[Neuroradiology of infective diseases in the immunocompromised host]

Just like the lung, the brain and the spinal cord are target organs for opportunistic infections and tumors in immunocompromised patients. HIV infections and AIDS-related conditions represent the most common cause of immunodeficiency: other causes are hemoproliferative disorders and organ transplantation, but especially long-term drug and radiation therapies. Neurologic (focal, diffuse, meningeal or spinal) signs are the results of CNS infections and/or tumors or of treatment complications. Neuroimaging techniques (MRI better than CT) allow the infective or neoplastic causes of neurologic complications to be nearly always recognized and are therefore major tools for diagnosis and treatment. Lesions characterization is more difficult, since CT and MR patterns are definitely more affected by the evolutive phases of the lesions (encephalitis, cerebritis, abscess) and by their sites than by specific infective agents. However, the knowledge of the statistical possibility of brain and spine infections according to the type of immunocompromission is useful in many cases.