Subolivary bulbar tractotomy (Schwartz-O’Leary, 1940) is indicated with pain in the nape of the neck and the shoulder, because a high cervical chordotomy has been shown to be dangerous. The basis of the procedure is the same as that described under 3a and 3b. It is, however, necessary to open up the posterior fossa by reflection of the occipital bone with a flap of about 5×6 cm, and to remove the arch of the atlas. After sectioning the dura, a free space is found between the origins of the 10th and 11th cranial nerves. A cut is made 6 mm deep and 4 mm wide.
Such an operation requires experience and fine technique. The thick network of arachnoidal adhesions may make the operation impossible or provide marked difficulties, both in locating the site and in carrying out the actual incision.
The dangers of this operation are quite considerable, and I do not think that they are less than those of a high cervical chordotomy in terms of an operative fall in blood pressure. Again, the results are good so long as the height of the level of insensitivity is maintained: White and Sweet have reported a 31-year-old patient with Raynaud’s syndrome, who remained without pain for eleven years following bulb tractotomy. So far, few surgeons have learned how to do this operation and reports are correspondingly few. I am not convinced however, that because this procedure does not produce marked improvements and is more exacting than those described above, it does not have a great future.