Chapter XVIII: , on Blood Pressure.) (3)

The osteoplastic method should be used in exposing the tumor, by which a bone flap is raised, along with the overlying scalp, from which it is not detached. The centre of this flap is supposed to be calculated to overlie the centre of the deep lesion which it is proposed to attack. In many instances the operation should be divided into two distinct procedures, the first consisting in removal of the bone and exposure of the dura; this exposure should be ample, including the whole lateral region if necessary, as Horsley has shown; the second, a week or two later, comprising the balance of that which is to be done. But comparatively little shock attends removal of the tumor in the second stage of such a divided operation. After removal of the growth its cavity is best packed with a gauze tampon, after prompt ligation of all bleeding vessels within the field of operation, although it is usually required merely on account of venous oozing, as it is often possible to cut to the depth of an inch in the brain without a single artery spurting except those in the pin. The tampon is of value if allowed to remain for forty-eight hours, as preventing filling of the cavity with clot or excessive bleeding during the vomiting which may follow the administration of the anesthetic. The vasoconstricting properties of adrenalin may prove of great service here; it should be used in the standard 1 to 1000 solution, diluted 1 to 3. I have no hesitation in spraying this upon the brain or in saturating tampons with it, which may be left _in situ_ so long as necessary. A number of the old-fashioned small serrefines, properly sterilized, can also be resorted to, if needed, for securing vessels, which may not be easily tied. They can be left in place along with the tampon and all may be removed together.

Next to the danger from hemorrhage is that of rapid edema of the brain, which may result from increased tension in the arteries or through venous stasis, which later produces lymph stasis, by which fluid collection in the tissues is still further facilitated. Another reason for using tampons is to prevent such relaxation of veins as may predispose to this edema. In most respects the operations for removal of brain tumors differ slightly from those whose general principles are elsewhere mentioned in this work. I am greatly in favor of using secondary sutures (_i. e._, those tied with bow-knots), which may be loosened on the second or third day, permitting the raising of the flap, removal of tampon, etc., and I employ them largely after all sorts of operations upon the cranium. If we desire to prevent any attempt at union of wound margins we may employ the green silk protective introduced by Lister, which should have been previously carefully sterilized by boiling.

The _operative treatment of cerebellar tumors_ is made doubly difficult by their protected position and the large sinuses with which this part of the brain is surrounded. The cavity is restricted in size, intradural tension is greater than above the tentorium, and there is no room for easy displacement or retraction of parts. The occipital bone varies much in thickness and at points is somewhat thin. Operation which is begun either as an exploration or with a fixed purpose may prove palliative, even should the original purpose fail of accomplishment, as relief may be afforded by reducing tension, such relief consisting perhaps in freedom from headache, vomiting, and vertigo. Incision should extend from the tip of the mastoid process, a little above the superior curved line, to beyond the median line, with a vertical median incision by which a flap sufficiently large may be reflected downward. It is best to reflect the periosteum with the other soft tissues in order to expose the bone. The bone should be bitten away with forceps or removed with a reliable engine as rapidly as possible, hemorrhage being controlled with Horsley’s wax.

The operation may be divided into two stages, confining the first stage to the exposure of the cerebellar surface, or the operator may attempt all at one time.

The second stage consists in raising a dural flap, by which the cerebellar surface is exposed for inspection. It will protrude promptly through the opening, so that, with the finger, it may be possible to detect a tumor by the sense of touch. If no tumor appear on or near the surface deeper exploration should be made, with the aid of a retractor and by removal of a portion of the cerebellar hemisphere. This may require further exposure of the lateral region of the skull. Tumors situated deeply or at the junction of the cerebellum and pons require all the room that can be afforded from the outside, and are better approached from the lateral region than from above or below. It is comforting to realize what considerable portions of the cerebellum can be removed without serious or extensive disturbance, but as the medulla and pons are approached there is need of great care. The opening may be extended across the middle line, and either the lateral or the longitudinal sinus, or both, may be doubly ligated and divided. The tentorium may also be divided nearly to the petrous portion, after the lateral sinus has been thus divided, and so better access given to the deep location.

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.

FIG. 1

Topographical Anatomy of Cortex. Localization of Functions. (Ziehen.)

FIG. 2

Topographical Anatomy of Inner Surface of Right Hemisphere. Localization of Functions. (Ziehen.)]

OPERATIONS UPON THE CRANIUM.

The _fissure of Rolando_ is the anatomical landmark whose position it is important to determine with reference to a number of modern surgical procedures, for around it cluster most of the motor areas or centres. It commences at the middle line about 56 per cent. of the distance backward from the glabella (root of the nose) to the inion (occipital protuberance), and, passing downward and forward, makes with the middle line an angle of 67 to 69 degrees. For most purposes it begins half an inch back of a point midway between the glabella and inion. It may be easily found by _Chiene’s method_, which consists in folding a square piece of paper diagonally and folding this again; after which it is three-quarters unfolded, the acute angle then representing 67¹⁄₂ degrees. If this be properly applied to the skull, one edge of its surface can be made to fall directly over the Rolandic fissure. The fissure may also be located by a simple instrument known as the cyrtometer--a gauged metal strip having a sliding arm upon it, which, when the long strip is placed over the longitudinal sinus (_i. e._, the middle line of the skull), can be made to fall directly over the fissure. While neither of these methods is invariably and minutely exact, either of them is sufficiently accurate for all practical purposes.

The _fissure of Sylvius_ may be indicated by a line drawn from a point 3 Cm. behind the external angular process to a point 2 Cm. below the most prominent part of the parietal eminence. The short and ascending limb of this fissure is of relatively small importance in this connection.

_Reid’s base-line_, so called, is a line drawn from the inferior margin of the orbit backward through the centre of the external auditory meatus. It is a line often alluded to in cranial topography. The colored plate (see Plate XLIV) will indicate with reliable accuracy the relations of the motor centres to each other and to the principal fissures and convolutions. It pertains merely to the left hemisphere of the brain, in whose third frontal convolution is placed Broca’s centre for speech, the corresponding area upon the right side having no exactly corresponding function. The centre for vision, it will be seen, is located in the cuneus, the most basal portions of the hemispheres being the seat of the special senses of taste, smell, and hearing.

=Operation.=--The word _trephine_ is at present used both as a noun and as a verb, the older term _trepan_ being now wellnigh discarded. The instrument consists of a section of a tube, one of whose extremities is arranged with sharply cut saw teeth, the whole provided with a grip or handle, which revolves in a plane parallel to that in which the saw teeth cut. The best instrument is that arranged in a slightly conical manner, so that it may less easily burst through the skull and do harm to parts within. The trephine proper is manipulated by the hand. A variety of substitutes have resulted from applications of human ingenuity to the problem of opening the cranial bones. Some of these are operated by foot or hand power, with reduplicated mechanisms, and others by electricity. The more complicated the mechanism the more likely it is to get out of order, and there are but few of these substitutes which give anything like lasting satisfaction.

The operation of trephining is made to include any method by which an opening is made in the uninjured cranium or by which an opening already existing is enlarged and made to subserve the surgeon’s purpose. Aside from the saws already alluded to, there are in use a variety of cutting bone forceps, rongeurs of various device, and a variety of chisels, which are to be used in connection with the mallet or hammer. In order to use any of the latter instruments to advantage the first attack should be made with a trephine of reasonable size, say 2 to 3 Cm. in diameter, after which forceps, chisel, or saw may be used. Straight saws also are of occasional usefulness. I do not favor the use of the chisel and mallet, feeling that the concussions resulting from blows of the hammer add to the shock of the operation. The common trephine is provided with a centre pin, which can be withdrawn after a shallow groove has been cut. To prevent slipping of the centre pin the point to which it is to be applied should be marked by cutting a nick with the point of a chisel.

The _Gigli saw_ should be in every surgeon’s outfit. It consists of a piece of steel wire having a thread cut around and along it by a die, by which it is made as effective as a series of saw teeth. Two small trephine openings are made, and it is then passed into one and out of the other, the dura protected by depressing it, and the wire then handled as though it were a chain saw. It can thus be made to cut its way quickly through the bones of the skull.

Other aids in mechanical procedures are revolving small saws and the surgical engine.

The Powell electric saw cutting a “trap-door” in the skull. (Illustrating the operation upon a cadaver.)]

In the absence of a wound a flap of scalp is raised before applying the instrument. This flap is ordinarily of horseshoe shape, and should be made with its convexity pointing toward the occiput, as drainage is best afforded later by this arrangement. The old crucial incisions are now wellnigh abandoned. The pericranium is detached, after incision, with the periosteum elevator, and it should be turned up with its overlying scalp without completely separating it. The scalp flap can be held out of the way by temporarily sewing it to some other part of the scalp, every portion of which should be previously shaved closely and thoroughly scrubbed. The operator has his choice--to seize vessels as they bleed or to make the operation in large degree bloodless by applying an elastic tourniquet tightly around the scalp above the eyebrows and beneath the occiput, the ears preventing it from sliding. If the tourniquet be used the vessels will often bleed in an annoying way after the wound is closed. If the operation be performed for fracture of the skull, should there be an opening already made by the depression of fragments, it may not be necessary to use the trephine, but with suitable bone forceps fragments may be removed or detached. In this case, however, there are often sharp points of bone which will require removal by cutting bone forceps, for the surgeon should leave the margin of the bone opening comfortably round and smooth. Should there be no opening into which the point of an elevator or of bone forceps can be inserted, then one should be made; it is for this purpose that the trephine is mainly used in cases of fracture of the skull. It should now be applied upon a firm and undetached surface of bone, one which will bear the pressure necessary in the process of perforation. As used for this purpose it should be so applied that at least two-thirds of the circle cut by its teeth will be upon unbroken skull; the remaining segment of the circle may be over the fractured area. After it has begun to cut a distinct groove the centre pin should be withdrawn and the instrument maintained in its position during its work by a firm and steady hand, which will force it evenly through the bone and not exercise undue pressure. As the diploë is perforated the bone-dust becomes soft and bloody and the resistance is diminished. As the instrument sinks deeper the operator should frequently intermit its use, and determine his position by means of the irrigator and of the probe or other instrument. The nearer the inner surface is approached the more caution must be exercised, remembering that the bone is likely to be of unequal thickness. When the skull has been completely perforated at one or two points around the little circle the operator should introduce the point of an elevator and pry up the disk of bone, or by rocking the handle of the trephine he may be able to remove the button with that instrument. When the operation is performed in the ideal manner the dura is scarcely touched, certainly not raggedly injured by the teeth of the instrument (Figs. 386, 387 and 388).

Construction of an osteoplastic flap; bone is exposed; first openings are made with a hand trephine or burr. (Marion.)]

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.

Exposure of cortex or of cerebellum after division of dura. (Marion.)]

Osteoplastic resection after Wagner. (Chipault.)]

Drains and drainage are to be avoided when possible, and should be removed early, except in cases of abscess. They may be made of catgut, horse-hair, gauze, rubber, or even of glass, like those short ones which Kocher inserts after extensive operations, their outer ends flanged to prevent their slipping beyond control.

_Opening the skull_, or, in general terms, _trephining_, is at present _resorted to for the following purposes_:

1. _For relief of compression_--

(_a_) By depressed bone, as in comminuted or gunshot fracture;

(_b_) By removal of clot or ligation of vessels;

(_c_) By evacuation of pus, either from the meningeal cavity or from
a deeper abscess;

(_d_) By the removal of serous effusions, either extraventricular or
intraventricular.

2. _For removal of foreign bodies._

3. _For relief of intracranial irritation_--_e. g._, epilepsy, the psychoses, etc.

4. _For removal of tumors._

5. _To compensate for defective development._

6. _For exploratory or purely empirical reasons_, including the making of “relief openings” for relief of pain, etc.

Aside from the ordinary methods of trephining as applied for common conditions, modern surgery comprises the resort to essentially new methods for raising areas of skull of considerable size and then restoring them to their previous position. These are ordinarily spoken of as _osteoplastic resections_, and have added very materially to the art and resources of the surgeon. These consist, in a general way, of the formation of a window, as it were, in the vertex or lateral region of the skull by outlining a quadrangular or horseshoe flap of scalp, which is detached only for a slight distance around the incision, after which, by use of the revolving saw or by chisel and mallet, a groove is cut through the bone running parallel with the margin of the scalp-flap, but perhaps a centimeter within it. After this bone area is completely cut through on three sides it is then sprung up or elevated in such a way as to be broken across the base of the bone-flap. It is not at all detached nor separated from the scalp, and so when subsequently lowered into position retains its vitality by virtue of its vascular connections.

When some particular measure seems indicated in order to atone for a large defect in bone it has become quite customary to insert some _artificial substitute_, mainly either _celluloid_ or a thin aluminum plate, previously absolutely sterilized and cut at the time into such shape as may be called for, but a trifle larger than the real defect, being let in or sprung in, as it were, either completely beneath the bone or into the bony opening, so as not to be easily detached or slip out of the way. By this _heteroplastic_ method most admirable results have been achieved. I have used celluloid for this purpose in the spinal column also, closing with it the defect which remained after the extirpation of the sac of a spina bifida. It is rarely _necessary_ to resort to this practice in the skull, as dense fibrous tissue in due time firmly protects the endocranial contents from external harm (Figs. 386, 387, 388 and 389).