The Ten Euro Neurotest: a new test of finger dexterity proves reliable in controls and patients with Huntington's disease

Introduction: In clinical practice and in research settings, neurologists need standardized motor tests to assess symptom severity and evaluate therapy. Unfortunately, only few motor tests have been formally validated. More specifically, validated simple tests of finger dexterity are lacking. We introduce a new quantified test of finger dexterity, called the Ten Euro Neurotest (TEN), that is easy and fast to use and may be easily standardized across different study centers.

Methods: The TEN is performed as follows: ten coins of one euro are aligned on a straight line in the middle of a plain A4-sized paper. The paper is positioned in front of the subject, with its lower border aligned to the edge of the desk. In this way, working material (coins of 1 euro) as well as working area (A4 paper) are standardized. The subject is instructed to turn the coins as fast as possible, starting with the most distant coin. After turning, each coin is replaced on the line starting from the top edge of the paper working downwards. The time needed to turn all coins is clocked with a stopwatch. The accuracy with which the coins are replaced on the line is measured using a ruler.

As a pilot, we tested 14 healthy control subjects and ten patients with late-stage Huntington's disease (HD). Subjects performed the TEN twice with both the dominant and the non-dominant hand to look at side differences and establish test-retest reliability.

Results: Test-retest reliability for the time needed to turn all coins proved very good in both control subjects (Pearson's R=0.93, p<0.0001) and HD patients (R=0.95, p=0.05). No differences were observed between the dominant and non-dominant hand. The TEN discriminated HD patients from controls (mean±SD time needed to turn all coins: 41.6±10.8s vs. 20.0±6.0s, p<0.001; mean±SD width of the row of coins after replacement: 45.7±12.6mm vs. 27.7±1.5mm, p<0.05). Moreover, time scores tended to correlate with CAG-repeat length in five HD patients in whom repeat length was known (R=0.86, p=0.06). Only two of the late-stage HD patients were not able to perform the test, suggesting that the TEN will prove applicable even in patients with severe disability.

Conclusions: This pilot study indicates that the Ten Euro Neurotest (TEN) is a simple yet reliable test of finger dexterity. It is able to discriminate healthy controls from patients with HD and possibly other motor disorders. A larger validation study of this promising test is currently underway.