About the symptomatology of such emboli little is known. An array of minute emboli from the breaking up of a thrombus in the left auricle, carotid, or even aorta, might possibly so block up large numbers of arterial twigs as to give rise to the ordinary symptoms of embolism; but considering the possibility of the re-establishment of circulation, provided a certain proportion of the minutest vessels escape, complete anæmia of a large tract produced in this way must be rare. It is possible that some of the slighter and more transitory attacks of hemiplegia or of more or less vague cerebral symptoms may be referred to a lesion of this kind, the first action of a large number of emboli being to cause an anæmia, which is compensated for much more rapidly and thoroughly than would be the case if a single considerable vessel were obliterated.
Various attempts have been made to connect definite and peculiar diseases with capillary embolisms. Chorea in particular has been said to depend upon a lesion of this kind, but, although cases have been observed where the symptoms and lesion coexisted, yet they are very far from being the rule, or even from constituting a respectable minority of cases. The lesion of chorea in the great majority of cases is not known, although attention has been directed to this theory long enough to have established its truth.
The same may be said of the relationship between pernicious attacks of intermittent and pigment embolism. There is occasional coexistence, but far from invariable. Cerebral symptoms of the same kind and severity occur without as with the pigment deposit. If pigment embolism is the cause of coma, delirium, etc. in pernicious fever, it is difficult to see why such cases can recover so rapidly, and why no symptoms referable to a localized cerebral lesion are observed after the primary unconsciousness.
Even less proof can be adduced as to any connection between leukæmic embolisms and the cerebral symptoms occurring toward the end of severe acute disease.
Calcareous embolism is a pathological curiosity.
DIAGNOSIS.—In the case of multiple capillary embolism it would be impossible, if it were complete, to distinguish it from a blocking of the main branch.
Cerebral symptoms arising in the course of ulcerative endocarditis might be referred, with a high degree of probability, to an embolus, but if they were distinct enough to be referred to a localized lesion, the probability of a single embolus would be much greater than that of a multitude of capillary ones occluding the same vascular territory. The diagnosis of pigment embolism might be a probable, or at any rate a possible, one if in a long-continued case of paludal fever, where the liver and spleen were enlarged and the skin had the slaty hue marking the deposit of pigment, there were decisive cerebral symptoms. It could not, however, be a positive one.
Fatty embolism might be suspected in a case of diabetic coma, though even if the condition were found it would not establish the relation of causation.
PROGNOSIS AND TREATMENT can hardly have a definite basis in the absence of all ground for a satisfactory diagnosis, but do not differ essentially from those of the larger occlusions.