In course of many neoplastic diseases the variety of the neurological syndromes many appear. They may precede the primary disease or appear during its follow up. They originate from the tumor itself or may be caused by secondary metabolic disturbances in electrolytes, lesions of the kidneys or liver. Infections in the central nervous system, conditioned frequently by immunodeficiency, could also cause the onset of various, neurological symptoms. In some cases they simply may happen as the toxic side effects of applied cytostatics.