[Infectious and metabolic nervous system complications of systemic cancer]

To review the incidence and causes of the infections and metabolic diseases of the nervous system in patients with systemic neoplasias.

Patients with immunodeficiency, particularly those with hematological neoplasias and persons treated with immunosuppressive drugs have a considerable tendency to infection due to opportunist germs. Infections of the nervous system are relatively rare (0.02%-1%) and the commonest neoplasms are lymphomas, especially those of Hodgkin type and lymphosarcomas. The most frequent infections are caused by the herpes virus, meningitis due to Listeria monocytogenes and the meningitis due to fungi (Aspergillus, Candida and Cryptococcus). Cerebral abscesses, although rarer, are relatively common and are caused by gram negative bacteria, fungi and toxoplasmosis. In recent years there has been a notable increase in the number of patients diagnosed as having progressive multifocal leukoencephalopathy due to the possibility of carrying out studies to detect the DNA of the JC virus by polymerase chain reaction techniques. Empirical treatment of patients with neurological infections and systemic cancer should be started following the guidelines for immunodepressed patients. The metabolic complications of these patients are mainly due to hormone overproduction, hydroelectrolytic changes and vitamin deficits, which in general cause alterations of mental function of the confusion state type.

In all patients with an infection or metabolic complication involving the nervous system, the presence of a systemic neoplasm makes it necessary to vary both the diagnostic approach and the empirical therapeutic measures taken.