Non-paraneoplastic Autoimmune Cerebellar Ataxia with Sensory Ataxia Associated with the Anti-Ca/ARHGAP26 Antibody: A Case Report.
Hongchao Zhang, Xiaoxuan Duan, Wancheng Zheng et al.
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Case in brief
A man in his 50s presented with one month of subacute, progressive gait instability, exhibiting both cerebellar and deep-sensory ataxia. Nerve conduction studies revealed a length-dependent axonal neuropathy, while proprioceptive loss in the arms was disproportionate to these findings. CSF testing showed a low titer of anti-Ca/ARHGAP26 antibody, leading to a diagnosis of primary autoimmune cerebellar ataxia. Treatment with intravenous methylprednisolone resulted in significant recovery.
What made this case unusual
This case uniquely demonstrates the coexistence of cerebellar ataxia with a reversible deep-sensory deficit, which is not typically associated with the anti-Ca/ARHGAP26 antibody.
Diagnostic / clinical pearl
Clinicians should consider low-titer CSF antibody testing in cases of suspected autoimmune cerebellar ataxia, especially when serum tests are negative.
Why it matters
This case suggests that the anti-Ca/ARHGAP26 antibody may affect central somatosensory pathways, expanding the understanding of its clinical implications.