Newly Developed Weakness of Lower Extremities Despite Improved Brain Metastasis of Lung Cancer after Radiotherapy

An intramedullary spinal cord metastasis (ISCM) rarely develops in systemic cancer but is indicative of a poor prognosis. A 56-year-old man was admitted due to weakness of the lower extremities. He had received radiotherapy 3 months prior for a brain metastasis that had developed 1 year after achieving a complete response from chemotherapy for extended stage small cell lung cancer. Although the brain lesion had improved partially, ISCM from the cervical to lumbar-sacral spinal cords, which was accompanied by a leptomeningeal dissemination, was diagnosed based on magnetic resonance imaging of the spine and cerebrospinal fluid cytology. Finally, he died of sudden cardiac arrest during treatment. This is the first case of ISCM involving the whole spinal segments. Physicians should be aware of the subsequent development of ISCM in lung cancer patients with a previously known brain metastasis who present with new neurological symptoms.