Neuroimaging Techniques in Assessment of Auditory Processing Disorders: A Review.
In the current scenario, audiologist diagnose APD majorly with the help of different behavioral tests, without probing into neurological aspects of it. MRI is a medical imaging technique which uses high radio waves, magnetic fields and field gradients to image the body, either structurally (sMRI) or functionally (fMRI). sMRI using the fluid attenuation inversion recovery (FLAIR) technique is a good method to identify brain lesions.
A study by BartelFriedrich and colleagues aimed at finding the areas responsible for processing auditory information with the help of fMRI in typically developing children. The tests used included Hannover phoneme discrimination test (HPDT) dichotic listening test (DLT) and auditory memory span test (MST). Depending on the processing required for each test, the activation occurred
was documented and the findings were: activations in dorsal portion of superior temporal gyrus in both sides, Broca’s area and left middle temporal gyrus are typical to HPDT.
Even though fMRI probes into additional information about auditory processing which in turn helps in the diagnosis, one has to be cautious while using it due to different factors like anatomical and age factors. Children and adults vary in relative extent of different cortical areas. Also with the increase in age (11-13 years), relation between grey and white matter varies.
Roberts et al9 used MEG technique to compare the neural response for pure tones of different frequencies, between typically developing children and children with autism spectrum disorder (ASD). However to date, there are no imaging studies used for diagnosis of APD in children. Also, to understand how the neuroimaging techniques assist in diagnosis of APD requires one to have basic understanding of how typical brain processes to any kind of auditory stimuli
Otolaryngol Open J. 2016; SE(1): S10-S14. doi: 10.17140/OTLOJ-SE-1-103