Childhood‐onset cerebellar ataxia in Japan: A questionnaire‐based survey

OBJECTIVE: The diagnosis of childhood‐onset cerebellar ataxia (CA) is often challenging due to variations in symptoms and etiologies. Despite the known regional differences in the prevalence of etiologies underlying CA, the frequency and characteristics of CA in Japan remain unclear. We conducted a questionnaire‐based survey to identify the clinical characteristics of childhood‐onset CA in the Japanese population. MATERIALS AND METHODS: Questionnaires were sent to 1,103 board‐certified pediatric neurologists in Japan from 2016 to 2017. The primary survey requested the number of patients with CA under care, and the follow‐up secondary questionnaire requested additional clinical characteristics of the patients. RESULTS: The primary survey obtained 578 responses (response rate, 52.4%) on 385 patients with CA, including 171 diagnosed and 214 undiagnosed cases (diagnostic rate, 44.4%). The most frequent etiology was dentatorubropallidoluysian atrophy (DRPLA), followed by mitochondrial disorders and encephalitis. The secondary survey obtained the clinical characteristics of 252 cases (119 diagnosed and 133 undiagnosed cases). Multiple logistic regression analysis revealed that a younger age at onset, hearing issues, and short stature were associated with a higher risk of remaining undiagnosed with CA in Japan. CONCLUSIONS: The diagnostic rate of childhood‐onset CA in the current study was comparable to those reported in other countries. The high prevalence of autosomal dominant ataxia, especially DRPLA, was a signature of CA in Japan. These data offer insights into the characteristics of childhood‐onset CA in the Japanese population.