B. Lesions of the Kinesodic System.—Limits of the Kinesodic System.—In general this includes the antero-lateral parts of the cord. In a trans-section of the cord (vide Figs. 5 and 6) the following columns and fasciculi are recognized, their location and limits being made known to us by embryology, descriptive and pathological anatomy: (7) The anterior (ventral) nerve-roots emerging from (8) the true anterior columns or anterior root-zones; (9) the ventral (anterior) gray horns with their groups of ganglion cells; (10) the crossed pyramidal fasciculus, which is the caudal continuation of the cerebral motor tract of the opposite hemisphere; (11) the direct pyramidal column (column of Türck), which is the caudal continuation of the cerebral motor part of the hemisphere on the same side; (12) the antero-lateral column. Fasciculi 10 and 11 bear an inverse relation to each other—i.e. 11 is larger in proportion as 10 is smaller.
FIG. 6.
Diagram of a Transverse Section of the Spinal Cord through the Lumbar Enlargement: The æsthesodic system is shaded; the kinesodic system unshaded. Parts of the æsthesodic system: (1) Posterior nerve-roots; (2) posterior gray horns; (3) fasciculi cuneati (columns of Burdach, inclusive of posterior root-zones); (4) fasciculi graciles (columns of Goll, or posterior median columns); (5) ascending cerebellar fasciculi; (6) columns of Clarke. Parts of the kinesodic system: (7) Anterior roots; (8) anterior columns (inclusive of anterior root-zones); (9) anterior gray horns; (10) crossed pyramidal fasciculi; (11) direct pyramidal fasciculi (columns of Türck) [10 and 11 are the intraspinal prolongation of the cerebral motor tract]; (12) lateral columns of ill-defined limits and unknown functions; P. R., posterior roots; P. S., posterior septum; A. R., anterior roots; A. F., anterior fissure.
In a general way it may be stated that lesions of the kinesodic system are characterized positively by the isolated existence or predominance of motor symptoms, by impairment of muscular nutrition, and by De R.; also by contractures. The reflexes are almost never normal, being either exaggerated or lost. Negative symptoms are—absence of sensory symptoms, of ataxia, and of vesical or rectal symptoms.
(a) Lesions of the anterior gray horns (9) are revealed by most definite and characteristic symptoms. There occurs a flaccid paralysis involving more or less extensive groups of muscles in the extremities, rarely truncal muscles, and never those of organic life. In a few weeks the paralyzed muscles undergo atrophy, sometimes to an extreme degree, and various degrees of De R. are present. Cutaneous and tendinous reflexes are abolished. The bladder and rectum are normal. Sensory symptoms absent, and if present consist only of mild paræsthesiæ, which are probably due to postural pressure upon nerve-trunks or to disturbance of the peripheral circulation. There is no tendency to the formation of bed-sores, but circulation and calorification are reduced in the paralyzed members. It should be remembered that paralysis due to systematic lesion of the anterior gray horns is never typically paraplegic, with horizontal limit-line of sensory symptoms, a cincture feeling, and vesical paralysis.
The above symptom-grouping is characteristic of lesion of the anterior horns en masse; in other words, of poliomyelitis. In that form of systematic disease of the anterior horns which consists primarily and chiefly of a degeneration or molecular death of the ganglion cells there is no true paralysis; the atrophy of muscles is infinitely slower, and it proceeds in various muscles fasciculus by fasciculus, the wasting being usually preceded by fibrillary contractions, and being almost always symmetrically located on the two sides of the body (affecting analogous or homologous parts). The electrical reactions are abnormal, in that musculo-faradic reaction is lost in exact proportion to the wasting; so that in a large muscle one part may contract normally, while the adjacent fasciculi do not. It is as yet uncertain whether De R. occur in this disease (progressive muscular atrophy). Calorification and circulation are much less impaired than in poliomyelitis; the negative symptoms are much the same.
It is sometimes difficult to distinguish poliomyelitis from generalized neuritis. The diagnosis is to be made by the presence in the latter disease of marked sensory symptoms—neuro-muscular pains, numbness, slight anæsthesia—and by a grouping of symptoms coinciding with the distribution of nerve-trunks and branches. No assistance can be derived from electrical tests, as both diseases yield more or less typical De R.