Research paper Disrupted functional brain connectome in unilateral sudden sensorineural hearing loss Haibo Xu a, c, *, 1 , Wenliang Fan a, 1 , Xueyan Zhao b , Jing Li a , Wenjuan Zhang b , Ping Lei a , Yuan Liu a , Haha Wang a , Huamao Cheng b , Hong Shi b a Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China b Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China c Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China article info Article history: Received 16 September 2015 Received in revised form 18 February 2016 Accepted 22 February 2016 Available online 9 March 2016 Keywords: Unilateral sudden sensorineural hearing loss Resting-state fMRI Connectome Graph theory abstract Sudden sensorineural hearing loss (SSNHL) is generally defined as sensorineural hearing loss of 30 dB or greater over at least three contiguous audiometric frequencies and within a three-day period. This hearing loss is usually unilateral and can be associated with tinnitus and vertigo. The pathogenesis of unilateral sudden sensorineural hearing loss is still unknown, and the alterations in the functional connectivity are suspected to involve one possible pathogenesis. Despite scarce findings with respect to alterations in brain functional networks in unilateral sudden sensorineural hearing loss, the alterations of the whole brain functional connectome and whether these alterations were already in existence in the acute period remains unknown. The aim of this study was to investigate the alterations of brain func- tional connectome in two large samples of unilateral sudden sensorineural hearing loss patients and to investigate the correlation between unilateral sudden sensorineural hearing loss characteristics and changes in the functional network properties. Pure tone audiometry was performed to assess hearing ability. Abnormal changes in the peripheral auditory system were examined using conventional magnetic resonance imaging. The graph theoretical network analysis method was used to detect brain connectome alterations in unilateral sudden sensorineural hearing loss. Compared with the control groups, both groups of unilateral SSNHL patients exhibited a significantly increased clustering coefficient, global ef- ficiency, and local efficiency but a significantly decreased characteristic path length. In addition, the primary increased nodal strength (e.g., nodal betweenness, hubs) was observed in several regions pri- marily, including the limbic and paralimbic systems, and in the auditory network brain areas. These findings suggest that the alteration of network organization already exists in unilateral sudden senso- rineural hearing loss patients within the acute period and that the functional connectome of unilateral SSNHL patients is characterized by a shift toward small-worldization. Additionally, we hope that these findings will help to elucidate unilateral SSNHL through a new research perspective and provide insight for the potential pathophysiology of unilateral SSNHL. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Sudden sensorineural hearing loss (SSNHL) is defined as a sensorineural hypoacusis of at least 30 dB over 3 consecutive speech frequencies within 3 days (Schreiber et al., 2010). SSNHL is typically unilateral and can be associated with tinnitus and vertigo (Schreiber et al., 2010). The incidence of SSNHL has been reported to range from 3.9 to 27.5 per 100,000 people per year and is considered to be an otologic emergency (Chen et al., 2015; Nosrati- * Corresponding author. Department of Radiology, Zhongnan Hospital of Wuhan University, No.169 Donghu Road, Wuhan 430071, China. E-mail addresses: xuhaibo1120@hotmail.com (H. Xu), fanwenliang168@163.com (W. Fan), yaner_323@126.com (X. Zhao), lijing80603@163.com (J. Li), juan_364@ 163.com (W. Zhang), leiping_rosemary@126.com (P. Lei), 309105825@qq.com (Y. Liu), ahahwang@163.com (H. Wang), chhmao@aliyun.com (H. Cheng), shihong5510@163.com (H. Shi). 1 Haibo Xu and Wenliang Fan contributed equally as joint first authors. Contents lists available at ScienceDirect Hearing Research journal homepage: www.elsevier.com/locate/heares http://dx.doi.org/10.1016/j.heares.2016.02.016 0378-5955/© 2016 Elsevier B.V. All rights reserved. Hearing Research 335 (2016) 138e148