Quantitative analysis of upper-limb ataxia in patients with spinocerebellar degeneration

Spinocerebellar degeneration (SCD) is a progressive neurodegenerative disorder in which cerebellar ataxia causes motor disability. There are no widely applicable methods for objective evaluation of ataxia in SCD. An objective system to evaluate ataxia is necessary for use in clinical trials of newly developed medication and rehabilitation. The aim of this study was to develop a simple method to quantify the degree of upper-limb ataxia. Forty-nine patients with SCD participated in this study. Patients were instructed to trace an Archimedean spiral template, and the gap between the template spiral and the drawn spiral (gap area; GA) was measured using Image J software. Ataxia was rated using the Scale for the Assessment and Rating of Ataxia (SARA) and cerebellar volume was evaluated in 37 patients using an axial cross-section of magnetic resonance images that were obtained within 6 months of clinical evaluation. Regression analysis was performed to assess the relation between GA and patient age, disease duration, SARA score, and cerebellar volume. GA was significantly related to total SARA score (r = 0.660, p < 0.001), the posture and gait (r = 0.551, p < 0.001), speech (r = 0.527, p < 0.001), hand movements (r = 0.553, p < 0.001), and heel-shin slide (r = 0.367, p = 0.036) SARA subscores, and cerebellar volume (r = 0.577, p < 0.001) but was not related to patient age (r = 0.176, p = 0.227) or disease duration (r = 0.236, p = 0.103). GA is a simple, useful method to objectively quantify the degree of cerebellar ataxia, especially upper-limb ataxia, and can be widely adopted in various settings, including clinical trials.