Sudden Sensorineural Hearing Loss (SSNHL) is an otological emergency defined by a decline of >30 dB in at least three consecutive frequencies on a pure-tone audiogram within 72 h (Chandrasekhar et al., 2019). Over 95 % of SSNHL cases present as unilateral, often accompanied by symptoms such as tinnitus and vertigo (Schreiber et al., 2010). Extensive epidemiological studies indicate that the annual incidence of SSNHL varies significantly across different regions, but there is a consistent upward trend (Kim et al., 2017). Currently, the pathogenesis of SSNHL is widely debated, with major hypotheses including viral cochleitis, vascular obstruction, and membrane rupture, but no definitive conclusion has been reached (Merchant et al., 2005). Due to the complexity and uncertainty of its pathophysiological mechanisms, it is often difficult to identify the cause of hearing loss in most SSNHL cases during routine clinical examinations, making it challenging for physicians to develop precise diagnostic and treatment plans. What’s worse, SSNHL may lead to central nervous system symptoms, including depression, anxiety, and even cognitive deficits, which can significantly diminish the quality of life for patients and impose a substantial economic burden on society (Young, 2020).

Prior functional MRI (fMRI) studies have found both static and dynamic abnormalities in functional indicators in SSNHL patients in both auditory and non-auditory regions (Chen et al., 2020; Li et al., 2022). As a sensitive, non-invasive, and reproducible technique, fMRI can effectively reflect neuronal activity using blood oxygen level-dependent (BOLD) signals (Hennig et al., 2003). Furthermore, functional connectivity (FC) assesses the temporal correlations of BOLD signal fluctuations across spatially separated brain regions, offering insights into the synchronization of neural activity and the functional relationships among various voxels or brain areas (Biswal et al., 1995). One study reported enhanced FC between the right anterior insular cortex and several key regions in the default mode network (DMN) in individuals experiencing long-term unilateral hearing loss (UHL) (Smallwood et al., 2021). The DMN is characterized by reduced neural activity during attention-demanding tasks while remaining active during the brain's resting state. Despite the increasing number of studies aimed at elucidating the changes in brain function and their potential mechanisms in individuals with hearing impairment, the relationship between FC changes in SSNHL and its prognosis remains poorly understood and warrants further investigation. Therefore, the aim of this study is to explore the FC differences associated with the prognosis of SSNHL patients. We hope that our findings will contribute to a better understanding of neural alterations in SSNHL and provide preliminary evidence for future research on potential neuroimaging correlates of clinical outcomes.