Validation of a graphic test to quantitatively assess the dominant hand dexterity.

Dexterity dysfunction is a key feature of disability in many neurological and non-neurological diseases. The Nine-Hole Peg Test (NHPT) is the most used test to assess hand dexterity in clinical practice but presents limitations. A new graphic test to enhance objective evaluation of the of the dominant hand dexterity is proposed. The task consists in drawing a continuous line in paths composed by a part with multiple orthogonal changes of direction ('meander'), and a second part derived from the Archimedean spiral ('spiral'). The test was validated in 200 healthy controls and 93 neurological patients. 48 patients performed also the NHPT. Several parameters were analyzed, among which total time, total length, number of touches and number of crossings. Healthy subjects display statistically significant differences with respect to pathological subjects in the case of total time, number of touches, and number of crossings (p<0.001), but not in the case of total length (p = 0.27) needed to complete the second sheet. Moreover, healthy controls display a learning effect, the time needed to complete the second sheet was significantly lower than for the first sheet (p<0.001), and an inverse correlation with age was observed (r = 0.56, p<0.001). The comparison between the NHPT and the new test showed a strong positive correlation (r = 0.71, p<0.001) whereas touches and crossing a weak positive one (r = 0.35, p = 0.01). The new test distinguishes between a slow but precise performance and a fast but imprecise performance, thus providing additional information with respect to NHPT.