European Radiology

, Volume 25, Issue 5, pp 1497–1503

Diagnostic Signs of Motor Neuropathy in MR Neurography: Nerve Lesions and Muscle Denervation

  • Daniel Schwarz
  • Markus Weiler
  • Mirko Pham
  • Sabine Heiland
  • Martin Bendszus
  • Philipp Bäumer
Musculoskeletal

DOI: 10.1007/s00330-014-3498-x

Cite this article as:
Schwarz, D., Weiler, M., Pham, M. et al. Eur Radiol (2015) 25: 1497. doi:10.1007/s00330-014-3498-x

Abstract

Objective

To investigate the diagnostic contribution of T2-w nerve lesions and of muscle denervation in peripheral motor neuropathies by magnetic resonance neurography (MRN).

Methods

Fifty-one patients with peripheral motor neuropathies underwent high-resolution MRN by large coverage axial T2-w sequences of the upper arm, elbow, and forearm. Images were evaluated by two blinded readers for T2-w signal alterations of median, ulnar, and radial nerves, and for denervation in respective target muscle groups.

Results

All 51 patients displayed nerve lesions in at least one of three nerves, and 43 out of 51 patients showed denervation in at least one target muscle group of these nerves. In 21 out of 51 patients, the number of affected nerves matched the number of affected target muscle groups. In the remaining 30 patients, T2-w lesions were encountered more frequently than target muscle group denervation. In 153 nerve-muscle pairs, 72 showed denervation, but only one had increased muscle signal without a lesion in the corresponding nerve.

Conclusions

MRN-based diagnosis of peripheral motor neuropathies is more likely by visualization of peripheral nerve lesions than by denervation in corresponding target muscles. Increased muscular T2-w signal without concomitant nerve lesions should raise suspicion of an etiology other than peripheral neuropathy.

Key Points

In peripheral neuropathy, T2-w nerve lesions are more frequent than muscle denervation.

Muscle denervation almost never occurs without detectable lesions in corresponding nerves.

MRN-aided diagnosis of peripheral motor neuropathy should focus primarily on nerve lesions.

Increased muscular T2-w signal intensity without concomitant nerve lesions indicates other aetiology.

Keywords

MR neurography Polyneuropathy MRI Muscle denervation Nerve lesion 

Supplementary material

330_2014_3498_Fig6_ESM.jpg (4.7 mb)
Supplementary Table 1

Clinical data for all patients. Detailed overview of clinical and demographic data of the patient collective. The functional specification of the symptom is followed by the respective MRC grading in brackets. Symptoms are listed in ascending MRC grading order. Muscles are abbreviated as follows: M. brachioradialis (BR), extensor carpi radialis (longus and brevis) (ECR), extensor digitorum communis (EDC), extensor indicis (EI), extensor carpi ulnaris (ECU), pronator teres (PT), flexor carpi ulnaris (FCU), flexor digitorum profundus (FDP), flexor carpi radialis (FCR), pronator quadratus (PQ), flexor pollicis longus (FPL), flexor pollicis brevis (FPB), abductor pollicis brevis (APB), opponens pollicis (OP), abductor digiti minimi (ADM), interosseous dorsalis (IDM). Electrophysiological abbreviations are: motor unit action potential (MUAP), compound muscle action potential (CMAP), sensory nerve action potential (SNAP), distal motor latency (dml), proximal motor latency (pml), sensory evoked potentials (SEP). The following (sixth) column states the corresponding diagnosis, and the seventh column lists the respective interval of time between onset of clinical symptoms and MR neurography. The penultimate column informs about additional MR sequences performed that were not routinely included in the protocol of the study. The last column shows the assigned group of every patient after evaluation of acquired images. At the bottom, the total numbers of male and female patients, the mean age, and the median and mean time delay between onset of clinical symptoms and MR neurography are given. (JPEG 4850 kb)

Copyright information

© European Society of Radiology 2014

Authors and Affiliations

  • Daniel Schwarz
    • 1
  • Markus Weiler
    • 2
    • 3
  • Mirko Pham
    • 1
  • Sabine Heiland
    • 4
  • Martin Bendszus
    • 1
  • Philipp Bäumer
    • 1
  1. 1.Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany
  2. 2.Department of NeurologyHeidelberg University HospitalHeidelbergGermany
  3. 3.Clinical Cooperation Unit NeurooncologyGerman Cancer Research Center (DKFZ)HeidelbergGermany
  4. 4.Section of Experimental Radiology, Department of NeuroradiologyHeidelberg University HospitalHeidelbergGermany

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