Radial symptom (sign) is a sign of loss of sensitivity of the skin of the extremities (usually extensors) on one side of the body, resulting from damage to the peripheral nerves of the lumbar or sacral spinal cord by a tumor, aneurysm, or other pathological formations of the nervous system. It is called Lunar Surface Syndrome and is characterized as follows: a loss of sensation is detected in the area of the soles, more characteristic of cancer of the lumbar region and metastases in the spine. It is one of the criteria for cancer.