Objectives: Evaluation of coordination with the Finger-Nose Test is an essential part of the neurological examination. This study explored the convergent and discriminant construct validity of the Standardized Finger-Nose Test (SFNT) in a neuromuscular disorder with ataxic features.
Method: A cross-sectional study was carried out with 24 participants with recessive spastic ataxia of Charlevoix-Saguenay. Convergent construct validity was tested by correlating the SFNT with other upper extremity function tests, a functional independence measure and social participation. Upper extremity function tests included gross and fine dexterity (Box and Block Test and Purdue Pegboard), upper extremity strength (dynamometry) and global upper extremity performance (TEMPA). The Functional Independence Measure (FIM) and the Assessment of Life Habits scale (LIFE-H) measured functional independence and social participation respectively. Discriminant construct validity was explored by comparing performance on the SFNT between two age groups (< 40 years and > or = 40 years).
Results: Convergent validity of the SFNT was demonstrated by moderate to strong correlations with gross and fine finger dexterity (r = 0.82-0.84), global upper extremity performance (0.74-0.79), functional independence (r = 0.74) and social participation (r = 0.78). Upper extremity coordination of the older group was significantly lower than in the younger group, suggesting the ability of the SFNT to discriminate between different levels of function.
Conclusion: This study demonstrated the convergent and discriminant construct validity of the SFNT in a neuromuscular disorder with ataxic features.