White Matter Plasticity in Trigeminal Neuralgia - FCD Mapping Study

Abstract

Central nervous system changes can follow trigeminal nerve dysfunction. Brain white matter and functional connectivity changes in TN patients were involved in pain perception, modulation, the cognitive-affective system, and motor function; moreover, changes in functional reorganization correlate with white matter alterations. The correlated brain structural-functional changes may be responsible for the persistence of long-term recurrent pain and sensory-related dysfunction in TN patients. Diffusion kurtosis imaging (DKI) characterizes non-Gaussian diffusion by estimating the excess kurtosis of the displacement distribution and functional connectivity density (FCD) mapping allows the calculation of functional connectivity maps in brain networks & overcomes the limitations of seed-based approaches for functional study. We examined both DKI and FCD in TN using multiple MRI technologies to provide insight into its central mechanisms. 10 TN patients and 20 healthy controls were studied. Diffusion kurtosis imaging was analyzed to extract diffusion and kurtosis parameters, and functional connectivity density (FCD) mapping was used to explore the functional reorganization in the brain. In the patient group, lower axial kurtosis and higher axial diffusivity in tracts participated in sensory, cognitive-affective, and modulatory aspects of pain, such as the cingulate gyrus, bilateral superior longitudinal fasciculus, bilateral anterior thalamic radiation, forceps major, bilateral inferior longitudinal fasciculus, bilateral inferior fronto-occipital fasciculus, and bilateral uncinate fasciculus. However, there were no significant differences in fractional anisotropy (FA), radial diffusivity (RD), and mean diffusivity (MD) between the two groups. Compared with healthy controls, TN patients exhibited significantly decreased axial kurtosis (AK) in white matter regions with fiber arrangement, such as in the right corticospinal tract, right superior longitudinal fasciculus, bilateral anterior thalamic radiation, bilateral inferior longitudinal fasciculus, and bilateral inferior fronto-occipital fasciculus. However, there were no significant differences in radial kurtosis (RK) and mean kurtosis (MK) between the two groups. Patients exhibited complex FCD reorganization of hippocampus, striatum, thalamus, precentral gyrus, precuneus, prefrontal cortex and inferior parietal lobule in multiple modulatory networks that played crucial roles in pain perception, modulation, cognitive-affective system, and motor function. Further, the correlated structural-functional changes may be responsible for the persistence of long-term recurrent pain and sensory-related dysfunction in TN. Abnormal increased diffusion in white matter tracts involved in sensory, cognitive-affective, and modulatory aspects of pain are correlated with decreased FCDs in pain perception and modulation in TN patients.