Intramedullary spinal cord metastasis. Diagnostic and therapeutic considerations.

The diagnosis of intramedullary spinal cord metastasis (ISM) is difficult, and treatment is usually ineffective. We review our own experience with ISM as well as the pertinent medical literature, and suggest a practical diagnostic and therapeutic approach. The problem of the diagnosis of ISM is essentially that of the differential diagnosis of a noncompressive myelopathy in a patient with systemic cancer. Most such patients prove to have ISM, meningeal carcinomatosis, radiation myelopathy, or paraneoplastic necrotizing myelopathy. Neurologic features of value in this differential diagnosis are pain, the tempo and mode of progression of symptoms, and tumor cells in the spinal fluid. Oncologic features of value are the location of the primary tumor, the past exposure to therapeutic radiation, cerebral metastases, and the extent of systemic metastatic disease. The myelogram in ISM is either normal or nonspecifically abnormal; therefore, the diagnosis must be made on clinical grounds. Although no single finding is diagnostic of ISM, a careful clinical analysis will lead to the correct diagnosis in most cases. Radiation therapy is effective treatment for ISM, but only if it is administered early, before paraplegia supervenes. Thus, the diagnosis should be made and treatment begun as soon as possible. Intramedullary spinal cord metastasis is often multifocal rather than solitary; therefore, whole-cord rather than local spinal radiation should be given, if possible. If local radiotherapy is chosen, the construction of the portal can be based on the myelogram or, in the event of a normal study, on the clinical localization of the tumor.