The finger-to-nose exam is typically used to detect a cerebellar lesion. In subtle cases though, this can be be difficult to detect.
How can you improve your sensitivity of this exam?
Trick of the trade: Elbows up!
I used to do the exam with the patient’s elbow down at his/her side. An abnormal finger-to-nose test can be masked because you are mainly testing only biceps and triceps strength. Also the arm motion momentum can easily compensate for a subtle deficit. Instead have the patient raise the elbows (a chicken-wing position) for the exam. It is a little more difficult to compensate now. I recently picked up a subtle cerebellar stroke with this maneuver.
Also, it is important to have the patient fully extend his/her arm so that it is stretching to reach your finger. A subtle deficit becomes more obvious.
Thanks to Dr. Farzan for demonstrating!