The immediate results are eminently satisfactory—headache is relieved, optic neuritis steadily diminishes, vomiting ceases, and the general condition of the patient is immensely improved.
The expectancy of life after such decompression operations requires careful consideration. So much depends on the nature of the tumour that it is difficult to make more than a general observation. In many cases life has been prolonged for one to two years, whilst instances are recorded in which the patient has lived for five to six years—not in a miserable condition as might be imagined, but in comparative comfort.
It might be added that, as the tumour grows, a one-sided subtemporal decompression may gradually become insufficient. In such cases, recrudescence of symptoms—redevelopment of optic neuritis, &c.—may be met by further decompression on the opposite side of the head.
Operations for tumours of the pituitary body.
The pituitary body may be approached by the frontal, temporal, and nasal routes. The temporal route, advocated by Caton and Paul[49] and Horsley, possesses the disadvantage that the surgeon, whilst utilizing an approach similar to that used in the Hartley-Krause operation for trigeminal neuralgia, encounters on his way the structures laterally situated to the pituitary body, the internal carotid, the cavernous sinus, the third, fourth, and sixth nerves, and the ophthalmic division of the fifth. The anatomical difficulties are therefore considerable. Added to this, the tumour, in its hollowing out of the central portion of the sella turcica, may leave such lateral osseous walls that an approach from the side is impossible.
The frontal route is strongly advocated by Krause.[50] He states that, ‘an osteoplastic flap is framed in the frontal region, immediately to one side of the middle line, so as to avoid the superior longitudinal sinus and frontal air sinus, and turned upwards. It is essential that the operator should approach the tumour along the floor of the anterior fossa, and, for this purpose, it may be deemed necessary to chip away the bone in the region of the supra-orbital ridge. Some days later, the final stages of the operation are conducted. The dura mater covering the frontal lobe is stripped away from the bone and traction applied to the dura by means of broad flat spatulæ. When the lesser wing of the sphenoid is exposed, the dura mater is opened in the vertical direction on a line with the lower median angle of the wound at a depth of 5 to 51⁄2 centimetres, as measured from the anterior surface of the frontal bone. If the incision is made at a deeper point there is danger of injury to the optic nerve, which is covered with dura mater in this situation. Laterally the dura is opened parallel to the posterior border of the lesser wing of the sphenoid, about 1⁄2 cm. in front of it, to avoid the sinus which lies immediately in contact with the edge of the bone. This exposes the optic nerve, coming from the chiasma and the internal carotid. The pituitary body is located beneath the anterior edge of the chiasma. The diaphragm of the sella turcica is now carefully incised with a small hook-shaped scalpel, and the hypophysis is readily removed.’
The nasal route, advocated by Bruns and successfully carried out by Schloffer[51] and Cushing, seems to offer the greatest advantages and give the most successful results. The general details of the operation are as follows: starting either beneath the upper lip or externally at the base of the septum, the mucous membrane is peeled away from each side of the vomer, and, by gradual piecemeal removal of that bone, the advance is carried out towards the base of the skull in what may be called an intra-mucous space. By the introduction of suitable instruments into this space the cavity is gradually enlarged, at the expense of the turbinated bones which are compressed by the dilating instruments. By this means—gradual removal of the septum—the operator approaches the base of the skull, always working between the two layers of mucous membrane, and always avoiding, with the greatest care, any laceration of the same. Laceration at once converts the more or less aseptic operation into an infected one. When the base of the skull is laid bare in the region of the sphenoidal sinus, the bone is there chiselled away and the under surface of the pituitary body exposed. It can then be removed piecemeal.
The general details of the operation as enumerated above may require amendment as our knowledge increases. Sufficient has been said, however, to point out the various methods of approach and the advantages claimed for the nasal route.
Results of operation on brain tumours.
Statistics are always fallacious, and this is especially the case with regard to operations on tumours of the brain. Few surgeons have operated on a sufficient number of cases to compile satisfactory statistical tables. These tables are generally made up from the combined experience of many operators, all using their own methods. The following, however, will serve to give an approximate idea as to mortality, &c.