Structural Integrity (DTI) and Functional Connectivity (Resting-State fMRI) in Chiari Malformation Type I: The Effects of Pain and Cognition.

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Event.

2nd Annual CSF Flow Meeting

Abstract.

Background: 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 most salient symptom of Chiari malformation Type I is chronic headache pain (Fischbein et al., 2015).  However, there is growing evidence of cognitive symptoms, as well (Allen et al., 2014, Garcia et al., 2018; Houston et al., in press; Rogers et al., 2018).  The goal of the present study was two-fold.  First, are there reliable group differences in structural integrity (DTI) and functional connectivity (resting-state fMRI)?  Second, if group differences in such fiber-tract effects occur, are they related to pain and cognitive effects?       

Methods: 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.  

Results: We observed group differences in DTI fractional anisotropy (FA) and diffusivity (radial and mean) in regions of the cerebellum, cingulum, and cerebrum—and this was positively correlated with SF-MPQ scores (i.e., CM1 patients showed higher FA values than controls).  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 the was no significant correlation between diffusion paramters 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). The implications for recent functional connectivity findings will also be discussed.

Contributors.

Philip A. Allen, James R. Houston, Michelle L. Hughes, Ilana J. Bennett, Francis Loth, Jeffrey M. Rogers, Marcus A. Stoodley, Mark G. Luciano, Sarel J. Voster