ACUTE MYELITIS. POLIOMYELITIS. INFLAMMATION OF THE SPINAL CORD.
Causes: Stimulating food to excess, sexual over-stimulation, violent overexertion, hot sun, chill, rheumatism, traumas, injury to spinal nerves, vertebral caries, microbian infection, narcotics, vegetable poisons, cryptogams. Lesions: discoloration of white or gray matter, swelling, friability, softening, extravasations in points, leucocytes in excess, nerve cells cloudy, granular, nucleus enlarged, stain highly, chromophile granules irregular, neuroglia thickened. Symptoms: Hyperthermia, rigor, hyperæsthesia, tonic contractions in neck and limbs, intense lameness, paresis, palsy, muscular atrophy, areas of heat followed by coldness, such parts may not perspire, palsy less complete than in broken back, circulation and breathing accelerated or slow, paraplegia in large herbivora. Diagnosis: progressive onset, hyperæsthesia or rigidity merging into palsy, retention and later incontinence of urine, extreme spinal tenderness, rapid atrophy of affected muscles, skin sloughing. Prognosis, always grave. Treatment: purgation, bleeding, hot fomentations, ice bags, compresses, derivatives, bromides, chloral, potassium iodide, atropia, ergot, electricity, strychnia, soft laxative food, bitters, phosphates.
Causes. Like congestion this may be a result of plethora in overfed animals, in those subjected to specially stimulating food like gluten meal, cotton seed meal, beans, peas, vetches in excess, animal food for herbivora (the waste of hotels and restaurants for cows, compressed meat products for pigs), a period of absolute rest on full rations in horses habituated to hard work and full feeding; of sexual over-stimulation in males (stallion, bull, ram); of violent overexertion, especially if under a hot sun; of sudden chill when over-fatigued and perspiring; of cold rain storms (Freirier); of rheumatism (Kowalski); of traumatism (fractures, sprains, slipping with overdistension); of falls upon the point of the ischium; of blows upon the back (Cruzel, Trasbot); of tumors implicating the cord; of too violent efforts in serving by stallions; of injuries of the great nerve trunks passing off from the cord (Gull, Trasbot, etc.); of extensions from caries or suppurations of the vertebræ (Decoste, Trasbot); of microbian infection, as in rabies, distemper, tubercle, dourine, louping ill, milk sickness, contagious pneumonia, influenza, and suppurations; of narcotic poisoning, as from ergot, smut, the poisons of the cryptogams and bacteria of mouldy bread, musty fodder, spoiled meats, fish, etc.; also the poisons of lolium, vetch, lupin, astragalus, oxytropis, arsenic, etc.
Lesions. These consist in a yellow or pink discoloration of the white and especially of the gray matter, and a special prominence of the puncta vasculosa in the affected part. Swelling or distortion of the part is not usual. This may involve only a single gray horn, the two horns on the same side, the two inferior horns, or all four at once, or the white matter adjacent may also show the rosy tint, the large puncta, and a characteristic softness and friability. Minute blood extravasations are very significant. Microscopically examined leucocytes are found in abundance in the perivascular spaces and in the neuroglia. The neurons (nerve ganglion cells) are degenerated, being cloudy, swollen, with enlarged nucleus, stain highly, and show enlargement of the chromophile granules. In a more advanced stage the cell has an indefinite outline and the nucleus is indistinct and may fail to take a stain; the chromophile granules are irregular and do not radiate evenly from a centre and many vacuoles appear. This may lead to fatty softening, or to fibrous increase of the neuroglia, and sclerosis.
Symptoms. These vary greatly in different cases according to the part involved, the meninges or some special region of the cord, to the essential cause of the inflammation and its acuteness. Usually the attack sets in slowly in contradistinction to the abrupt attack of congestion. Hyperthermia and rigor are usually among the first symptoms, though in many cases hyperæsthesia is the most marked early symptom. The skin covering the muscles which derive innervation from the affected section of the cord is the most sensitive. This is often so extreme along the vertebral column that percussion on the spinous processes or pinching between the fingers and thumb causes the most pronounced wincing and dropping of the back. Copland and Laposso have noticed that a sponge of hot water drawn along the line of the vertebræ causes acute pain and contractions of the muscles of the back and limbs, which are almost tetanic in their force. This probably implies the existence of meningitis, since the absence of rigidity of the muscles of the neck, back and limbs, usually implies the absence of meningeal inflammation. It may, however, occur in localized or commencing myelitis. The existence of unilateral lesions and rigidity determines intense lameness, which is further characterized by the most marked hyperæsthesia.
The morbid phenomena of the motor system are more characteristically paretic or paralytic than spasmodic. When rigidity or spasm ushers in the attack it is superseded in a few hours or in two or three days by flaccidity of the muscles of the affected part, with imperfect control or even complete paralysis. The muscles affected will depend on the seat of the spinal lesion. If in the neck it may affect fore and hind limbs, and even the chest and abdomen; if in the back or loins it will induce paraplegia, the anterior limit of which will correspond to the seat of the lesion; if near the caudal extremity of the cord, (lumbar portion), paralysis of the tail and of the sphincters ani and vesicæ may be prominent features. Retention of urine and fæces (spasm) may precede incontinence (palsy).
Common sensation may be dull or abolished on one or on both sides. If on one side only, the other may show hyperæsthesia.
Trophic modifications are very marked though they may not be noticeable at first. The paralytic muscles waste rapidly and the impaired nutrition is manifested in the rapid formation of sloughing and intractable sores where pressure comes in recumbency (the hips, stifles, hocks, shoulders, etc.). This is especially noticeable on parts supplied by the cord at or behind the seat of the lesions.
Vaso-motor changes are usually marked by a preliminary hyperthermia of the affected parts, followed by a corresponding hypothermia. Sometimes the affected part of the skin will remain quite dry while the rest of the body is covered by perspiration.
Choked optic disc and retinitis are sometimes present.
The febrile reaction which is at first moderate, gradually increases in force; the animals become dull, drowsy, careless of food, and the hyperæsthesia merges into paresis or paralysis. This is rarely so complete as in fracture of the vertebræ. If the inflammation is restricted to the lower columns only, there may be akinesis without change of the sensitiveness or with hypersensitiveness. If restricted to the upper columns there may be sensory paralysis only on the opposite side.
The heart sounds and pulse are usually altered, palpitations may appear early with acceleration and sharpness of the pulse, and this may alternate with a tardy slow pulse with intermissions. Breathing also becomes accelerated and in violent cases with trembling, though in moderate inflammation with effusion, softening and degeneration, it is liable like the heart beats to become slow and tardy.
When vertigo appears it may be attributed to extension to the bulb or cerebellum, or to the sympathetic implication of these organs.
The frequency with which paraplegia occurs in the large herbivora suggests a special susceptibility of the lumbar portion of the cord, probably in connection with severe muscular effort of the hind limbs.
In protracted cases the fever may run very high, being complicated by septic poisoning from the numerous cutaneous sloughs and sores, as well as by cystitis and nephritis.
Diagnosis. This may be based on the progressive onset, unlike the sudden attack of congestion; on the occurrence of primary fever with hyperæsthesia or even muscular rigidity, merging into a later paresis or paralysis; on the retention of urine, followed by incontinence; on the torpor of the rectum; on the extreme tenderness of the spine in the region of the inflammatory lesion; and on the tendency to rapid atrophy of the affected muscles, and the death and sloughing of the skin under pressure over the prominent parts of the body. The definite localization of the muscular symptoms, and the different temperature and secretion of the affected part of the skin, from the unaffected, are further confirmatory of myelitis.
Prognosis. While always grave, myelitis induced by narcotic elements in the food which can quickly be eliminated from the system, and that which has not caused compulsory decubitus, or persistent retention of urine and fæces, may be considered as hopeful. When, on the other hand, the nature and extent of the lesions have entailed a prolonged paralysis, or in the large animals, (especially solipeds), a persistently recumbent position, there is little to be hoped for. The degenerated myel, and the badly wasted muscles, combine to prevent rising and the use of the limbs, the sloughing bed sores quickly poison the blood and general system, and the animal sinks beyond hope of remedy. Again, if the fæces accumulate in the rectum causing general retention of the bowel contents and fermentation, the shock to the nervous system and the toxins absorbed add materially to the prostration and danger. Finally the retained urine infected through the blood or by a catheter, quickly passes into ammoniacal fermentation, with softening and detachment of the cystic epithelium, septic infection of the mucosa, and the extension of this infection through the ureters of the kidneys. The complication of infective inflammation of bladder and kidneys introduces one of the most dangerous conditions possible.
Treatment. In an acute case, at the outset, elimination of any extraneous poison should be sought as the first step toward a restoration of the normal spinal functions. Purgatives may be employed to this end, and if the case is urgent and without spasms immediate action may be sought by a hypodermic injection of 1½ gr. eserine and 2 grs. of pilocarpin. Meanwhile the horse may receive a dose of aloes or the cow one of Epsom salts. Abundance of watery or demulcent liquids given by the mouth, or as enemas, should not be omitted.
When plethora has been a prominent factor and symptoms are urgent, a free bleeding (4 to 5 quarts for horse or cow) from the jugular vein may serve to relieve the vascular tension, dilute the vital fluid, and moderate the inflammation. Hot fomentations or sinapisms to the limbs, and even cupping on the neck and chest, may contribute to relieve the tension on the spine. When the temperature is already high, bags of ice may be applied to the tender parts of the spine or those indicated to be the inflamed parts by the groups of rigid or paretic muscles. Wet compresses or evaporating lotions may be substituted. In the absence of mustard, tartar emetic, biniodide of mercury, or euphorbium may be used, or even croton oil in a carefully guarded manner, but cantharides, oil of turpentine, and other agents calculated to irritate the kidneys are to be avoided.
Bromides, hydrobromic acid, potassium iodide, chloral, or belladonna may be availed of. Some prefer ergot, but this, like strychnia, is of doubtful effect or positively injurious in most cases in the early stages. Even in the early stages electricity may be used in the form of a constant current, which tends to vaso-motor contraction and a better tone of the capillaries. The electrodes may be applied along the affected side of the spine so that the current may traverse the affected part. It may be kept up for ten to twenty minutes at a time and repeated daily. Any undue suffering under the current may be accepted as a demand for the reduction of its force or its suspension for the time being.
When the hyperthermia has subsided and the occurrence of paresis or paralysis demands nervous stimuli, these may be sought in counter-irritants, strychnia, and interrupted currents of electricity. The blisters already mentioned may be used. Strychnia may be used internally (horse or ox 2 grs., sheep ¼ gr., dog ¹⁄₅₀ to ¹⁄₁₆ gr.) or hypodermically (horse 1½ gr., sheep ⅛ gr., dog ¹⁄₁₀₀ to ¹⁄₃₀ gr.). Should this excite the animal or aggravate the symptoms it must be stopped and deferred until the inflammation shall have more completely subsided. The same remark applies to electricity which may be tried in the interrupted current, and graduated to the endurance of the patient or entirely abandoned for the time.
If the patient is able to support itself on its limbs, it is best kept in a sling to avoid the formation of sloughs and sores. If it cannot so support itself a very thick soft bed of litter is essential to avoid the sloughing and septic poisoning. Food must be laxative and easily digestible such as mashes, hay tea, and boiled or pulped roots. Fresh green grass may be employed when obtainable.
During convalescence a course of bitters with calcium phosphate and carefully regulated exercise are important. In tardy cases Trasbot especially recommends cauterization.