A 45-year-old woman with known metastatic breast cancer experienced rapid paresthesia in both arms and neck pain for 1 week. A neurologic examination revealed decreased muscle power, sensitivity to pinprick, ability to sense hot/cold, and ability to sense light touching on both arms. She denied having bowel or bladder dysfunction. Spinal gadolinium-enhanced magnetic resonance imaging showed an enhancing, well-circumscribed mass with secondary syringomyelia at the upper cervical level, indicating breast cancer with intradural intramedullary spinal cord metastasis (Figure). The patient was subsequently treated with radiation therapy and had symptomatic improvement. However, she died 6 months after undergoing radiation therapy.