Article

OBJECTIVE: To determine whether there were differences in the cross-sectional
area (CSA) and the flattening ratio of the normative ulnar nerve as it passes
between the medial epicondyle and the olecranon at 30 degrees of elbow flexion
versus 90 degrees of elbow flexion. DESIGN: Bilateral upper extremities of normal
healthy adult volunteers were evaluated with ultrasound.
The CSA and the
flattening ratio of the ulnar nerve at the elbow as it passes between the medial
epicondyle and the olecranon were measured, with the elbow flexed at 30 degrees
and at 90 degrees , by 2 operators with varying ultrasound scanning experience by
using ellipse and direct tracing methods. The results from the 2 different angles
of elbow flexion were compared for each individual operator. Finally, intraclass
correlations for absolute agreement and consistency between the 2 raters were
calculated. SETTING: An outpatient clinic room at a regional rehabilitation
center. PARTICIPANTS: Twenty-five normal healthy adult volunteers. MAIN OUTCOME
MEASUREMENT: The mean CSA and the mean flattening ratio of the ulnar nerve at 30
degrees of elbow flexion and at 90 degrees of elbow flexion. RESULTS: First, for
the ellipse method, the mean CSA of the ulnar nerve at 90 degrees (9.93 mm(2))
was slightly larger than at 30 degrees (9.77 mm(2)) for rater 1. However, for
rater 2, the mean CSA of the ulnar nerve at 90 degrees (6.80 mm(2)) was slightly
smaller than at 30 degrees (7.08 mm(2)). This was found to be statistically
insignificant when using a matched pairs t test and the Wilcoxon signed-rank
test, with a significance level of .05. Similarly, the difference between the
right side and the left side was not statistically significant. The intraclass
correlations for absolute agreement between the 2 raters were not very high due
to different measurement locations, but the intraclass correlations for
consistency were high. Second, for the direct tracing method, the mean CSA at 90
degrees (7.26 mm(2)) was slightly lower than at 30 degrees (7.48 mm(2)). This was
found to be statistically nonsignificant when using the matched pairs t test and
the Wilcoxon signed-rank test with a significance level of .05. There was no
significant difference in the average flattening ratio between the 2 angles for
the left arm (0.54 at 30 degrees vs 0.56 at 90 degrees ; P = .619 for the matched
pairs t test and .274 for the Wilcoxon signed-rank test). However, for the right
arm, the flattening ratio at 90 degrees was significantly higher than that at 30
degrees (0.58 at 90 degrees vs 0.50 at 30 degrees ; P = .007 for both the matched
pairs t test and the Wilcoxon signed-rank test). CONCLUSIONS:
The mean CSA of the
ulnar nerve at the elbow at 30 degrees was not significantly different than at 90
degrees . However, the average flattening ratio at 90 degrees was found to be
significantly higher than at 30 degrees for the right arm.
CI - Copyright (c) 2014 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS