Peripheral nerve involvement in multiple sclerosis: Demonstration by magnetic resonance neurography

Area of Science:

• Neuroimaging
• Neurology
• Radiology

Background:

• Multiple Sclerosis (MS) is a chronic demyelinating disease of the central nervous system.
• Peripheral nerve involvement in MS has been suggested but not well-characterized.
• High-resolution Magnetic Resonance Neurography (MRN) offers potential for visualizing peripheral nerves.

Purpose of the Study:

• To detect and quantify peripheral nerve lesions in patients with Multiple Sclerosis (MS) using MRN.
• To investigate microstructural changes in peripheral nerves associated with MS.
• To establish MRN as a tool for assessing peripheral nerve involvement in MS.

Main Methods:

• Thirty-six MS patients and 35 healthy controls underwent detailed neurological and electrophysiological examinations.
• Three Tesla (3T) MRN with large anatomical coverage of the lumbosacral plexus and legs was performed.
• Utilized 2D fat-saturated T2-weighted (T2w) and dual echo turbo spin echo sequences, plus a 3D T2w SPACE sequence.
• Nerve assessment included qualitative visual evaluation, T2w signal quantification (proton spin density, T2 relaxation time), and morphometric nerve diameter measurements.

Main Results:

• All MS patients exhibited T2w hyperintense nerve lesions, with significantly higher lesion counts compared to controls (151.5 vs. 19.1, p < 0.0001).
• MS patients showed increased nerve proton spin density (tibial/peroneal: 371.8/368.9 vs. 266.0/276.8, p < 0.0001) and decreased T2 relaxation time (tibial/peroneal: 64.3/61.2 vs. 82.0/78.3, p < 0.0001) compared to controls.
• Proximal tibial and peroneal nerve caliber was significantly larger in MS patients than in controls (p < 0.0015 for tibial, p = 0.0049 for peroneal).

Conclusions:

• High-resolution MRN can effectively visualize and quantify peripheral nerve lesions in MS patients in vivo.
• MS-related peripheral nerve lesions are characterized by increased proton spin density and decreased T2 relaxation time, suggesting altered extracellular matrix organization.
• This study provides proof-of-concept for peripheral nervous system involvement in MS, potentially offering new insights into disease pathophysiology and treatment strategies.