We report DTI and resting-state fMRI results on a sample of adults diagnosed with Chiari malformation Type I (CM1) and eligible for decompression surgery and 18 age- and education-matched controls. The goals of the present study were to test for group differences in structural integrity (DTI) and functional connectivity (resting-state fMRI), and to assess whether group differences were moderated by self-reported pain and cognitive effects.
We scanned 18 CM1 individuals and 18 age- and education-matched controls using a 3T Siemens scanner with Prisma software. All participants were also assessed on the McGill Pain Questionnaire-Short Form and the RBANS neuropsychological assessment battery.
We observed group differences in DTI fractional anisotropy (FA) and diffusivity (radial and mean) in regions of the cerebellum, cingulum, and cerebrum—and these effects were no longer significant after controlling for self-reported pain. Also, controls showed a significant correlation between FA and radial diffusivity and RBANS Coding scores in brain regions that have been associated with the frontoparietal attentional pathway, but there was no significant correlation between diffusion parameters and Coding scores for CM1 patients. For the functional connectivity analyses (resting-state fMRI), seed-based analysis showed group differences in functional connectivity for Lobules IX and X, as well as the default mode network (both positive and negative) and frontoparietal attentional pathway.
Discussion and Conclusions
We observed both structural (DTI) and functional (resting-state fMRI) group differences. The cases in which CM1 patients had either higher FA or increased functional connectivity relative to controls were associated with self-reported pain levels. Alternatively, controls showed increases in FA as RBANS Coding scores increased (but no effect for CM1 patients). For fMRI, there were six significant group differences (four positive and two negative), and group differences for Lobules IX and X were eliminated after controlling for RBANS Attention scores.