are many diseases that affect the nervous system. These however don't
just appear on their own, they include genetic malformations, poisoning,
vascular disorders, degeneration, inflammations, metabolic defects, and
tumors. All of which affect either the neuron or the 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. These
diseases sometimes come due to outside climates or age. For instance,
multiple sclerosis is very common in temperate areas as a degenerative
disease but very rare in the tropics.
A very common reason for a disorder of the system are bacterias, parasites, and viruses. For example, meningitis, which is the infection of the meninges investing the brain and spinal cord, can be caused by such pathogens. On the other hand, one specific virus causes rabies. Some viruses causing neurological ills affect only certain parts of the nervous system. For example, the virus causing poliomyelitis commonly affects the spinal cord; viruses causing encephalitis attack the brain.
Inflammations of the nervous system are named according to the part affected. Myelitis is an inflammation of the spinal cord; neuritis is an inflammation of a nerve. It may be caused not only by infection but also by poisoning, alcoholism, or injury. Tumors originating in the nervous system usually are composed of meningeal tissue or neuroglia (supporting tissue) cells, depending on the specific part of the nervous system affected, but other types of tumor may metastasize to or invade the nervous system. In certain disorders of the nervous system, such as neuralgia, migraine, and epilepsy, no evidence may exist of organic damage. Another disorder, cerebral palsy, is associated with birth defects.
[©Martin and Ambrose 2001]