Multisequence magnetic resonance neurography of brachial and lumbosacral plexus in chronic inflammatory demyelinating polyneuropathy: correlations with electrophysiological parameters and clinical features

Abstract

Background: Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare and challenging demyelinating disorder. It is necessary to increase our understanding of potential connections between imaging, electromyography, and clinical characteristics.

Objective: The aim of this study was to evaluate the relationships between multisequence magnetic resonance neurography (MRN) findings, electrophysiological parameters, and clinical characteristics in CIDP patients.

Design: A cross-sectional study.

Methods: Overall, 51 CIDP patients underwent MRN of the brachial and lumbosacral plexus, and nerve conduction studies. The inflammatory Rasch-built overall disability scale (I-RODS) questionnaire, CIDP disease activity status (CADS) scale, and muscle strength scores were evaluated by two neurologists. Electrophysiological parameters, clinical information, and multiparameter-MRN were analyzed for correlations. Multiparameter-MRN includes diameter, nerve-to-muscle T2 signal intensity ratio (nT2), contrast-enhanced ratio (CR), fractional anisotropy (FA), and apparent diffusion coefficient (ADC) of bilateral plexus nerve roots.

Results: Electrophysiological parameters that were not elicited were significantly higher in the lower extremities than in the upper extremities, and those were higher in sensory nerve conduction than in motor. There were moderate correlations between motor nerve conduction velocity and distal motor latency in nerve diameter, nT2, FA, and ADC, respectively (|r|, 0.45-0.64, p < 0.05). The correlations between CR and sensory nerve conduction velocity and peak latency were moderate, and ADC had a positive correlation with compound motor action potential amplitude (|r|, 0.45-0.63). FA correlated negatively with the course (r = -0.62) and cerebrospinal fluid (CSF) protein (r = -0.41), whereas ADC had correlated positively with CSF protein (r = 0.34). Only CR had a moderately negative correlation with CADS (r's = -0.57). Muscle strength in all extremities was positively correlated with FA (r's range, 0.41-0.49). There was no significant correlation between I-RODS scores and multiparameter-MR.

Conclusion: MRN-derived multiparameter [nerve size, nT2, and diffusion tensor imaging (DTI) parameters] could serve as quantitative biomarkers of myelin sheath integrity in CIDP. DTI parameters and CR correlated with clinical characteristics better than morphological parameters-MR for CIDP patients.

Keywords: chronic inflammatory demyelinating; diffusion tensor imaging; electrophysiology; magnetic resonance imaging; polyradiculoneuropathy.

Figure 1.

MRN showed that diffuse hypertrophy of the LS plexus (a, b) and brachial plexus (f) nerve roots, bundles, and branches with increased T2 signal intensity, accompanied by mild enhancement (d, e) in CIDP patient. Schematic diagram showed the measurement of the diameter in the left S1 nerve root (yellow line in b), signal intensity of bilateral S1 nerve roots on TIRM sequence (circles in c), and on non-ce VIBE and ce VIBE sequences, separately (circles in d, e).

Figure 2.

Schematic diagram showed the measurement of the DTI parameters, including FA and ADC values (circles in bilateral S1 nerve roots). Diffusion tensor tractography showed thickened and distorted discontinuous tracts in the LS plexus.

Figure 3.

Non-elicited rate of the motor and sensory nerve conduction in lower extremities was significantly higher than those of upper extremities (a, b). Non-elicited rate of the conduction velocity, latency, and amplitude of action potential in sensory nerve conduction was significantly higher than those of motor nerve conduction (c). CMAP, compound muscle action potential; DML, distal motor latency; LE, lower extremities; MCV, motor conduction velocity; MNC, motor nerve conduction; PL, peak latency; SCV, sensory nerve conduction velocity; SNAP, sensory nerve action potential; SNC, sensory nerve conduction; UE, upper extremities. *p < 0.05. ***p < 0.001.

Figure 4.

The heatmap shows significant correlation coefficients (r) between quantitative magnetic resonance multiparameters and electrophysiological parameters. ADC, apparent diffusion coefficient; CR, contrast-enhanced ratio; D, diameter; DML, distal motor latency; FA, fractional anisotropy; L., lower extremities; MCV, motor conduction velocity; nT2, nerve-to muscle T2 signal intensity ratio; PL, peak latency; SCV, sensory nerve conduction velocity; SNAP, sensory nerve action potential; U., upper extremities. *p < 0.05. **p < 0.01.

Figure 5.

Pearson correlation shows that FA value has significantly moderate negative correlations between (a) disease course and (b) CSF protein, respectively (p < 0.05). There was a slight significantly positive correlation between (c) ADC value and CSF protein. ADC, apparent diffusion coefficient; CSF, cerebrospinal fluid; FA, fractional anisotropy. *p < 0.05. **p < 0.01. ****p < 0.0001.