本文报道1例以站立及行走不稳起病的老年女性，既往有长期素食史，发病前3个月存在明确的营养摄入不足，颈髓MRI影像提示颈髓后索“倒V征”，结合患者的症状、体征、辅助检查及治疗随访结果，最终诊断为亚急性联合变性。通过回顾脊髓“倒V征”这一特殊影像表现的病理生理学机制，探讨脊髓“倒V征”的鉴别诊断思路。

This article reports a case of an elderly female who presented with instability in standing and walking. She had a long-term vegetarian diet and experienced nutritional deficiency in the three months preceding onset. Cervical spinal MRI revealed an "inverted V sign" in the posterior columns. Based on the patient's symptoms, signs, auxiliary examinations, and treatment follow-up results, a final diagnosis of subacute combined degeneration was made. By reviewing the pathophysiological mechanism of the "inverted V sign" as a distinctive imaging manifestation, this article explores the differential diagnostic considerations for this radiological finding.