CHAPTER IV. Fractures of the Skull

FRACTURES OF THE SKULL

=General considerations.= Fractures of the skull do not form more than one-twentieth part of the fractures admitted annually into the hospitals, but, in spite of this relative infrequency of occurrence, the difficulties attendant on diagnosis, the numerous associated complications, and the all-important question of treatment, invest this subject with a special interest.

The whole question of skull fractures is beset with difficulties, many of which, it is hoped, will be swept away in this and subsequent chapters.

Brief allusion must first be made to some important points in connexion with the anatomical structure of the skull, such as bear relation to fractures and aid in the appreciation of the extent and mechanism of the fracture.

The =vault= varies in density to a remarkable degree, not only in its several parts, but also in different individuals. Cases have now and again been recorded in which a very trivial blow, totally insufficient to produce any definite osseous lesion in the normal individual, has resulted in the production of a vault or basic fracture. Each case, therefore, must be judged on its own merits.

The vault derives its strength from its shape and structure. The two tables are of equal strength, and, for the most part, separated from one another by a variable amount of diploic tissue. This diploe is most abundant in the frontal, parietal, and upper occipital regions. These parts are proportionately strong. Two regions are practically devoid of this inter-tabular buffer--the squamo-temporal and cerebellar (see Figs. 29 and 30). A recognition of this comparative weakness is of great practical importance in view of the fact that both these regions are liable to special lesions--injury to the middle meningeal artery in the first case, and, in the second, cerebello-medullary lesions. Nature’s ‘mistake’ in providing coverings unsuited to requirements has been compensated for in part by additional protection--the temporal and nuchal muscles.

Further, not only does the skull vary in density in its several parts, but it is also ribbed and strengthened by various bony bars and buttresses that pass up from base to vault (see Fig. 28). These ‘ribbings’ are seen to extend upwards from the crista galli, from the external angular frontal process, from the auditory region, and from the occipital protuberance. Presumably, these ‘ribbings’ were so constituted for a definite purpose; in any case, it is clear that they play an important part in the reception and conduction of forces to the base of the skull. It is apparent, moreover, that the parts intervening between these ‘ribbings’ are liable to injury in direct proportion to their general position and strength. The deep groovings of the bone for the reception of the middle meningeal artery afford an additional source of weakness to the bone in the squamo-temporal region. (See Fig. 50).

Further reference will be made to the relative strengths of the various regions of the skull. Sufficient has been said to show that nature has provided the skull with various paths by means of which forces applied to the vault can be conducted and distributed to the base.

Before, however, proceeding to discuss the effects produced on the base of the skull, it is necessary to add that nature provides other methods by means of which the intensity of a blow, delivered over the vertex of the skull, is diminished. The forces are broken up and distributed in the following manner:--

1. Though the force tends to travel in the direction of the applied force, yet the convexity of the skull allows of the dissemination of that force over a large superficial area.

2. The intervention of cartilage or fibrous tissue between two or more of the component bones of the vault tends to diminish the intensity of the force, to break it up and to alter its direction.

3. The bony ridges, along which the forces tend to travel, themselves terminate blindly (see Fig. 28). Thus,

(a) Forces passing from the frontal region converge, more or less, to the crista galli.

(b) Forces from the external angular frontal process pass along the wings of the sphenoid bone to the anterior clinoid process.

(c) Forces from the auditory region are projected along the summit of the petrous bone towards the apex of that process and to the posterior clinoid process.

(d) Forces applied to the occipital region travel inwards along the internal occipital crest to the strengthened margins of the foramen magnum, or are projected outwards along the lateral sinus ridges. In the former case, the force either passes forwards towards the dorsum ephipii and so again reaches the posterior clinoid process, or is directed more laterally towards the jugular process of the occipital bone, there meeting the fibrous tissue intervening between that process and the corresponding part of the temporal bone.

4. All forces, whether transmitted along the internal occipital crest, the temporal bone, the sphenoidal wings, or the crista galli of the ethmoid, are further transmitted to the dura mater attached to those prominences and ridges. The dura mater undoubtedly plays an important part in the reception and transmission of the forces.

5. The forces all show a tendency to converge towards the pituitary region, the great ‘water-cushion’ of the brain--a region bounded by the clinoid processes. That these processes receive a considerable part of the forces transmitted is confirmed by the fact that they are frequently torn away from their basic attachments. This is especially the case with respect to the attenuated base of the anterior clinoid process.

It is obvious, therefore, that forces tend to be transmitted from the vault to the base, and yet the base is, in many respects, the weakest part of the skull. It is perforated by numerous foramina, it is hollowed out in places for the formation of air sinuses and for the reception of the integral portions of the auditory apparatus. Furthermore, it presents a more or less plane surface, one differing in all respects from the marked convexity of the vault. Those forces, therefore, which are received by the base of the skull are not subjected to that diffusion which forms so conspicuous a feature in the case of the vault.

All these points tend to show that the base of the skull is more or less unsuited for the reception of severe blows, direct or transmitted, whilst, on the other hand, nature has taken into consideration and provided fairly adequately against the dangers incident to vault injuries.

It is not proposed at this stage to discuss further the relative strength of vault and base. Points, other than those already enumerated, will be brought forward in subsequent sections.

FRACTURES OF THE BASE OF THE SKULL

Fractures of the base of the skull are produced in two ways:--

1. By violence applied directly to the base--perforating wounds of the orbit, bullet-wounds through the mouth and base of skull, the driving inwards of the bones of the face, the driving upwards of the condyle of the jaw (the ‘knock-out’ blow of the pugilist), and, as the result of heavy falls on to the feet or buttocks, the upward driving of the condyles of the occipital bone.

2. By violence applied indirectly--blows applied directly to the vault and transmitted to the base. This variety will be considered first as it receives the greatest prominence in surgical textbooks. Various explanatory theories have been advanced, of which the following are the more important:--

(a) =Aran’s theory of irradiation.= This theory states that ‘fractures of the base result as extensions from fractures of the vault, the fracture following the shortest anatomical route to the base’. Although this theory must be accepted as offering a satisfactory explanation for the occurrence of a certain proportion of basic fractures, such, for instance, as result from a blow applied directly to the vertex, it certainly cannot be accepted as accounting for the great majority of basic fractures. The theory was advanced on the hypothesis that basic and vault fractures were necessarily co-existent. That combined lesions of this nature are frequently in evidence is not to be doubted for one instant. It is, however, ‘putting the cart before the horse’ to say that the vault fracture is always the primary lesion. Such is by no means the case.

(b) =The bursting and compression theories.= The skull is here regarded as an highly elastic sphere, compression of which leads to diminution in the diameter along the axis of greatest pressure, bulging occurring in other diameters. The bulging exceeding the limits of elasticity a fracture occurs, the line of fracture varying according to the different features present. Thus, when the lines of fracture run parallel to the direction of the compressing force the bone bursts open along the convexity (bursting fractures), and when the lines of fracture run at right angles to the direction of the compressing force a fracture by compression is said to result (compression fractures).

These theories are based on experiments carried out on the cadaver, the skull being enclosed in a tight-fitting box and subjected to pressure sufficing to bring about a fracture. Undoubtedly, the head may be compressed between two forces, as, for instance, when a person is knocked down in the street, the vehicle passing over the head, or, as in a case recently under my care, where a boy, hanging by his feet from the side of a barge, was crushed between the barge and the wharf as the vessel swung inwards with the tide. Cases of bilateral compression are, however, of infrequent occurrence, the great majority of basic fractures resulting from blows applied directly at the region of the level of the base of the skull (see p. 76), or from the forward propulsion of the body, the head coming into violent contact with a resisting object, as, for instance, when a person is thrown out from a motor-car, the head striking against a tree, brick wall, &c. In the first case, there can be no question of bilateral compression, and in the second the compression is exerted between the vertex and the occipital condyloid region.

Moreover, the fundamental points on which the bursting and compression theories are grounded are based on erroneous principles. The skull cannot in any sense be regarded as a sphere, nor does it possess the requisite elasticity to bulge and allow of compression in the manner that the theory demands. The skull, in reality, forms rather less than two-thirds of a sphere, the base passing inwards from the lower limits of this partial sphere in a more or less horizontal plane. This can be readily verified by placing the skull on a table so that its base corresponds to the surface of the table. The elastic properties of the skull have also been greatly exaggerated, and far too little attention has been paid to the peculiar anatomical formation of the base.

(c) =The contre-coup theories.= Fractures of the base occasionally occur in which evidence is conclusive that the blow was received on the vault, the vault itself remaining uninjured. Such cases have given origin to this theory, one stating that ‘from the point struck a wave is transmitted through the semi-fluid brain, producing a fracture at some more distant point’. Helferich, for instance, maintains that isolated fractures of the orbital roof, and more rarely of other parts of the base, are produced by the influence of hydrostatic pressure. There can be no question that waves are transmitted through the brain and cerebro-spinal fluid, but that such waves should be capable of producing a basic fracture is, in my opinion, beyond the bounds of possibility. The theory is opposed to all my experience of basic fractures, and the cases brought forward in support are capable of a much more probable explanation. The base is undoubtedly the weakest part of the skull, and a blow on the vault may fail to produce a local lesion and yet, when the force is transmitted to the weaker base, may there bring about a more definite result. For instance, it is by no means uncommon to find that a blow on the frontal region fails to fracture the vertical plate of that bone and yet suffices to produce a fracture, often comminuted, of the orbital plate of the frontal bone or of the cribriform plate of the ethmoid, two fragile plates, either of which may shatter like a plate of glass from the effect of forces transmitted across them. In further support of this theory, the following case, recently under my care, may be cited. The patient received a heavy blow over the left occipital region. A fracture passed inwards across the left cerebellar fossa towards the posterior border of the foramen magnum, and a second fracture, entirely distinct from the first, passed across the right orbital plate of the frontal bone. In this case, the force conducted across the base, from behind forwards, failed to fracture the strong basi-occiput, but succeeded in producing a more definite lesion on reaching the fragile orbital plate.

Some of the celebrated surgeons of the last century insisted that the course pursued by basic fractures was to be explained on anatomical grounds, but their views have been neglected and theories based on experimental evidence have been accepted in their place. All experiments, such as those previously mentioned, are useless, and definite conclusions can only be gained by carrying out in every case the following method of investigation: (1) by obtaining in the first case an accurate history as to the manner in which the injury was received; (2) by noting all visible and palpable signs of external injury; (3) by careful observation of all the clinical symptoms during the progress of the case; (4) by comparison of such with the lesions found in case of death.

Over 300 cases have been investigated by me after these principles. In about 30 per cent. of the cases sufficient evidence was obtained to show that the basic fracture resulted and extended from a primary fracture of the vault. These cases were to be explained by Aran’s theory of irradiation. This theory, however, errs in stating further that the fracture follows the shortest anatomical route to the base. This is not correct, for the line of fracture corresponds to the direction of the applied force and is influenced to a very large extent by the resistance offered, the weaker areas being picked out and the strong buttresses avoided. It is only in the most severe cases that the fracture travels to and traverses across the base in such a direction as to show that, for the time being, all laws are in abeyance.

In about 5 per cent. of cases the fracture resulted from bilateral compression, from falls on to the buttocks, &c., and from blows applied to the angle of the jaw. These cases afforded examples of the bursting and compression theories.

On the other hand, in over 60 per cent. of cases, the injury was received over one of the following situations: (1) in front, over the frontal eminence or supra-orbital ridges; (2) in the antero-lateral region, over the external angular frontal process; (3) in the lateral region, over the lower temporal, auricular, and mastoid regions; (4) in the posterior region, over the superior curved line of the occipital bone or over the external occipital protuberance.

In all these cases, therefore, the blow was inflicted at or near the level of the base of the skull, the resultant fracture being a fracture by direct violence, the fracture traversing the base and splitting it much in the same way as a chisel splits a board of wood. The ‘grain’ of the wood may be regarded as representing the weaker basic lines, and any ‘knot’ the resistance offered by the strong basic buttresses, the forces being momentarily turned aside, but soon again passing onwards, parallel to the original direction, but not necessarily in the same straight line.

Any blow delivered at or near the basic level tends primarily to involve the weaker area, the base, passing secondarily upwards on to the vault. One may go even so far as to say that in most combined vault and basic fractures, the vault fracture is a secondary development, the basic fracture being the primary lesion.

There is, however, still another important anatomical feature bearing on the mechanism of basic fractures, one that must necessarily come into force in the greater number of such fractures. The base of the skull may be said to consist of two parts, one lying anterior to the condyles of the occipital bone, the other posterior to and including the condyles with their vertebral attachment. These two segments are united to one another by a weak chain--represented by a line drawn from one external auditory meatus to the other, with, as a connecting link, the sphenoidal sinus in the middle line.

When the base of the skull is viewed from below, it will be seen that the weak line includes both Glaserian fissures, both petro-sphenoidal sutures, both foramina lacera media, with the sphenoidal sinus again as a connecting link. The two parts of the skull are, to all intents and purposes, merely cemented together by the union of the basi-sphenoid and basi-occiput. Consequently, if a blow be received on the antero-lateral region of the head, the anterior segment tends to be split off from the more fixed posterior part, the fracture following the weak line previously indicated. This weak line occupies so important a position in the mechanism of basic fractures that careful observation will show that the greater number of middle fossa fractures follow that line, wholly or in part. Such a fracture of the middle fossa may be termed ‘the typical fracture of the base of the skull’ (see Figs. 30, 34 and 39).

=Summary of theories.= Aran’s theory of irradiation, with certain modifications, accounts satisfactorily for about 30 per cent. of basic fractures.

The contre-coup theory may be rejected entirely.

The bursting and compression theories are unsatisfactory, accounting for not more than about 5 per cent. of fractures.

The majority of cases result from direct violence applied at or near the basic level, the fracture passing across the base in the general direction of the applied force, but not necessarily in the same straight line.

Up to this point certain facts and theories have been discussed, such as bear on the general mechanism of basic fractures. It now remains to consider other factors that exercise influence on the general direction of the fracture.

=The influence of sutures on the line of the fracture.= Complete maceration of the skull is always essential in endeavouring to estimate in what way the various sutures of the skull influence the extent and direction of a fracture. Sutural separation is generally regarded as of infrequent occurrence. An examination of a large number of macerated skulls has shown, however, that sutural separation is in reality of common occurrence. Certain sutures show a special liability to such changes, especially the masto-occipital, the petro-occipital, and the petro-sphenoidal. Separation of the sutures is more common in the young adult; in the infant and in the old such conditions are seldom observed.

Allusion has already been made to the fact that forces transmitted from the vault to the base, or vice versa, undergo a marked diminution in intensity when the sutures of the skull are encountered, the ‘fracture’ showing a marked disposition to follow the line of the suture. When the force is excessive, all rules are temporarily in abeyance, but, under ordinary circumstances, the separation along the line of a suture corresponds fairly accurately with the dentations and serrations of the suture involved. Sutural separation without actual fracture is a possible occurrence, but is decidedly rare. Such isolated fractures are confined, more or less, to the sagittal suture in the vault, and the masto- and petro-occipital sutures in the base.

=The influence of air-sinuses, &c., on the line of the fracture.= The sphenoidal sinuses, two in number, are usually separated from one another by a thin septum. This septum is, however, often deficient, and a single cavity exists. The sinuses make their appearance about the seventh or eighth year; they vary greatly in size but, when fully developed, occupy the greater part of the so-called body of the sphenoid, extending backwards almost as far as the junction of the basi-sphenoid and basi-occiput, and spreading outwards into the wings of the sphenoid and over the roof of the orbit.

The sinus is bounded on all sides by a thin lamella of bone; its roof forms part of the middle fossa of the skull, the sides are separated by a thin bony wall from the cavernous venous sinus, and the floor aids in the formation of the roof of the naso-pharynx. There exists, therefore, in the very centre of the base of the skull--in the region of the so-called buttress of connexion between the posterior and anterior segments of the skull--an exceedingly weak area, one which must be implicated in the great majority of basic fractures. The ‘weak line’ of the base of the skull--previously referred to--is now still more accentuated.

The sphenoidal sinus is involved in at least 40-50 per cent. of basic fractures, comminution of the sinus wall being often so excessive that a probe can be passed with the greatest ease from the middle fossa into the naso-pharynx. Blood is thus allowed to escape readily into the naso-pharynx, and a source is opened up for the possible development of meningeal infection.

Reference to the various illustrations of fractures of the base will supply further evidence as to the special liability of the sinus region to injury. It will be seen that nearly all fractures that pass one middle fossa to the other, or from one middle fossa to the opposite anterior fossa, traverse this region.

The frontal sinuses, also two in number, are separated from one another by a thin osseous septum. Up to the age of puberty these sinuses are either absent or represented by a small cell. Subsequently, they develop rapidly, often extending into the orbital roof. The upper and inner boundary--usually very fragile--assists in the formation of the anterior fossa of the skull. The outer boundary--the perpendicular plate of the frontal bone--is much more dense, and, consequently, a fracture of the outer wall is almost necessarily associated with a fracture involving the inner or orbital boundary, that is to say with a fracture of the anterior fossa.

The ethmoid cells. The ethmoid bone consists of a collection of cells which communicate with the nasal cavity (middle and superior meati), and which are merely separated from the anterior fossa of the skull by the thin cribriform plate. This plate of bone is of so fragile a nature that splintering occurs in the great majority of anterior fossa fractures. The special dangers that arise from the possibility of meningeal infection are obvious.

The auditory region. That part of the petrous bone which encloses the auditory apparatus, and which transmits the seventh and eighth pair of nerves, is proportionately weakened and correspondingly liable to fracture. The special details of these fractures are dealt with on p. 102.

=The influence of basic foramina.= It has often been stated that a basic fracture is arrested on meeting one of the larger foramina of the skull. With this view I am not in agreement, for not only are the larger foramina frequently involved, such as the foramen lacerum posterium and medium, but the largest foramen of all, the foramen magnum, is often implicated. It will be granted that certain foramina are but rarely involved, but this is due to the fact that they are aside of the chosen and definite paths of basic fracture. Thus, the foramen ovale and the foramen spinosum are only exceptionally involved because they lie immediately anterior to the petro-sphenoidal suture, whilst the anterior condyloid foramen--transmitting the hypoglossal nerve--is rarely implicated because it lies internal to the usual posterior fossa fracture. On the other hand, the foramen lacerum medium is involved in nearly every fracture that passes from one middle fossa to the other.

=The probable line of basic fracture in any given case.= When the various weaker lines and areas are taken into consideration, and when the direction and site of the applied force are known, one is generally enabled to foretell with considerable accuracy the probable transbasic course of the fracture. After investigating over 300 cases, I was enabled to frame the following rules with respect to the probable line of transbasic fracture.

Direction, &c., of Probable resultant basic fracture. the applied force.

1. Force applied to The fracture passes backwards from the the median frontal perpendicular plate of the frontal bone to the region. cribriform plate of the ethmoid, thence between the optic foramina to the body of the sphenoid, the thin sinus roof being usually comminuted. From there the fracture diverges to the opposite side, and tearing off the posterior clinoid process, passes along the petro-occipital suture to the jugular foramen, being then continued on the other side of that foramen along the masto-occipital suture, and so again to the vault.

2. Force applied to The fracture passes across the anterior fossa the lateral frontal towards the sphenoidal fissure, tearing away the region, in the anterior clinoid process, and again comminutes the situation of the roof of the sphenoidal sinus. Progressing onwards, external angular with or without fracturing the posterior clinoid frontal process. process, the fracture passes either along the anterior part of the petrous bone at its junction with the greater wing of the sphenoid towards the opposite middle and external ears, or along the petro-occipital suture to the jugular foramen, and continued along the masto-occipital suture as in the previous case.

3. Force applied to The fracture passes across the roof of the bony the region of the auditory meatus towards the junction of the external ear. anterior and inner walls of the middle ear, the membrane undergoing a variable amount of destruction and displacement. The fracture is then continued across the tegmen tympani, and after following the petro-sphenoidal suture reaches the foramen lacerum medium, being again continued on the opposite side of that foramen to the sphenoidal body. Thence it pursues one of two courses. Most commonly the fracture passes backwards obliquely to the opposite middle and external ears, following a course similar to that already indicated.

In such cases the fracture may extend on each side up on to the vault in such a manner that the two segments are merely united by the soft parts; whether the fracture be so complete or not, a more minute examination of the line of separation will evidence many interesting points. An inspection of the anterior aspect of the posterior fragment shows that the fracture passes just in front of the geniculate ganglion of the facial nerve, the ganglion being laid bare, whilst its petrosal branches are usually torn. The fracture also passes anterior to the Eustachian tube and the horizontal part of the internal carotid artery. On examining this posterior fragment the following structures will be seen, passing from without inwards: the posterior half of the external auditory meatus, the mastoid antrum, the lacerated membrane and the ossicles of the middle ear, the geniculate ganglion of the facial nerve, the Eustachian tube, the horizontal part of the internal carotid artery, the Gasserian ganglion, and the posterior half of the sphenoidal sinus in the middle line (see also Fig. 39).

After reaching the sphenoidal body, the alternative course for the fracture to pursue is to pass towards the opposite sphenoidal fissure and, tearing off the anterior clinoid process, to be directed across the anterior fossa, parallel to the original direction but not in the same straight line.

4. Force applied to The fracture follows the occipito-mastoid suture the mastoid region. to the jugular foramen, and is again continued on the opposite side of that foramen along the petro-occipital suture towards the apex of the petrous bone. It then passes across the sphenoidal body to the sphenoidal fissure of the opposite side, and so across the anterior fossa. It is especially common in this particular variety of fracture to find fissures diverging from the region of the sphenoidal sinus forwards towards the cribriform plate of the ethmoid, these fissures usually passing between the optic foramina.

This fracture is also peculiar in so much that, when the degree of separation along the occipito-mastoid suture is excessive, there is special liability to a tearing of the lateral sinus wall as the sinus begins to turn downwards and inwards.

5. Force applied to The fracture passes across the thin cerebellar the lateral fossa and strikes the foramen magnum immediately occipital region. behind the condyle. Starting again from a similar point on the opposite side of the foramen, the fracture passes outwards to the jugular foramen. Again, two courses are now available, the fracture either cutting outwards across the body of the petrous, ‘external’ to the internal auditory meatus and cutting across the facial nerve in the region of the geniculate ganglion, and finally terminating in the roof of the middle ear, or else passing along the petro-occipital suture and so to the foramen lacerum medium, the sphenoidal fissure, and the anterior fossa as in the previous case.

6. Force applied to The resultant fracture varies according to the the posterior direction of the applied force. A force which is occipital applied to the posterior occipital region at right region. angles to the transverse axis of the skull results in a fracture which, on reaching the posterior margin of the foramen magnum, is continued again on the opposite side of the foramen along the dorsum ephipii. When the force is more oblique in direction (as is usually the case) the fracture traverses the thin cerebellar fossa to the outer margin of the jugular foramen, and then follows one of the two courses indicated in the previous case.

More commonly the fracture cuts across the petrous bone.

=Summary.= Basic fractures tend to follow certain definite paths, this transbasic course varying according to the direction of the force applied and the site of application of the same. Whether the fracture completely traverses the base depends on the character of the force and the resistance offered, for bases, as well as vaults, vary greatly in strength. To every rule there must be exceptions, and cases are at hand in which the fracture appears to have obeyed no law, or in which the force applied was of so forcible a nature that the fracture traversed the base, regardless of all the ordinary rules.

The principles enumerated above were formulated by me some four years ago, and, in spite of certain adverse criticisms, I am more than ever convinced that the rules are correct, and that time and research are alone required to add to the strength of my assertions.

SYMPTOMS RESULTING FROM FRACTURE OF THE BASE OF THE SKULL

The symptoms resulting from a fracture of the base of the skull vary according to the particular fossa fractured. From a general point of view, the following symptoms require consideration:--

Hæmorrhages.

Escape of cerebro-spinal fluid.

Escape of brain-matter.

Escape of air from the air-sinuses into the surrounding tissues.

Involvement of certain cranial nerves.

Symptoms pointing to fracture of the Anterior Fossa.

=Hæmorrhages=: (a) Subconjunctival hæmorrhage usually makes its appearance at the outer canthus of the eye, progressing inwards towards the corneo-scleral margin, and, in the most severe cases, completely surrounding the cornea, bulging the conjunctiva forwards in such a manner as to constrict the field of vision. The extravasated blood is usually bright red in colour, makes its appearance within a few hours of the accident, and reaches its maximum within thirty-six to forty-eight hours.

In some cases a condition of subconjunctival œdema (chemosis) is observed. This also usually originates at the outer canthus.

Taken by themselves, neither hæmorrhage nor œdema are of any great diagnostic value. Both conditions, however, aid materially in confirming the diagnosis.

The blood is almost invariably completely absorbed, and no ill effects remain.

(b) Palpebral and peri-palpebral hæmorrhage is seen in most cases of fracture of the anterior fossa. This form of hæmorrhage differs from the one mentioned above in that it usually commences at the inner canthus of the eye, thence progressing in the outward direction. The extravasated blood may be wholly anterior to the suspensory ligaments of the lid, in which case it may be surmised that the fracture only involves the perpendicular plate of the frontal bone. More commonly, however, the cribriform plate of the ethmoid shares in the lesion, in which case palpebral, peri-palpebral, and subconjunctival hæmorrhage are all present.

(c) Orbital hæmorrhages may be so extensive that marked forward protrusion of the globe exists. The time at which proptosis makes its appearance, and the degree to which it progresses, vary according to the nature of the lesion. Thus:--

Proptosis severe, appearing implies a fracture associated with almost at once, injury to the cavernous sinus or internal carotid artery.

Proptosis moderate, and „ a fracture involving the appearing after a few hours, walls of the orbit, the blood being derived from lacerated ethmoidal and other small vessels.

Proptosis appearing days or „ a fracture involving the weeks after the accident, region of the sphenoidal body usually progressive, and complicated by the formation of a fistulous communication between the cavernous sinus and the carotid artery (see Traumatic orbital aneurysm).

(d) Retinal hæmorrhages. Fleming, in 1902, reported 12 cases of fracture of the skull, all except one being fractures of the base, in which retinal hæmorrhages were present. All cases were associated with hæmorrhage into the subarachnoid space, and when this hæmorrhage was of a unilateral nature the retinal changes were likewise one-sided. It was also found that in 4 cases of cerebral hæmorrhage without osseous lesion retinal hæmorrhages were present in three, these three being all associated with considerable effusion into the subarachnoid space.

These observations are not only of value in the general diagnosis of intracranial lesions, but are also of considerable importance in the differential diagnosis between extra- and intradural hæmorrhages.

(e) Hæmorrhage from the nose and mouth is almost invariably present in fractures of the anterior fossa, with the inference that the fracture involves the cribriform plate. The blood--derived mainly from lacerated ethmoidal vessels--escapes from the anterior nares or, passing back into the naso-pharynx, escapes by the mouth or is swallowed, to be vomited up later.

=Escape of cerebro-spinal fluid.= Blandin, of the Hôtel-Dieu, drew attention to this condition in the year 1840. The fracture involves the cribriform plate of the ethmoid, and is associated with laceration of the overlying dura mater and arachnoid, and of the prolongations of those membranes along the olfactory nerves.

The escape of cerebro-spinal fluid from the nose may be regarded as diagnostic of a fracture of the anterior fossa, in spite of the fact that Goucard, Malgaigne, and others describe cases in which, as the result of a severe fracture of the petrous bone (middle fossa) without laceration of the membrana tympani, the fluid escaped along the Eustachian tube to be expelled by mouth and nose.

At this stage, it will be necessary to allude more fully to the general question of cerebro-spinal discharge from the nose, mouth, and ear. The symptom is an important one, though undoubtedly of far less frequent occurrence than stated in text-books. This was proved by Crandon and Wilson, who reported 27 cases in which there was a cerebro-spinal discharge out of a total number of 530 cases examined. Phelps mentions 13 in a series of 286 cases of fractured base. My experience coincides with these statements.

The escape of a slightly blood-stained fluid from the ear and nose does not necessarily imply that the fluid is cerebro-spinal in nature, for it has been proved on numerous occasions that fluid may escape in considerable quantities without the existence of a basic fracture. In such cases the fluid is derived either from the membranous labyrinth (the liquor cotunnii) or from the mucous membrane lining the ear and nose, the result of great vaso-motor dilatation of aural and nasal vessels.

If the fluid be cerebro-spinal in nature, the natural inference is that the subarachnoid space is opened up to the exterior, either directly or indirectly along the course of a cranial nerve. A chemical analysis of the fluid will determine the nature thereof, provided that the fluid be collected EARLY.

Thus, cerebro-spinal fluid is whilst fluid derived from other rich in chlorides, contains sources contains chlorides, a little or no albumen, but fair amount of albumen, and no shows a trace of a reducing sugar. substance, allied to pyro-catechin,

Certain factors, however, must be taken into consideration which diminish the value of these chemical tests, for, though the fluid be cerebro-spinal in nature, the admixture of blood at once interferes with the delicacy of the test. Furthermore, even in the event of a profuse discharge of cerebro-spinal fluid, the first part collected alone contains sugar, the discharge soon becoming nothing more or less than a serous exudation.

The fluid is almost certainly cerebro-spinal if the discharge begins within twenty-four hours of the accident, if it be practically colourless, fairly profuse, and continuing for two or three days, perhaps longer.

Though the discharge usually originates early, cases are recorded in which the flow commenced some weeks after the accident. The discharge may continue for hours or for weeks. Sir W. Savory recorded a case in which fluid escaped for one month from both ears. The quantity also varies greatly, usually a few ounces, but sometimes many pints. Sir W. MacCormac recorded a case in which 10 pints escaped within five hours. A profuse discharge is due to the fact that, as the original cerebro-spinal fluid drains away, its place in the subarachnoid space is taken by a serous exudation from the cerebral venous system. This exudation occurs as soon as the subarachnoid pressure is sufficiently reduced, the serous exudation progressing till the venous and cerebro-spinal pressures are again equal.

As regards the prognosis, it is interesting to note that the escape of cerebro-spinal fluid implies of necessity that the subarachnoid space is opened up to the exterior, with all attendant dangers of meningeal infection, yet that the prognosis is generally favourable. One might even go further and state that the prognosis in such cases is rather more favourable than under more ordinary circumstances. Thus, Battle records 36 cases with a mortality of 25 per cent., the general mortality of fractured base being about 44 per cent. My own experience tallies with these statistics. The more favourable result hinges no doubt on the fact that the prolonged outflow tends to wash away organisms existent in the aural and nasal passages.

With regard to any special points in treatment, it is obvious that syringing of ear or nose is absolutely contra-indicated. The cavities should be lightly plugged with gauze, the dressings to be renewed as soon as they are soaked. The patient must also be prevented from interfering with the dressings.

With regard to the routine use of urotropin to guard against the advent of meningitis, see p. 116.

=Escape of brain-matter from the nose.= This diagnostic symptom is of very rare occurrence. For its development the following factors are requisite:--

Great comminution and destruction of the anterior fossa.

Severe local laceration of the brain (frontal lobes).

A copious discharge of blood and cerebro-spinal fluid.

A general increase in the intracranial pressure.

One case only of this nature has come under my own observation, that of a man whose right nostril was blocked with brain substance. He died shortly after admission into the hospital, and at the post-mortem examination the above conditions were found.

=Escape of air from the air-sinuses into the surrounding regions.= When the fracture involves the frontal, ethmoidal, and mastoid sinuses, any sudden increase of the intrasinus air-pressure, such as is caused by sneezing, blowing of the nose, &c., may force air into the surrounding tissues. A distinction must be made between those cases in which the pericranium overlying the seat of fracture is torn and those in which it remains intact. In the former case, the escaping air may spread widely into the neighbouring loose tissues, leading to a condition of ‘surgical emphysema’. In the second case, the air remains confined to a smaller area, giving rise to a soft, more or less rounded swelling. Gentle palpation of this swelling imparts to the fingers that crackling sensation peculiar to the condition. Firm pressure results in diminution in the size of the tumour, the contained air being forced back into the sinus cavity. Such localized collections of air are known as ‘pneumatoceles’.

As regards the special treatment of these conditions, the patient must, in the first case, be warned against straining of all sorts. Pneumatoceles require no other treatment. The condition soon disappears if the patient recovers. In widespread surgical emphysema, an incision should be made over the injured sinus, thus allowing of the direct escape of the air expelled from that sinus.

=The involvement of nerves.= The following nerves may be involved in anterior fossa fractures:--

(a) The olfactory nerve. The great majority of anterior fossa fractures traverse the cribriform plate, necessarily injuring the fine branches of the olfactory bulb. The bulb itself may be lacerated, with or without injury to the under surface of the frontal lobes. Sir Prescott Hewitt considered that anosmia, or loss of smell, resulted most frequently from blows applied to the back of the head, the frontal region being injured by contre-coup. From my own experience it would appear, however, that anosmia, whether uni- or bilateral, whether transient or permanent, generally results from direct injuries of the cribriform plate with associated lacerations of the olfactory nerves. It is difficult to estimate the presence or degree of immediate loss of smell on account of the general condition of the patient and because the nostrils are usually more or less filled with blood coagulum. Experience shows, however, that early loss of smell is the rule and total and permanent anosmia the exception. Anosmia is usually associated with some degree of loss of taste.

(b) The optic nerve. Many cases have been recorded in which visual defects resulted from blows applied to the head. The blindness may be partial or complete, immediate in onset or developing at some future date. In the latter case, the loss of vision is due to retinal changes or results from post-neuritic atrophy.

The occurrence of complete or partial blindness as the immediate result of the injury is, at first sight, difficult to explain, for the vast majority of anterior fossa fractures avoid the immediate vicinity of the optic foramina, passing by preference between the two foramina or diverging towards the sphenoidal fissures. Small fissured fractures not infrequently radiate through the optic foramina, usually, however, of so slight a nature as to be incapable of leading to any gross lesion of the optic nerves. Hæmorrhage into the sheath of the nerve is probably responsible for a certain proportion of cases, more especially those in which there is a peripheral concentric loss of vision, the more central fibres escaping. It is possible, also, that cases evidencing temporal or nasal blindness may be due, as J. J. Evans thinks, to a contre-coup contusion of the nerve through it being forcibly driven against the bony boundaries of the foramen. Taking into consideration, however, the very frequent presence of a fracture through the anterior clinoid process (see p. 82), and the usual displacement of that process, it would appear probable that immediate and more or less complete loss of vision results from the compression and crushing of the optic nerve by reason of the pressure exercised by a displaced clinoid process.

The following statistics add confirmation to this view. Thus, Callen collected 17 cases in which the optic nerve was compressed by osseous fragments in the region of the optic foramen, whilst Holder observed injury to the bones entering into the formation of the foramen in 53 out of 86 cases of fracture involving this region.

The prognosis varies according to the cause of the blindness. When resulting from concussion of the nerve trunk or from hæmorrhage into its sheath, certain fibres may regain their function. In the majority of cases, however, that have come under my own observation, blindness of the affected eye was immediate and permanent.

(c) The nerves passing through the sphenoidal fissure. The ophthalmic division of the fifth nerve is rarely injured to such a degree as to cause anæsthesia of all the regions supplied. Blood extravasation into the surrounding regions, or direct involvement of one of the branches of the nerve, often results in areas of anæsthesia, and some few cases have been recorded in which there was complete anæsthesia of both cornea and conjunctiva, with subsequent ulceration and sloughing. The nasal nerve may be implicated as the result of a fracture involving the cribriform plate, whilst the supra-orbital and supra-trochlear branches may be damaged by fractures of the vertical plate of the frontal bone.

The third nerve is similarly liable to injury, in any part of its orbital course. It is quite exceptional, however, for the whole trunk to be affected, some of the branches being taken, others left. The fourth nerve is also occasionally involved, generally in association with other orbital nerves.

When anæsthesia or paralysis of muscles results from pressure exercised on the nerves by extravasated blood, the ultimate prognosis is not unfavourable. When due to direct implication, in the line of the fracture, the prognosis is much more uncertain, partial or complete loss of function resulting.

SYMPTOMS POINTING TO FRACTURE OF THE MIDDLE FOSSA

=External hæmorrhages.= (a) Hæmorrhage into the temporal region. The extravasated blood may either be confined to the temporal region--temporal hæmatoma--or diffused throughout the subaponeurotic space. A temporal hæmatoma is always highly suggestive of a fracture involving the temporal fossa, especially in the event of marked outward bulging, with stretching and discoloration of the overlying tissues. In many cases also the hæmatoma pulsates, in which case it can be presumed that the fracture of the temporal fossa is associated with hæmorrhage from a lacerated middle meningeal artery (see Fig. 38). In such cases the application of pressure to the hæmatoma may lead to the development of fits on the contra-lateral side, originating in the face or arm regions and spreading to the higher cortical motor area.

FIG. 38. TO ILLUSTRATE THE PROBABLE SOURCE OF PROFUSE HÆMORRHAGE FROM THE EAR. A, The fracture the roof of the external auditory meatus. B, Comminution of the tegmen tympani, the fracture involving the groove for the posterior branch of the middle meningeal artery.]

(b) Hæmorrhage from the ear and mouth. The great majority of middle fossa fractures involve the external auditory meatus, passing inwards across the roof and floor of the middle ear towards the body of the sphenoid. Examination will show that the fracture passes inwards towards the junction of the inner and anterior walls of the middle ear, that is to say, towards the tympanic orifice of the Eustachian tube. The membrana tympani undergoes a variable degree of destruction. In the lesser cases the membrane is torn in its upper and front part only--in the region of the membrane of Shrapnell--whilst in the more serious cases it may be completely destroyed. The blood that escapes from the ear is derived from those vessels that supply the lining cuticle of the external and middle ears, from the numerous tympanic vessels, from the lateral sinus, and from the middle meningeal artery. The amount of blood which escapes varies according to the source of the hæmorrhage. When hæmorrhage occurs from the smaller vessels, the blood either clots in the external meatus or trickles from the ear. In the most severe cases the hæmorrhage is profuse and long-continued. Some years ago a case came under my observation that threw light on the probable source of such severe hæmorrhages.

A man was admitted into the hospital, suffering from profuse hæmorrhage from the ear as the result of a fall down an area. The bleeding continued for fourteen hours, soaking the dressings and continuing so long as the man lived. At the post-mortem examination an extensive comminution of the tegmen tympani was discovered, the fracture being associated with great extra-dural extravasation of blood from a lacerated middle meningeal artery. The extra-dural hæmorrhage was enabled to escape through the tegmen tympani into the middle ear, and thence by means of the lacerated membrana tympani (see Fig. 38).

Profuse and long-continued hæmorrhage from the ear should always arouse suspicion as to the possibility of injury to the middle meningeal artery. Since meeting the case recounted above, many similar cases have come under my care, and, in several instances, guided by this symptom alone, operative measures have been carried out successfully.

The two following cases show, however, that the extra-dural extravasation may be derived not only from the middle meningeal artery but also from the lateral sinus.

‘A man fell down an area and suffered from continuous hæmorrhage from the ear. He remained in bed for a few days, and then, becoming tired of confinement, got up, walked some distance on a cold and frosty day, and visited a sage femme. On returning home he complained of feeling ill, the hæmorrhage from the ear ceased, and shortly afterwards he became unconscious and died. The autopsy showed an extensive fracture of the petrous bone with extensive extra-dural hæmorrhage from a torn lateral sinus and from a lacerated meningeal artery.’

The man had remained fairly well so long as the extra-dural blood was permitted a free means of escape through the tegmen tympani and external auditory meatus, but, so soon as clotting occurred, compression symptoms developed and the man died in that condition.

‘A man, 50 years of age, fell down, striking his head against the kerb. On admission it was seen that blood was trickling freely through a torn membrana tympani. He rapidly became unconscious and died. The post-mortem examination revealed a fracture involving the middle ear and external auditory meatus, passing backwards across the lateral sinus, in which region there was a large extra-dural extravasation of blood.’

The above statements are confirmed by Dwight, who, in 146 autopsies, found that, in 69 per cent. cases of fracture of the middle fossa of the skull, there was bleeding from the ear, and that in 29 per cent. cases the fracture was associated with laceration of branches of the middle meningeal artery.

Although hæmorrhage from the external auditory meatus may be regarded as almost diagnostic of a middle fossa fracture, especially of that variety previously described as the ‘typical basic fracture’, yet the blood may be derived from a torn membrana tympani or from laceration of the lining cuticle of the external meatus. Aural examination will soon prove whether the blood is coming through a rent in the membrane, in which case the diagnosis is clear. Sometimes bleeding takes place from both ears, a symptom practically diagnostic of the transverse middle fossa fracture known as the ‘typical basic fracture’.

The following statistics will supply further information as to the relative frequency with which hæmorrhage occurs from ears, nose, and mouth, and the proportionate mortality. The cases were collected and tabulated by Crandon and Wilson.

-------------------------+--------+--------+-------+------------- |Cases.|Lived.|Died.|Mortality. -------------------------+--------+--------+-------+------------- Hæmorrhage from the ear | 281 | 170 | 111 | 39 per cent. Hæmorrhage from both ears| 47 | 16 | 31 | 66 per cent. Hæmorrhage from the nose | 44 | 17 | 27 | 61 per cent. Hæmorrhage from the mouth| 168 | 73 | 93 | 33 per cent. -------------------------+--------+--------+-------+-------------

Special points in prognosis and treatment. It is not possible to formulate any very definite prognosis when the hæmorrhage takes place from one ear only, though the mortality is about 40 per cent. When bleeding takes place from both ears the outlook is more grave, the mortality being about 66 per cent.

With regard to special treatment, two points are obvious: (1) that syringing of the ear is absolutely contra-indicated, on the ground that such treatment carries with it a considerable risk of bringing about meningeal infection; and (2) that plugging the external meatus with strips of gauze is an unsurgical form of treatment, insomuch as the escape of blood from the ear is an important factor in preventing compression of the brain, more especially in those cases where hæmorrhage is profuse. Under the last named conditions, operative measures--exploration for a torn meningeal artery or lacerated venous sinus--are to be carried out.

Hæmorrhage from the mouth may be slight or copious, according to the source from which the blood is derived. In the former case, the bleeding takes place from sphenoidal and pharyngeal vessels, in the latter from the cavernous sinus or from the internal carotid artery (see p. 148), the bone being shattered in the region of the sphenoidal body, with comminution of the walls of the contained air-sinus.

=Escape of cerebro-spinal fluid.= This condition was first investigated by Van der Wiel in 1727, and more completely by Langier in 1839. The majority of those middle fossa fractures which involve the petrous portion of the temporal bone pass immediately anterior to the genu of the facial nerve (see p. 102), and it follows, therefore, that the fracture cannot so involve the dural and arachnoid prolongations of that nerve in such a manner as to allow of the escape of cerebro-spinal fluid. This fact probably explains another fact, namely, that aural cerebro-spinal discharge is an infrequent symptom in middle fossa fractures. On the other hand, as a result of blows applied to the occipital region, a fracture originating in the posterior fossa may cut across the petrous bone, almost at right angles, in such a manner as to sever the seventh nerve in the region of the genu (see Fig. 41). This is the usual nature of a basic fracture associated with the escape of cerebro-spinal fluid from the external auditory meatus. More rarely, this particular class of fracture is unaccompanied by any injury to the tympanic membrane, in which case the fluid may escape along the Eustachian tube into the nose and naso-pharynx (see p. 91). Cerebro-spinal fluid may also escape from the nose and mouth in middle fossa fractures in the event of extensive injury to the basi-sphenoid with involvement of the overlying cisterna basalis. The following case exemplifies that condition:--

A man suffered from a severe fracture of the middle fossa. Three weeks later there was a sudden and profuse discharge of cerebro-spinal fluid from the nose. Meningitis developed and the patient died. The basi-sphenoid was extensively comminuted, the overlying membranes torn, whilst a probe could be passed readily from the cranial cavity into the naso-pharynx.

Special points in prognosis and treatment. The question of cerebro-spinal discharges has been discussed previously (see p. 91). It is therefore merely necessary to lay further stress on the fact that syringing of the ear is absolutely contra-indicated, for reasons already stated. The ear should be cleaned out with wool and gauze and lightly packed with strips of gauze, these to be renewed when soaked with fluid. When the cerebro-spinal discharge is long continued, acute eczema of the side of the neck may develop as a result of the irritating effect of the fluid. Under these circumstances it is advisable to adopt precautionary measures, painting the skin with ‘new skin’ or collodion. Ointments are of but little use. The eczema will clear up so soon as the discharge ceases.

=Escape of brain-matter.= The conditions needful for the discharge of brain-matter from ear or nose have been enumerated previously (see p. 93). There are but few cases recorded in literature, and one case only has come under my own observation:--

A lad, 11 years of age, fell some distance out of window on to his head. He was admitted under the care of my colleague, Mr. Lockwood. On admission he was unconscious, and was bleeding freely from the right ear and nose. Shortly afterwards it was noticed that brain-matter was issuing from the right external auditory meatus, sufficient brain-matter being obtained to fill a teaspoon. The extensive nature of the brain-injury was confirmed by the fact that the left arm and leg were paralysed for some days. On the fourth day the boy regained consciousness and recognized his relations. From this period onwards he made an uninterrupted recovery. I have seen the lad on various occasions, the last time one year after the accident. At that time he was an exceedingly bright and intellectual boy.

Special points in treatment and prognosis. The brain-matter should be gently wiped away from the ear, and the meatus cleansed and lightly plugged with gauze. Operative measures are required in the event of the development of symptoms pointing to brain compression. The prognosis must necessarily be unfavourable, but, as the conditions are almost entirely confined to the young, the most astonishing recoveries are reported.

=Involvement of nerves.= The second and third divisions of the fifth nerve pass respectively through the foramen ovale and the foramen rotundum, two foramina which lie anterior to the petro-sphenoidal suture, a suture traversed by the majority of middle fossa fractures. These two nerves are therefore seldom involved.

In all the cases of fractured base which have come under my observation I have never seen the foramen rotundum implicated, and in one case only was the foramen ovale involved.

In certain rare instances, a fracture, passing in the antero-posterior direction, may cut across the apex of the petrous bone in close relation to the cavum Meckelii--the bed of the Gasserian ganglion--in which case all three terminal divisions of the fifth nerve may suffer. Thus, a case was reported by Lee in 1853 in which, seven weeks after the accident, the following symptoms were present:--anæsthesia of the left face and forehead, anterior two-thirds of tongue, and left nostril, together with weakness of the left masticating muscles, and an opaque left cornea.

The sixth nerve. The sixth nerve may be involved either by itself or in conjunction with other cranial nerves. In the latter case the paresis is due to blood extravasated in the sphenoidal fissure or in the orbital cavity. In the former case the nerve is injured where it grooves the lateral aspect of the dorsum ephipii, a process frequently fractured in lesions of the middle fossa. Fractures tend to pass obliquely across this process, one nerve usually escaping. The prognosis as to functional recovery is very problematical.

The seventh and eighth nerves. There can be no doubt that the seventh nerve, on account of its complicated intrapetrous course, is more frequently involved than any other cranial nerve. Köhler records 22 cases in 48 middle fossa fractures. My own experience coincides closely with Köhler’s, facial paresis or paralysis being noted in nearly 50 per cent. cases of middle fossa fracture.

The question of facial nerve implication is so intimately associated with involvement of the eighth nerve that the two subjects must be considered together. Thus, cases may be classified as follows:--

1. Cases of paresis of the facial nerve with a variable degree of deafness.

2. Cases of complete facial paralysis with complete deafness.

The greater number of middle fossa fractures involve the middle and external ears, as is evidenced, amongst other symptoms, by hæmorrhage from the ear. Some degree of facial paralysis is frequently existent, not always evident at first sight, but requiring careful examination and comparison between the two sides of the face. The fracture involves both roof and floor of the external ear and passes inwards towards the junction of anterior and inner walls of the middle ear, the membrana tympani undergoing a variable degree of destruction whilst the ossicles may also be injured. Thence, the fracture passes inwards towards the petro-sphenoidal suture in such a manner that the geniculate ganglion of the facial nerve is exposed and laid bare on the anterior aspect of the posterior portion of the skull.

The facial nerve, therefore, escapes direct injury except in so far that the ganglion may be compressed by blood-clot or fragments of bone. Partial loss of function results. In most cases the blood is absorbed and a complete recovery may be anticipated. The degree of deafness is directly proportionate to the damage incurred by the membrana tympani and ossicles.

In the second group of cases a different picture is obtained. Usually the result of blows applied to the occipital region, the fracture traverses the thin cerebellar fossa towards the outer angle of the jugular foramen, thence cutting across the petrous bone, external to the internal auditory meatus, and terminating, usually by comminution, in the tegmen tympani. It is in the transpetrous part of the fracture that the damage is done, for, not only is the facial nerve cut across in the region of the ganglion, but the auditory apparatus is also severed into two parts. The exact line of the fracture is shown in Figs. 40 and 41.

FIG. 40. TO SHOW THE RELATION OF BASIC FRACTURES TO THE PETROUS BONE. A, The basic fracture, resulting from a force applied to the left occipital region, follows the course depicted in Fig. 36. B, The inner half of the petrous bone, being loose, is thrown forward so as to show the relation of the fracture to the integral parts of the petrous bone.]

In this class of fracture, though facial paralysis and deafness are both immediate in onset and permanent in duration, there is, in many cases, no bleeding from the ear as the membrana tympani may be uninjured.

The facial nerve may also be implicated in that rare type of basic fracture which was described by Lèon Boullet in 1878, under the title of ‘Fracture of the Mastoid portion of the Temporal bone’. This fracture is fully described on p. 108. It will suffice to mention that the mastoid process may be torn away from the base of the skull, the facial nerve being lacerated as it descends the aqueductus Fallopii.

Bilateral facial paralysis is exceedingly rare. Two cases were described by the late Professor von Bergmann. Its occurrence is pathognomonic of the typical basic fracture (see p. 84).

FIG. 41. TO SHOW THE RELATION OF BASIC FRACTURES TO THE PETROUS BONE. A shows the course pursued by an antero-posterior fracture of the petrous bone. Note that it lies external to the internal auditory meatus. B shows--enlarged--the inner aspect of the outer fragment. Note the relation of the fracture to the semicircular canals, and that the membrana tympani and ossicles are quite uninjured.]

Complete facial paralysis may be associated with the following symptoms:--

Epiphora, conjunctivitis, and keratitis (from paralysis of the orbicularis palpebrarum).

Loss of taste (from involvement of the chorda tympani).

Impaired nasal air-entry (from paralysis of dilator alæ muscle).

Impaired acoustic sensibility (from paralysis of the stapedius).

Impaired mastication (from involvement of the buccinator muscle).

Impaired secretion of saliva (from the cutting off of the secretory and vaso-dilator fibres of the chorda tympani).

Lastly, it is necessary to add that facial paralysis developing some days or weeks after the accident, though sometimes dependent on degeneration of nerve-fibres as the result of pressure in the region of the geniculate ganglion, may also arise from an ascending neuritis or from meningeal infection.

SYMPTOMS POINTING TO FRACTURE OF THE POSTERIOR FOSSA

=External hæmorrhages.= In fractures of the posterior fossa, blood effused into the deeper tissues of the scalp has considerable difficulty in coming to the surface and thus making itself evident. Furthermore, the resistance offered by the nuchal muscles tends to confine the blood to the subtentorial region, thus adding to the already grave prognosis of fractures in this region. On careful palpation, however, it will be noted that the nuchal tissues present a doughy or boggy condition, whilst ecchymosis becomes evident after twenty-four to thirty-six hours. A peculiar ecchymotic patch is occasionally observed, appearing in front of the mastoid process and travelling upwards in a curved direction, concavity forwards, following the outline of the ear. It is said to result from the tracking of blood along the course of the posterior auricular artery. Whether this is the case or not, the hæmorrhage usually implies a separation along the line of the masto-occipital suture.

=Escape of cerebro-spinal fluid.= } Neither of these symptoms =Escape of brain-matter.= } are present.

=Involvement of nerves.= When dealing with fractures of the middle fossa, allusion was made to the implication of the seventh and eighth pair of nerves as the result of a fracture traversing the posterior fossa of the skull towards the outer angle of the jugular foramen and cutting across the petrous bone (see p. 104).

The ninth, tenth, and eleventh cranial nerves may be injured in the same variety of fracture. These three nerves are, however, so protected by their dural sheaths that they generally escape injury.

In the following cases the nerves were involved:--

The patient was admitted suffering from a fracture resulting from a blow on the posterior parietal region. During the next four days no special symptoms developed. On the fifth day, during a sudden attack of dyspnœa and dysphagia, death occurred. A fissured fracture was found which extended into the jugular foramen, a region occupied by blood-clot.

A man committed suicide by means of a pistol-bullet fired through the mouth. The bullet lodged against the under surface of the petrous bone, tearing the jugular vein and lacerating the nerves passing through that foramen.

In another case the patient was admitted with a fractured base. He progressed favourably until the tenth day when, on sitting up suddenly in bed, he was seized with rigors, dyspnœa, and dysphagia, dying shortly afterwards. A basic fracture was found, practically dividing the skull into two parts and involving the jugular foramen. Displacement had occurred with consequent compression of the ninth, tenth, and eleventh nerves.

The twelfth nerve. The anterior condyloid foramen is most favourably situated with respect to the course pursued by posterior fossa fractures. No instance of its involvement has come under my own observation.

Stierlein records a case in which the tenth and twelfth nerves were injured, with inability to speak or swallow, paralysis of the right half of the tongue, soft palate, vocal cords and pharyngeal constrictions. Death resulted in seven weeks.

The late Professor von Bergmann mentions a case of hypoglossal paralysis together with paralysis of the sterno-mastoid and trapezius muscles (eleventh nerve).

For treatment of basic fractures, see p. 116.

FRACTURE OF THE BASE OF THE SKULL: SUMMARY OF SYMPTOMS

----------------------+----------------------+---------------------- Anterior Fossa. | Middle Fossa. | Posterior Fossa. ----------------------+----------------------+---------------------- Hæmorrhages. | Hæmorrhages. | Hæmorrhages. Subconjunctival. | Into the temporal | Into the nuchal Palpebral. | region. | region. Peripalpebral. | From the mouth. | Into the occipital Orbital. | From the nose. | region. Retinal. | From the ear. | Into the From the nose. | | post-auricular From the mouth. | | region. | | Cerebro-spinal | Cerebro-spinal | Cerebro-spinal fluid. | fluid. | fluid. From the nose. | From the nose. | None. From the mouth. | From the mouth. | | From the ear. | | | Brain-matter. | Brain-matter. | Brain-matter. From the nose. | From the ear. | None. | | Air-escape. | Air-escape. | Air-escape. From the frontal | From the mastoid | From the mastoid sinus. | antrum. | antrum. From the ethmoidal | | cells. | | | | Nerve-involvement. | Nerve-involvement. | Nerve-involvement. Olfactory. | Fifth (second and | Seventh. Optic. | third divisions). | Eighth. Third. | Sixth. | Ninth. Fourth. | Seventh. | Tenth. Fifth (first | Eighth. | Eleventh. division). | | Twelfth (?). Sixth. | | ----------------------+----------------------+----------------------

FRACTURE OF THE MASTOID PORTION OF THE TEMPORAL BONE

Fractures limited to this region are of rare occurrence. Our knowledge of the condition is obtained from the researches of Lèon Boullet, who first described the fracture in 1876, reporting at the same time 26 cases.

The fracture usually results from sharp blows delivered along the posterior border of the mastoid process, the force acting obliquely from above downwards and forwards. More rarely, the process is detached as the result of a blow delivered immediately above the ear, that organ sharing in the displacement. In either case the detachment is usually of an incomplete nature, mainly on account of the muscular and pericranial attachments in the region involved.

According to Boullet, the following symptoms result:--

=Surgical emphysema and pneumatocele.= Air escapes from the mastoid cells and antrum into the overlying tissues, either spreading widely through the subaponeurotic space of the scalp and cellular tissues of the neck (surgical emphysema), or remaining localized and forming a tumour of inconsiderable size (pneumatocele). In either case palpation reveals that peculiar crepitation which is pathognomonic of tumours of this nature.

=Bleeding from the ear.= Hæmorrhage takes place into the middle ear, and, as the tympanic membrane is usually lacerated, the blood escapes from the external ear. In the event of the tympanic membrane being uninjured, the blood may escape along the Eustachian tube into the naso-pharynx.

Boullet also pointed out that certain complications may be associated with the mastoid lesion. These are as follows:--

Immediate. Remote.

Wound of the lateral sinus. Deafness. Laceration of dura and brain. Otitis media. Injury to the aqueductus Fallopii Caries and necrosis of the and paralysis of the petrous bone. seventh nerve.

=Treatment.= The displacement of the mastoid process is of so incomplete a nature that the question of replacement by open operation seldom arises. In the event, however, of intracranial complications, operative treatment must be carried out. Under ordinary circumstances the treatment consists mainly in the prevention of suppuration. When suppuration occurs, frequent cleansing of the ear must be carried out in order to prevent accumulation of pus in middle ear and antrum. This object is to be attained, not by syringing, but by gentle irrigation and light packing. Later on it may become necessary to carry out the complete mastoid operation.

FRACTURES OF THE VAULT OF THE SKULL

Fractures of the vault of the skull may be restricted to the vault or associated with a basic fracture. Evidence has been brought forward previously to show that many vault fractures may be regarded as mere upward extension from a primary basic lesion. The limitation of a fracture to the vault depends on the nature of the productive force, the degree of violence used, the site of application, and the direction of the force. Thus, the smaller the weapon, the greater the violence, the nearer the site of application to the vertex, the more direct the blow, the greater is the tendency to vault limitation. Again, compound fractures are much more liable to vault limitation than simple fractures, as is proved, for instance, by the reports of Sir Prescott Hewitt--20 compound fractures in which the fracture was restricted to the vault of the skull, and 56 simple fractures in which the base was involved in all but one.

Fractures of the vault may involve:--

(a) the external table only;

(b) the internal table alone;

(c) the whole thickness of the skull.

=Fractures of the external table alone.= These fractures are excessively rare. Their existence was even doubted till the recent South African War, when Makins saw one case of this nature. They appear to be due to the impact of a glancing bullet (see p. 297). A ‘gutter-shaped’ depression results, the comminuted fragments of the external table being carried away or distributed in the region of the lacerated scalp (see