Healthy-side dominance of middle- and long-latency neuromagnetic fields in idiopathic sudden sensorineural hearing loss.

Full Abstract

Any lesion along the neural axis may induce a subsequent functional reorganization at the level above. The present study used magnetoencephalography to investigate auditory-evoked magnetic fields [a component of the middle-latency auditory evoked fields peaking at approximately 50 ms (P50m) and a component of the long-latency auditory evoked fields peaking at approximately 100 ms (N100m)] on stimulation of both healthy and affected ears in patients with acute unilateral idiopathic sudden sensorineural hearing loss (ISSNHL) of moderate degree in order to elucidate the functional plasticity of the auditory system. Sixteen right-handed, previously untreated adult patients with acute unilateral left (n = 8) or right (n = 8) ISSNHL of moderate degree were studied. Sixteen right-handed healthy volunteers with normal hearing served as control. Auditory neuromagnetic responses, measured by a whole-head 306-channel neuromagnetometer, were detected by monaural tone stimulation applied to affected and healthy ears, respectively, in different sessions. Intragroup and intergroup interhemispheric differences of peak dipole strengths and latencies of P50m and N100m, respectively, to monaural tones were evaluated. Healthy-side amplitude dominance of both P50m and N100m was found in ISSNHL, i.e. contralateral dominance was preserved on affected-ear stimulation but ipsilateral dominance was seen on healthy-ear stimulation. The phenomena could be attributed to the combined contralateral attenuation and ipsilateral enhancement of P50m and N100m activity in response to healthy-ear stimulation. Our findings confirmed that functional modulation can occur within the first few tens of milliseconds of evoked response at the auditory cortex in ISSNHL. The mechanisms of healthy-side dominance might be ascribed to a functional retune of auditory pathways, i.e. conjoined contralateral inhibition and ipsilateral excitation of the auditory pathway in response to healthy-ear stimulation. The effect could be registered in cortical responses.

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Author information

Author/s: Li, L P H (LP); Shiao, A S (AS); Chen, L F (LF); Niddam, D M (DM); Chang, S Y (SY); Lien, C F (CF); Lee, S K (SK); Hsieh, J C (JC);

Affiliation: Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: The European journal of neuroscience (Eur J Neurosci), published in France. (Language: eng)

Reference: 2006-Aug; vol 24 (issue 3) : pp 937-46

Dates: Created 2006/08/25; Completed 2006/11/01; Revised 2006/11/15;

PMID: 16930421, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Acoustic Stimulation
Adult
Auditory Cortex - physiology; physiopathology
Auditory Pathways - physiology; physiopathology
Evoked Potentials, Auditory - physiology
Female
Functional Laterality - physiology
Hearing Loss, Sensorineural - diagnosis; physiopathology

Hearing Loss, Sensorineural - diagnosis; physiopathology
Humans
Magnetoencephalography
Male
Middle Aged
Neuronal Plasticity - physiology
Reaction Time - physiology
Recovery of Function - physiology

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