the potential clinical relevance of fNIRS-derived cortical measures.

Background/Objectives: Mastoid obliteration is being increasingly used to reduce cavity-related morbidity after mastoidectomy. Alongside autologous grafts, synthetic biomaterials and tissue-engineering approaches have emerged as potential alternatives. This systematic review synthesized the clinical and preclinical evidence on biomaterials for mastoid obliteration, focusing on efficacy, safety, biological integration, and translational potential. Methods: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant search of PubMed, Scopus, and Web of Science identified studies published between January 2010 and May 2026. Eligible studies evaluated biomaterials for mastoid obliteration in clinical settings or experimental models. Data on study design, biomaterial type, intervention, outcomes, complications, and biological endpoints were extracted. Risk of bias was assessed using the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I), Revised Cochrane Risk of Bias Tool for Randomized Trials (RoB 2), and the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk-of-bias tool. Results: Twenty-eight studies were included (19 clinical, 9 preclinical). Clinical evidence supported mastoid obliteration as an effective strategy for improving cavity stability, reducing chronic otorrhea, promoting epithelialization, and aiding cholesteatoma control. Outcomes appeared to depend more on successful cavity elimination than on the superiority of a specific biomaterial. Autologous materials showed reliable and reproducible results, while S53P4 bioactive glass demonstrated comparable effectiveness with additional antibacterial properties. Hydroxyapatite-based materials and allografts showed more variable outcomes. Biologically enhanced approaches, including concentrated growth factors and composite constructs, yielded promising but limited clinical evidence. Preclinical studies indicated that conventional biomaterials are primarily osteoconductive, whereas composite scaffolds, bone morphogenetic protein-2 (BMP-2) delivery systems, and stem cell-based strategies may enhance osteogenesis and tissue integration. However, clinical translation remains limited. Conclusions: Mastoid obliteration is an effective reconstructive strategy whose success depends mainly on stable cavity reduction and adequate epithelial coverage. Autologous materials and S53P4 bioactive glass currently have the strongest clinical support, whereas advanced tissue-engineering approaches require further validation through prospective comparative studies, standardized outcomes, long-term follow-up, and translational research.

Background and Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy has raised concerns regarding possible fetal consequences, including potential effects on auditory system development. Although the current literature suggests that overt congenital hearing loss is uncommon among newborns exposed in utero, subtle cochlear functional alterations may not be detectable through conventional threshold-based screening alone. The objective of this study is to investigate whether in utero exposure to maternal COVID-19 is associated with early cochlear functional changes in newborns, as assessed by frequency-specific transient evoked otoacoustic emission (TEOAE) amplitude ratios, and to determine whether such alterations are accompanied by differences in click-evoked auditory brainstem response (ABR) thresholds. Materials and Methods: This prospective cohort study was conducted between October 2021 and September 2022 and included 61 pregnant women: 30 with laboratory-confirmed SARS-CoV-2 infection during pregnancy (study group) and 31 without documented infection (control group). All newborns underwent standardized audiological evaluation shortly after birth, including otoscopy, TEOAE, click-evoked ABR, and tympanometry. Frequency-specific TEOAE amplitude ratios at 500, 1000, 1500, 2000, and 4000 Hz were compared between groups. A logistic regression analysis was performed to identify audiological predictors of newborn exposure to SARS-CoV-2 in utero. Results: No significant differences were observed in ABR thresholds or in TEOAE “pass/refer” outcomes between the control and study groups, indicating the absence of clinically overt HL. However, newborns exposed to SARS-CoV-2 in utero showed significantly reduced TEOAE amplitude ratios at 2000 Hz (p = 0.0077) and 4000 Hz (p = 0.020). Logistic regression identified the 4000 Hz amplitude ratio as an independent negative predictor of in utero exposure (OR = 0.75; p = 0.0352). No significant differences were detected at lower frequencies. Conclusions: Maternal COVID-19 during pregnancy was not associated with immediate neonatal HL but was linked to subtle high-frequency cochlear functional modulation. Longitudinal audiological follow-up is needed to clarify the clinical significance of these findings.