Longitudinal MRI Analysis of Volumetric Differences in Brainstem Neurons Following Noise Induced Temporary Threshold Shift

Details

• Personal Author:
  Holt A ; Mori S ; Muca A ; Patel J ; Ratnanather T
• Description:
  Background: Even exposure to loud noise resulting in temporary deafness often leads to conditions such as tinnitus. Noise overexposure has been a major risk factor for chronic tinnitus for those in occupations associated with noisy environments. Currently there is no effective treatment for tinnitus. This emphasizes the need to determine metrics that will allow for longitudinal studies of tinnitus progression. Noise induced tinnitus has been associated with changes in neuronal activity. Magnetic resonance imaging (MRI) has been used to track longitudinal changes in tinnitus related neuronal activity using manganese enhanced MRI (MEMRI). In addition to activity, neuronal volume has also been suggested to change in people with chronic tinnitus. Temporal and spatial changes in brain volume were examined longitudinally in several brain regions, including the inferior colliculus (IC), following a single noise exposure. Methods: Hearing thresholds were determined (ABRs) in two groups (noise and no noise) of male Sprague Dawley rats. Noise animals were exposed to a 16 kHz, 106 dB SPL tone for 1 hour. For each group, T1 -weighted MRI images were obtained (7T Clinscan) before (baseline) and after noise exposure (1, 28, and 84 day(s)). Deficits in Gap detection were used as a measure of tinnitus. Morphology for regions of interest (ROIs) was identified on a single subject brain atlas using MRIStudio software. The atlas was registered to the subjects using Automated Image Registration (AIR) and Large Deformation Diffeomorphic Metric Mapping (LDDMM) in order to map the ROIs onto each subject. ROI volumes from the two groups were compared at each time point. Results: Differences in the volume of the IC occurred as early as 1 day after noise exposure, with significant decreases in the central nucleus of the IC (CIC) of noise exposed animals compared to control. Although hearing thresholds had returned to normal, significant volumetric decreases were seen 84 days after noise exposure in the CIC of noise exposed animals. With the exception of the first week, Gap detection deficits were present at all time points (20 kHz, 60dB). Conclusions: An outcome of our study is the production of a rat volumetric atlas with brain region coordinates that can be used as a template by others. Volumetric information may provide another crucial metric for understanding the effects of noise over-exposure on the progression of tinnitus. [Description provided by NIOSH]
• Subjects:
  Animals Noise Noise, Occupational Occupational Exposure Occupational Health Safety
• Keywords:
  Animal Studies Auditory System Ear Disorders Magnetic Resonance Imaging MRI Neurological System Noise Exposure Occupational Exposure Tinnitus Volumetric Analysis
• ISSN:
  0742-3152
• Publisher:
  Association for Research in Otolaryngology
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  California ; Maryland ; Michigan ; OSHA Region 3 ; OSHA Region 5 ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  254-255
• Volume:
  39
• NIOSHTIC Number:
  nn:20060977
• Citation:
  Abstr Midwinter Res Meet Assoc Res Otolaryngol 2016 Feb; 39:254-255
• Federal Fiscal Year:
  2016
• Performing Organization:
  University of Michigan, Ann Arbor
• Peer Reviewed:
  False
• Start Date:
  20050701
• Source Full Name:
  Abstracts of the 39th Midwinter Research Meeting of the Association for Research in Otolaryngology, Febuary 20-24, 2016, San Diego, California
• End Date:
  20280630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8882a263331878b711e4fd666ccc2682501c0a46aefbc0382b5375b558f967bc1ba6aa5ccf84e1b666fcfdcdd4121d2699081c0c8e2d02477077850b47ccd89d
• Download URL:
  https://stacks.cdc.gov/view/cdc/224693/cdc_224693_DS1.pdf
• File Type:
  [PDF - 911.77 KB ]