Fig. 4. The Scalp-tourniquet. Front View.
Fig. 5. The Scalp-tourniquet. Back View.
There is one other exception to the satisfactory working of the scalp-tourniquet. In the presence of a superficial cerebral tumour, especially when of a malignant nature, the normal communication between the intra- and extra-cranial vascular systems may be so exaggerated that those scalp-vessels which receive diploic and emissary venous communications will give rise to some trouble. This difficulty should be overcome—not by rapidity in the formation and turning down of the flap—but by clipping each vessel as exposed or divided, by the application of pressure and by foraminal occlusion (see also p. 17).
I found Cushing’s tourniquet rather inconvenient in its application, and, after various modifications, am accustomed to use the one depicted in the illustration. It consists of two flat metal bands connected posteriorly by a strong rubber connecting link, the two bands passing in front through a metal fixation piece possessing a screw which, when tightened up, allows of the maintenance of the desired pressure. The median tape, previously mentioned, helps to keep the tourniquet in position.
The tourniquet is applied as follows: the whole head is enveloped in gauze—two or three layers thick, and cut to the size and shape of a large handkerchief. The tourniquet is slipped over the head, as low down as possible, and then tightened up. The median tape, having a loop behind through which the tourniquet passes, is laid in the middle line and tied round the screw on the fixation piece.
The gauze should then be moistened with saline solution or some mild antiseptic, so that it clings tightly to the underlying scalp and becomes sufficiently translucent to allow of the recognition of any underlying landmarks that may have been previously mapped out with the scalpel, iodine, silver nitrate, or aniline pencil.
The scalp-flap is then framed by incisions carried down to the bone, through gauze and scalp, in one sweep. The flap is turned down and covered with gauze. By the adoption of this method hæmorrhage from scalp-vessels is efficiently controlled and the risk of wound infection is reduced to a minimum.
After the completion of the operation, the scalp-flap is approximated and sewn into position, first by numerous buried fine silk sutures bringing together the aponeurotic layer of the scalp, and finally by a few silk or salmon-gut sutures passed through the skin itself. Gauze dressings are applied, the tourniquet loosened, and a roll-gauze bandage quickly applied circumferentially around the head, low down over the forehead and occipital region. This roll bandage in reality takes the place of the tourniquet, but is, of course, applied with moderate pressure only.
If the wool and bandage now applied over all should include the ears, these two organs should be well covered with vaseline. Few things are more uncomfortable to the patient than the contact of wool and bandage to the ears.
The tourniquet should be utilized whenever possible. In operations, however, that are conducted near the base of the skull—subtemporal decompression, cerebellar exploration, &c.—the surgeon, in his effort at hæmostasis, must rely on the application of digital pressure on either side of the incision, the more careful exposure of the vessels, and the application of forceps as soon as they are seen or divided, or by the utilization of Vorschütz’s hæmostatic safety-pins.
Other methods of controlling scalp-bleeding are as follows:—
1. Kredel’s hæmostatic sutures, passed with a large curved needle which slides along the bone and emerges about 5 to 7 cm. from the point of introduction. The silk ligatures are then tied over metal plates, so curved as to lie flush with the surface of the skull in the particular region involved. Four of these plates would be used in the formation of an osteoplastic flap, one on the distal side of each of the three scalp incisions, and one along the base of the flap.
2. The enclosure of the proposed incision by a running suture which, passing down to the bone, emerges about 1 inch further on, then so to speak repeating itself in part until the whole region is surrounded. The ligatures are then tightened up. This method takes some time in its application, and presents no advantages over the scalp-tourniquet.
3. The blocking of the main arterial supply—temporal, occipital, and supra-orbital vessels—by modified safety-pins, mass ligatures, &c. Arterial compression by means of the modified safety-pin as suggested by Vorschütz will be found most useful in those operations in which the scalp-tourniquet cannot be utilized—subtemporal decompression, &c.
Severe bleeding may take place from the mastoid and other emissary veins, and from the open mouths of those abnormally dilated diploic and emissary veins so often encountered in the exposure of an underlying dural or superficial cerebral tumour. The foramina in the bone, when exposed, must be occluded as quickly as possible. For this purpose we have the following methods at our disposal—plugging with small bone or wooden pegs, blockage with minute plugs of cotton-wool, and the utilization of Horsley’s wax, smeared over the part and well pressed home.
Hæmorrhage may also occur from the bone during trephining, more especially when the operation is conducted over that part of the anterior division of the middle meningeal artery which runs through a channel in the spheno-parietal region. Here the disk of bone should be removed as quickly as possible and the channel plugged with pegs, cotton-wool, or wax.
Oozing from the raw surface of the cut bone is controlled by rubbing in aseptic wax, or by the crushing together of the inner and outer tables.
In this case the bleeding may occur from three sources, meningeal veins—often of considerable size when related to neighbouring tumour-formation—the middle meningeal artery, and the venous sinuses of the brain.
Hæmorrhage from meningeal veins may be arrested by one or other of the following methods:—
1. Gentle pressure as applied either by dry gauze, or wet gauze soaked in saline solution at a temperature between 110 and 115 degrees Fahrenheit.
2. The application of a piece of muscle to the bleeding-point. This method was, I believe, first introduced by Sir Victor Horsley. Some muscle is usually available for the purpose, usually the temporal muscle. A small portion of muscle is snipped off, spread out as a flat muscular pad, the bleeding area dried, and the graft quickly applied. It soon adheres, and usually arrests the hæmorrhage.
3. The application of a ligature. This method is placed last, being the most difficult. It is usually necessary to underrun the bleeding-point with a fine needle threaded with the finest of silk. It presents the disadvantage in that the needle may perforate the dura mater and puncture one of the superficial cerebral veins.
Fig. 6. Cushing’s Clips. A, The holder of the clips; B, A clip ready to be applied; C, Two clips applied to the middle meningeal artery.
Hæmorrhage from the middle meningeal artery may be controlled by ligature or torsion, and added to these methods we have one other, recently introduced by Cushing—silver wire ‘clips’. These clips are U-shaped, loaded on a magazine, picked up as required in the jaws of a specially indented forceps, and clipped on to the vessel—usually one on either side of the bleeding-point.
Hæmorrhage from venous sinuses is dealt with on p. 150.
This form of hæmorrhage, one of the most troublesome complications arising in head-operations, most commonly results from hasty or careless opening of the dura mater. Thus, when the dura is incised in a case of greatly increased intracranial pressure, the brain herniates suddenly outwards, and the incautious use of the knife will damage one of the dilated superficial cortical veins. The dura should always be opened with the greatest care, the knife being passed lightly over the membrane till the pia-arachnoid is exposed, when the dural margins are lifted up with small tenaculum forceps and the membrane slit up with blunt-pointed scissors or on a grooved director.
In the event of injury, the bleeding may often be controlled by light pressure with dry gauze, or wet gauze wrung out in hot saline solution as described above. If this fails, a very fine silk ligature may be passed beneath the vessel on either side of the site of bleeding. This procedure is not easy to accomplish, the tissues are so soft and friable. However, every effort must be made to arrest the bleeding, for not only does the hæmorrhage obscure the field of operation, but the presence of a blood-clot beneath the dura mater will lead at a later date to the formation of adhesions between the various membranes of the brain—a potent cause of headache, epilepsy, &c.
Two methods are adopted in the exposure of meninges and brain—craniectomy and craniotomy.
Craniectomy implies the formation of a scalp-flap, exposure of the bone, trephining of the skull, and enlargement of the gap to the required size and shape.
Craniotomy implies the formation of a flap of scalp and bone in one, and the exposure of an area of dura and brain directly proportionate to the size of the bone-flap.
After the application of protective gauze and tourniquet, the scalp-flap is framed according to the requirements of the case. If the tourniquet is used, the knife is entered at one extremity of the proposed flap, carried down to the bone—through gauze and scalp in one—and the incision completed in a single sweep. Under other circumstances, digital pressure is applied to the main flap-supplying vessel, e.g. the temporal artery over the base of the zygoma, or else Kredel’s clamps or Vorschütz’s hæmostatic safety-pins are passed in such a manner as to control bleeding from the main supplying vessel. In the event of bleeding, the surgeon goes along quietly, deepening his incision and seizing each vessel as exposed.
In turning down the scalp-flap it is usually recommended that the pericranium should be included. This is quite unnecessary, and, under certain circumstances, should certainly be omitted (see p. 129). It should be stripped away from the underlying bone as required.
Fig. 7. Hudson’s Trephine. Showing the usual method of using the spiral perforator, spiral follower, and enlarging burr.
The trephining may be carried out with the hand-trephine, or by means of saws, burrs, and trephines driven by electricity. With the exception of a few words on Hudson’s trephine, I do not propose to discuss the relative advantages and disadvantages of these mechanically-driven instruments. I hold the opinion that the hand-driven instrument is sufficiently rapid in its work, that it is infinitely safer, and that the surgeon should accustom and perfect himself with those instruments which are to him most convenient and most portable. He will not always be conducting his operations in a perfectly equipped hospital, much of his work will be carried out in the nursing home or in the country. Whatever method be adopted, the operator should use those instruments to which he is most accustomed.
Hudson’s trephine is shaped after the style of the carpenter’s brace and is fitted with three cutting heads—the perforator, the follower, and the enlarging burr. It is claimed that injury to the dura and brain is impossible, the instrument becoming automatically locked so soon as the resistance of the internal table is overcome, a thin film of bone being pushed in front of the advancing head. I have had the opportunity of using this instrument, and so far as my experience goes it answers all requirements. Still, I prefer the ordinary hand-trephine so long as it satisfies certain requirements. It must be of simple mechanism and strong, the handle of good size and shaped to fit the hand, the shaft and head so interlocked as to allow of no independent movement, and the hollow head sharply toothed and bevelled externally, in continuity with the teeth, for a distance of half an inch. The bevelling is so arranged that the actual cutting process is only effected during supination of the hand and forearm. The pin of the trephine should not project beyond the cutting edge for a greater distance than about ·2cm. This pin should be readily removable.
Fig. 8. The Hand-trephine.
The pattern which I am accustomed to use is depicted in Fig. 8. The trephines are kept in three sizes—diameter 1⁄2, 1, and 11⁄2 inches. The intermediate size is used for ordinary trephining, the small one for the formation of the osteoplastic flap, the large for the removal of a disk of bone which includes within its circumference the area involved in some depressed and punctured fractures (see p. 133).
Fig. 9.
Fig. 10.
To show the technique of Trephining. Fig. 9 illustrates the act of trephining for cerebellar exposure. Fig. 10 shows a trephine-disk to one side of a depressed fracture.
The site of trephining may be fixed by the introduction of a bradawl through the scalp, so indenting the external table that the spot can be verified on turning down the scalp-flap. The pin of the trephine is there applied, and the trephine directed at right angles to the surface of the skull, or at that angle which is suited to the region attacked. The pin is discarded when a sufficient groove has been attained. The trephine must be kept under perfect control, muscular effort only being required during the act of supination.
Fig. 11. Horsley’s Disk or Bone Elevator.
Fig. 12. Horsley’s Dural Separator.
Fig. 13. Keen-Hoffmann’s Craniectomy Forceps.
The firm nature of the external table will be readily appreciated; so soon as this resistance is overcome the trephine will be felt to be cutting its way through a softer structure, whilst the increased bone-dust and venous oozing will make it evident that the instrument is biting its way through the diploic tissue. Greater resistance is again encountered on meeting the internal table, warning the operator that the time has come when greater care must be exercised. The bone-dust must be wiped away, the teeth of the trephine cleansed with nail-brush or sponge, and the depth of the groove estimated. The groove should be of the same depth throughout its circumference, or of that depth which is suited to the part involved.
The readiness of the disk for removal is best demonstrated by digital pressure. When it gives to that pressure, whether in whole or in part, the elevator may be applied and the fragment removed.
In the temporal and cerebellar regions special care is required by reason of the absence of diploic tissue.
It is impossible to lay too much stress on the necessity of avoiding injury to underlying dura and meningeal vessels. Injury to these structures not infrequently upsets the whole plan of campaign.
Fig. 14.
Lane’s Fulcrum
Craniectomy Forceps.
Fig. 15.
Horsley’s Gouge
Forceps.
Fig. 16. De Vilbiss’s Craniectomy Forceps.
Previous to any attempt at enlargement of the trephine hole, the dura mater must be separated from the bone with the aid of Horsley’s dural separator or other suitable instrument. Of the many patterns of craniectomy forceps, the following will be found to suit all requirements:—
The visceral blade is introduced between the dura and the bone and ‘morcellement’ carried out. It is essential that the surgeon should not be too greedy, resting content with the removal of small fragments at a time.
They possess great mechanical advantage and are mainly suited for the rapid removal of large portions of bone.
This instrument is mainly utilized in the smoothing and refreshing of sharp edges of bone, and in the ‘morcellement’ of the thinner portions of the skull—temporal and cerebellar regions.
A clever contrivance whereby the operator is enabled to cut a narrow channel in the bone. Mainly utilized in the formation of the osteoplastic flap.
Craniotomy, or osteoplastic resection of the skull, was first carried out by Wagner. It is proposed to describe that method only which, by experience, has been found to meet all requirements—the formation of the osteoplastic flap by means of the hand-trephine, Gigli’s saw, and de Vilbiss’s forceps.
The protective gauze dressing and scalp-tourniquet are applied as before. A large Upside-down topless triangle-shaped incision is made in such a manner as to include the area which it is desired to expose. The two vertical limbs of the incision should converge to such a degree as to allow of the subsequent ready fracture of the flap along its base. The knife is entered at one extremity, carried down to the bone, and the three incisions rapidly made, one after the other. Along the line of each of the three incisions, the pericranium is stripped away from the bone so as to allow of adequate exposure. At the anterior and posterior angles of the flap the tissues are retracted a little more, permitting the application of a half-inch diameter trephine. Here the two trephine-holes are bored—with the usual precautions against damage to the dura mater—and the two disks of bone elevated and removed.
Between these two trephine-holes the dura mater is separated from the bone and the special director introduced, entering at the one hole, emerging at the other, and lying throughout between the dura and the bone. The saw is now passed along the groove of the director, the handles affixed, and the bone intervening between the two trephine-holes divided, not straight out to the surface, but bevelled or cut in such an oblique manner that the bone-flap, when replaced, rests on a ledge (see Figs. 17-19). The sawing process generates considerable heat, and the assistant should be instructed to keep up irrigation with saline solution or sterilized water. The sawing is carried out by steady side-to-side traction, without jerks; if the saw breaks, the special handle may be attached, thus obviating the necessity of introducing a new saw.
Fig. 17. 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.
Fig. 18. Second Stage in the Formation of an Osteoplastic Flap. The bone-flap turned down and the dura mater exposed.
Fig. 19. 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.
The dura is now separated from the bone along the line of the two vertical incisions, and the visceral blade of de Vilbiss’s forceps insinuated beneath the bone, starting at one trephine-hole and working downwards to the lower limit of the incision. It is essential that the operator should be satisfied with the ‘morcellement’ of small portions of bone at each bite of the instrument. At the lower end of each of the vertical incisions the forceps is directed inwards for 1⁄4 to 1⁄2 inch so as to weaken the base of the flap.
To lift up the osteoplastic flap, a stout elevator or spatula is introduced beneath the bone at its upper part, leverage applied, and, as soon as sufficient elevation has been attained, the dura mater carefully separated from the whole of the under aspect of the flap. The flap is then grasped at its upper part with both hands and, with a quick but forcible jerk, broken across at its base, the assistant at the same time aiding the correct linear fracture of the bone by a flat spatula applied to the outer aspect of the base of the flap. Insomuch as the flap is most usually framed in the parieto-temporal region—for the exposure of the motor area—the base of the flap, being formed from the squamous portion of the temporal bone, is comparatively weak. Fracture is then readily obtained. Under other circumstances the base may be sufficiently weakened by the application of the de Vilbiss forceps or by the use of the Gigli saw.
The bone-flap is thrown back and enveloped in gauze. Its basal region is examined for a possible injury to meningeal vessels. In the event of such complications the bleeding vessel is clipped, ligatured, or underrun. Possibly some branch of the anterior division of the middle meningeal artery, running in an osseous canal, may require to be controlled by foraminal occlusion—with a wooden match, bone peg, cotton-wool, or aseptic wax.
In comparing the relative advantages and disadvantages of craniectomy and craniotomy, although there are certain definite contra-indications to the latter method, yet craniotomy should always be carried out when the surgeon desires to expose a large surface area of brain, more especially in the exposure of a tumour diagnosed to lie in relation to the motor cortex. Even if the operator should be unsuccessful in his exploration, or, if finding the tumour, should deem it irremovable, the dura can be sewn up and the bone-flap replaced, resting on its bevelled edge, with little defect in the skull and a normal surface contour.
The three main disadvantages to craniotomy are as follows:—(1) the operation can seldom be done under much less than thirty minutes; (2) there is some slight risk of complication through injury to the middle meningeal artery; and (3) the dura mater may be so adherent to the bone as to be torn in the process of flap-elevation. Time, however, is usually of little importance; bleeding from the middle meningeal artery may be controlled, and dural lesions may be avoided by careful technique. In general, the advantages of osteoplastic resection greatly outweigh the disadvantages.
The more definite contra-indications to the formation of the bone-flap are as follows:—
1. This operation is unnecessarily severe in most cases of intracranial hæmorrhage, e. g. from the middle meningeal artery. It is also usually impracticable by reason of the associated damage to the bones of the vault and base.
2. It is contra-indicated in operations conducted for the exposure of the Gasserian ganglion, its root and its branches (trigeminal neuralgia). In these operations it is essential that the operator should get down as low as possible towards the base of the skull.
3. It is contra-indicated in operations conducted in the cerebellar region. Even after cerebellar exposure by craniectomy, the surgeon is working in a sufficiently confined space. The presence of a bone-flap only adds further difficulty and complication. Added to this is the fact that the thin wall of the cerebellar fossa is not adapted to osteoplastic flap-formation.
Reference has already been made to the great importance of opening the dura in such a manner as to avoid injury to the underlying superficial cerebral vessels (see p. 19). It may be incised in a crucial manner or by flap-formation. Flaps are usually to be preferred if the surgeon desires to have the widest possible view of the brain surface. In the formation of the flap, advantage should be taken of the vessels that minister to its vitality. Thus, in the lateral region of the head, the base lies below, the middle meningeal artery supplying the flap. Under special circumstances, the blood-supply may be disregarded; the flap never sloughs, so far as my experience goes.
Considerable difficulty may be experienced in sewing up the dura—by reason of the bulging of the brain. How these difficulties may be overcome is dealt with on p. 236. The edges should be united by numerous fine silk sutures.
The flap is replaced, care being taken that its lower or fractured edge does not injure the dura mater. The aponeurotic and subcutaneous tissues of the scalp-flap are sewn up in the manner stated on p. 16.
Whether the operation be carried out by craniectomy or craniotomy, the patient is put back to bed in the so-called head-down position, the lower end of the bed being raised at least a foot above the level of the head. In the event of shock, a hypodermic injection of a 1⁄4 gr. of morphia should be given, the lower extremities may be bandaged firmly from below upwards, and saline infusions administered, preferably per rectum.
The term ‘Cephalocele’ has been applied to all those tumours which project through a gap or deficiency in the bones of the vault and base of the skull. The tumour may be congenital or traumatic in origin: the membranes of the brain may alone protrude (meningocele), or the tumour may be composed of normal or altered brain-substance: all the varying conditions, however, are included under one term—cephalocele. Congenital and traumatic cephaloceles differ, however, so markedly from one another, both with regard to their pathology and treatment, that they must be considered separately.
Billroth and the late Professor von Bergmann were the first to narrate cases in which this deformity was present, Lyssenkow[4] added much to the previous records, and de Quèrvain,[5] by prolonged researches, drew further attention to the subject.
Lyssenkow divided the congenital variety into two main groups—exencephaly and cephalocele—the former resulting from a general error in development (the ‘Acrania’ of Muscatelle), the latter a partial or local developmental failure. In exencephaly there is an extensive gap in the vault of the skull, the remainder of the skull being microcephalic in nature, the brain projecting outwards in a varying degree, and the ventricular spaces distended with fluid. In cephaloceles the hole in the skull is usually circumscribed, although the sutures may be widely separated and the ventricles distended with fluid, yet both skull and brain may be normally developed in all other respects.
presents but few points of surgical interest, insomuch as the condition is barely compatible with life.
occupy a very different position. The condition is by no means confined to man, and many instances are recorded as occurring throughout the animal kingdom. Norsa Gurrieri,[6] for instance, records a case occurring in the embryo of Mus decumanus vel albinus. The same writer insists that the developmental error involves bones of either cartilaginous or membranous origin, and that the atrophic condition of the bone is the primary cause and the ectopia of the brain a secondary result.
Lyssenkow,[7] after careful investigation of tumours removed by operation and after death, found scattered nerve-fibres, fat-cells, striated muscle and vessels—the products, therefore, of both ectoderm and mesoderm. He also observed the frequent occurrence of an intimate union or fusion between the cephalocele and the overlying integument, and, in consequence, the theory was formulated that the greater number of cephaloceles were in reality cephalomata or true teratoid tumours.
It would appear, therefore, that a cephalocele results from the incomplete cutting off of the neural canal in the head region of the embryo from the overlying epiblast, with consequent fusion between the primary neural tube (from which the brain is developed) with the primordial mesoblastic membranous cranium (from which the membranes are developed), and with the overlying epiblastic layer (from which the epidermal portion of the scalp is developed). In consequence of this localized fusion of layers, the outer dermic coat (from which the membranous skull is developed) fails to form. Bony defects therefore exist through which brain-matter protrudes, the projecting portion often being intimately attached to the skin, and containing not only epiblastic elements, but also mesoblastic tissue from irregular occlusion of the same. The mesoblastic involvement is proved by the presence in the tumour of muscle tissue, vessels, &c.
The tumour may project through the vault or base of the skull. In the former case, it is almost invariably situated in close relation to the middle line of the skull, from nasion to below the inion.
Fig. 20. An Occipital Cephalocele. (For further description, see text.)
1. Occipital cephaloceles—the commonest variety—occupy, anatomically, two positions (1) between the two lower segments of the occipital bone (inferior occipital cephaloceles), often involving the foramen magnum and sometimes complicated by a condition of cervical spina bifida, and (2) between the two upper segments of the occipital bone (superior occipital cephaloceles), occasionally involving the posterior fontanelle.
The tumour may possess a broad base or may be definitely pedunculated. In the former instance the gap in the bone may be of considerable size and the margins everted: in the latter case, the hole may be quite small.
The deformity is frequently associated with other congenital defects—hydrocephalus, microcephalus, spina bifida, hare lip, hernia, and talipes.
2. Sincipital cephaloceles occur next in order of frequency. The tumour projects between the nasal bones and the nasal process of the superior maxilla (naso-frontal), between the nasal process of the maxilla and the orbital plates of the ethmoid (naso-ethmoidal), or between the nasal bones (nasal).
Fig. 21. A Cephalocele over the Anterior Fontanelle.
(For further description, see text.)
3. More rarely, the tumour overlies the anterior or posterior fontanelle. A case of this nature is depicted in Fig. 21, the tumour, situated over the anterior fontanelle, bulging over the temporal and frontal regions to a remarkable extent.
4. Basal cephaloceles protrude through the cartilaginous base of the skull, either through the cribriform plate of the ethmoid, between the pre- and basi-sphenoid, or between the basi-sphenoid and basi-occiput, often projecting as a polypoid growth in the nose or naso-pharynx.
An interesting case of basal hernia was reported by von Mayer.[8] The child, 3 days old, was admitted with a tumour projecting into the right nostril, covered with mucous membrane, translucent, encrusted with scabs, pedunculated, and closely resembling a nasal polypus. The possibilities were fully recognized and all necessary precautions taken. The right half of the nose was turned back as a flap, the tumour isolated, ligatured, and removed. Death occurred after six weeks. An oval hole was found in the left half of the cribriform plate through which the dura mater projected and to the margins of which the membrane was firmly adherent. The pedicle contained ganglion-cells and nerve-fibres, whilst the parts removed showed, from without inwards, mucous membrane, dura mater, arachnoid, pia, and glial tissue.
Sincipital cephaloceles are usually quite small, but the occipital variety and those situated in the region of the anterior fontanelle frequently attain a great size (see Figs. 20-22).
Fig. 22. An Occipital Cephalocele. (For further description, see text.)
It is not always possible to determine whether the tumour consists of a mere outward protrusion of membranes (meningocele), or whether brain-matter enters into the formation of the tumour (meningo-encephalocele). Fluctuation, translucency, and pulsation are all points to be investigated. All these features are, however, deceptive, and several cases are on record in which operative measures were carried out under the impression that the surgeon had to deal with a pure meningocele, and in which it was afterwards found that brain-matter formed the basis of the swelling.
When the tumour is large, the skin adherent, when no pedicle is present, when fluctuation and pulsation are absent, and when the tumour is of firm consistency, then it is practically certain that brain-matter shares largely in the formation of the tumour. On the other hand, it is not unusual to find that the brain projects markedly outwards without resulting in any symptoms of brain irritation: fluctuation and pulsation are also not infallible signs, since the brain may occupy the base of the tumour, ‘corking-up’ the gap in the bone, or the brain may be so thinned by ventricular distension that a mere shell of cerebral matter lies beneath the scalp-covering.
Looking at the question from all points of view, it may be accepted that most cephaloceles contain either true brain-matter or the mixed epiblastic and mesoblastic elements described by Lyssenkow.
The following case serves to illustrate some of these facts:[9]—
The child was 3 months old, and presented a tumour, the size of an orange, situated between the occipital protuberance and the nape of the neck. The mass was pedunculated, the stalk being about the size of a four-shilling piece in diameter. It was soft, translucent, irreducible, and swelled up on coughing. An attempt at removal was carried out, and, after incising the outermost layers, three ounces of cerebro-spinal fluid escaped. A second tumour was then found occupying the base of the swelling. This was also punctured, more fluid escaping. Both sacs were cut away and the wound sewn up. Death occurred on the third day, preceded by convulsions, retraction of the head and neck, and high fever. The autopsy showed that the fontanelles were widely open, the anterior measuring 4 inches from side to side and 21⁄2 from before backwards. The bones of the vault were markedly thinned. In the subdural space there was a quantity of fluid, and the cerebral substance was soft and diffluent, the convolutions flattened, and the ventricles distended. There was a broad gap in the occipital bone, extending downwards into the foramen magnum, and in this situation the cerebellum had bulged backwards into the protruding mass. (See Fig. 22).
For differential diagnosis, see p. 57.
In considering the question of treatment, the late Professor von Bergmann[10] divided the cases into two groups:—
1. Inoperable cases. When associated with premature synostosis and microcephaly.
When associated with hydrocephalus or marked deformity.
When the tumour is situated below the occipital protuberance.
2. Operable cases. Limited protrusions with none of the above defects and disadvantages.
This classification undoubtedly forms a practical basis on which to estimate the feasibility of operative measures, and it would appear that sincipital and small occipital cephaloceles are the only cases that come within the realms of operative treatment. In estimating the possibility of operation, however, due consideration must be paid to the fact that, in the very great majority of cases, the tumour tends to increase in size, the bones become further thinned, the margins of the gap more everted, and the development of the brain suffers correspondingly. Again, in spite of the fact that some few cases have survived to adult age, yet it is the general rule for the patient to die within a few weeks or months of birth. For desperate ills, corresponding measures must be undertaken, and in the consideration of the more serious cases the surgeon should be biased in favour of operation unless the general condition of the child shows clearly that no success is possible. The best results have been attained in cases of pure meningocele.
The unhealthy condition of the overlying integument, especially at the apex of the tumour, prohibits any extensive preparatory cleansing, this process being carried out for the most part when the child is under the anæsthetic.
Scalp-flaps are framed from the region of the base of the tumour, advantage being taken of the more healthy parts. These flaps must be so sized and framed that accurate approximation and complete covering to the gap will be attained at the termination of the operation. The flaps are dissected back to their base. The pedicle of the tumour is defined and an endeavour made to detach it completely from the margins of the osseous defect. This is often a matter requiring considerable patience. The sac of the tumour should then be tapped with trocar and cannula, and the fluid contents allowed to escape slowly, after which the opening into the sac is enlarged and the membranes slit up towards the base of the protrusion.
When dealing with a pure meningocele, the membranous protrusion is cut away in such a manner that sufficient tissue is left to allow of closure of the dural gap. This closure can be carried out either by means of a purse-string suture or by the union of two lateral flaps. In either case, accurate approximation is essential in order to prevent as far as possible the further escape of cerebro-spinal fluid.
If the sac should contain an irregular mass of neuroblastic and mesoblastic tissue, apparently not true cerebral or cerebellar substance, this material can be dissected from the membranous sac, ligatured at its base, and freely cut away.
If the sac should contain true brain substance, the possibility of excision can be raised. In the cerebellar region such measures are contra-indicated, and the surgeon must remain content with an attempt at replacing the cerebellar substance within the cranial cavity. This attempt at reposition will be aided by elevation of the head and, occasionally, by lumbar puncture. If the protrusion corresponds to a region which has no known important function, it may be ligatured and cut away flush with the surface of the gap. Hæmorrhage may be considerable, but can be controlled by ligature, pressure, and irrigation with hot water at a temperature between 110 and 115 degrees Fahrenheit. The degree of shock attendant on the operation may be severe, necessitating the most complete attention to preliminary, operative, and post-operative details (see Chap. I).
To remedy the defect of the bone Lyssenkow recommends an osteoplastic operation, a flap composed of pericranium, together with the external table of the skull, being framed from the bone above the defect.
The flap is then turned down in such a way that the pericranial surface faces towards the dura, and the fragment is suspended by the continuity of the pericranium. He reports 72 cases so treated, with 37 recoveries and 35 deaths.
König and von Bergmann oppose this osteoplastic operation on the ground that the extreme thinness of the bone seldom permits of the necessary splitting off of the external table of the skull, and that, even when such a course is feasible, the fragment undergoes necrosis.
Transplantation of decalcified and calcined bone, silver and celluloid plates, have all been tried, with no great amount of success. Ssamoylenko proposes paraffin and vaseline injections, especially for the sincipital variety of cephalocele.
When the surrounding bone is of such a nature that it is possible to form an osteoplastic flap, that course should be adopted. Under other circumstances, it would appear preferable to postpone any attempt to close in or protect the gap in the bone in the hope that nature will remedy the defect in part, the surgeon stepping in at a later date with one of the measures advocated for the protection of gaps in the skull (see p. 196).
Many cases have been recorded in which a cephalocele developed after an injury to the skull. In such conditions it is necessary that a comminuted or fissured fracture of the vault should be present, that the underlying dura mater should be torn, and that the adjacent brain substance should be severely contused or lacerated. Cerebro-spinal fluid may alone escape through the gap in the skull to the subaponeurotic and subcutaneous regions, leading to the formation of a false traumatic meningocele. When the brain shares in the outward protrusion the condition is known as false traumatic meningo-encephalocele. This protrusion of the brain is dependent on the fact that the injury—necessarily a severe one—leads to considerable brain lesion, with subsequent œdema and localized or general increase in the intracranial pressure.
Occasionally, the external accumulation of cerebro-spinal fluid communicates with one of the horns of the lateral ventricle. A meningo-encephalocele, having such connexions, is produced in the following manner:—the protruded brain includes that part of the cerebral substance which bounds one of the horns of the lateral ventricle, usually the descending cornu. The ventricular channel becomes elongated in the outward direction, towards and through the gap in the skull, whilst the increased intraventricular tension gradually dilates up the new channel, and, in course of time, still further spreads out and thins that part of its cerebral boundary which lies external to the skull deficiency.
There can be no question that after the patient has reached the age of three years traumatic cephaloceles are of exceedingly rare occurrence. This special liability in quite young children has been ascribed to the greater elasticity of the infant skull, and to the supposed greater adherence of the dura mater. Though these factors may exercise some influence on the production of the tumour, it seems more probable that the development of a cephalocele is dependent to a greater degree on the general vitality of the child. Thus, a blow that produces in the adult a comminuted or widely fissured fracture of the skull, with laceration of the dura mater and injury to the underlying brain, frequently leads to a fatal result, whilst the child often recovers. Again, in the adult, the force required to produce such a lesion usually suffices to lacerate the integument. Consequently a compound comminuted fracture of the vault with hernia cerebri is relatively more common in the adult than in the infant.
The right side of the head is more frequently affected than the left, and, of all bones in the skull, the parietal is the one most constantly involved.
During the first few days subsequent to the injury the child merely suffers from the symptoms common to all severe head-injuries—concussion and brain irritation. The osseous lesion is obscured by the presence of a well-marked cephalhæmatoma. After the lapse of a short time—usually one to two weeks—the partial resolution of the hæmatoma allows one to observe, for the first time, that a definite tumour remains. This tumour is irreducible, pulsates freely, and may be translucent. If the protruding brain substance includes the precentral region—the motor area—definite weakness or paralysis of the opposite face and extremities may be observed. Usually, however, no such symptoms are forthcoming, and the child appears but little the worse for the accident. Shortly afterwards the tumour becomes more defined in outline, and careful palpation will reveal the defined margins of an osseous deficiency. Compression of the protruded mass will often throw the child into general convulsions, or induce a state of compression with dilated pupils, slow pulse, and stertorous respiration. Compression, however, seldom results in any marked diminution in the size of the tumour. The conditions may remain stationary, but, as a general rule, the hernial protrusion slowly increases in size and the child dies in general convulsions, preceded by symptoms of brain irritation or compression.
Three courses are available in the treatment of this condition:—