Little finger abduction and adduction testing in ulnar nerve lesions

We aimed to evaluate the abduction and adduction of the little finger based on a new clinical test in the context of ulnar nerve lesions. We tested little finger abduction and adduction in 34 patients with an isolated ulnar nerve injury and 20 patients with cubital tunnel syndrome. With their forearms supinated, patients were asked to fully abduct their little finger. Then, the examiner held the patients' index, middle, and ring fingers in extension and maximal radial deviation, and then asked the patients to touch their little finger to their radially deviated ring finger. In patients with ulnar nerve injuries, either above or below the elbow, little finger abduction and adduction were impossible. In the patients with cubital tunnel syndrome, 19 had partial paralysis of little finger adduction and one patient had complete paralysis. Abduction and adduction of the little finger is not possible when the ulnar nerve is transected. In cubital tunnel syndrome, this little finger adduction test was able to identify decreased range of motion, possibly indicating muscle weakness.