Abstract
Purpose
The aim of this study is to assess the value of magnetic resonance imaging in identifying the etiology of sudden sensorineural hearing loss, and to correlate the high signals in the labyrinth with clinical features to identify if inner ear hemorrhage could be implicated.
Materials and methods
In this retrospective study, inner ear magnetic resonance imaging was given to 112 patients with sudden sensorineural hearing loss in the First Affiliated Hospital of Sun Yat-sen University from 2011 to 2012. The clinical features of patients with high signals in the labyrinth on magnetic resonance imaging were analyzed.
Results
Abnormal magnetic resonance images were identified in 13 (11.6%) patients. Retrocochlear pathology was found in six patients, including two cases of lacunar infarction, one case of multiple ischemias in the brainstem and bilateral centrum semiovale, two cases of acoustic neuroma, and one case of inner ear hemangioma. There were seven cases showing high signals in the labyrinth on unenhanced T1-weighted and fluid-attenuated inversion recovery images. Clinical features of these seven patients were characterized by irreversible profound hearing impairment and vestibular dysfunction. These findings were consistent with the hypothesis that their symptoms were caused by an inner ear hemorrhage.
Conclusion
The results indicate the importance of magnetic resonance imaging in sudden sensorineural hearing loss in patients. Moreover, patients with vestibular dysfunction and sudden profound hearing loss may have an inner ear hemorrhage evident by interpreting clinical and magnetic resonance imaging results.
1
Introduction
Sudden sensorineural hearing loss (SSNHL) is typically defined as > 30 dB sensorineural hearing loss in at least three frequencies occurring over a span of less than 72 hours . Despite efforts to clarify the pathophysiologic characteristics of this condition, the exact cause of SSNHL remains unclear. It is estimated that approximately 90% of SSNHL cases are idiopathic . Possible causes include viral infection, microcirculatory disturbance of the inner ear, and immune factors. The unpredictability of idiopathic SSNHL presents a challenge to preventive care and thus etiological research investigating SSNHL is required.
Imaging studies are frequently utilized for the evaluation of SSNHL in patients. Magnetic resonance imaging (MRI) has the added advantage of identifying other causes of SSNHL (eg, cochlear inflammation or multiple sclerosis) or findings that imply an underlying etiology for the SSNHL (eg, small vessel cerebral ischemia), compared to other imaging techniques. According to the guidelines by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Foundation, it is recommended that patients with SSNHL undergo audiometry and MRI scans of the middle and inner ear .
In 1992, Weissman et al. described two patients with high signals in the labyrinth on unenhanced T1-weighted MRI who presented with SSNHL and vertigo . They suggested the possibility that the high signal was caused by hemorrhage. Subsequently, a few reports of high signals on the labyrinth on unenhanced T1-weighted image (T1WI) have been presented to support this hypothesis ; however, pathological verification has not yet been obtained.
In this retrospective study, we evaluate the MRI findings of 112 patients with SSNHL in the First Affiliated Hospital of Sun Yat-sen University from January 2011 to December 2012. The goal of our study is to add our experience to the current body of data regarding the importance of routine MRI for SSNHL and the possibility of inner ear hemorrhage, not to provide a new standard of examination for SSNHL. Nevertheless, the relatively high positive rate of MRI findings and strong evidence of inner ear hemorrhage by MRI and clinical features reiterate the necessity for this examination. Therefore, the role of inner ear hemorrhage in the etiology of SSNHL should be investigated further.
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