The central nervous system consists of the brain and the spinal cord, the nerves proceeding from them being known as the peripheral or cerebrospinal nerves. The nervous system is a very delicate and complicated set of nerves which spread throughout the body and control all bodily and mental functions. The slightest disturbance in the finely-balanced conglomeration of nerves produces disorders some of which are quite difficult to handle. The autonomic nervous system is situated in the neck, thorax and the abdomen and acts independently of the brain and is connected with plexuses or nerve fibers.
The spine and the brain being beyond the reach of direct examination, disorders of the nerves are very difficult to diagnose and treat. The existence of the disorders can only be found from some external symptoms of behavior.
The factors that cause nervous disorders are many: some diseases may be induced by a particular temperament or a way of life. You would notice that people with a high IQ and great intellectual power are generally born with a nervous temperament. There are somatic (bodily) factors too and heredity also plays an important part in disorders of the nerves. The stresses and strains of modern life aggravate nervous maladies. The loss of a loved one, reverses in business, an unfortunate love affair, an accident or a shocking news may trigger a nervous shock which unhinges the mind. Poisons-those produced in the body by disease or ingested accidentally or by design-also lead to many nervous disorders. Syphilis, for example, gives rise to locomotor ataxia (disordered movement of the limbs), paralysis and tumors of the brain or the spinal cord. If a person is an incurable alcoholic, he may suffer mental derangement.
Like many other diseases, nervous disorders are also categorized as (i) organic-due to disturbance in the arrangement of the nerves or injuries to them; and (ii) functional. The first category includes disorders in which there are bodily changes, e.g. paralysis; and in the second category are those disorders for which no somatic factors are responsible. Epilepsy, hysteria and neuralgia (pain of nervous origin) are functional disorders.
Nervous disorders sometimes give rise to physical discomfort and actual disease. An example is the dyspepsia of nervous origin. The digestive system may be all right, but extreme worry may hamper the functioning of digestive organs. Tension, as is well-recognized, gives rise to techycardia (palpitation) and hypertension (high blood pressure) among other diseases. The diseases of the nervous system can be broadly categorized into two main classes: (i) those in which there is a disturbance of sensation, or perverted sensation, as in insanity and delusion; and (ii) those in which a part or the whole body is paralyzed. In other words, the second category comprises diseases in which the nervous system fails to carry out its nutritional purpose and some of the limbs are starved of sustenance, and die. If the sympathetic system is diseased, the functioning of the internal organs of the body is impaired. For example, natural functions like the clearing of the bowels and the bladder are seriously impaired if the spinal nerves are affected. Diseases of the cranial nerves would disturb the sense of smell, vision, hearing, touch and others.