The effect of wrist position on the conduction velocity of the ulnar nerve

Interexaminer Repeatability of Antidromic Ulnar Sensory Nerve Conduction Velocity Measurements

OBJECTIVE

To determine the interexaminer repeatability of the ulnar antidromic sensory nerve conduction velocity (NCV).

DESIGN

Test-retest design. Based on a randomization list of various combinations and sequences from 2 of a total of 3 examiners, the measurement was repeated within half an hour by a second examiner blinded to the results of the first examiner.

SETTING

Outpatient department.

PARTICIPANTS

Twenty-four consecutive healthy subjects (mean age, 38 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The intraclass correlation coefficient (ICC) and the coefficient of repeatability (CR) were determined for the below elbow to wrist (BE-to-W), above elbow to below elbow (AE-to-BE), and axilla to above elbow (AX-to-AE) segments.

RESULTS

The ICC was .42 for the BE-to-W, .15 for the AE-to-BE, and -.05 for the AX-to-AE segment. The CR was 12.2m/s for the BE-to-W, 16.2m/s for the AE-to-BE, and 21.4m/s for the AX-to-AE segment.

CONCLUSIONS

During the assessment of the antidromic sensory NCV of the ulnar nerve, a moderate amount of interexaminer variability must be taken into account for the BE-to-W segment. More proximally, an extremely large amount of interexaminer variability must be taken into account. This calls into question the usefulness of the antidromic ulnar sensory NCV for the AX-to-AE and AE-to-BE segments.

The aging hand

Hand function decreases with age in both men and women, especially after the age of 65 years. A review is presented of anatomical and physiological changes in the aging hand. The age-related changes in prehension patterns (grip and pinch strength) and hand dexterity in the elderly population are considered. Deterioration in hand function in the elderly population is, to a large degree, secondary to age-related degenerative changes in the musculoskeletal, vascular, and nervous systems. Deterioration of hand function in elderly adults is a combination of local structural changes (joints, muscle, tendon, bone, nerve and receptors, blood supply, skin, and fingernails) and more distant changes in neural control. These age-related changes are often accompanied by underlying pathological conditions (osteoporosis, osteoarthritis, rheumatic arthritis, and Parkinson's disease) that are common in the elderly population. Assessment of hand function and prehension patterns is needed in order to determine specific treatment approaches.

Ulnar nerve conduction velocity as function of wrist position

Ulnar nerve conduction velocity (CV) calculated across the elbow has been shown to be significantly influenced by the position of the elbow. This study investigated the effect of wrist position on ulnar nerve CV in 19 control subjects. Ulnar nerve CV was determined with the elbow flexed at 90 degrees at two different wrist positions. The below-elbow-to-wrist CV was not significantly different between the wrist extended and the wrist flexed. Similarly, the mean across-elbow CV with wrist extended was not significantly different from the CV with the wrist flexed. The authors conclude that wrist position does not affect the calculated ulnar nerve CV across the elbow.

Three ulnar nerve conduction studies in patients with ulnar neuropathy at the elbow

OBJECTIVE

Ulnar neuropathy at the elbow is often difficult to localize by standard electrophysiologic testing. This study compared three ulnar nerve conduction studies to determine which was more sensitive in localizing ulnar neuropathy at the elbow.

METHODS

Motor studies to the first dorsal interosseous and the abductor digiti quinti and a mixed ulnar nerve sensory study across the elbow.

RESULTS

Motor studies to the first dorsal interosseous and abductor digiti quinti were abnormal in 81% and 71% of patients, respectively. The ulnar mixed sensory study across the elbow was abnormal in 57%. In 38%, all three tests were abnormal.

CONCLUSION

Motor studies were more sensitive than the ulnar mixed sensory study across the elbow in localizing ulnar neuropathy of the elbow.