Glucose Metabolism in the Primary Auditory Cortex of Postlingually Deaf Patients: An FDG-PET Study

Abstract

Background/Purpose: Previous FDG-PET studies have indicated neuroplasticity in the adult auditory cortex in cases of postlingual deafness. In the mature brain, auditory deprivation decreased neuronal activity in primary auditory and auditory-related cortices. In order to reevaluate these issues, we used statistical analytic software, namely a three-dimensional stereotaxic region of interest template (3DSRT), in addition to statistical parametric mapping (SPM; Institute of Neurology, University College of London, UK). MaterialsandMethods:¹⁸F-FDG brain PET scans were performed on 7 postlingually deaf patients and 10 healthy volunteers. Significant increases and decreases of regional cerebral glucose metabolism in the patient group were estimated by comparing their PET images with those of healthy volunteers using SPM analysis and 3DSRT. Results: SPM revealed that the glucose metabolism of the deaf patients was lower in the right superior temporal gyrus, both middle temporal gyri, left inferior temporal gyrus, right inferior lobulus parietalis, right posterior cingulate gyrus, and left insular cortex than that of the control subjects. 3DSRT data also revealed significantly decreased glucose metabolism in both primary auditory cortices of the postlingually deaf patients. Conclusion: SPM and 3DSRT analyses indicated that glucose metabolism decreased in the primary auditory cortex of the postlingually deaf patients. The previous results of PET studies were confirmed, and our method involving 3DSRT has proved to be useful.

Early cortical metabolic rearrangement related to clinical data in idiopathic sudden sensorineural hearing loss

“…These findings could further reinforce the relative cerebral glucose metabolism (rCGM) or blood flow decrease found in the auditory cortex and in many associative areas in previous studies on patients with chronic deafness and tinnitus (Okuda et al, 2013;Ueyama et al, 2015;Lanting et al, 2009), suggesting that reorganizational behaviour also occurs during ISSNHL. One hierarchical organization of primary and associative auditory cortex (Ruytjens et al, 2006) involves carrying out demanding neural computations, performed automatically and efficiently by the normal brain.…”

Functional Magnetic Resonance Imaging Reveals Early Connectivity Changes in the Auditory and Vestibular Cortices in Idiopathic Sudden Sensorineural Hearing Loss With Vertigo: A Pilot Study

“…If deprived sound input activates fewer excitatory fibers, the activities of excitatory and inhibitory neurons can become unbalanced and, as a result, the neuronal response in one hemisphere will be reduced compared to the other ( Fan et al, 2015 ). This finding is consistent with the previous studies in patients with chronic deafness or tinnitus reporting reduced blood flow in the AC ( Lanting et al, 2009 ; Okuda et al, 2013 ; Micarelli et al, 2017 ). However, some recent studies reported no significant difference in the ReHo value between the ISSNHL patients and the healthy controls in any brain region.…”

Inefficient Involvement of Insula in Sensorineural Hearing Loss

“…Lee et al (2001) reported hypoperfusion in the primary cortex and auditory-association cortex of prelingually deaf patients; the hypoperfusion was positively correlated with degree of hearing improvement after cochlear implantation. Prior PET reports from subject with postlingual deafness ( n = 7) (Okuda et al, 2013) and idiopathic sudden SNHL patients ( n = 14) (Micarelli et al, 2017) indicated lower glucose metabolism in the temporal lobe and insula attributed to the absence of sensory input. The difference between our insula results and these earlier reports may be related to the types of hearing loss (i.e., unilateral vs. bilateral, genetic factors), duration of deafness, small sample size, and other factors such as cognitive and emotional differences as illustrated by worse scores on SDMT, SAS, and HAMD in our SNHL subjects.…”