Disorders of the Nervous System
Consideration of disorders of the nervous system is the province of neurology; psychiatry deals with behavioral disturbances of a functional nature. The division between these two medical specialties cannot be sharply defined, because neurological disorders often manifest both organic and mental symptoms. For a discussion of functional mental illness, Mental Illness . Diseases of the nervous system include genetic malformations, poisonings, metabolic defects, vascular disorders, inflammations , degeneration, and tumors, and they involve either nerve cells or their supporting elements. Vascular disorders, such as cerebral hemorrhage or other forms of stroke , are among the most common causes of paralysis and other neurologic complications. Some diseases exhibit peculiar geographic and age distribution. In temperate zones, multiple sclerosis is a common degenerative disease of the nervous system, but it is rare in the Tropics. The nervous system is subject to infection by a great variet