This explanation can hardly be accepted, since muscles, whether imperfectly or not at all paralyzed, which from position and adapted atrophy have become retracted, have necessarily undergone structural changes. The greater these changes, the greater the diminution of reflex excitability; and in any muscle completely paralyzed and degenerated this is entirely lost. If, however, the afferent nerves retain enough vitality, if the muscle be slightly paralyzed or altogether intact, then irritation of its tendon by stretching may serve to excite contractions in the belly of the muscle. The possibility of such spinal reflexes is demonstrated by the now familiar phenomenon of the tendon reflex in various spinal diseases.186 The contractions must be painful from the impediments offered to the progress of the contracting nerve, and from the exaggeratedly vicious position into which they tend to force the limb. Under these circumstances prothetic apparatus must be deferred until section of the tendons has been made.
186 “Passive muscular tension excites tonic contraction in a muscle, and this action may, in abnormal conditions, be excessive, as in the myelitic contractions (so-called tendon reflexes).... The afferent nerves commence in the fibrous tissues of the muscle, and seem to be especially stimulated by extension” (Gowers, On Epilepsy, 1881, p. 97).
DISEASE OF ONE LATERAL HALF OF THE SPINAL CORD.
BY H. D. SCHMIDT, M.D.
SYNONYMS.—Unilateral lesion of the spinal cord; Spinal hemiplegia and hemiparaplegia; Unilateral spinal paralysis.
INTRODUCTION.—This disease remained unnoticed until twenty years ago, when Brown-Séquard, observing that certain lesions of the spinal cord were accompanied by symptoms resembling those which he witnessed in animals after section of one lateral half of the cord, recognized it as a special affection. Although some of the accompanying phenomena of such a section had likewise been observed by Stilling, Budge, Eigenbrodt, Tuerk, Schiff, Von Bezold, and Van Kempen,1 nevertheless this whole group of symptoms, as belonging to the same disease, was first clearly recognized and anatomically demonstrated by Brown-Séquard.2 According to this physiologist, a section or a destruction of a small portion of a lateral half of the spinal cord in its cervical region gives rise to the following phenomena: namely, on the injured side is observed a paralysis of voluntary motion, of the muscular sense, and of the blood-vessels; the latter, manifesting itself by a greater supply of blood and a higher temperature of the parts, may continue to exist for some years. There is, furthermore, an increased sensibility of the trunk and extremity to touch, prick, heat, cold, electricity, etc., owing to vaso-motor paralysis, though in some cases a slight anæsthesia may exist in a limited zone above the hyperæsthetic part, and also in certain parts of the arm, breast, and neck. Besides these symptoms, vaso-motor paralysis of the corresponding side of the face and of the eye, manifested by an elevated temperature and sensibility, partial closure of the eyelid, contracted pupil, slight contraction of some of the muscles of the face, etc., may also be present. On the opposite side of the injury an anæsthesia of all kinds of sensation, excepting the muscular sense, is observed in both extremities; there is also an absence of motor paralysis. The anæsthesia on this side is owing to the decussation of the sensory nerves in the spinal cord.
1 Eckhard, “Physiologie des Nervensystems,” in Handbuch der Physiologie, edited by L. Hermann, 2d part of vol. ii. p. 165.