770. 



THE VASOMOTOR CENTER AND NERVES. 



of the thoracic duct and the receptacle, as did also suspension of breath- 

 ing. Irritation of the thoracic cord of the sympathetic is followed by 

 dilatation or contraction of the thoracic duct. The constrictor fibers, 

 however, are more readily exhausted. 



Pathological. Disorders in the function of the vasomotor nerves (angioneu- 

 roses) may occur in different forms. The points of attack for the abnormal 

 irritations of the vasomotor nerves may be the ganglia in the vessels themselves 

 or the spinal centers, together with the dominating center in the medulla, or, 

 finally, the cortical vasomotor centers in the cerebrum. The action may be either 

 direct or reflex. In conformity with the phenomena of physiological experimen- 

 tation, irritation of the vasomotor nerves will give rise to contraction of the blood- 

 stream, pallor and reduction of temperature in the external integument and 

 diminished diffusion in the tissues. Conversely, paralysis must give rise, in addi- 

 tion to dilatation of the vessels, to elevation of temperature and redness of the 

 integument, as well as increased transudation in the tissues. 



In the skin, affections of the vasomotor nerves give rise, first of all, to diffuse 

 redness or pallor, which may be unilateral. There may, however, also be cir- 

 cumscribed disorders, such as the local cutaneous arterial spasm induced by 

 irritation of individual vasomotor nerves. Later on, various forms of paralytic 

 phenomena involving the cutaneous vasomotor nerves appear upon the skin, in 

 the sequence of a number of acute febrile diseases, after preceding initial severe 

 irritation of the vasomotors, especially in the stage of chill in the course of 

 various fevers. These may appear as simple circumscribed areas of redness or 

 as increased transudation from the paralyzed vessels, with the formation of 

 wheals, or even escape of red- and white blood-corpuscles from the paralyzed, 

 greatly dilated vascular areas, or edema, eruptions or even partial gangrene. 

 In individuals suffering from epilepsy or other severe nervous affections, pe- 

 culiar, red angioparalytic areas of geographical outline have occasionally been 

 observed (Trousseau's taches cerebrales). Weir Mitchell, in 1872, designated as 

 erythromelalgia an angioneurosis in which paroxysmal redness and swelling of the 

 skin appear at the periphery of the extremities usually in association with pain. 

 As occasionally trophic and secretory disorders also appear, the condition is not 

 exclusively a vasomotor but a combined neurosis. Long-continued, strong irrita- 

 tion of the vasomotor nerves may cause interruption of the circulation, in conse- 

 quence of which the affected parts may undergo gangrene, which may involve 

 deeper parts, as well as the skin. Inflammations in cutaneous areas whose vaso- 

 motors are paralyzed are aggravated in the course of time. 



Among the angioneuroses of circumscribed distribution is the unilateral spasm 

 of the branches of the carotid on the head, which is attended with severe head- 

 ache', so-called sympatheticotonic hemicrania. Under such circumstances the cer- 

 vical sympathetic is greatly irritated; and pallor, relaxation and coolness of one- 

 half of the face, cord-like contraction of the temporal artery, dilatation of the 

 pupil and discharge of viscid saliva are unequivocal signs of this affection. Eulen- 

 burg has described as the converse of this disorder a sympathetico paralytic hemi- 

 crania, in which at the height of the attack the opposite symptoms appear, in 

 conjunction with paralysis of the sympathetic. This form may succeed immedi- 

 ately upon the first, as paralysis in the sequence of intense irritation. Berger even 

 observed both forms in alternation. 



Exophthalmic goiter is a remarkable affection of the sympathetic, in which the 

 vasomotor nerves are involved. It occurs in individuals of a neurotic disposition, 

 and there develop consecutively palpitation of the heart (from 90 to 120 or 200 

 beats in a minute) , enlargement of the thyroid gland (struma) and protrusion of 

 the eyeballs (exophthalmos) , with defective associated movement of the upper 

 eyelid in elevating and depressing the plane of vision. It is believed that per- 

 verted function of the thyroid gland results in the formation of materials that 

 act like a poison on the nerves affected. As a matter of fact exophthalmos is 

 wanting in one-half and goiter in one-fifth of the cases. It is possible that this 

 obscure disease depends upon simultaneous irritation of the accelerator nerve of 

 the heart, of the motor filaments for the muscles of M tiller in the orbits and the 

 eyelids, and perhaps also of the filaments for the unstriated muscles discovered 

 by Sappey in the orbital aponeurosis, as well as of the dilators of the thyroid 

 vessels. The disorder might arise as result of direct irritation of the sympathetic 

 paths named or of their final areas of origin, or finally it might be the result of 



