Neuroimaging and Cognitive Assessments in Ataxia

We defined age at onset as the age at which the earliest symptoms occurred according to statements given by patients or their caregivers and scored clinical severity of ataxia using the 40-point (0 being normal) validated Scale for the Assessment and Rating of Ataxia (SARA).^{14 (link),15 (link)} Study participants underwent brain MRI and magnetic resonance spectroscopy (MRS) in a 1.5-T system (Signa EXCITE, GE Medical Systems, Milwaukee, WI). For MRS, we calculated peak areas for N-acetylaspartate (NAA) at 2.02 parts per million (ppm), creatinine (Cr) at 3.03 ppm, and the metabolite intensity ratio (NAA/Cr ratio) of both cerebellar hemispheres and vermis using FuncTool software (GE Healthcare, Milwaukee, WI).^{16 (link),17 (link)} We also conducted nerve conduction studies (NCS) and EMG and pure tone audiometry^{18 (link)} of air conduction hearing thresholds at 4 frequencies (500, 1,000, 2,000, and 4,000 Hz) using a calibrated diagnostic audiometer and evaluated somatosensory evoked potentials (SSEPs).
We conducted a global cognitive performance assessment using the Mini-Mental State Examination^{19 (link)} (MMSE, score range 0–30), one of the most widely used screening instruments for cortical dementia, and Montreal Cognitive Assessment^{20 (link)} (MoCA, score range 0–30). Frontal lobe executive function was evaluated using the Frontal Assessment Battery (FAB, score range 0–18).^{21 (link)}