314: DISEASES OF THE PERIPHERAL NERVES. 



The neurilemma is always affected at the same time, and consequently 

 we find the different bundles of nerve-filaments separated by the swell- 

 ing of their envelopes and by interstitial exudation. Occasionally, 

 after reabsorption of the disintegrated medulla of an inflamed nerve, 

 only a simple cord of connective tissue is left. 



SYMPTOMS AND COURSE. The symptoms of neuritis cannot be 

 clearly distinguished from those of neuralgia, or rather neuritis is one 

 of the various causes of neuralgia. The most important symptom of 

 neuritis is pain in the course of the inflamed nerve, extending to its 

 peripheral terminations. The pain is increased by pressure on the 

 nerve, and its exacerbations and remissions are usually less distinct, 

 and the paroxysms and intervals particularly are usually less marked 

 than in other forms of neuralgia. While this pain lasts, the sense of 

 touch is usually lost in the parts supplied by the inflamed nerve ; and 

 this symptom may be easily explained, although it seems paradoxical 

 on superficial examination. The morbid excitement of the trunk of 

 the nerve, caused by the inflammation in the medulla or neurilemma, 

 is conducted to the brain, and excites the sensation of severe pain ; 

 but the inflamed part of the nerve has become a bad conductor ; hence 

 irritation of its peripheral termination and the papillae of touch are 

 conducted to the brain either incompletely or not at all, and cause 

 either no sensation or an indistinct one. At first, at the correspond- 

 ing portion of the periphery, the patient has a feeling of numbness ; 

 subsequently, if resolution of the inflammation do not take place, there 

 is complete anaesthesia to external injuries, while the pain continues. 

 If the inflamed nerve contain motor fibres, the pain is accompanied by 

 twitching and contraction, while the patient's power of voluntarily 

 contracting the muscles is much affected or entirely lost. This also 

 depends on the morbid excitability of the motor nerves being increased 

 by the inflammation while their conducting power is lost. If the in- 

 flamed nerve lie near the surface, it may occasionally be felt as a hard 

 cord ; and we often find the skin covering it slightly reddened and 

 O3dematous. In most cases there is no fever, unless there be some 

 other inflammation besides the neuritis. 



The course of neuritis may be either acute or chronic. The more 

 acute it is, the sooner anaesthesia and paralysis follow the neuralgia 

 and contractions, and the more probable it is that these symptoms 

 were caused by an acute neuritis that has destroyed the nerve. Even 

 after resolution of the inflammation, the nerve usually remains to some 

 extent incapable of function for a long time. When the neuritis runs 

 a chronic course, if the nerve be destroyed, anaesthesia and paralysis 

 occur in the same way ; but, if the nerve be preserved and is only sub- 

 jected to pressure from the swollen and thickened neurilemma, the 



