346 DISEASES OF THE PERIPHERAL NERVES. 



In anaesthesia of the muscular nerves, perception of the degree of 

 contraction or relaxation of the muscles is diminished or destroyed. 

 Sometimes such patients are capable of making every motion required 

 of them, but are unable to tell, without the help of vision, to what ex- 

 tent they have moved. They can hold fast to an object as long as 

 their eyes serve them as " check-lines of motion " (Romberg], but let 

 it fall as soon as their eyes are closed. If anaesthesia of the muscular 

 nerves affect the lower extremities, the patient is often able to move 

 about tolerably well during the day, but in the dark he will stagger 

 about, and is quite unable to walk even a step or two (see chapter on 

 tabes, page 305). 



Very often anaesthesia is complicated with derangement of circu- 

 lation and nutrition in the insensible region. The temperature of the 

 part is often depressed several degrees, its function is impaired, and 

 its secretions are diminished. Besides this, there is an increased vul- 

 nerability of the region. A comparatively trifling degree of heat or 

 cold suffices to burn or freeze the part. Wounds and ulcers heal more 

 slowly, or not at all ; bed-sores are very apt to form. The epidermis 

 and nails become fissured and liable to scale off; the skin becomes 

 livid, and oedema develops in the subcutaneous areolar tissue. This 

 peculiar state of the insensible region is in some degree attributable to 

 the retardation of the circulation, but the cause of this retardation is 

 obscure. From experiments made by Axmann, it seems probable that 

 it is due to an implication of the sympathetic fibres which accompany 

 the spinal nerves. In frogs, whose spinal nerves had been divided be- 

 tween the spinal marrow and the spinal ganglion, Axmann only found 

 anaesthesia and palsy, but no nutritive disorder of the palsied part. 

 If, however, the nerves were divided at a point beyond that at which 

 they are joined by the communicating branches of the sympathetic, in 

 addition to the anaesthesia and palsy, there was desquamation of the 

 epidermis, obstruction of the capillary circulation, and oedema. 



If the nerve, which has been cut off from its central organ, or which 

 has lost its irritability from any other cause, contain both motor and 

 sensory fibres, partial anaesthesia and partial palsy are combined. It 

 would almost seem as if a nerve which had lost its irritability could 

 transmit this passive condition through its ganglion to other nerves, 

 just as an excited nerve can communicate its excitement by means of 

 its ganglion-cells to other nerves. It is in this way that we account 

 for the impairment of the sense of taste and smell in anaesthesia of the 

 .rigeminus, and for the anaesthesia of the auditory organs in cases of 

 nervous deafness, as well as for the partial paralysis which sometimes 

 supervenes upon long-continued anaesthesia. 



It is not always easy to distinguish peripheral from central anses- 



