Myelopathies in malignant tumors most often cause compression of the spinal cord. But if with the help of additional instrumental diagnostics on MRI or CT of the spinal cord, it is not possible to detect the cerebrospinal fluid block, then in the future it is also difficult to distinguish between intracerebral (intramedullary) metastases, paracarcinomatous myelopathy, and radiation myelopathy.
If cancer metastases are detected in a patient with progressive myelopathy without signs of spinal cord compression on myelography, CT, or MRI of the spinal cord, metastasis within the spinal parenchyma (intramedullary metastasis) is most likely. Paraneoplastic myelopathy occurs much less frequently in patients. A patient's complaint of back pain may be the first (but not mandatory) symptom of tumor metastasis inside the spinal cord parenchyma (intramedullary metastasis). With this type of location of metastases, the patient may develop an increasing spastic paraparesis or paresthesia.
Dissociated loss of sensitivity or its complete preservation in the sacral segments of the spinal cord is characteristic of internal compression of the spinal cord. This condition is rarely observed in patients. Asymmetric paraparesis and partial loss of sensitivity are more common.
When a patient is diagnosed with myelography, CT, or MRI, spinal cord edema will be visible without signs of external compression. In half of the spinal cord examinations in patients on CT and myelography, a normal picture can be seen. Therefore, MRI of the spinal cord as a diagnostic method is most informative in differentiating a metastatic focus from a primary tumor inside the spinal cord parenchyma (intramedullary tumor).
Tumor metastases within the spinal cord parenchyma (Intramedullary metastases) usually originate from bronchogenic carcinoma, less often from breast cancer and other solid tumors. Melanoma metastases are rarely the cause of external spinal cord compression. Melanoma metastases are more common as a tumor within the spinal cord parenchyma (intramedullary volumetric process). Melanoma metastasis is a single eccentrically located node that forms as a result of entering the spinal cord with the bloodstream. Radiation therapy for metastasis of melanoma in the spinal cord may be effective.
Meningitis due to carcinoma is a common form of CNS damage in cancer. Carcinomatous meningitis does not cause myelopathy unless it spreads and infiltrates under the arachnoid membrane of the spinal cord from the adjacent nerve roots. Otherwise, it leads to the formation of nodules and secondary compression or infiltration of the spinal cord.
Incomplete, not accompanied by pain syndrome of lesion of the cauda equina can be caused by carcinomatous infiltration of the roots forming it. Patients with carcinomatous meningitis often complain of headaches. In analyzes of cerebrospinal fluid (CSF, cerebrospinal fluid) in dynamics in such patients, malignant cells, increased protein content, and a decrease in glucose concentration will be detected.
Progressive necrotizing myelopathy
Progressive necrotizing myelopathy, which combines mild inflammation, occurs as a long-term cancer effect in solid tumors. Myelographic findings and cerebrospinal fluid (CSF) are usually normal, with a slight increase in protein levels. Subacute progressive spastic paraparesis develops in patients over several days or weeks and is usually characterized by asymmetry. This is accompanied by paresthesias in the distal extremities, extending upward to the formation of the level of sensory disorders, and later - dysfunction of the pelvic organs (bladder dysfunction). In progressive necrotizing myelopathy, several adjacent spinal cord segments are also affected.
Radiation therapy of oncological diseases causes in patients a distant, not acutely proceeding, but progressive myelopathy. It is caused by hyalinization and blockage (occlusion) of blood vessels. Radiation myelopathy often becomes a serious differential diagnostic problem for a neurosurgeon or neuropathologist when the spinal cord is within the area undergoing radiation therapy to other structures, for example, to the lymph nodes of the mediastinum. The difference between radiation (radiation) myelopathy from paracarcinomatous myelopathy and intramedullary metastasis is difficult, except for those cases when the patient's history has clear information about previous radiation therapy.