Preventable Diseases

by Woods Hutchinson

We have discovered, by half a century of careful study in the hospital and in the sick-room, not only that the nerve-tissues are usually poisoned by defect of other tissues of the body, but that they are among the very last of the body-stuffs to succumb to an intoxication. The complications of a given disease involving the nervous system are almost invariably the last of all to appear. This is one of the things that has given nervous diseases such a bad name for unmanageableness and incurableness, and that for years made us regard their study as so nearly hopeless, so far as any helpful results were concerned.

When a disease has, so to speak, soaked into the inmost core of the nerve-fibre, it has got a hold which it will take months and even years to dislodge. And before your remedies can reach it, it will often have done irreparable damage. An illustration of the care taken to spare the nervous system is furnished by its behavior in starvation. If a man or an animal has almost died of starvation, the tissues of the body will be found to have been wasted in very varying degrees, the fat, of course, most of all; in fact this will have almost entirely disappeared, all but three per cent. Then come the liver and great glands, which will have shrunk about sixty per cent; then the muscles, thirty per cent; then the heart and blood-vessels. Last of all, the nervous system, which will scarcely have wasted to any appreciable degree. In fact, it is an obvious instance of jettison on the part of the body, throwing overboard those tissues which it could most easily spare, and hanging on like grim death to those which were absolutely essential to its continued existence, viz., the heart and the nervous system. To use a cannibalistic and more correct illustration, it is killing and eating the less useful and valuable members of its family, in order that their flesh may keep alive the two or three most indispensable.

Another illustration is the actual behavior of the nerve-stuff in disease. This is most clearly shown in those clear-cut disturbances which are definitely known to be due to a specific infection; in other words, invasion of the body by a disease-organism, or germ.

First of all, it may be stated that physicians are now substantially agreed that two-thirds of the general diseases of the nervous system are due to the extension of one of these acute infections to the nerve-tissue; and this extension almost invariably comes late in the disease. The only exceptions to this rule in the whole list of infectious diseases are two, epidemic cerebro-spinal meningitis (spotted fever), and tetanus (lockjaw). Both of these have an extraordinary and deadly preference for the nervous system from the very start, and this is what gives them their frightful mortality and discouraging outlook. Even of this small number of exceptions, we are not altogether certain as to epidemic meningitis, inasmuch as we do not know how long the germ may have existed in the other tissues of the body before it succeeded in working its way to and attacking the brain and spinal cord.

The case of tetanus, however, is perfectly clear in this regard, and exceedingly interesting, inasmuch as it explains why a disease specially involving the nervous system from the start is so excessively hard to check or cure. The germ of the disease, long ago identified as one having its habitat in farm or garden soils,—particularly those which have been heavily fertilized with horse manure,—gets into the system through a cut or scratch upon the surface, into which the soil is rubbed. These infected cuts, for obvious reasons, are most frequently upon the hands or feet.

Small doses of the organism have been injected into animals; then, when they have recovered, larger ones, and so on, after the manner of the bacillus of diphtheria, until a powerful antitoxin can be obtained from their blood, very minute quantities of which will promptly kill the bacilli in a test-tube. For seven or eight years past we have been injecting this into every patient with tetanus that came under our observation, but so far with very limited benefit, even though the injections were made directly into the spinal cord, or brain substance. The problem puzzled us for years, until finally Cattani stumbled upon the explanation. While we had been supposing that the poison was carried, as almost every other known poison is, through the blood-vessels, or lymph-channels, to the heart and thence to the brain, he clearly proved that it ran up the central axis of the nerve-trunks, and consequently, when it had got once fairly started up this channel, was as safe from the attack of any antitoxin merely present in the general circulation and fluids of the body, as the copper of the Atlantic cable is from the eroding action of the sea-water. If, in his experimental animals, he carefully sought for the cut end of the nerve-trunk in the wound that had been infected, and injected the antitoxin directly into that, the disease was stopped. Or it might even be "headed off" by the crude method of cutting directly across the nerve-trunk at a point above that yet reached by the infection.

The commonest and most fatal of all forms of general diseases of the nervous system are those which are due to the later extensions of general infections.

First and foremost stands syphilis, due to the invasion of the blood by a clearly defined spirillum, the Treponema pallida of Schaudinn. This first attacks the mucous membranes of the throat and mouth, then the skin, then the great internal organs like the liver and stomach, then the bones, and, last of all, the nervous system. The length of time which the poison takes to reach the nervous system is something which at first sight is almost incredible, viz., from one and a half to fifteen years. It is true that in rare instances brain symptoms will manifest themselves within six or eight months; but these are usually due to pressure by inflammatory growths on the bones of the skull and its lining membrane (dura mater). It is not too much to say that this disease plays the greatest single rôle in nervous pathology. Three of the commonest and most fatal diseases of the spinal cord and brain, paresis (general paralysis of the insane), locomotor ataxia, and lateral sclerosis, are due to it.

Naturally, when a poison has taken a decade or a decade and a half to penetrate to the nerve-tissues, it does irreparable damage long before it can be dislodged or neutralized.

A similar aftermath may occur in almost all of the acute infectious diseases. Every year adds a new one to the list capable of causing cerebral complications. Tuberculosis, diphtheria, scarlet fever, typhoid, smallpox, influenza, have now well-recognized cerebral and nervous complications, some temporary, some permanent. A form of tuberculosis attacking the coverings (meninges) of the brain—hence known as meningitis—is far the commonest fatal brain-disease of infancy and childhood.