Inner ear hearing loss modulates ipsilateral temporal lobe activation by monaural speech stimuli

Lateralization of the Dichotic Digits Test, Central Auditory Processes, and Evoked Potentials in Multiple Sclerosis

Lateralization for central auditory processing (CAP) with dichotic digits recognition (DDR) test is believed expression of hemispheric dominance. Multiple sclerosis (MS) is considered an inflammatory and autoimmune alteration of central nervous system (CNS). Hearing alterations in MS and their role in CAP has not been well studied. A patient with MS and new kind of alteration in lateralization of CAP with DDR test is presented. A 53 year of age female with MS of 16 years of evolution, nine of them remained asymptomatic. She has a persistent advantage of the right ear for DDR test; but other monaural tests showed predominance of the left afferent pathway. Brainstem auditory evoked potentials (BAEPs) and long latency auditory evoked potentials (LLAEPs) showed adequate right response with deficits in organization of left response in BAEP, and N2 wave. In the contrary direction of previous publication, we disclosed advantage for DDR test, BAEP, and LLAEP in the right ear. We observed no left ear suppression; with predominance of correct left percentages in monaural psychoacoustics tests. We must keep on searching to find pathophysiological meaning of predominant of right or left auditory laterality as a CAP disorder in patients with MS.

Different cortical metabolic activation by visual stimuli possibly due to different time courses of hearing loss in patients with GJB2 and SLC26A4 mutations

Conclusion.

We have demonstrated differences in cortical activation with language-related visual stimuli in patients who were profoundly deafened due to genetic mutations in GJB2 and SLC26A4. The differences in cortical processing patterns between these two cases may have been influenced by the differing clinical courses and pathogenesis of hearing loss due to genetic mutations. Our results suggest the importance of hearing during early childhood for the development of a normal cortical language network.

Objectives.

To investigate the cortical activation with language-related visual stimuli in patients who were profoundly deafened due to genetic mutations in GJB2 and SLC26A4.

Methods:

The cortical activity of two adult patients with known genetic mutations (GJB2, SLC26A4) was evaluated with fluorodeoxyglucose-positron emission tomography (FDG-PET) with a visual language task and compared with that of normal-hearing controls.

Results:

A patient with a GJB2 mutation showed activation in the right auditory association area [BA21, BA22], and the left auditory association area [BA42] even with visual language task; in contrast, a patient with an SLC26A4 mutation showed no significant activation in the corresponding area.

Brain metabolism of children with profound deafness: a visual language activation study by 18F-fluorodeoxyglucose positron emission tomography

CONCLUSION

The use of fluorodeoxyglucose positron emission tomography (FDG-PET) with a visual language task provided objective information on the development and plasticity of cortical language networks. This approach could help individuals involved in the habilitation and education of prelingually deafened children to decide upon the appropriate mode of communication.

OBJECTIVES

To investigate the cortical processing of the visual component of language and the effect of deafness upon this activity.

SUBJECTS AND METHODS

Six prelingually deafened children participated in this study. The subjects were numbered 1-6 in the order of their spoken communication skills. In the time period between an intravenous injection of 370 MBq 18F-FDG and PET scanning of the brain, each subject was instructed to watch a video of the face of a speaking person. The cortical radioactivity of each deaf child was compared with that of a group of normal- hearing adults using a t test in a basic SPM2 model.

RESULTS

The widest bilaterally activated cortical area was detected in subject 1, who was the worst user of spoken language. By contrast, there was no significant difference between subject 6, who was the best user of spoken language with a hearing aid, and the normal hearing group.