Fig. 387
Division of bone by use of hammer and chisel. (Marion.)
Before opening the dura every loose particle of bone and every splinter should be removed, depressed fragments should be picked out, and those which are semidetached should be raised to their proper level. Through the opening thus made the dura is carefully examined; extradural collections of blood are recognized instantly, while some idea as to the amount of intracranial tension may be secured, even through a small opening. Absence of pulsation means probably the presence of cyst, tumor, or abscess deeper. Edema of the membranes usually subsides after nicking or opening them. A yellowish discoloration of the dura often indicates the existence of a tumor beneath. Nothing abnormal being discovered outside of the dura, should brain tension be great or should the dura be discolored, as by blood beneath, the membrane should be opened, by a triangular or horseshoe flap, and the subdural condition accurately estimated. In some cases of meningeal hemorrhage clots will be ejected with some force the instant the dura is opened. In other cases of intracranial pressure, either from tumor or from intraventricular hemorrhage, the brain will instantly protrude to such an extent as to make its reposition difficult or even impossible. Horsley’s dural separator is exceedingly useful, both outside and inside the dura, for detecting and separating adhesions, and as a retractor.
Incisions in the dura should be made, so far as possible, parallel with its vessels rather than across them. When accessible, dural vessels can always be secured and tied. Vessels of the pia can also be picked up and secured with fine catgut ligatures. When the brain tissue itself is diseased it should be carefully excised. The cortex itself is not so vascular as to afford much trouble. Upon any portion of the membranes or cerebral surface a sterilized solution of adrenalin can be sprayed or applied without hesitation. In all deliberate operations sinuses are avoided. When exposed or when necessary to attack them they may be ligated and divided, or may be packed with tampons of sterilized gauze, or may be seized with serrefines or light hemostatic forceps, which may be left for a day or two included within the dressings.
Any of the exposed motor areas or centres can be stimulated, when desired, if the patient be not too deeply anesthetized, by the faradic current of mild degree, applied to surfaces which have not been bathed with antiseptics, nor long exposed to the vapor of the anesthetic, through a double brain electrode made for the purpose, or by sterilized probes connected with the battery.
Buttons of bone or chips of the skull may be replaced after suture of the dura, when desired, though this is seldom advisable. When fragments are thus to be replaced they should be placed in warm sterile salt solution at once after removal, and kept warm. When a button is thus put back the periosteum may be sewed over it with buried catgut sutures.
The dura should be stitched with fine catgut as closely as possible. I have often placed beneath the dural opening a piece of gold, silver, or aluminum-foil, carefully sterilized, with a view to preventing dense adhesions between the dura and the membrane or cortex beneath. I have never known it to do harm.
Fig. 388
