Of all the considerations enumerated above, for which palliative measures are indicated, there is no symptom which more urgently demands alleviation than optic neuritis. This question of sight-saving may be accepted as a basis on which to estimate the value of palliative measures in general. It is obvious that no mere ‘decompression’ operation will save the sight when the optic inflammation has progressed to atrophy, and even in the earlier conditions of neuritis cases must be carefully chosen. Herbert Bruce[47] admirably clinches the matter in the following words: ‘As to the prediction of improvement of vision after trephining, everything depends on the condition of the disks. Yellowish white patches of exudate or white atrophic changes, especially when associated with macular changes, all indicate that the secondary changes in the disks will be permanent. In proportion to this development will the vision be impaired, whilst when the loss of vision has been dependent on the swelling of the disks, then not only will the sight be saved but largely improved. In other words, one might say, therefore, that when the neuritis has not progressed on to atrophy the sight would be saved.’ Even in the event, however, of the ocular conditions being unfavourable for palliative operation, other factors in the case still remain--the terrible and persistent headache, the fits, the emaciation from vomiting, &c., all of which require the most careful consideration, and all of which can be remedied by an efficient decompression operation. =Radical operation for cerebral tumours.= After the usual preparatory treatment and the application of the scalp-tourniquet, the skull is opened either by craniectomy or craniotomy. The two methods--with their relative advantages and disadvantages--have already been described (see Chapter II), but there can be no question that a brain tumour should be exposed by the formation of an osteoplastic flap. Such a procedure is called for on the ground that the exact localization of the tumour is always a matter of very great difficulty, and that it is impossible to foretell with certainty as to whether it will be feasible to remove the tumour or not. [Illustration: FIG. 71A. FIRST STAGE IN THE FORMATION OF AN OSTEOPLASTIC FLAP. Gigli’s saw, protected from the dura mater by the special director, passing between the two trephine holes. For further description, see text.] [Illustration: FIG. 71B. SECOND STAGE IN THE FORMATION OF AN OSTEOPLASTIC FLAP. The bone-flap turned down and the dura mater exposed.] [Illustration: FIG. 71C. THIRD STAGE IN THE FORMATION OF AN OSTEOPLASTIC FLAP. The dural flap turned down and the brain exposed. Note the relation of the scalp, bone, and dural incisions to one another.]