Neural Changes in Patients with Post-Traumatic Anosmia: Insights from Resting-State fMRI

Functional Magnetic Resonance Imaging (fMRI) is a powerful modality for investigating changes in healthy brains and those with disorders. Anosmia, an olfactory disorder, is commonly associated with traumatic brain injury, particularly in patients suffering from severe trauma.

In this study, we aimed to utilize Resting-State fMRI (rs-fMRI) to examine changes in Functional Connectivity (FC) networks between Healthy Controls (HCs) and patients with Post-Traumatic Anosmia (PTA).

In this retrospective study, we performed rs-fMRI on forty-four PTA patients and forty-three HCs. The Sniffin' Sticks test was used to assess olfactory function. Seed-based Analysis (SBA) and Independent Component Analysis (ICA) were conducted using MATLAB-based imaging software.

PTA patients showed lower Threshold-Discrimination-Identification (TDI) scores compared to HCs. SBA revealed increased FC correlations in the anterior cingulate cortex, piriform, insular cortex, and prefrontal area in PTA patients. Using ICA on the whole brain network, we found increased FC in the right frontal pole, cerebellum, right putamen, anterior cingulate cortex, postcentral gyrus, orbitofrontal cortex, and amygdala in PTA compared to HCs. In PTA patients, global efficiency of the entire brain network showed a significant association with olfactory performance.

This study suggests that neural-level olfactory deficits following head trauma are most accurately characterized through SBA and ICA analyses in higher-order regions outside the primary olfactory cortex.