678 PATHOLOGICAL VASO-MOTOR PHENOMENA. 



m.-chauisms, the subordinate centres in the cord, the dominating centre in the medulla, or the 

 grey matter of the cerebrum. The effect may be direct or reflex. The dilatation of the vessels 

 may also be due to stimulation of vaso-dilator nerves, and the physician must be careful to 

 distinguish whether the result is due to paralysis of the vaso-constrictor nerves or stimulation 

 of the vaso-dilator fibres. 



Angio-neuroses of the skin occur in affections of the vasomotor nerves, either as a diffuse 

 redness or jwillor ; or there may be circumscribed affections. Sometimes, owing to the stimula- 

 tion of individual v iso-motor nerves, there are local cutaneous arterio-spasms (Nothnagel). In 

 certain acute febrile attacks after previous initial violent stimulation of the vaso-motor nerves, 

 especially during the cold stage of fever there may be different forms of paralytic phenomena 

 of the cutaneous vessels. In some cases of epilepsy in man, Trousseau observed irregular, red, 

 angio-paralytic patches (ataches cerebrales). Continued strong stimulation may lead to 

 interruption of the circulation, which may result in gangrene of the skin and deeper-seated 

 parts ( ll'ciss). 



Hemicrania, due to unilateral spasm of the branches of the carotid on the head, is accom- 

 panied by severe headache (Du Bois-Reymond). The cervical sympathetic nerve is intensely 

 atimulated a pale, collapsed, and cool side of the face, contraction of the temporal artery like 

 a firm whip-cord, dilatation of the pupil, secretion of thick saliva, are sure signs of this affec- 

 tion. This form may be followed by the opposite condition of paralysis of the cervical sympa- 

 thy ic, where the effects are reversed. Sometimes the two conditions may alternate. 



Basedow's disease is a remarkable condition, in which the vaso-motor nerves are concerned ; 

 the heart beats very rapidly (00 to 129-200 beats per minute), causing palpitation ; there is 

 swilling of the thyroid gland (struma), and projection of the eyeballs (exophthalmos), with 

 imperfectly co-ordinated movements of the upper eyelid, whereby the plane of vision is raised 

 or lowered. Perhaps in this disease we have to deal with a simultaneous stimulation of the 

 sccelerans cordis ( 370), the motor fibres of Midler's muscles of the orbit and eyelids ( 347, I.), 

 as well as of the vasodilators of the thyroid gland. The disease may be due to direct stimula- 

 tion of the sympathetic channels or their spinal origins, or it may be referred to some reflex cause. 

 It has also been explained, however, thus, that the exophthalmos and struma are the conse- 

 quence of vaso-motor paralysis, which results in enlargement of the blood-vessels, while the 

 increased cardiac action is a sign of the diminished or arrested inhibitory action of the vagus. 

 All these ithenomena may be caused, according to Filehne, by injury to tlie upper part of both 

 restiform bodies in rabbits. 



Visceral Angio-neuroses. The occurrence of sudden hyperemia with transudations and 

 ecchymoses in some thoracic or abdominal organs may have a neurotic basis. As already 

 mentioned, injury to the pons, corpus striatum, and optic thalamus may give rise to hyperemia, 

 and ecchymoses in the lungs, pleura*, intestines, and kidneys. According to Brown-Sequard, 

 compression or section of one-half of the pons causes ecchymoses, especially in the lung of the 

 opposite side ; he also observed ecchymoses in the renal capsule after injury of the lumbar 

 |>ortion of the spinal cord ( 379). 



The dependence of diabetes meUitus upon injury to the vaso-motor nerves is referred to in 

 175 ; the action of the vasomotor nerves on the secretion of urine in 276 ; and fever in 220. 



372. VASO-DILATOR CENTRE AND NERVES. Although a vasodilator 

 centre has not been definitely proved to exist in the medulla, still its existence there 

 has been surini.sed. Its action is opposite to that of the vaso-motor centre. The 

 centre is certainly not in a continuous or tonic state of excitement. The vaso-dilator 

 nerves behave in their functions similarly to the cardiac branches of the vagus ; 

 both, when stimulated, cause relaxation and rest (Schif, CI. Bernard). Hence, 

 these nerves have been called vam-inhibitory, vaso-hypotonic, or vaso-dilator 

 nerves. Dyspnceic blood stimulates this centre as well as the vaso-motor centre, 

 so that the cutaneous vessels are dilated, while simultaneously the vessels of the 

 internal organs are contracted and the organs anaemic, owing to the stimulation of 

 their vaso-motor centre (Dastre and Morat). Nicotin is a powerful excitant of the 

 vaso-dilator nerves (Ostroumoff) ; it raises the temperature of the foot (dog), and 

 increases the formation of lymph (Rogowicz). 



[The existence of vaso-dilator nerves is assumed in accordance with such facts as 

 the following : If the chorda tympani be divided, there is no change in the 

 blood-vessels of the sub-maxillary gland ; but if its peripheral end be stimulated, in 

 addition to other results ( 145), there is dilatation of the blood-vessels of the sub- 

 maxillary gland, so that its veins discharge bright florid blood, while they spout 

 like an artery. Similarly, if the nervi erigentes be divided, there is no effect on 



