ARTERITIS (THROMBOSIS, EMBOLISM) OF THE SPINAL CORD AND MEMBRANES.
Conditions of spinal circulation favorable to embolism and microbian invasion. Slow currents. Blood stasis. Free anastomosis a compensation. Symptoms. Treatment.
Facts are wanting with regard to these lesions in the domestic animals, but anatomical, physiological and pathological consideration are strongly suggestive of their occurrence. The vascular network of the spinal cord favors a tardy circulation, and this in turn is favorable to the arrest of solid bodies and the delay, proliferation and colonization of microbes. The median spinal artery receives a supply of blood by two trunks, right and left, entering by the intervertebral foramina at each intervertebral articulation. It has not, therefore, one continuous, equable, onward flow, but rather numerous independent currents corresponding to the entering vessels, and with intervening eddies or areas of comparative stagnation. The nervous material of the cord admits no large arteries but only capillary trunks which anastomose freely in its substance. This would seem to entail a sluggish flow, which would favor microbian arrest and colonization, even if the small size of the vessels serves to shut out clots of any material size. Finally the abundant venous plexus, and especially the two lateral venous sinuses, communicating freely with each other and, through each intervertebral foramen, with the extra spinal veins determine a similar tardy flow that should be favorable to morbid processes. If we pass back of these vessels, we find the posterior aorta to be at once the largest and the most direct channel for the entrance of emboli coming from the left heart or lungs. This danger is counteracted in greater part by the fact that the greater part of this blood passes into the large vessels which supply the liver, spleen, kidneys, stomach, bowels, and hind limbs, and while embolism is well known in these parts it has not been demonstrated as yet in the spinal cord. The toxins produced in infectious diseases and circulated in the blood can often lead to destruction of the endothelium, and inflammation of the deeper structures. In this way any circulating microbes find a ready infection atrium. Hektoen seems to have demonstrated this in the case of tubercular meningitis. By pressure of the neoplasm on the vessel or by fibroid thickening and contraction of the walls of the vessel, the subsidiary cord is denied its full supply, and degeneration of the nervous substance is invited. In the human subject degeneration of the cord has been shown to follow the line of such diseased arteries. Thrombosis follows in every case in which the serous coat is involved, and embolism can easily occur from clots small enough to enter the capillary vessels. Lamy’s experiment of blocking the small arteries with inert powder, shows that this will give rise to foci of hemorrhagic softening, which commence in the gray substance. The blocking, however, must be multiple to produce any material effect, as the free anastomosis of the spinal capillaries otherwise secures an abundant blood supply to adjacent parts. In case of an infective embolism the disease will advance even if the obstruction is single.
The general symptoms of these conditions would depend on the exact seat of the lesion, and treatment would have to proceed on general principles, the object being to check the inflammatory conditions, and trust to the vis medecatrix naturæ in connection with rest and good hygienic conditions.
HEMORRHAGES INTO THE SPINAL MEMBRANES.
Meningeal Spinal Apoplexy. Hæmatorrachis. Hemorrhage into the Spinal Cord. Spinal Apoplexy. Hæmatomyelia.
Definition. Causes: violent exertion, blows, falls, morbid blood, fractures, caries, tumors, tubercle, aneurisms. Lesions: Clot between or outside membranes in meningeal hæmorrhage, in gray matter and even in white in myelon bleeding. Cord bulges. If survives, nervous matter absorbed. Symptoms: Sudden stiffness or palsy of given areas; spasms more common in meningeal extravasation. Rapid muscular wasting. No fever at first. Treatment: cold to part; slings; atropia, ergot, lead acetate. Later as for myelitis. Large clot may warrant surgical interference.
In the first of these forms the bleeding takes place between the arachnoid and the two contiguous membranes—pia and dura, or outside the dura. In the second it takes place into the substance of the cord though it may encroach on the pia mater. Both conditions have been attributed to violent muscular efforts or contractions as in draught, racing, fighting, leaping, tetanic convulsions, also to blows on the back, or falls from a height. Morbid states of the blood in which there is a hemorrhagic tendency (scurvy, purpura, hæmophilia, anthrax) may be contributory causes. Spinal fractures, aneurisms, caries, tumors, and tubercle may be additional causes.
Lesions. In meningeal bleeding the clot is found outside the dura, or between the dura and arachnoid which may or may not be ruptured. A clot on the pia mater may press seriously on the cord or may cause rupture of the arachnoid. In hemorrhage of the cord, the effusion usually begins in the gray matter, though it may extend far into the white. It may be circumscribed to half an inch in diameter or affect almost the entire length of the cord. The cord may be distinctly enlarged at the point of effusion, and in exceptional cases the blood may have broken through to the membranes. If the patient survives, absorption and degenerations of the cord are inevitable.
Symptoms. In both forms there is a sudden attack, with stiffness or paralysis of given muscles and without hyperthermia. Rigidity and spasms of the muscles are more characteristic of meningeal hemorrhage, and early paralysis of the spinal. An early hyperæsthesia is also most significant of an effusion in the cord. Rapid muscular atrophy is also characteristic of this. The two conditions resemble meningitis and myelitis but come on much more suddenly and are unattended by fever.
Treatment. Such cases are not hopeful. Cold to the affected part of the spine, keeping the patient in slings to solicit the good effect of gravitation, and giving ergot or lead acetate internally are among the first indications. Later, the treatment would be practically the same as for meningitis or myelitis. In case of complete paralysis from the sudden formation of a large clot, it has even been advised to cut down on the seat of the injury and evacuate the blood, using antiseptic precautions.