ANAESTHESIA OF THE CUTANEOUS NERVES. 



347 



thesia. We may rely for a diagnosis, in some degree, upon the fol- 

 lowing points : 1. Upon the extension of the anaesthesia and its com- 

 plication 01 non-complication with motor palsy. If the anaesthesia be 

 confined to one side, and be combined with hemiplegia, it is probably 

 of the cerebral form. If, however, it extend over the lower half of the 

 body, and be combined with paraplegia, the case is almost always one 

 of disease of the spinal marrow. The coexistence of palsy of the face 

 with facial anaesthesia indicates a central cause of disease, while anaes- 

 thesia, with normal motion, indicates its peripheral origin. 2. The 

 character of the reflex symptoms are of great importance as a means 

 of distinguishing between the two forms. When the anaesthesia is 

 peripheral, the nerve being either separated from the brain, or having 

 lost its power of excitability, no stimulus can be transmitted from it to 

 the motor nerves, and there can be no reflex symptoms ; but if the 

 anaesthesia be central, that is, if the region of the brain in which we 

 become conscious of impressions be disabled, the route by which the 

 excitement is transmitted from sensory to motor fibres may still re- 

 main quite perfect, and reflex symptoms may readily appear. It is 

 just the same, in cases of circumscribed disease of the spinal mar- 

 row, as in spondylarthrocasis, and partial myelitis. On the other 

 hand, in diffuse inflammation, as in tabes dorsualis, reflex symptoms 

 are not apt to be seen. The following is a striking example of the 

 difference of these two conditions. When anaesthesia of the conjunc- 

 tiva occurs from apoplexy, the eye may be touched without the pa- 

 tient's perceiving it, and yet he involuntarily closes the eye because a 

 stimulus is transmitted from the sensory fibres of the trigeminus to the 

 motor ones of the facial. But if the anaesthesia be dependent upon 

 loss of the ganglion of Gasser, or of the ramus-ophthalmicus, the pa- 

 tient neither feels the touch, nor does he involuntarily close his eye, 

 since transmission of the excitement to the facial has then become im- 

 possible. 



The course of an anaesthesia depends upon the main disease. If a 

 nerve be divided by an incision, sensation is sometimes restored after 

 a while. If, however, a large portion of a nerve have been destroyed, 

 the anaesthesia will remain during life. Rheumatic anaesthesia, as well 

 as that occasioned by a moderate and uniform pressure over the course 

 of the entire nerve, warrants a better prognosis than the other forms. 



TREATMENT. The treatment of anaesthesia is never satisfactory, 

 excepting when it is possible to remove the cause. Sometimes a sur- 

 gical operation is indicated, sometimes a course of antirheumatic 

 treatment. It does not always immediately happen that cessation 

 of the cause is followed by removal of the effect. In such cases 

 spirituous and ethereal embrocations may be used, as well as eleo 



