Neuromagnetic index of hemispheric asymmetry predicting long-term outcome in sudden hearing loss

• Published in: NeuroImage (Orlando, Fla.) Vol. 64; pp. 356 - 364
• Main Authors: Li, Lieber Po-Hung, Chen, Kuang-Chao, Lee, Po-Lei, Niddam, David M., Cheng, Chou-Ming, Chou, Chih-Cher, Hsieh, Jen-Chuen, Shiao, An-Suey
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.01.2013; Elsevier; Elsevier Limited
• Subjects: Adult; Aged; Asymmetry; Auditory Cortex - physiopathology; Biological and medical sciences; Brain Mapping - methods; Diagnosis, Computer-Assisted - methods; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Ears & hearing; Evoked Potentials, Auditory; Female; Fundamental and applied biological sciences. Psychology; Hearing; Hearing loss; Hearing Loss, Sudden - diagnosis; Hearing Loss, Sudden - physiopathology; Hemispheric asymmetry; Humans; Longitudinal Studies; Magnetoencephalography (MEG); Magnetoencephalography - methods; Male; Medical sciences; Middle Aged; Neuroplasticity; Non tumoral diseases; Otorhinolaryngology. Stomatology; Prognosis; Reorganization; Reproducibility of Results; Sensitivity and Specificity; Severity of Illness Index; Studies; Vertebrates: nervous system and sense organs; Neuroplasticity; Hemispheric asymmetry; Hearing; Magnetoencephalography (MEG); Prognosis; Reorganization; Central nervous system; Auditory disorder; Inner ear; Organ of hearing; ENT disease; Perception hearing loss; Evolution; Laterality; Human; Hemispheric specialization; Magnetoencephalography; Internal ear disease; Acute; Monoaural hearing; Idiopathic; Long term; Chronic; Brain plasticity; Perception; Auditory pathway; Sensory hearing loss
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2012.09.002

The neuromagnetic index of hemispheric asymmetry in terms of ipsilateral/contralateral ratio at acute stage was previously revealed to prognosticate the 1-month hearing outcome of acute unilateral idiopathic sudden sensorineural hearing loss (ISSNHL), showing a dynamic relationship between top- and down-levels of auditory pathway. However, the prognostic effect of reorganization pattern for the long-term results remained elusive. This study aimed to probe the prognosticating relevance of hemispheric asymmetry to the hearing at chronic stage of ISSNHL. Using magnetoencephalography (MEG), inter-hemispheric differences in peak dipole of N100m responses to monaural tones were evaluated in 21 controls and 21 ISSNHL patients at initial and final (12months later) stages. Predictive value of hemispheric asymmetry was assessed by correlating hearing level and ipsilateral/contralateral ratio (I/C) of N100m latency and amplitude. Healthy-side dominance of N100m was observed in ISSNHL initially, and remained in three final prognostic subgroups (complete, partial, and no recovery) of ISSNHL. The initial I/Camplitude on affected-ear stimulation strongly correlated with the hearing level of final stage in ISSNHL. However, there was no prognostic effect of hemispheric asymmetry pattern for the 12-month hearing improvement. The heterogeneity between neuromagnetic index and hearing levels possibly echoed different pathogeneses of ISSNHL. Since a restored hearing status did not necessarily lead toward a normal functional organization, the dynamics of hemispheric asymmetry could actually index a central resilient reorganization in the brain for sound processing in ISSNHL. Our finding showed not only a clinically relevant measure to predict final hearing of ISSNHL, but also a linkage between central plasticity and cochlear lesion. This finding suggests a new perspective, and perhaps new interventions, to diagnose and treat unilateral ISSNHL. ► Initial I/Camplitude on affected-ear stimulation predicted final hearing in ISSNHL. ► Our finding showed dynamics of top–down relationship in auditory pathway. ► Our finding showed a clinically relevant measure to predict final hearing of ISSNHL. ► Our finding showed a linkage between central plasticity and cochlear lesion. ► Our finding suggests a new perspective and intervention to diagnose and treat ISSNHL.