Prognostic and relapsing factors of primary autoimmune cerebellar ataxia: a prospective cohort study

Objective The objective of this study was to investigate the factors influencing relapse and prognosis in patients with primary autoimmune cerebellar ataxia (PACA), an area previously not well understood. Methods This prospective cohort study included patients who satisfied the modified diagnostic criteria of PACA. A modified Rankin scale score ≤ 2 at the last follow-up was defined as a favorable prognosis. Cox and Logistic regression were utilized to identify relapsing and prognostic factors, respectively. Results A total of 68 patients were included and 35.3% were male. The median onset age was 42.9 years (IQR 22.1–54.0). Neuronal autoantibodies were detected in 33 (50.8%) patients. Of the 65 patients who received first-line immunotherapy, 55 (84.6%) were responsive and 10 (15.4%) were not. Responsiveness to first-line immunotherapy emerged as an independent factor for favorable prognosis (HR 16.762; 95% CI 2.877–97.655; p = 0.002), as did the absence of peripheral neuropathy/radiculopathy (HR 14.286; 95% CI 2.41–83.333; p = 0.003). Relapses occurred in 19 (27.9%) patients. Onset age ≤ 43 years (HR 5.245; 95% CI 1.499–18.35; p = 0.009), presence of peripheral neuropathy/radiculopathy (HR 4.280; 95% CI 1.622–11.298; p = 0.003) and elevated cerebrospinal fluid (CSF) protein concentration (HR 3.443; 95% CI 1.083–10.951; p = 0.036) were statistically significant relapsing factors. Conclusion This study identified younger onset age, presence of peripheral neuropathy/radiculopathy and elevated CSF protein concentration as relapsing factors, and absence of peripheral neuropathy/radiculopathy and responsiveness to first-line immunotherapy as independent factors for favorable prognosis in PACA patients. These findings may guide individualized treatment strategies and potentially improve patient outcomes.