[Clinical features of intradural spinal cord metastases in primary lung cancer]

We retrospectively investigated the clinical features of 9 consecutive cases of intradural spinal cord metastasis from primary lung cancer treated at our hospital between April 1999 and March 2002. During those three years, spinal cord metastasis was diagnosed in seven of 49 (14.3%) cases with small cell carcinoma and only two of 284 (0.7%) cases with non-small cell carcinoma. Eight of the 9 cases had concomitant brain metastasis that preceded spinal cord metastasis and had received brain irradiation. The other patient without brain metastasis had also received prophylactic cranial irradiation. The interval from brain irradiation to the diagnosis of spinal cord metastasis ranged from 116 to 708 days (median 183 days). The most common initial symptom was muscle weakness of the lower extremities in five cases. Seven of the patients rapidly developed transverse myelopathy within two weeks. Magnetic resonance imaging (MRI) with contrast enhancement demonstrated intramedullary tumors in seven cases and intradural extramedullary tumors in two cases. Spinal cord metastasis was often multifocal, and in each case lumbar enlargement was commonly involved. Radiation therapy with or without concurrent chemotherapy produced both neurologic improvement and a tumor response shown on MRI in 4 patients. Heightened awareness of the increasing incidence and background risk factors of this unusual complication could lead to earlier diagnosis and more effective treatment for neurologic palliation.