T2-signal of ulnar nerve branches at the wrist in guyon's canal syndrome

Jennifer Kollmer; Philipp Bäumer; David Milford; Thomas Dombert; Frank Staub; Martin Bendszus; Mirko Pham

doi:10.1371/journal.pone.0047295

T2-signal of ulnar nerve branches at the wrist in guyon's canal syndrome

PLoS One. 2012;7(10):e47295. doi: 10.1371/journal.pone.0047295. Epub 2012 Oct 10.

Authors

Jennifer Kollmer¹, Philipp Bäumer, David Milford, Thomas Dombert, Frank Staub, Martin Bendszus, Mirko Pham

Affiliation

¹ Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany. jennifer.kollmer@med.uni-heidelberg.de

Abstract

Objective: To evaluate T2-signal of high-resolution MRI in distal ulnar nerve branches at the wrist as diagnostic sign of guyon's-canal-syndrome (GCS).

Materials and methods: 11 GCS patients confirmed by clinical/electrophysiological findings, and 20 wrists from 11 asymptomatic volunteers were prospectively included to undergo the following protocol: axial T2-weighted-fat-suppressed and T1-weighted-turbo-spin-echo-sequences (3T-MR-scanner, Magnetom/Verio/Siemens). Patients were examined in prone position with the arm extended and wrist placed in an 8-channel surface-array-coil. Nerve T2-signal was evaluated as contrast-to-noise-ratios (CNR) from proximal-to-distal in ulnar nerve trunk, its superficial/sensory and deep/motor branch. Distal motor-nerve-conduction (distal-motor-latency (dml)) to first dorsal-interosseus (IOD I) and abductor digiti minimi muscles was correlated with T2-signal. Approval by the institutional review-board and written informed consent was given by all participants.

Results: In GCS, mean nerve T2-signal was strongly increased within the deep/motor branch (11.7±4.8 vs.controls:-5.3±2.4;p = 0.001) but clearly less and not significantly increased in ulnar nerve trunk (6.8±6.4vs.-7.4±2.5;p = 0.07) and superficial/sensory branch (-2.1±4.9vs.-9.7±2.9;p = 0.08). Median nerve T2-signal did not differ between patients and controls (-9.8±2.5vs.-6.7±4.2;p = 0.45). T2-signal of deep/motor branch correlated strongly with motor-conduction-velocity to IOD I in non-linear fashion (R(2) = -0.8;p<0.001). ROC-analysis revealed increased nerve T2-signal of the deep/motor branch to be a sign of excellent diagnostic performance (area-under-the-curve 0.94, 95% CI: 0.85-1.00; specificity 90%, sensitivity 89.5%).

Conclusions: Nerve T2-signal increase of distal ulnar nerve branches and in particular of the deep/motor branch is highly accurate for the diagnostic determination of GCS. Furthermore, for the first time it was found in nerve entrapment injury that T2-signal strongly correlates with electrical-conduction-velocity.

Publication types

Evaluation Study
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Female
Humans
Magnetic Resonance Imaging / methods
Male
Middle Aged
Sensitivity and Specificity
Ulnar Nerve / pathology*
Ulnar Nerve Compression Syndromes / diagnosis
Ulnar Nerve Compression Syndromes / pathology*
Wrist / pathology*

Grants and funding

This study was supported by a Postdoctoral-Fellowship granted to MP from the Medical Faculty of the University of Heidelberg and a project grant from the German Osteoarthritis Foundation (Deutsche Arthrose Hilfe e.V.), Grant number P215-A482. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.