Whereas the lesions in diffuse neurosyphilis are chiefly chronic inflammatory and degenerative changes of a diffuse nature (with vascular changes incidental or subordinate to the inflammation and the degeneration), there is an important and large group of cases that we have termed vascular neurosyphilis in which the factors of inflammation and degeneration are subordinate to vascular insults. These are cases of syphilitic arteriosclerosis and the best examples are victims of cerebral thrombosis. The clinical symptoms of the immediate attacks (of apoplectiform, epileptiform or other acute nature) are not in themselves distinguishable from the immediate effects of non-syphilitic vascular disease; nevertheless the establishment of their syphilitic etiology is of the utmost importance on account of the possibilities of treatment of the underlying syphilis. For, as the neuropathologist must always insist, the immediate effects of vascular insults whether syphilitic or non-syphilitic are much more extensive than the ultimate paralytic or residual irritative effects; and by consequence a greater optimism is justifiable in the confronting of these cases than the nihilistic observer is likely to entertain.
Physicians dealing with chronic disease in general are apt to be somewhat nihilistic, but this nihilism is increased a hundred fold in disease of the nervous system. How important then is any work which shall demonstrate partial or even complete recovery from serious looking apoplectic and other seizures, besides all of which the point of syphilitic treatment naturally lies in the prevention of future insults of the same sort. Therapeutic experience in this vascular group has almost as good a toll of successes as in the diffuse neurosyphilis group above mentioned, that is to say, the modern systematic treatment and even the old pre-salvarsan treatments have succeeded fairly well in removing the products of inflammation from the membranes of the nervous system and in abolishing vascular disease.
The old principle that the dead neurone in the central nervous system cannot be regenerated remains a perfectly firm principle; but there are any number of neurones and even neurone systems that are not essential to life or to the pursuit of happiness. We accordingly have just as good a theoretical therapeutic outlook in many instances of chronic neurosyphilis as we have in chronic diseases of many other organs. Add to this the fact that a great number of the most sharply-defined and grave symptoms are probably not due to destruction of neurones but to irritation and functional disability of neurones, and the conclusion is compelled that, as hinted above, an entirely unjustifiable pessimism and nihilism have prevailed in some quarters. Of course, the recoil from such pessimism with the onset of salvarsan treatment led various enthusiasts to an undue optimism.
Another great group distinguished by the existence of spinal cord disease is the group we have termed tabetic neurosyphilis, which group contains the classical tabes dorsalis or locomotor ataxia and its congeners.
The question of therapeutic optimism comes up most forcibly in the field of tabes. It is hard, however, at this time to give a proper and scientifically founded estimate of the therapeutic outcome in tabetic neurosyphilis with modern methods. So much can be said: namely, that the alleviation of pain and the palliation of other symptoms can be successfully claimed as a result of the renewed interest in the treatment of this affection. What was said above concerning the finality of the death process in a dead neurone is very strikingly true, of course, of some of the neurones of the posterior columns in tabes dorsalis. Still only portions of these neurones (namely, those which run an intradural course) are strikingly altered in a great many cases. Now and again one is greatly astonished to observe the restoration of the lost knee-jerk in cases of neurosyphilis (see for instance the case of Alice Morton (1), with discussion). In short, the relation of several tabetic symptoms to irritative conditions and functional disability of neurones may be considered established. Naturally, moreover, if therapy can stop the upward course of the affection as it passes from lower to higher nerve roots (according to reasonably well-established ideas of the genesis and progress of this affection), we are entitled to a further degree of optimism.
The question of therapeutic optimism versus pessimism is forced upon attention in the fourth great group of neurosyphilitic diseases which we have chosen to distinguish, namely, the group of paretic neurosyphilis including the disease formerly known as general paresis, paralytic dementia, softening of the brain and the like.
Of course, no one can gainsay there is a group of cases having in the natural course of events a prognosis of fatality within a term of years, say three to five years, and we have cases in our series which go to show that even with the modern intensive treatment the characteristic down-grade symptomatic progress and ultimate fatality occur. Still, we have other cases diagnostically on all fours with the fatal cases that have seemed to get either entirely well with the laboratory tests returning to normal and without further mental symptoms, or else lose mental symptoms on the one hand or laboratory signs on the other. We should strongly object to any account of paretic neurosyphilis which should insist that its necessary outcome is fatality within a term of years. Of course, viewing our knowledge of the affection in the past, we should be compelled to object to the generalization “paresis fatal” on the evidences of the universally recognized remissions. If nature can stop a paretic process, why cannot man do as much? Can it be alleged that our own apparent therapeutic successes and those of others are merely curious examples of coincidences, namely, that remissions have chosen to occur precisely when therapy was systematically applied? The percentage of therapeutic successes with modern intensive treatment, wherever it may ultimately stand, is already too high for this hypothesis of fortuitous remissions.[[31]]
Moreover, we believe that the details of the clinical progress of some of the reported cases are convincing on this point. What, however, is the distinguishing feature of paretic neurosyphilis? It is in one sense a particular kind of diffuse neurosyphilis. The tissues are apt to show not only encephalic but also spinal changes. There is apt to be a more or less well-defined meningitis, but the characteristic feature, without which the diagnosis of paretic neurosyphilis would hardly be rendered, is the existence of disease of the cerebral cortex. This disease is parenchymatous in the sense of showing nerve cell destruction. There is also an interstitial reaction in the shape of a neuroglia overgrowth, but the striking and pathognomonic feature is the infiltration of the sheaths of the small vessels in the cortex, giving evidence of an inflammation very intimately affecting the cellular mechanisms of the nervous system. It is striking how often a smaller or larger share of the cells found in the vessel sheaths are plasma cells. It does not appear, however, that the diagnosis of paretic neurosyphilis as against diffuse non-paretic neurosyphilis can be made in the stained sections with complete safety on the basis of plasmocytosis in the former and lymphocytosis in the latter. Whatever the results of careful histological differentiation by future neuropathologists may yield, it is at all events true that we cannot yet make an important differentiation clinically on the basis of the differential count of plasma cells and lymphocytes in the puncture fluids. However this may be, there is an important distinction between diffuse neurosyphilis of the non-paretic type and paretic neurosyphilis in that paretic neurosyphilis rarely if ever fails to show important degrees of intracortical perivascular inflammation with larger or smaller numbers of plasma cells.
What has the therapeutist to face in this matter? The answer, as elsewhere, depends somewhat upon what the future may decide as to the habitat and toxic or antitoxic activities of the spirocheta pallida. The early claims that the spirocheta pallida was extravascular and lay for the most part in the parenchyma and not in the vessel sheaths were perhaps overbold, since other workers have found the spirochete in the vessel sheaths also (Mott).
Aside from the spirochete and its accessibility to spirochetocidal drugs, there seems to be no reason for supposing that the perivascular sheaths cannot be cleansed of their inflammatory contents. There is, again, no reason why the phagocytic cells should not continue to perform their scavenger function until such time as the degenerative process in the parenchyma (a process not necessarily progressive in the absence of the spirochete or its products) ceases. There is every reason to suppose that a great many of the clinical phenomena are not necessarily due to permanent destruction of neurones and neuronic organs (dendrites, axis-cylinders, nets and the like) but are due to various microphysical conditions of pressure, intoxication and the like.