By means of the data above given we are also enabled to determine the length—i.e. fronto-caudal extension—of the systematic lesions of the cord.
The symptoms of transverse lesions of the spinal cord are not exclusively caudad of the lesion, and some very striking ones are observable in the head. In lesions of the upper part of the dorsal cord and of the cervical enlargement (e, f, g) we observe vaso-motor and pupillary symptoms, due to injury of the spinal origin of the cervical sympathetic nerve; the pupils are contracted; the cheeks and ears congested and unnaturally warm; the cutaneous secretions are increased. In other words, the symptoms about the head, frontad of the lesion, are the same as those we produce experimentally in animals by section of the cervical sympathetic or of the lower cervical cord. In hemi-lesion of the cord, in man as in animals, these symptoms are unilateral, on the same side as the injury.
Another point to be remembered in the study of transverse lesions of the spinal cord is that the lesion may involve enough of the anterior gray horns to give rise to atrophic paralysis with De R. in some few muscles deriving their motor innervation from the focus of disease. This is not rarely seen in cervical paraplegia.
THIRD QUESTION.—BEING GIVEN VERY LIMITED MOTOR OR SENSORY SYMPTOMS OF SPINAL ORIGIN, TO DETERMINE THE EXACT LOCATION OF THE FOCAL LESIONS CAUSING THEM.
(a) In the range of sensory disturbances this question rarely presents itself for solution. Localized anæsthesia and pain of spinal origin (except the fulgurating pains of tabes) are rare, and we do not know the relation of cutaneous areas with the spinal segments as well as we know the motor innervations. It should be stated here, however, that the location of a fixed pain and of a zone of anæsthesia is often of great value in determining what spinal nerve is affected, just outside of the cord itself, by such directly-acting lesions as vertebral caries, spinal pachymeningitis, tumors upon the spinal cord, etc. Among the various symptoms of Pott's disease of the spine, fixed pains in one side of the trunk, in one thigh, or in the upper occipital region, etc. is a sign against which the physician should always be on his guard, as it is a very early and valuable indication of the existence of an affection which requires special treatment as soon as a diagnosis can be made.
(b) Localized motor symptoms of spinal origin calling for a diagnosis of the focal lesions causing them are frequent, and are mostly met with in two affections—viz. progressive muscular atrophy and poliomyelitis. The problem is now capable in many cases of an approximately exact solution by the deductive application of our knowledge of the intimate connection between certain muscles and muscular groups and limited portions or segments of the spinal cord (anterior gray horns more especially). This knowledge has been accumulated and organized from ordinary anatomy, physiological experiments, and more especially from carefully-made autopsies with microscopic examination of the cord. We cannot present this subject better than by reproducing a tabular statement of these results prepared by M. Allen Starr.5 Future autopsies may correct this table, and in making use of it the occurrence of anomalous nerve-distribution should be remembered:
LOCALIZATION OF FUNCTIONS IN THE VARIOUS SEGMENTS OF THE SPINAL CORD.
