8. This seems the proper place to introduce such facts as have been observed, and they are very few, that directly illustrate the material changes occurring in neuralgia.
Very much the most important of these facts is the history of a remarkable case recorded by Romberg. ["Diseases of Nervous System," Syd. Soc. Trans., vol. i.] The patient, a man sixty-five years old at the time of his death, had suffered for several years from the most violent and intractable epileptiform trigeminal neuralgia, complicated with interesting trophic changes of the tissues. Post-mortem examination showed that the pressure of an internal carotid aneurism had almost destroyed the Gasserian ganglion of the painful nerve, that the trunk and posterior root of the nerve were in a state of advanced atrophic softening, and the atrophic process had extended in less degree to the nerve of the opposite side. Now, the value of this case is by no means restricted to the fact that it records the existence of a particular anatomical change in one example of neuralgia. Its most striking teaching is the fact that the acutest agonies of neuralgia can be felt in a nerve, the central end of which is reduced to such a pitch of degeneration that conduction between centre and periphery must very shortly have entirely ceased had the patient lived. And hardly less important is its illustration of the fact that permanent injury to the ganglion of the posterior root of a spinal nerve impairs the vitality of the posterior root itself--a fact which has been independently made out by the physiological researches of Bernard and of Augustus Waller.