668 GENERAL THERAPEDTIC MEASURES 



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 ex- 

 plicable. The subduing influence of a twitch in the case of 

 pain inflicted upon a horse is an analogous example. Wechs- 

 berg, in some late experiments, notes, as a most striking 

 effect of counter-irritants, oedematous infiltration of the skin, 

 subcutaneous tissue and muscle in subadjaceut parts, with 

 compression of blood vessels in the deeper-lying structures. 

 He attributes the relief of pain afforded by counter-irritants 

 to anaemia and rapid compression brought to bear on the 

 nerves in these underlying parts; a result similar to the 

 anodyne influence observed following the injection of nor- 

 mal salt solution over a nerve-trunk, which is the principle 

 of Schleich's method of local ansesthesia by tissue infil- 

 tration. 



Still this explanation does not interpret the relief of 

 pain sometimes seen in parts remote from the point of 

 application of counter-irritants. 



Pain is usually referable to the peripheral ends of an 

 affected nerve. It is good practice to apply counter-irrita- 

 tion directly over a deep-seated inflammation or seat of pain, 

 but in assuaging superficial pain it is found, tljat where the 

 treatment can be made over the root of the painful nerve, 

 better results are obtained. In pain in the chest wall a 

 blister should be placed next the spine over the root of the 

 spinal nerve involved ; in pain in the head in man, counter- 

 irritation is applied over the back of the neck. Counter- 

 irritation should be done behind the ear to relieve pain and 

 inflammation in the eye and ear. 



In the treatment of enlarged glands and in acute inflam- 

 mations, as abscess, boils and carbuncles, by counter- 

 irritants, the application should be about the lesions rather 

 than directly upon them. 



Among other actions accomplished by counter-irritants 

 are : possible stimulation of trophic nerves and nutrition of 

 a part ; augmentation of tissue change, locally and gener- 



