II. Localization of Lesions in the Spinal Cord.
Diseases of the spinal cord are distinguished by the following general characters, positive and negative:
Positive Characters.—Tendency to primary bilateral or paraplegic distribution of all the symptoms. In the majority of cases preservation of electro-muscular excitability, and in one well-defined group of cases De R. more or less typically developed in the paralyzed parts. Frequent vesical and rectal paralysis, either of the retaining or of the ejecting apparatus. Pains and other paræsthesiæ in the extremities, the pains often possessing the electric or fulgurating character. Anæsthesia of paraplegic distribution. Sensations of constriction or cincture about a limb or about the body at various levels. Occurrence of ataxia without paralysis. Progressive muscular atrophy without actual paralysis. Easy production of eschars (bed-sores).
Negative Characters.—Absence of typical hemiplegic or monoplegic distribution of symptoms. Rarity of head symptoms, as headache, vertigo, mental disturbance; of lesions of the optic nerve. Absence of epileptiform convulsions. Absence of such grouping of motor and sensory symptoms as would exactly correspond to the area of distribution of one or more large nerve-trunks.
The above symptomatic indications are, of course, of the most general meaning only, and are liable to exceptions and subject to varying conditions.
The DIAGNOSIS of the exact localization of lesions in the spinal cord, considered from the clinical standpoint, is perhaps best arrived at by following an anatomical and physiological order of subdivision of the problem into three questions, as follows:
FIRST QUESTION.—BEING GIVEN SYMPTOMS INDICATING DISEASE LIMITED TO ONE OR MORE SYSTEMS OF THE SPINAL CORD, TO DECIDE WHICH ARE AFFECTED.
Physiology and the results of embryological and pathological researches justify us in making a general division of the spinal cord, for purposes of diagnosis, into two great systems, whose limits are fairly well known—viz. the æsthesodic or sensory system, and the kinesodic or motor system. The following outline diagram (Fig. 5) of section through the spinal cord exhibits the ascertained limits of the two systems.
FIG. 5.