Peripheral nerve involvement in multiple sclerosis Demonstration by magnetic resonance neurography

Abstract

Objective:To detect and quantify peripheral nerve lesions in multiple sclerosis (MS) by magnetic resonance neurography (MRN).

Methods: 36 patients diagnosed with MS based on the 2010 McDonald criteria (34 with the relapsing-remitting form, 2 with clinically isolated syndrome) with and without disease modifying treatment were compared to 35 healthy age/sex-matched volunteers. All patients underwent detailed neurological and electrophysiological examinations. 3T MRN with large anatomical coverage of both legs and the lumbosacral plexus was performed by using 2D fat-saturated, T2-weighted and dual echo turbo-spin-echo sequences as well as a 3D T2-weighted, fat-saturated SPACE sequence. Besides qualitative visual nerve assessment, a T2w-signal quantification was performed by calculation of proton-spin-density and T2-relaxation time. Nerve diameter was measured as a morphometric criterion.

Results:T2w-hyperintense nerve lesions were detectable in all MS patients with a mean lesion number at thigh level of 151.5±5.7 vs. 19.1±2.4 in controls (p<0.0001). Nerve proton-spin-density was higher in MS (tibial/peroneal: 371.8±7.7/368.9±8.2) vs. controls (tibial/peroneal: 266.0±11.0/276.8±9.7;p<0.0001). In contrast, T2-relaxation time was significantly higher in controls (tibial/peroneal:82.0±2.1/78.3±1.7) vs. MS (tibial/peroneal:64.3±1.0/61.2±0.9; p<0.0001). Proximal tibial and peroneal nerve caliber was higher in MS (tibial:52.4±2.1mm²; peroneal:25.4±1.3mm²) vs. controls (tibial:45.2±1.4mm²; p<0.0015; peroneal:21.3±0.7mm²; p=0.0049).

Interpretation:Peripheral nerve lesions could be visualized and quantified in MS in vivo by high resolution MRN. Lesions are defined by an increase of proton-spin-density and a decrease of T2-relaxation time, indicating changes in the microstructural organization of the extracellular matrix in peripheral nerve tissue in MS. By showing involvement of the peripheral nervous system in MS, this proof-of-concept study may offer new insights into the pathophysiology and treatment of MS. This article is protected by copyright. All rights reserved.

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