Spinal Nerve Root Hypertrophy on MRI: Clinical Significance in the Diagnosis of Chronic Inflammatory Demyelinating Polyradiculoneuropathy

Abstract

To investigate the clinical usefulness of measuring diameters of spinal nerve roots on magnetic resonance imaging (MRI) in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with regard to the diagnosis and estimation of neurofunctional impairment. Fourteen patients with CIDP (mean age, 38.9+/-19.2 years) and 10 controls were enrolled in this study. Diameters of cervical and lumbosacral spinal nerve roots were determined on the short tau inversion recovery image of MRI. Correlations between these diameters and clinical indices, including the conduction velocity of median and tibial nerves, were examined. Mean diameters of cervical and lumbosacral spinal nerve roots in CIDP patients were 6.0 to 6.8 mm and 7.3 to 10.4 mm, respectively. CIDP patients showed higher values of the diameter in C5 (p<0.05), C6 (p<0.05), C7 (p<0.005) and C8 (p<0.01) than controls. C7 and C8 showed significantly negative correlations between diameters of spinal nerve roots and the F-wave conduction velocity (FWCV) (p<0.05). In the lumbosacral region, L3, L4 and S1 showed significantly negative correlations between diameters of spinal nerve roots and FWCV (p<0.005, p<0.0005 and p<0.005, respectively). The latency-time difference between F- and M-waves increased with diameters of spinal nerve roots, and there were significantly positive correlations between them in L3 (p<0.05) and L4 (p<0.005). Hypertrophy of spinal nerve roots shown on MRI may be useful as a clue to the diagnosis of CIDP and also as a clinical marker suggesting impairment of peripheral nerve conduction, particularly FWCV.