DISEASES OF THE PERIPHERAL NERVES. 



tricity, cold douches, the baths of Gastein, Wildbad, or Pfaffers, and 

 even the disgusting so-called Thierbader. The ree'stablishment of ex- 

 tinguished sensibility of sensory nerves by such means, however, is a 

 very uncertain matter. 



CHAPTER XIV. 



ANESTHESIA OP THE TRIGEMINUS. 



ETIOLOGY. According to an explanation given in a previous chap- 

 ter, the same pernicious agents which we have found to be the causes 

 of prosopalgia, when of greater severity or of longer duration, may 

 give rise to anaesthesia over the region of the trigeminus. In anaes- 

 thesia of one-half of the face, the Gasserian ganglion of that side has 

 been found compressed, degenerate, or destroyed by a tumor or in- 

 flammatory process. In other cases but one of the three branches has 

 suffered permanent pressure or other injury within the skull, or else in 

 the passage through the sphenoid bone. In still others, which indeed 

 are the most common of all, a few twigs only of the trigeminus have 

 been cut through, or have been destroyed by the pressure or suppura- 

 tion of glands or tumors, or torn during the extraction of teeth (espe- 

 cially the inferior alveolar branch). The favorable course taken by 

 some cases shows that anaesthesia of the trigeminus may also proceed 

 from transitory affections of the neurilemma, or of the nerve itself, 

 which probably are due to cold. 



SYMPTOMS AND COURSE. When all the fibres of the trigeminus 

 have lost their irritability, it may be assumed that its main trunk or 

 the ganglion of Gasser is degenerated or destroyed. In such cases 

 the face is divided into halves, standing in abrupt contrast with one 

 another, the one being sensitive, the other insensible. The various 

 cavities of the face, whose supply of nerves comes from the trigeminal, 

 are in similar condition. Upon the affected side the eye may be 

 touched, the bulb pinched or pricked, the nose irritated with a sharp 

 instrument, with snuff, or with acrid vapors, without the patient's feel- 

 ing it. If the patient put a glass to his lips, he feels but one side of 

 it, and receives the impression that it is broken. Half of the tongue 

 also is insensible. The saliva flows from the mouth at the affected 

 side, and the remains of food hang to the lips without the patient's 

 being aware of it. Upon irritating the conjunctiva, there are none of 

 the reflex movements referred to in the previous chapter. If, how- 

 ever, the eye be exposed to a strong light, reflex action occurs, as irri 

 tation of the optic nerve transmits its impression to the facial nerve 

 Not only do the patients fail to wink when the conjunctiva is touched 



