Neuroimaging supports central pathology in familial dysautonomia

Familial dysautonomia (FD) is a hereditary peripheral and central nervous system disorder with poorly defined central neuropathology. This prospective pilot study aimed to determine if MRI would provide objective parameters of central neuropathology. There were 14 study subjects, seven FD individuals (18.6 ± 4.2 years, 3 female) and seven controls (19.1 ± 5.8 years, 3 female). All subjects had standardized brain MRI evaluation including quantitative regional volume measurements, diffusion tensor imaging (DTI) for assessment of white matter (WM) microstructural integrity by calculation of fractional anisotropy (FA), and proton MR spectroscopy (¹H MRS) to assess neuronal health. The FD patients had significantly decreased FA in optic radiation (p = 0.009) and middle cerebellar peduncle (p = 0.004). Voxel-wise analysis identified both GM and WM microstructural damage among FD subjects as there were nine clusters of WM FA reductions and 16 clusters of GM apparent diffusion coefficient (ADC) elevations. Their WM proportion was significantly decreased (p = 0.003) as was the WM proportion in the frontal region (p = 0.007). ¹H MRS showed no significant abnormalities. The findings of WM abnormalities and decreased optic radiation and middle cerebellar peduncle FA in the FD study group, suggest compromised myelination and WM micro-structural integrity in FD brains. These neuroimaging results are consistent with clinical visual abnormalities and gait disturbance. Furthermore the frontal lobe atrophy is consistent with previously reported neuropsychological deficits.