LIST OF ILLUSTRATIONS

FIGS.	PAGES
[1] and [2]. Cranio-cerebral topography	2, 3
[3]. The cortical motor and sensory areas	8
[4] and [5]. The scalp-tourniquet	14, 15
[6]. Cushing’s ‘clips’	18
[7]. Hudson’s trephine	20
[8]. The hand-trephine	21
[9] and [10]. The technique of trephining	22
[11]-[16]. Instruments used in trephining	23, 24
[17]-[19]. The formation of an osteoplastic flap	26, 27
[20]. An occipital cephalocele	33
[21]. A cephalocele over the anterior fontanelle	35
[22]. An occipital cephalocele	37
[23]. A depressed birth-fracture	45
[24 A and B]. A case of depressed birth-fracture, before and after operation	47
[25]. To illustrate the effects and position of a birth-hæmorrhage	53
[26]. The author’s operation for Hydrocephalus internus	64
[27]. The conversion of Hydrocephalus internus into cephalocele	65
[28]. Illustrating the lines along which forces received on the vault are transmitted to the base	69
[29 A and B]. The base of the skull and the base as seen on transillumination	70, 71
[30]. Plan of the base of the skull	77
[31]. To illustrate the relation of basic fractures to cranial nerves	81
[32]-[37]. The lines pursued by basic fractures	83-8
[38 A and B]. To illustrate the probable source of profuse hæmorrhage from the ear	97
[39]. To show the relation of a typical basic fracture to the middle ear and its adjuncts	103
[40] and [41]. To show the relation of basic fractures to the petrous bone	104, 105
[42]. A comminuted fracture of the skull	112
[43 A and B]. An explosive fracture of the vault of the skull	113
[44]. A temperature chart illustrating the changes in temperature observed in head-injuries	117
[45]-[48]. Intermusculo-temporal cerebral decompression	122, 123
[49 A and B]. The elevation of a depressed fracture of the vault	131
[50 A and B]. The inner aspect of the skull and the same seen on transillumination	137
[51]. To illustrate compression of the brain as produced by an extra-dural hæmorrhage from the middle meningeal artery	141
[52 A and B]. The operative treatment of middle meningeal hæmorrhage	144, 145
[53]. A basic fracture with laceration of both carotid arteries	148
[54]. A basic fracture with laceration of the cavernous sinus	149
[55]. A basic fracture with laceration of both lateral sinuses	151
[56 A and B]. The operative treatment of subdural hæmorrhage	156, 157
[57]. The areas concerned in speech expression	163
[58]. The cortical motor and sensory areas	165
[59]. The König-Müller osteoplastic flap	197
[60]. The author’s method of covering in a gap in the skull	199
[61]. A case of traumatic orbital aneurysm	207
[62]. A glioma of the brain	211
[63]. A sarcoma of the brain	211
[64]. An endothelioma of the dura mater	212
[65]. A fibroma of the dura mater	212
[66]. An acoustic tumour	213
[67]. Symmetrical tuberculomata	214
[68]. The cortical motor and sensory areas	220
[69]. The visual paths	223
[70]. A pituitary tumour	226
[71 A, B and C]. The exposure of a tumour by osteoplastic flap	230, 231
[72]. Combined flap formation and decompression	235
[73 A, B, C and D]. The exposure of a cerebellar tumour by craniectomy	239-41
[74 A and B]. To illustrate the extension of disease from the tympanic cavity and the surgical anatomy of that region (after Hunter Tod)	251
[75]. A large right-sided temporo-sphenoidal abscess	256
[76]. To illustrate the pressure effects of a temporo-sphenoidal abscess	257
[77]. A cerebellar abscess	259
[78]. To illustrate diagrammatically the symptoms observed in cerebellar abscess formation (after Luciani)	261
[79]. The exposure of a temporo-sphenoidal abscess	265
[80]. The ‘radical’ mastoid operation (after Hunter Tod)	269
[81]. Exploration for a temporo-sphenoidal abscess (after Hunter Tod)	270
[82]. Exploration for a cerebellar abscess (after Hunter Tod)	271
[83]. A fracture of the anterior fossa which was followed by the development of meningitis	275
[84]. Basal meningitis secondary to temporo-sphenoidal abscess	277
[85 A and B]. To illustrate the exposure of the lateral sinus (after Hunter Tod)	285
[86]. A case of Hernia cerebri and the abscess after removal	292
[87]. Diagrammatic illustration of the three forms of ‘gutter’ fracture	297
[88]. Diagrammatic representation of the effects produced on bone and brain by a perforating bullet-wound	299
[89 A and B]. Sheen’s bullet probe, forceps, and telephone bullet-detector	302, 303
[90]. To illustrate the operations on the Gasserian ganglion	317
[91]. To illustrate the operations for exposure of the Gasserian ganglion	321
[92]. Ivory exostoses of the skull	326
[93]. The development of the frontal bone	327
[94]. An exostosis of the orbit	330
[95]. An extrinsic sarcoma of the skull	331
[96]. An intrinsic sarcoma of the skull	333

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.