320 DISEASES OF THE PERIPHERAL NERVES. 



ysms, spreading from a point along the course of the nerve ; the pain 

 is terrible and almost unbearable. The points douloureux occur par- 

 ticularly where the nerve escapes from a bony canal, or from fascia 

 that it has perforated, and approaches the surface. These spots seem 

 larger to the patient than they prove to be when we mark them out 

 by pressing the finger around. Budge made some very interesting 

 observations on the excitability of the motor nerves of frogs at differ- 

 ent places ; he found some spots very excitable while the parts im- 

 mediately next to them were very slightly so ; perhaps Valleix's points 

 douloureux on the sensory nerves correspond to those that Budge 

 found peculiarly excitable in the motor nerves. While Valleix almost 

 always found the points douloureux in neuralgia, other observers have 

 just as constantly failed to find them. The paroxysmal pains some- 

 times pass downward, sometimes pass upward along the course of the 

 nerve, so that there has been a division made into neuralgia descendens 

 and ascendens, the latter being far the more rare. Patients usually 

 say that the pain is not superficial but deep. It is rare for the parox- 

 ysms of pain to be limited to one small twig of a nerve ; usually 

 several twigs of one branch, but only rarely all the twigs of one nerve 

 participate in the affection. It is very remarkable that not unfre- 

 quently the neuralgia extends from one nerve to another that has a 

 different origin. From the laws of conduction we should suppose that 

 such a transfer could only occur in the central organs, through the 

 ganglia ; but the observation that neuralgia not unfrequently extends 

 from a cerebral nerve, as the trigeminus, to a spinal nerve, as the 

 occipital, renders the transfer in that way very improbable ; and we 

 must content ourselves with having mentioned the curious fact. 



Anomalies in the distribution of blood, in the secretion and in the 

 nutrition of the parts supplied by the affected nerve, are not unfre- 

 quently observed without our understanding how the morbid excite- 

 ment of the sensory can cause abnormal excitement of the vasomotor 

 nerves. At the commencement of neuralgic attacks we occasionally 

 see the skin become pale, more frequently at the height of the attack 

 that it reddens, that the secretion from the nasal mucous membrane , 

 conjunctiva, and from the lachrymal and salivary glands, is increased 

 In the same category come the exanthemata that develop in thecourst 

 of the affected nerve in some neuralgias, particularly in intercostal 

 neuralgia (herpes zoster), and lastly, the atrophy or excessive develop 

 ment of fat in parts supplied by the affected nerve, when the disease 

 has lasted a long while. The morbid excitement of the sensory nerve 

 is rarely transferred through a gland to a motor nerve. We musi 

 beware of carelessly considering the twitchings of patients, during theii 

 attacks of pain, as reflex symptoms. 



