Marieke van Rosmalen

MRI of the intraspinal nerve roots in chronic inflammatory neuropathies 79 5 independent samples t test between ventral and dorsal nerve roots, and a paired t test to compare successfully performed measurements between the right and left side of one patient. We evaluated intrarater reliability of our measurements using the intraclass correlation coefficient (ICC). We considered an ICC < 0.50 as poor reliability, 0.50 – 0.75 as moderate, 0.75 – 0.90 as good and > 90 as excellent reliability. 12 To calculate means of intraspinal nerve root sizes per study group (CIDP, MMN, disease controls and healthy controls) we used a univariate general linear model with the measurements as dependent variable and diagnosis as fixed factor. Tukey HSD was used to correct for multiple testing. Additionally, we used a second univariate general linear model to calculate mean intraspinal root sizes per clinical phenotype (sensorimotor, pure motor, and sensory or ataxic) with again the measurements as dependent variable. Results with a p value < 0.05 were considered significant. Figure 5.1 Example of intraspinal nerve root measurements Method of measurements with calipers are placed in transversal plane in the ventral (red) and dorsal (blue) intraspinal nerve root at C5 to C7 level, here at C6 level. In the upper left corner the 3D TSE SPIR (anatomical reference) with the reference line (green). Abbreviations: R = right; L = left. RESULTS Patients and clinical data We included a total of 106 participants (CIDP = 40, MMN = 27, disease controls = 34, healthy controls = 5). There were 31 patients with a sensorimotor phenotype, 29 with a pure motor and 7 with a pure sensory or ataxic phenotype. Patient characteristics are summarized in Table 5.1 . We found no differences in the baseline characteristics between groups, other than a younger age in patients with MMN compared to patients with CIDP and MND ( p = 0.003).