CHRONIC MYELITIS. SCLEROSIS.
Sequel to acute. Result of sprains and spinal injuries. Symptoms: paresis on exertion, lameness in one or more limbs, knuckling, circumductive movement of feet, uncertain planting, dropping, worse if blinded, phenomena progressive. Lesions: sclerosis of cord; absorption of nerve cells and fibres, in gray horns, and columns, superior, lateral and inferior, cord, altered in color, unduly firm, in points softening. Stains deeply in carmine, lightly in osmic acid or hæmatoxylin. Meninges thickened, nerve roots atrophied. Diagnosis: previous acute myelitis; later muscular weakness, and paresis, under exercise; from embolism. Treatment: hopeless if advanced: progress delayed only. Good hygiene, tonics, open air, gentle exercise, pure water, grooming, succulent pasture, nourishing food, alkalines, common salt, phosphates.
Cases of this kind have not been satisfactorily diagnosed, and as a rule domestic animals affected with partial paralysis are rarely allowed to live in a condition in which they are offensive to themselves and owners, a source of constant expense with little or no hope of recovery nor profit. Again, in the case of the large mammals, the prolonged recumbency and the low grade of nutrition in the semi-paralyzed parts, usually entail unhealthy sores and septic poisoning which sooner or later prove fatal. It is only, therefore, in the slighter cases, in which a fair measure of control over the limbs remains, that these cases are likely to survive. Trasbot suggests that many cases which pass for lumbar sprains are really chronic myelitis and on careful examination will show spinal sclerosis.
Causes. These are largely speculative, yet doubtless the same causes which determine the acute form, will produce the chronic when acting with less force and greater persistency. The lesions that are left after an acute attack are calculated to keep up a measure of vascular and trophic disorder which will be found associated with more or less sclerosis.
Symptoms. In Weber’s case in the horse (Recueil de Med. Vet., 1884, p. 432) the advance was slow, so that for nearly a year the manifestations were not diagnostic. At first there was weakness of the hind limbs when worked to fatigue. Perfect rest led to improvement, and work, to aggravation which became steadily worse and worse. For a length of time the horse maintained good condition, glossy skin, elevated head, alert expression, keen sight and hearing, and normal breathing and pulse. Standing in the stall there was no abnormal position of the limbs, nor evidence of lack of perfect control.
But when moved all this was changed. He showed first lameness in the right fore limb and soon in all four members. The feet were swung and planted uncertainly, the animal swayed and staggered, the limb would knuckle over at the knee or fetlock, or bend at the hock, and be recovered with difficulty. After going slowly for a few steps he moved with greater freedom though still with difficulty, and the trouble was greatly aggravated when the eyes were blindfolded. Then every step threatened to precipitate him to the ground. The symptoms were essentially those of locomotor ataxy.
The tactile sensibility was unimpaired, the loins had the normal sensibility, urination and defecation were natural and the appetite remained good. After ten months he showed loss of condition, dullness of the special senses, stupor, and a special sensitiveness about the head, and resented its handling.
Lesions. Thirteen months after the commencement of the attack this horse was destroyed and the cord was found to be profoundly altered by fibroid degeneration of the neuroglia and absorption of the nerve elements (cells and fibres), the lesions affecting different portions of the gray horns, and the columns—superior, lateral and inferior. The affected portion of the cord usually shows in man a grayish, opaque or translucent appearance, with in some cases a shrunken aspect and undue firmness of texture, with at points, centres of softening. If hardened, the sclerosed sections take the carmine stain deeply, but the osmic acid or hæmatoxylin stain very slightly, contrary to what holds in health. In recent cases there is only slight thickening of the neuroglia, but when the disease is advanced the trabeculæ are thick, dense, and firm, and the nerve fibres have largely disappeared. The coats of the blood vessels adjacent to the sclerosis are thickened and their lumen is narrowed. Thickening of the meninges is not uncommon, either confined to those covering the diseased portion of the cord or extending completely around it. Atrophy of the nerve roots is often appreciable by the naked eye.
Diagnosis. This depends largely on the fact that the condition follows an acute attack of myelitis, on the supervention of muscular weakness and lack of muscular control, whenever the animal is exercised to fatigue, the morbid symptoms subsiding promptly when he is allowed to rest, the aggravation of these symptoms when the patient is blindfolded and a gradual though slow advance of the symptoms with the lapse of time. From arteritis and embolism it is to be distinguished by the absence of the local symptoms of pain and tenderness, and by the absence of pulsation in the same artery distal of the obstruction and of improvement by the lapse of time or a run at grass.
Treatment: Unless in the very early stages even a partial recovery is not to be looked for. By a run at grass or by gentle well regulated exercise the impaired nerves and muscles may be educated to a better control for a limited period but the progress of the disease is not really arrested and the final issue is likely to be ruinous. Even in man, where 90 per cent. of the cases are connected with syphilis, the fibroid hyperplasia (sclerosis) is not remedied asgummata are, by mercury and iodides. In the soliped, where no such specific disease can be charged, the repair of the structural changes is no more hopeful. The many different methods of treatment in man,—electricity, blisters, firing, stretching of the spine, stretching, of the sciatic and crural nerves,—though inducing transient improvement in many cases, produce no real permanent benefit, and are to be remanded to the region of psychic inferences which have little or no place in the therapeutics of the lower animals. Strychnia, veratrin and other spinal stimulants are of little permanent value. A general hygienic and corroborative treatment may be used with the view of retarding the progress of the disease rather than of curing it. Open air exercise, sunshine, succulent pasturage, an ample supply of pure water, and active grooming are valuable. Nourishing food is all important. Lecithin or the hypodermic injection of spermin or other rich albuminous animal product is useful. A course of bicarbonate of soda and carbonate of iron with or without bitters may be tried. When the animal must be kept on dry winter food, he should have free access to common salt and water. This favors at once absorption, assimilation, and elimination, and by fostering nutrition and the removal of waste matters, it contributes to keep the disease in abeyance. Phosphoric acid and the various phosphates have been largely used and largely rejected, their main value being in the tonic effect on the spinal centres. Trasbot especially recommends the neutral gelatinoid phosphate of lime as having proved especially valuable in his hands. He gave from 1 grain upward to dogs twice a day.