COUNTER-IRRITANTS 493 



unless the irritation is very widespread and severe, when the reverse 

 happens. 'JLfte aodommai vessels are tnose constricted; tiie vessels of 

 tlie sKin and limbs are unanected. In accordance with the ioregoing 

 remarJsSj tne use of considerable lieatj togetlier with mustard or turpen- 

 tine, IS of great value m conditions of vital depression, surgical shock, 

 collapse and coma. Moreover, the ettect on local blood supply is still 

 greater and full of importance, since it may explain the benencial action 

 obtained in the ordinary use of counter-irritants. In experiments con- 

 ducted upon animals, it iias been observed that when sinapisms are placed 

 over the head, the blood vessels in the pia mater are lirst dilated, but soon 

 contract and remain in that condition for some time. Likewise there was 

 seen, following energetic counter-irritation of the chest, anemia of the 

 underlying parts, including the muscles, pleura, and even the pulmonary 

 tissue. It is essential to bear in mind, then, that while counter-irritants 

 induce local congestion in their immediate vicinity, they also cause reflexly 

 vascular contraction in more remote areas. In accordance with this dem- 

 onstration, the importance of these agents in remote inflammation lies 

 not so much in their bringing blood to the surface, as in forcing it out of 

 distant parts. This fact is not generally appreciated. The use of the 

 word "drawing" signifies the common idea of a counter-irritant, and 

 implies the first proposition. 



Temperature is not materially affected by the therapeutic use of 

 counter-irritants, and they are not necessarily contraindicated in fevers. 

 Experiments, however, appear to show that mild counter-irritation may 

 lead to a slight elevation of body-heat, owing to stimulation of the calori- 

 facient centres, while extensive and prolonged action lowers temperature 

 by depression of the heart and heat centres, and because more blood 

 flows through the peripheral vessels owing to constriction of the vessels 

 in the abdominal organs. 



Counter-irritants notably relieve pain. This result is not only due 

 to overcoming congestion, but occurs when pain is purely neuralgic. The 

 phenomenon is not altogether explicable. The subduing influence of a 

 twitch in the case of pain inflicted upon a horse is an analogous example. 

 Wechsberg, in some late experiments, notes, as a most striking effect of 

 counter-irritants, edematous infiltration of the skin, subcutaneous tissue 

 and muscle in sub-adjacent parts, with compression of blood vessels in 

 the deeper-lying structures. He attributes the relief of pain afforded 

 by counter-irritants to anemia and rapid compression brought to bear on 

 the nerves in these underlying parts. The viscera supplied by the sympa- 

 thetic nerves have no pain sense. Pain attributed to the viscera is really 

 "referred pain" felt in the cerebro-spinal nerves through reflex action. 

 Thus pain and tenderness are felt in the belly wall when the viscera are 

 inflamed. 



In disease of internal organs Head has constantly found certain 

 corresponding areas of skin tenderness. This because both the internal 

 organ and the skin area are innervated from the same segment of the 

 brain or cord. Theoretically and practically counter-irritation of a skin 

 area affects the internal organ corresponding (by nervous connection) to 

 this area more than ot'gfg]?,^*^ j(j Jj^^oso^"^ ^^^^ tenderness for dis- 



