Please see the [Transcriber’s Notes] at the end of this text.

OXFORD MEDICAL PUBLICATIONS

THE SURGERY OF
THE SKULL AND BRAIN

PUBLISHED BY THE JOINT COMMITTEE OF
HENRY FROWDE AND HODDER & STOUGHTON
AT THE OXFORD PRESS WAREHOUSE
FALCON SQUARE, LONDON, E.C.

OXFORD MEDICAL PUBLICATIONS

THE SURGERY OF
THE SKULL AND BRAIN

BY

L. BATHE RAWLING, F.R.C.S.
SURGEON, WITH CHARGE OF OUT-PATIENTS, SENIOR DEMONSTRATOR OF PRACTICAL SURGERY
DEMONSTRATOR OF OPERATIVE SURGERY, ST. BARTHOLOMEW’S HOSPITAL
LATE HUNTERIAN PROFESSOR, ETC.

LONDON

HENRY FROWDE
Oxford University Press

HODDER & STOUGHTON
Warwick Square, E.C.

1912

OXFORD: HORACE HART
PRINTER TO THE UNIVERSITY

PREFACE

This work on the Surgery of the Skull and Brain is based on experience derived, and on research carried out, during the past ten years.

Cranio-Cerebral Surgery, though still in its infancy, has progressed with leaps and bounds during the past few years. This book represents the most modern aspects of the case and is brought up to date by means of a recent visit to some of the leading surgical clinics of the United States of America.

I have realized to the full the difficulties of the task which I have undertaken, but have every confidence that they have been overcome and that a reasonable measure of success has been obtained. With this anticipation, this work on the Surgery of the Skull and Brain is offered to the Profession.

L. BATHE RAWLING.

April 1912.

CONTENTS

LIST OF ILLUSTRATIONS

THE SURGERY OF
THE SKULL AND BRAIN

CHAPTER I
CRANIO-CEREBRAL TOPOGRAPHY

The surgeon who is called upon to carry out operations on the skull and brain must possess an accurate knowledge of the anatomy of the parts involved. Added to this, he must have at his command some simple method of depicting on the surface of the skull the more important structures.

The more complicated systems of cranio-cerebral topography are of little practical value to the surgeon. Simplicity is essential, and the following outline will be found to furnish an adequate practical guide.

Firstly, the skull can be divided into two lateral halves by the surface-marking of the superior longitudinal venous sinus.

The superior longitudinal sinus.

This sinus originates at the crista galli and, passing backwards along the attached margin of the falx cerebri, terminates at the internal occipital protuberance. It may be represented by a line drawn from the base of the nose (the nasion), over the vertex of the skull, to the external occipital protuberance (the inion)—this line corresponding in its course to the occasionally persistent metopic suture between the two halves of the frontal bone, to the sagittal suture between the parietal bones, and to the middle line of the upper or tabular portion of the occipital bone.

Secondly, each lateral half of the skull can be subdivided into supra- and infratentorial regions by a line which marks the external attachment of the tentorium cerebelli; in other words, by the line of the lateral sinus.

The lateral sinus.

This sinus is represented by a line presenting a slight upward convexity, which is drawn from the external occipital protuberance to the upper and posterior part of the mastoid process of the temporal bone.

Fig. 1. Cranio-cerebral Topography. 1, The nasion; 2, The inion; 3, The mid-point between nasion and inion; 4, The Rolandic fissure; 5, The superior temporal crest; 6, The inferior temporal crest; 7, The Sylvian point; 8, The anterior horizontal limb of the Sylvian fissure; 9, The vertical limb of the Sylvian fissure; 10, The posterior horizontal limb of the Sylvian fissure; 11, The parietal prominence; 12, The malar tubercle; 13, The lambda; 14, The first temporo-sphenoidal sulcus; 15, The external parieto-occipital sulcus; 16, The lateral sinus; 17, 17, 17, The level of the base of the cerebrum; 18, The external auditory meatus; 19, 19, Reid’s base-line. (Reproduced, by the permission of Mr. H. K. Lewis, from the author’s work on ‘Landmarks and Surface-markings’.)

[Larger illustration (top)]
[Larger illustration (bottom)]

Fig. 2. Cranio-cerebral Topography. 1, 1, Reid’s base-line; 2, 2, A line parallel to the above at the level of the supra-orbital margin; 3, The middle meningeal artery; 4, The anterior branch; 5, 5, 5, The three sites for trephining; 6, The posterior branch; 7, The site for trephining; 8, The point for trephining to reach the descending horn of the lateral ventricle; 9, The lateral sinus; 10, The inion; 11, The mastoid process; 12, Macewen’s suprameatal triangle; 12a, The mastoid antrum; 12b, The facial nerve; 13, The suprameatal and supramastoid crests; 14, 14, The temporal crest; 15, The temporal fossa; 16, The external angular frontal process; 17, The tendo-oculi attachment; 18, The lachrymal groove. (Reproduced, by the permission of Mr. H. K. Lewis, from the author’s work on ‘Landmarks and Surface-markings’.)

[Larger illustration (top)]
[Larger illustration (bottom)]

The infratentorial region.

The cerebellum lies wholly beneath the tentorium cerebelli, and it is obvious that, in operations carried out over this portion of the brain, the surgeon is limited in his field of exposure, above by the line of the lateral sinus, and on either side by the posterior border of the mastoid process. The division between the halves of the cerebellum may be represented by a line drawn vertically downwards from the external occipital protuberance to the nuchal region. This line also represents the surface-marking of the occipital sinus and falx cerebelli.

The supratentorial region.

Brief allusion must be made to certain landmarks that aid in the representation of structures situated in this region:—

(a) The external angular frontal process.

The suture between the external angular frontal process and the corresponding process of the malar bone lies immediately above the central point of the outer border of the orbital cavity.

(b) The malar tubercle.

A slight prominence on the posterior border of the frontal process of the malar bone, about ¹⁄₄ inch below the external angular frontal process.

(c) The temporal crest.

A prominent ridge that is directed upwards and backwards from the external angular frontal process. The crest cuts across the lower portion of the parietal bone, passing below the parietal prominence, and curves downwards towards the upper and posterior portion of the mastoid process. It terminates by becoming continuous with the upper root of the zygomatic process. The crest consists of two parts, the upper and lower temporal crests. To the upper is attached the temporal fascia, to the lower the temporal muscle. The lower crest is almost invariably the more prominent.

(d) The parietal prominence.

The central and most prominent part of the parietal bone. It indicates the point at which ossification commenced, and lies about ³⁄₄ inch above the termination of the posterior horizontal limb of the fissure of Sylvius.

(e) The zygoma.

When traced in the backward direction, the zygoma is found to divide immediately in front of the ear into three roots, of which the anterior, merging into the eminentia articularis, and the middle, aiding in the formation of the post-glenoid process, are of no practical utility in surface-marking. The upper or posterior root sweeps backwards above the external auditory meatus to become continuous with the suprameatal and supramastoid crests, the former of which forms the upper boundary of Macewen’s suprameatal triangle, a triangular depression at the upper and posterior border of the external auditory meatus. This triangle may be taken as representing the opening of the mastoid antrum into the middle ear.

These landmarks having been determined, the following structures may be mapped out on the surface of the skull.

The middle meningeal artery.

This artery is given off from the internal maxillary; after a short extra-cranial course it enters the skull through the foramen spinosum, and soon divides into two main terminal branches. The site of division corresponds to a point situated just above the centre of the zygoma.

The anterior branch passes at first in a forward and upward direction towards the anterior inferior angle of the parietal bone, and then turns upwards and backwards towards the vertex of the skull. The main ‘danger zone’ in the course of this vessel may be mapped out by taking points which lie respectively 1, 1¹⁄₂, and 2 inches behind the external angular frontal process and an equal distance above the upper border of the zygoma. A line uniting these three points represents that part of the anterior division of the middle meningeal artery which is most liable to injury and which therefore most frequently requires exposure.

The uppermost point may, however, be regarded as the ‘site of election’ for exposure of the artery, as, in trephining over either of the two lower points, difficulty may be experienced in the removal of the disk of bone, since the posterior border of the great wing of the sphenoid tails off on to the anterior inferior angle of the parietal bone in such a manner that to effect a clean removal of the disk is often impossible. Another disadvantage to trephining low down lies in the fact that in about 30 to 40 per cent. of cases the artery occupies, in that situation, a canal in the bone.

The posterior branch passes almost horizontally backwards, parallel to the zygoma and supramastoid crest, towards the posterior inferior angle of the parietal bone. The vessel can readily be exposed by trephining over the point at which a line drawn backwards from the upper border of the orbit, parallel to Reid’s base-line,[1] cuts another line directed vertically upwards from the posterior border of the mastoid process.

Both branches of the middle meningeal artery possess important relations to the cortex cerebri, the anterior branch passing upwards in relation to the precentral or motor area, traversing, from below upwards, the motor speech area (on the left side of the head), the centres for the movements of the face, upper extremity, trunk, and lower extremity. The posterior branch, on the other hand, passes backwards in relation to the temporo-sphenoidal lobe, one of the so-called ‘silent areas’ of the brain. Throughout their course the middle meningeal vessels lie between the dura mater and the bone.

The lower limit of the cerebrum.

The lower limit of the cerebrum can be mapped out in the following manner: From a point situated about ¹⁄₂ inch above the nasion a line is drawn outwards which follows the curve of the upper border of the orbit as far as the external angular frontal process, thence curving upwards and backwards to the Sylvian point (see below). The temporo-sphenoidal lobe sweeps forwards to the posterior border of the malar bone, and its lower limit lies practically flush with the upper margin of the zygoma. At and behind the ear the lower limit of the cerebrum corresponds to the suprameatal and supramastoid crests, subsequently following the curve of the lateral sinus from the mastoid process to the external occipital protuberance.

The Sylvian point and fissure.

The Sylvian point represents the site of divergence of the three limbs of the Sylvian fissure. It lies 1¹⁄₄ inches behind the malar tubercle and 1¹⁄₂ inches above the upper border of the zygoma. The main posterior horizontal limb passes backwards and upwards to a second point situated ³⁄₄ inch below the parietal prominence.

The vertical limb is directed upwards for about 1 inch, whilst the anterior horizontal limb passes forwards for about the same distance.

The fissure of Rolando.

This, from a surgical point of view, the most important fissure of the brain, is represented as follows: A point is taken in the median antero-posterior line which lies ¹⁄₂ inch behind the mid-point between nasion and inion, and from this point a line is drawn, for 3¹⁄₂ to 4 inches, towards the mid-point of the zygoma. This line is inclined to the median antero-posterior line at an angle of 67¹⁄₂° (three-quarters of a right angle).

The parieto-occipital and first temporo-sphenoidal fissures.

In the representation of these two fissures, two points require to be determined—the malar tubercle and the lambda. Allusion has already been made to the former; the latter is usually readily located as the point of intersection of the sagittal and lambdoid sutures. A line uniting these two points corresponds in its middle third to the temporo-sphenoidal fissure, and in its posterior inch or so to the external parieto-occipital sulcus, a fissure separating the occipital and parietal lobes of the brain.

The cortical motor and sensory areas.

The researches of Sherrington and Grünbaum,[2] Campbell,[3] and others tend to show that the cortical motor areas are situated entirely anterior to the central fissure or fissure of Rolando, extending above well over on to the mesial aspect of the brain, though not so far as the calloso-marginal fissure, and in the downward direction to within a short distance of the fissure of Sylvius. In the posterior direction the motor area includes the anterior boundary and part of the bottom of the fissure of Rolando, whilst in front it spreads, by means of gyri annectantes, on to that part of the brain which lies anterior to the precentral sulcus. The anterior termination is indefinite, but the motor strip is, on an average, not more than ³⁄₄ inch in breadth.

The genua of the Rolandic fissure are said to bear a more or less definite relation to the motor areas. In my experience, however, they are too variable, and any importance which might obtain is further diminished by the fact that the surgeon should never rest content with that limited exposure of the brain which was so much in vogue till recent years. The suspected region is widely exposed by osteoplastic flap, and if doubt exists as to the particular part of cortex exposed the question is accurately settled by faradization.

This motor strip corresponds, from above downwards, to the movements of the contralateral lower extremity (toe to hip), trunk, upper extremity (shoulder to fingers), neck and face. It is a point of some general utility to bear in mind that the temporal crest intervenes approximately between the regions responsible for the movements of the upper extremity (above the crest) and those for the movements of the head and face (below the crest).

Fig. 3. The Cortical Motor and Sensory Areas.

On the left side of the head—in normal right-handed individuals—the motor speech area of Broca corresponds to the third left frontal convolution, in the angle between the anterior and posterior horizontal limbs of the Sylvian fissure.

The ‘primary registration’ of ‘common sensation’ occurs in the post-central gyrus, immediately posterior to the fissure of Rolando. This tactile area occupies a position behind the fissure of Rolando similar in extent to that occupied by the motor area in front. It commences at the bottom of the fissure of Rolando and extends backwards over rather more than half the exposed area of the post-central convolution. It reaches down to near the Sylvian fissure and extends over on to the mesial aspect of the brain. Furthermore, it is probable that sensation in any given part lies on more or less the same level as the corresponding motor area.

Immediately posterior to the tactile area and occupying the posterior and upper part of the post-central convolution, the area responsible for muscle-sense is situated.

Stereognosis—memory pictures, object perception, &c.—is referred to the superior parietal lobe.

Primary visual impressions are received in the occipital lobe, more especially on the mesial aspect thereof.

Finally, the four areas concerned in speech—motor speech, writing, reading, and hearing—are anatomically separated from one another and yet closely associated, so much so that one can hardly be involved without the other. The motor speech centre of Broca has already been mentioned as occupying—in right-handed individuals—the posterior part of the third left frontal convolution. Writing lies immediately above and in front, in the posterior part of the middle frontal gyrus, auditory impressions are received in the posterior and upper part of the first temporo-sphenoidal lobe, whilst the power of reading is dependent on the integrity of the supramarginal and angular gyri (see also [Fig. 57]).

Smell and Taste lie in close relation to the anterior pole of the temporo-sphenoidal lobes.

[1] Reid’s base-line is a line drawn around the skull, starting in front at the lower border of the orbit and passing through the central point of the external auditory meatus.

[2] Proceedings and Philosophic Transactions of the Roy. Soc., 1901.

[3] Localization of Cerebral Function. Camb. Univ. Press, 1905.

CHAPTER II
THE SPECIAL TECHNIQUE IN OPERATIONS ON THE SKULL AND BRAIN

Preparatory treatment.

Where possible at least two or three days should elapse between the admission of the patient and the day of operation. During this period the patient should be confined to bed with all possible cheerful surroundings. The bowels are regulated and the diet restricted.

The extent to which the scalp should be shaved and the time at which this procedure should be carried out vary according to the circumstances of the case. Much depends on the sex and age of the patient and the nature of the proposed operation. Insomuch, however, as it is always inadvisable to prolong the period of anæsthesia, it follows that the shaving should be carried out previous to the operation. With regard to extent, each case must be judged on its own merits. For instance, considerable concession must be made in the case of a young woman on whom the surgeon proposes to carry out a subtemporal decompression operation, and in the case of a neurotic or elderly patient who is the subject of trigeminal neuralgia. There can, however, be no question that the limitation of operative field advocated by some surgeons is fraught with considerable risk from the point of view of wound infection.

If the question be discussed with the patient the surgeon will find the ground cut away from beneath his feet, and that he has to make considerable and inadvisable concessions. Taking everything into consideration, although it is seldom necessary to shave the whole head, I am accustomed to order such preparation as will allow of a very wide margin. To shave the whole head is not only unnecessary but is also exceedingly distasteful to the patient. The front, back, or side of the head should be prepared only—on the morning of the operation, so as to allow of a comfortable night’s rest. After shaving, the scalp is thoroughly cleansed with soap and water, and the head surrounded by a sterilized towel. The final skin sterilization is carried out when the patient is under the anæsthetic.

The iodine method has always given satisfactory results, the skin being painted, half an hour previous to operation, with a 2¹⁄₂ per cent. solution of iodine, and again after the administration of the anæsthetic. Still, I cannot avoid a certain penchant for the older method—sponging with ether to remove the fats, washing with a 1 in 500 spirit solution of biniodide of mercury, and finally douching with a weaker mercury solution.

Precautions against the development of shock.

It is almost inevitable that all serious head-operations should be associated with some degree of shock, though, from my experience, I am convinced that, with due precautions, it is far less serious than is generally supposed. The development of shock is very largely dependent on the amount of blood lost during the operative procedures. The various methods adopted to control hæmorrhage are enumerated later. In addition, attention should be paid to the following details:—

1. Half an hour before the operation an injection of a quarter of a grain of morphia should be given hypodermically. The addition of one-hundredth of a grain of atropin, recommended by some surgeons, interferes somewhat, by its action on the pupil, with the data deemed necessary for the administration of the anæsthetic.

2. The theatre should be maintained at a temperature between 65 and 75 degrees Fahrenheit. The table should be suitably warmed.

3. The patient’s body should be covered with warm blankets, and, in the more serious cases, the lower extremities may be bandaged, from below upwards.

It has been recommended that the brain, if exposed, should be protected from the cooling effects of the atmosphere by irrigation with saline solution at a temperature between 110 and 115 degrees Fahrenheit. Personally I prefer to keep the operative field as dry as possible.

An assistant should be told off, whose duty lies in keeping a record both of blood-pressure and pulse-rate. The lowering of blood-pressure is the surest guide to the surgeon of approaching danger.

It is often considered that rapidity of operation is essential. There can be no greater error. To ensure success the utmost care must be taken to control the loss of blood, for which it is essential that each step of the operation should be carried out deliberately and carefully.

The anæsthetic.

Needless to say, it is essential that the surgeon should have at his disposal an anæsthetist of great experience in head operations.

Ether is regarded with favour in the United States, and in other countries, but we prefer chloroform on the ground that, by its lowering effect on the blood-pressure, there is less venous oozing, and added to this there is probably less tendency to post-operative vomiting. I have recently had the opportunity of seeing the open ether method as carried out in the States, on one occasion for an operation lasting four hours, and in this and in other cases the patient left the operation table in excellent condition, recovering also rapidly from the effects of the anæsthetic.

The lowering of blood-pressure as produced by chloroform might be advanced as an argument against the use of that drug, shock being the greatest danger to be feared in these operations. Still, I must say that I prefer chloroform so long as it is administered by a skilled anæsthetist.

In any case, it is advisable to have oxygen ready to hand.

The position of the patient.

Special tables have been invented and special positions advised. Thus, the dental-chair position is recommended for operations on the Gasserian ganglion, and, in cerebellar operations, it is urged that the patient should be turned on his face, the forehead resting on a tripod, the shoulders on supports fastened to the head of the table. Personally, I do not consider that any special arrangements are required in the majority of cases. Much can be done with sand-bags and firm pillows. Even in the exposure of one cerebellar hemisphere I prefer to utilize the semi-prone position.

In bilateral cerebellar exposure, however, the patient must be placed on his face, the forehead resting on special supports, and the shoulders on props or pillows so as to allow of free entry of air into the chest. In such cases the anæsthetic is administered from below.

I am not enthusiastic over the so-called dental-chair position, but the operating table should be constructed in such a manner that the head and shoulders of the patient can be well raised, the body being inclined to the floor at an angle of about 30-40 degrees.

Preparation of the operative field.

When the patient is fully under the anæsthetic, the final cleansing of the scalp is carried out and the operative field cut off from all possible sources of infection. In the States, in Cushing’s clinic, the anæsthetist is completely covered with a large sterilized sheet, which is fastened to the head of the patient. In this country we prefer that our anæsthetist should have full knowledge of the progress of the operation, and I think that the advantages are with us. In any case, the whole head is enveloped in gauze, two or three layers thick and about 18 inches square. This sheet is thrown over the patient’s head and maintained in position by means of the scalp-tourniquet (see [pp. 14], [15]). Around this sterilized towels are arranged, either fastened to one another or stitched to the scalp. When the operation is conducted in the temporal region the towels, unless fastened to the skin by means of a few sutures or safety-pins, tend to become displaced, and by so doing add to the risk of wound infection.

THE CONTROL OF HÆMORRHAGE

Hæmorrhage from vessels of the scalp.

All surgeons must have appreciated the difficulty attendant on the application of forceps to, and the ligature of, divided scalp-vessels. The patient may lose a considerable quantity of blood, and much valuable time will be wasted before the more essential part of the operation is commenced. All this can, under ordinary circumstances, be avoided by the use of the scalp-tourniquet. As used by Cushing it consists of a rubber ring fashioned after the style of an Esmarch’s tourniquet, encircling the head and passing from the lower frontal region in front, above the ears, to the lower occipital region behind. A median tape, passing from glabella to occiput, prevents any tendency for the tourniquet to slip down over the eyes, at the same time acting as a convenient landmark for the superior longitudinal sinus.

The tourniquet, when applied with the correct pressure, should, under ordinary circumstances, completely control all hæmorrhage from the divided scalp-vessels. It should be noted, however, that bleeding will be rather increased than otherwise if the tourniquet be so loosely applied as to impede the venous return without compressing the scalp arteries. A little experience will soon enable the operator to gauge the requisite pressure.

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.

Hæmorrhage from the bone.

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.

Hæmorrhage from the dural vessels.

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].

Hæmorrhage from the superficial vessels of the brain.

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.

THE OPENING OF THE SKULL

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.

Craniectomy.

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.

The enlargement of the trephine hole to the required size and shape.

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:—

Keen-Hoffmann.

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.

Lane’s fulcrum forceps.

They possess great mechanical advantage and are mainly suited for the rapid removal of large portions of bone.

Horsley’s nibbling or rongeur forceps.

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.

De Vilbiss’s forceps.

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.

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

-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.

Opening the dura mater.

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.

Sewing up the dura mater.

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.

Replacement of the osteoplastic flap and sewing up.

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].

After-treatment.

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.

CHAPTER III
CEPHALOCELES. BIRTH-HÆMORRHAGES. BIRTH-FRACTURES. DERMOIDS. HYDROCEPHALUS

CEPHALOCELES

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.

Congenital cephaloceles.

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.

Exencephaly

presents but few points of surgical interest, insomuch as the condition is barely compatible with life.

Cephaloceles

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.

Position of the tumour.

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.

Size, structure, and contents.

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].

Treatment.

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.

Operation.

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]).

TRAUMATIC CEPHALOCELES

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.

Symptoms.

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.

Treatment.