Even such mild infections as measles, scarlet fever, and influenza may poison certain nerves supplying the muscles of an arm or a leg, causing temporary paralysis, or even permanent laming; or they may attack the nerve of sight or of hearing and produce blindness or deafness.
A great many of the cases of paralysis and insanity are caused by alcohol.

Alcohol in excess may attack the nerves supplying the arms and legs, producing severe pain and partial paralysis.

It may also, after long-continued use, affect the cells of the brain itself, producing the horrible condition known as delirium tremens--a form of acute insanity with distressing delusions, in which the patient imagines that he sees rats, snakes, and other reptiles and vermin crawling over him, or in his room.

Even in those who never use it to such excess as this, or indeed in those who may never become intoxicated, the long-continued use of alcohol may produce a slow poisoning and general breaking-down of the whole nervous system, causing in time the hand to tremble, the eye to become bleared and dim, the gait weak and unsteady, the memory uncertain, and the judgment poor.
Are Nervous Diseases Increasing?
The direct use of the brain and nervous system has much less to do with the production of its diseases or even its serious disturbances than is usually believed.

Most of these, as we have seen, are due either to the poisons of disease or alcohol, or to the fatigue-poisons, or other poisons, produced in the stomach, the liver, the muscles, or other parts of the body.