The modern operation of section of the posterior root of the fifth cranial nerve for trigeminal neuralgia is one of the greatest achievements of surgery. There are series of hundreds of cases on record with a mortality of less than 1 per cent. The operation has become so standardized and so satisfactory that, in the United States at least, few attempts have been made to find any substitute for it. It has, however, certain undeniable disadvantages. In the first place, the mortality can be kept low only by a certain degree of selection of cases. In the second place, section of the root is a major operation entailing discomfort and a period of disability, which should not be taken lightly. In the third place, the results of operation cannot be predicted in cases which are at all atypical, and many a surgeon is haunted by one or more "gasserian ghosts"