Use of Magnetic Resonance Neurography for Evaluating the Distribution and Patterns of Chronic Inflammatory Demyelinating Polyneuropathy

Abstract

Objective: To evaluate the distribution and characteristics of peripheral nerve abnormalities in chronic inflammatory demyelinating polyneuropathy (CIDP) using magnetic resonance neurography (MRN) and to examine the diagnostic efficiency.

Materials and methods: Thirty-one CIDP patients and 21 controls underwent MR scans. Three-dimensional sampling perfections with application-optimized contrasts using different flip-angle evolutions and T1-/T2- weighted turbo spin-echo sequences were performed for neurography of the brachial and lumbosacral (LS) plexus and cauda equina, respectively. Clinical data and scores of the inflammatory Rasch-built overall disability scale (I-RODS) in CIDP were obtained.

Results: The bilateral extracranial vagus (n = 11), trigeminal (n = 12), and intercostal nerves (n = 10) were hypertrophic. Plexus hypertrophies were observed in the brachial plexus of 19 patients (61.3%) and in the LS plexus of 25 patients (80.6%). Patterns of hypertrophy included uniform hypertrophy (17 [54.8%] brachial plexuses and 21 [67.7%] LS plexuses), and multifocal fusiform hypertrophy (2 [6.5%] brachial plexuses and 4 [12.9%] LS plexuses) was present. Enlarged and/or contrast-enhanced cauda equina was found in 3 (9.7%) and 13 (41.9%) patients, respectively. Diameters of the brachial and LS nerve roots were significantly larger in CIDP than in controls (p < 0.001). The largest AUC was obtained for the L5 nerve. There were no significant differences in the course duration, I-RODS score, or diameter between patients with and without hypertrophy.

Conclusion: MRN is useful for the assessment of distribution and characteristics of the peripheral nerves in CIDP. Compared to other regions, LS plexus neurography is more sensitive for CIDP.

Keywords: Brachial plexus; Chronic inflammatory demyelinating polyneuropathy; Cranial nerves; Lumbosacral plexus; Magnetic resonance neurography.

Fig. 1. Representative healthy subject of plexus.

Coronal reconstructed MIP 3D SPACE image of healthy subject showing expected symmetrical and uniform signal intensities of brachial (A), lumbosacral (B) plexus and intercostal nerves (open arrows in B), with gradual fading of signal along courses of nerves. Ganglia exhibit low signal intensities similar to filling defects (long arrows in A, B). MIP = maximum intensity projection, 3D SPACE = three-dimensional sampling perfection with application-optimized contrasts using different flip angle evolution

Fig. 2. Representative hypertrophy patterns and characteristic in CIDP patients with large field of view magnetic resonance neurography.

Patients (type I) with 5-year (A) and 3-year (B) disease courses, showed strikingly symmetric uniform enlargements in brachial and lumbosacral plexus with increased signal intensity. Patients (type II) with 7-year (C) and 6-year (D) relapsing-remitting courses, showed bilateral multiple fusiform wheat-spike hypertrophy in brachial and lumbosacral plexus, with irregular thickening in intercostal nerves (open arrows in C, D). Neural stems had characteristic signal reduction zone worm-like cavity in both type I (long arrow in B) and type II (long arrow in D) CIDP patients. CIDP = chronic inflammatory demyelinating polyneuropathy

Fig. 3. Representative abnormality of nerve branches in CIDP patients.

CIDP patient with 2-year disease courses (A), showed pronounced distal nerves trunk thickening not proximal to nerve roots. MIP 3D SPACE showed symmetrical hypertrophic hyperintense extracranial trigeminal branches (B), auriculotemporal nerves (short arrow), inferior alveolar nerves (long arrow), lingual nerves (open arrow), and bilateral vagus nerves (long arrow) (C). Images show bilateral hypertrophy of femoral (D) and obturator nerves (type I, E; type II, F). Images (G, H) show markedly thickened enhancement of cauda equina.

Fig. 4. Comparison of nerve diameters between CIDP and controls.

Diameters of brachial (C5–C8) (A) and lumbosacral (L4–S1) nerve roots and sciatic and femoral nerves (B) were significantly higher in patients with chronic inflammatory demyelinating polyneuropathy than in healthy controls (all p < 0.01).

Fig. 5. Receiver operating characteristic plots showing curves for diameters of brachial (A) and lumbosacral (B) nerve roots.

AUCs of lumbosacral plexus were higher than those of brachial plexus. Largest AUC was L5 nerve root. Numbers in parentheses indicate respective AUC values. AUC = area under curve