Marieke van Rosmalen

Chapter 5 86 morphology. 13,14 MRI of the intraspinal nerve roots allowed us to image the most proximal parts of the peripheral nervous system, and provided the unique opportunity to study the motor and sensory roots separately. MRI of the intraspinal nerve roots has been previously used to assess the intraspinal nerve root integrity in traumatic brachial plexus injuries. 15–17 A few smaller studies describe MRI results of the intraspinal nerve roots in patients with Guillain-Barré syndrome (GBS). 18–22 These studies report nerve root enhancement in the spinal roots, with preferential involvement of the ventral spinal roots in patients with pure motor GBS and enhancement of the ventral and dorsal spinal roots in patients with a sensorimotor phenotype. We here corroborate these results in a much larger patient sample. Our data seem to indicate that motor and sensory nerves can be specific targets in inflammatory neuropathies. We think that it is likely that the widespread thickening of peripheral nerves is caused by specific isolated changes in motor or sensory nerves in MMN and sensory CIDP. Our study has limitations. We included a small group of healthy controls, but the variability in spinal nerve root sizes in this group was limited. Absolute nerve root size differences between groups were small and in terms of hundredth of a millimeter. The fact that intrarater reliability was good indicates that the methodology is sound and that the resolution is high. An even higher resolution is probably technically feasible and could result in even more accurate measurements and less artifacts, in particular of ventral roots. This study contributes to our understanding of inflammatory neuropathies. This high-resolution technology might have biomarker value in the future.