These remarks apply especially to operations for tumors of the cerebellum. The other features of such operative attack are those common to brain tumors in any location.
In all operations for brain tumor, but particularly for cerebellar tumor, it will prove of the greatest advantage to have the operating table so inclined that the patient’s head will be three or four feet above his heels. In this position the veins are drained by gravity, and the operation is complicated by but little venous oozing. Crile’s pneumatic suit, or at least the lower part of it, should be worn, and an assistant should watch and report on the blood pressure. These two precautions permit such an operation to be conducted with an ease and safety hitherto unknown.[44]
[44] New York Medical Journal, February 11 and 18, 1905.
Cushing, dealing especially with a group of brain tumors in which radical procedures are impossible, where nevertheless relief from symptoms would prove a therapeutic desideratum, has proposed to afford this by removal of a portion of their bony covering, in order to allow a part of the brain to protrude, and thus provide a means of relief for the constantly increasing pressure. The incomplete union of the bones in infancy permits something of this kind to occur through natural causes, but after fusion of the elements of the cranial vault it is no longer possible, save in those rare cases where an opening results from the process of slow pressure absorption, which comes only when the tumor is in actual contact with the bone.
It would be mechanically ideal if, during adult life, a dislocation of cranial sutures could be produced similar to that observed in very small children. The dangers of such operation are many, among them being the possible injury to the functions of that portion of the cortex which protrudes through the opening thus made, by which, for example, preëxisting paralyses might be aggravated. For this reason it is preferable to establish the hernia over some “silent” or unimportant part of the cortex and to avoid making it unnecessarily large. Cushing, after various trials, recommends to make the bone defect under the temporal muscle, which not only affords a certain degree of protection, but exposes an area where few important motor centres are involved. He has reported several cases, with gratifying results, with a minimum of undesirable sequels.
Obviously in tumors below the tentorium the opening would best be made in the suboccipital region. Nevertheless, Cushing believes that even here the final result would be no more effectual than were the defect placed elsewhere.
Beck has called attention to the value of the temporal fascia as a substitute for the other firm coverings, by which the brain should be left enclosed after exposure, and when these latter are not available. For the purpose he would fold over a flap made from the temporal muscle and the adjoining periosteum in such a manner that fascia originally external should now be placed deeply and in contact with the cortex.
PLATE XLIV
FIG. 1
