ORIGINAL RESEARCH article
Front. Immunol.
Sec. Multiple Sclerosis and Neuroimmunology
Autoimmune cerebellopyramidal syndrome as a complex form of autoimmune cerebellar ataxia: a cohort study
Provisionally accepted
- Peking Union Medical College Hospital (CAMS), Beijing, China
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Background: Autoimmune cerebellar ataxia (ACA) is a significant and treatable cause of sporadic cerebellar syndrome. Pyramidal tract damage affects approximately 30% of ACA patients, profoundly impacts motor function and prognosis, yet this complex form remains under-investigated. Methods: We retrospectively analyzed patients with pyramidal signs from our institutional ACA cohort, excluding those with intrinsic upper motor neuron impairment due to specific ACA subtypes. Clinical and paraclinical data were compared between patients with and without pyramidal signs. Results: Among the 48 ACA patients with pyramidal signs, primary autoimmune cerebellar ataxia was the most common subtype (50%), and neuronal antibodies were detected in 66.7%. Compared to ACA patients without pyramidal signs, those with pyramidal signs were younger at onset (44 vs 47 years, p=0.048) and more frequently presented with limb ataxia (97.9% vs 78.8%, p=0.002) and diplopia (48.9% vs 18.2%, p<0.001). Brain MRI revealed pyramidal tract and/or semiovale centrum lesions in 29.8% of patients with pyramidal signs, a finding absent in the non-pyramidal sign group (p<0.001), which could subside with immunotherapy. Cerebrospinal fluid (CSF) analysis showed higher protein concentration and a significantly higher rate of specific oligoclonal bands in the pyramidal sign group. Patients with pyramidal signs 2 had a significantly higher risk of relapse (52.5% vs 32.8%, p=0.034). Conclusions: Autoimmune cerebellopyramidal syndrome represents a distinct and complex ACA phenotype, characterized by unique clinical and imaging features, CSF abnormalities indicative of a more pronounced autoimmune response, and a higher relapse rate. Comprehensive evaluation and long-term maintenance immunotherapy may be warranted in these patients.
Keywords: Autoimmune cerebellar ataxia, pyramidal tract damage, autoimmune cerebellopyramidal syndrome, Clinical features, prognosis
Received: 14 Oct 2025; Accepted: 24 Nov 2025.
Copyright: © 2025 Liu, Ren, Fan, Zhang and Guan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Hongzhi Guan, pumchghz@126.com
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