2 “On Spinal Hemiplegia,” Lancet, Nov. 7, 21, and Dec. 12, 26, 1868, reported in Virchow and Hirsch's Jahresbericht for the year 1868, vol. ii. p. 37.
If the hemisection of the cord is made in the dorsal region, the functional disturbances are limited to that part of the body below the point of division, and a hemiparaplegia, or paralysis of the corresponding lower extremity, will be the result.
From these facts it will be readily understood that a lesion occurring in any portion of one lateral half of the spinal cord of man must be followed by some or all of the above-mentioned symptoms, and that the phenomena produced by physiological experiments on animals constitute, in reality, the pathological basis of unilateral spinal paralysis in man. They will be more clearly understood by calling to mind the course of the musculo-motor, vaso-motor, and sensitive tracts in the spinal cord. Thus, the musculo-motor tracts, after having descended to the crura cerebri, cross one another in the pyramids of the medulla oblongata and adjoining upper portion of the spinal cord, forming the so-called decussation of the pyramids; they then descend through the spinal cord to supply the muscles of the same side of the body.3 A section of one lateral half of the cord therefore causes motor paralysis on the same side. The vaso-motor tracts remain uncrossed, and pass, each, through one lateral half of the cord to supply the vessels on the same side; some regions of the body are stated to make an exception to this rule. According to Brown-Séquard, the sensitive tracts conducting the different kinds of sensation, with the exception of the muscular sense, on the contrary, cross over to the opposite half of the spinal cord soon after their entrance into it, and thence pursue their further course to the brain. A section of one lateral half of the cord, therefore, will be followed by a loss of sensation of touch, pain, heat, tickling, etc. on the other side of the body.
3 Though, in the majority of cases, a complete decussation of the motor tracts probably takes place in the pyramids, the researches of Flechsig have shown (Die Leitungsbahnen im Gehirn und Rückenmark des Menschen, p. 273) that there are a number of others in which the decussation is not complete, but where a part of these tracts passes to the spinal marrow uncrossed on the inner surface of the anterior white columns.
The symptoms above mentioned must of course vary according to the extent, the intensity, and the particular nature of the lesion, as well as the height at which it is located in the spinal cord.
DEFINITION.—The chief characters of unilateral spinal disease are motor paralysis, hemiplegia, or hemiparaplegia, paralysis of the muscular sense and of the blood-vessels on the side of the lesion, and paralysis of sensation with preservation of the muscular sense on the other side of the body. These symptoms may vary, and be accompanied by other phenomena according to the particular seat, extent, and depth of the lesion.
SYMPTOMS.—According to the nature of the lesion, the symptoms of unilateral disease of the spinal cord may be developed suddenly, as, for instance, when caused by traumatic injuries; or in a gradual and slow manner, when they may be preceded by premonitory symptoms, such as vertigo, pain on the side of the lesion, etc. The most prominent clinical phenomena, as before mentioned, are motor paralysis on the side of the lesion, and anæsthesia on the opposite side of the body. The motor paralysis on the side of the lesion may, according to the seat of the latter, manifest itself in either the form of a hemiplegia or hemiparaplegia, and even extend in a light form to the opposite side of the body. In typical cases, however, in which the injury or disease is strictly confined to one lateral half of the cord, the motor power on the other side of the body remains entirely undisturbed. At the same time, the muscular sense on the injured side is paralyzed or considerably diminished, and in some cases (Fieber, Lanzoni, Allessandrini) the electro-muscular excitability also has been found lowered, while in others it has remained normal. There is furthermore observed, on the side of the lesion, a vaso-motor paralysis, manifesting itself by a greater supply of blood to, and a higher temperature of, the paralyzed trunk and limbs, giving rise to an increase of sensibility (hyperæsthesia) of touch, prick, heat, cold, electricity, etc. in these parts. If the seat of the lesion is sufficiently high up in the cord, this paralysis extends, moreover, to the corresponding side of the face and eye, where it also causes an elevation of temperature, increase of sensibility, partial closure of the eyelid, contracted pupil, slight contraction of some of the muscles of the face, etc. In a number of cases at the boundary of the hyperæsthetic region a narrow anæsthetic zone is observed to exist on the breast, neck, or arm. This anæsthesia is owing to the division, at the level of the section, of some nerves of sensation on their way to the other half of the spinal cord. An increase of the reflex irritability of the tendons has in some cases (Erb, Schulz, Revillons) been observed, while in one case (Glaeser) the reflex was found to be absent. Swelling and œdema of the paralyzed limbs have also been met with (Glaeser), and in one case (Allessandrini) even swelling and pain in all the joints of the injured side were observed before death, while masses of coagulated blood in these joints, particularly in the knee, were revealed by the autopsy. The inflammatory affection of the knee-joint of the paralyzed leg has, moreover, been observed by Viguès, Joffroy, and Solomon.4 Frequently, atrophy of the paralyzed muscles takes place, especially in chronic cases. In one case (Fieber) even atrophy of the upper extremity of the uninjured side of the body was observed.
4 Erb, “Diseases of the Spinal Cord, etc.,” Cyclopædia of the Practice of Medicine, edited by H. v. Ziemssen, Amer. ed.
The most prominent symptoms observed on the side of the body opposite to the seat of the lesion are anæsthesia of every kind of sensation, preservation of the muscular sense, and absence of motor paralysis. Reflex action and electro-muscular contractility generally remain normal, though in one case (Fieber) the latter was found increased. Although the anæsthesia of the skin generally comprises every kind of sensation, three cases were observed (Fieber) in which the sensation of heat remained unimpaired, while the electro-cutaneous sensibility appeared to be lost. As a general rule, there is no vaso-motor paralysis on the uninjured side, though in some cases (Erb, Allessandrini) an elevation of temperature has been observed.
Besides the above symptoms, some others, less characteristic in nature, are now and then observed in individual cases. They are painful sensations on one or the other side, or even simultaneously on both sides of the body, and also a feeling of constriction at the level of the lesion (Erb). Disturbances of the functions of the bowels or bladder are also met with, though in other cases they are absent.