Developing an objective evaluating system to quantify the degree of upper limb movement impairment in patients with severe Friedreich’s ataxia

The use of standardized tools and objective measurements is essential to test the effectiveness of new drugs or rehabilitative protocols. Friedreich’s ataxia (FRDA) patients with severe disease are often unable to perform the quantitative measurement tests currently used. The purpose of our study was to develop an easy-to-use application, for touchscreen devices, able to quantify the degree of upper limb movement impairment in patients with severe Friedreich’s ataxia. The APP, which we named “Twelve-Red-Squares App-Coo-Test” (12-RSACT), assesses the upper limb ataxia by measuring the test execution time. All patients were clinically evaluated using the Composite Cerebellar Functional Severity (CCFS) and the Scale for the Assessment and Rating of Ataxia (SARA). We recruited 92 healthy subjects and 36 FRDA patients with a SARA mean value of 28.8.1 ± 8.2. All participants in our study underwent upper limb movement assessment using the new 12-RSACT, the Click Test, and a well-established system, i.e., the Nine-Hole Peg Test (9HPT). We observed a strong linear correlation between the measurements obtained with the 12-RSACT and those obtained with 9HPT, Click Test, CCFS, and SARA. The 12-RSACT was characterized by excellent internal consistency and intra-rater and test-retest reliability. The minimal detectable change (MDC%) was excellent too. Additionally, the 12-RSACT turned out to be faster and easier to perform compared with the 9HPT. The 12-RSACT is an inexpensive test and is easy to use, which can be administered quickly. Therefore, 12-RSACT is a promising tool to assess the upper limb ataxia in FRDA patients and even those with severe diseases.