Background. Hereditary paraganglioma-pheochromocytoma syndrome is characterized by paragangliomas (tumors that arise from neuroendocrine tissues symmetrically distributed along the paravertebral axis from the base of the skull to the pelvis) and by pheochromocytomas (paragangliomas that are confined to the adrenal medulla). Sympathetic paragangliomas hypersecrete catecholamines and are located in the lower mediastinum, abdomen, and pelvis.
Evidence based medicine is integration of medical experience and best research evidence into the healthcare of medical patients. There are millions of published studies, journal articles available to clinicians, therefore choosing the best resource to search is an important decision. It is essential to formulate a proper clinical question, to choose the best available keywords for a database search and analyze reliable sources only. Metaanalysis and systematic reviews are considered as highest reliability sources. Randomized controlled trials provide high level of evidence either.
