Quantitative analysis tool for clinical functional MRI in mild traumatic brain injury.

Functional magnetic resonance imaging (fMRI) has been available commercially for clinical diagnostic use for many years. However, both clinical interpretation of fMRI by a neuroradiologist and quantitative analysis of fMRI data can require significant personnel resources that exceed reimbursement. In this report, a fully automated computer-based quantification methodology (Enumerated Auditory Response, EAR) has been developed to provide an auditory fMRI assessment of patients who have suffered a mild traumatic brain injury. Fifty-five study participants with interpretable auditory fMRI sequence data were assessed by EAR analysis, as well as both clinical radiologist fMRI interpretation and voxelwise general linear model (GLM) analysis. Comparison between the clinical interpretation and the two computer analysis methods resulted in 67% concordance (identical), 32% nearconcordance (one level difference), and 1% discordant. Comparison between the clinical computer-based quantification (EAR) and GLM analysis yielded significant correlations in right and left ear responses (p⟨0.05) for the full subject group. Automated fMRI quantification analysis equivalent to EAR might be appropriate for both future research projects with constrained resources, as well as possible routine clinical use.

Olfactory and other sensory impairments in Alzheimer disease.

The vast increase in Alzheimer disease (AD) worldwide has grave implications for individuals, family support systems and the health-care systems that will attempt to cope with the disease. Early markers of the disease are essential for efficient selection of clinical trial participants for drug development and for timely treatment once an intervention becomes available. There is avid interest in noninvasive, inexpensive markers that have the potential to identify prodromal AD. This Review considers sensory impairments that have the potential to serve as early indicators of AD, with a focus on olfaction, hearing and vision. Current evidence regarding the potential markers of AD in each modality is examined, with a particular emphasis on olfaction and current findings that olfactory function is associated with prodromal AD. Research suggests that olfactory impairment is associated with other markers that signal the emergence of prodromal AD. Auditory impairment is associated with dementia in epidemiological studies and visual system deficits have been reported in AD; however, the emergence of these deficits in prodromal AD is unclear. Further research is necessary to address the relative sensitivity and specificity of olfactory, auditory and visual measures for the detection of prodromal AD.

Auditory Pathway Features Determined by DTI in Subjects with Unilateral Acoustic Neuroma.

PURPOSE: In the studies concerning the pathology of the auditory pathway in the vestibulocochlear system, few use advanced neuroimaging applications of magnetic resonance imaging (MRI) such as diffusion tensor imaging (DTI). Those who did use reported DTI changes only at the lateral lemniscus and inferior colliculus level. The aim of our study was to determine diffusion changes in the bilateral auditory pathways of subjects with unilateral acoustic neuroma (AN) and compare them with healthy controls. MATERIAL AND METHODS: A total of 15 subjects with unilateral AN along with 11 controls underwent routine MRI and DTI. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values obtained from the lateral lemniscus, inferior colliculus, corpus geniculatum mediale, and Heschl's gyrus of the auditory pathway were then compared. RESULTS: The subjects' ADC values measured from the contralateral side were significantly higher at the lateral lemniscus, inferior colliculus, and corpus geniculatum mediale compared with those of the controls. Also, decreased FA values were noted at the inferior colliculus for both the contralateral and ipsilateral sides. The highest ADC values were detected in the inferior colliculus of the auditory pathway. CONCLUSIONS: In the auditory pathway of subjects with AN, the contralateral side is more affected than the ipsilateral side, the most affected region being the inferior colliculus. DTI is an advanced neuroimaging technique that can be used to determine the presence of microstructural damage to the auditory pathway in subjects with AN, whereas conventional MRI is not sensitive enough to detect damage.

Cortical auditory disorder caused by bilateral temporal infarctions.

We present a 55-year-old man who suddenly became afflicted with a bilateral auditory disturbance. Auditory acuity was preserved relatively well. Brainstem auditory evoked potentials (BAEPs) were normal. Middle latency auditory evoked potentials (MLAEPs) revealed the total absence of all waves. Brain computed tomography (CT) showed infarctions of the temporal lobes bilaterally, involving the superior temporal and transverse temporal gyri. The recognition of verbal and nonverbal sounds was also impaired. Brain CT, MLAEPs and auditory recognition tests were useful in diagnosing the cortical auditory disorder.

Central auditory and vestibular pathology.

MR is the radiologic examination of choice when a patient's symptoms indicate the presence of some retrolabyrinthine pathology. CT dynamic studies now permit both heart and brain assessment for poor blood circulation problems of the hindbrain.