Manual of Surgery Volume II Part 38

FRACTURES OF THE BASE

The base of the skull may be fractured by a pointed object, such as a fencing foil, a knitting pin, or the end of an umbrella, being forced through the orbit, the nasal cavities, or the pharynx. These injuries will be referred to in describing fractures of the anterior fossa.

The majority of basal fractures result from such accidents as a fall from a height, the patient landing on the vertex or on the side of the head, or from a heavy object falling on the head. The violence is therefore indirect in so far as the bone breaks at a point other than the seat of impact.

In other cases the base is broken by the patient falling from a height and landing on his feet or b.u.t.tocks, the force being transmitted through the spine to the occiput, and the bone giving way around the foramen magnum. Sometimes the condyle of the lower jaw is driven through the base of the skull by a blow or fall on the chin, and fissures radiate into the base from the glenoid cavity. It is usual to describe these also as fractures by indirect violence, but as the skull gives way at the point where it is struck, these are really fractures by direct violence. Von Bergmann, Bruns, and Messerer have done much to elucidate the mechanism of basal fractures.

In the consideration of the mode of production of basal fractures by indirect violence, the irregular shape of the cavity, the varying strength and thickness of its different parts, and the existence of the foramina through the bone are to be borne in mind. The force acting on the skull tends to increase one diameter of the cavity, and to diminish the opposite diameter. The resulting fracture, therefore, is due to bursting of the skull, and tends to take place at the part which has least elasticity--that is, at the base. It has been found that the site and direction of basal fractures bear a fairly constant relation to the direction of the force by which they are produced.

When, for example, the skull is compressed from side to side, the line of fracture through the base is usually transverse, and it may implicate one or both sides (Fig. 191). On the other hand, when the pressure is antero-posterior, the fracture tends to be longitudinal; and when oblique, it tends to be diagonal.

[Ill.u.s.tration: FIG. 191.--Transverse Fracture through Middle Fossa of Base of Skull.]

Fractures of the base usually take the form of a single fissure, or a series of fissures, which, as a rule, run through the foramina in their track. Small portions of bone are sometimes completely separated. It is common for a fissure through the base to be continued for a considerable distance on to the vault.

The fracture may involve only one fossa, but as a rule fissures radiate into two or all of them. Fractures of the anterior and middle fossae are usually rendered compound by tearing of the mucous membrane of the nose, the pharynx, or the ear.

Basal fractures are frequently a.s.sociated with contusion and laceration of the brain, and also with injuries of one or more of the cranial nerves.

#Fracture of the anterior fossa# may result from a blow on the forehead, nose, or face; or from a punctured wound of the orbit or of the nasal cavity. Often the injury is at first considered trivial, and it is only when infective complications, in the form of meningitis or cerebral abscess, develop, that its true nature is suspected. This fossa may also be implicated in fractures of the vault, fissures extending from the vertex to the orbital plate of the frontal bone, or to the lesser wing of the sphenoid.

_Clinical Features._--Unless the fracture is compound through opening into the nose or pharynx, there are few symptoms by which it can be recognised. When compound, there may be bleeding from the pharynx or nose from tearing of the periosteum and mucous membrane related to the basi-sphenoid and ethmoid respectively. When the haemorrhage is profuse, it is probable that the meningeal vessels or even the venous sinuses have been torn. Cerebro-spinal fluid may escape along with the blood, but it is seldom possible to recognise it. If the flow is long continued, the patient may be conscious of a persistent salt taste in the mouth, due to the large proportion of sodium chloride which the fluid contains. In very severe injuries, brain matter may escape through the nose or mouth.

Fracture of the anterior fossa is often accompanied by extravasation of blood into the orbit, pushing forward the eyeball and infiltrating the conjunctiva (_sub-conjunctival ecchymosis_). This occurs especially when the orbital plate of the frontal bone is implicated.

The blood which infiltrates the conjunctiva pa.s.ses from behind forwards, appearing first at the outer angle of the eye and spreading like a fan towards the cornea. Later it spreads into the upper eyelid.

When the orbital ridge is chipped off, without the cavity of the skull being opened into, the haemorrhage shows at once both under the conjunctiva and in the upper lid. If the frontal sinus is opened, air may infiltrate the scalp.

The olfactory, optic, oculo-motor, pathetic, ophthalmic division of the trigeminal, and the abducens nerves are all liable to be implicated.

_Diagnosis._--It is scarcely necessary to state that bleeding from the nose or mouth may occur after a blow on the face without the occurrence of a fracture of the skull. It is only when it is long continued and profuse that the bleeding suggests a fracture. Similarly effusion of blood in the region of the orbit may be due to a simple contusion of the soft parts ("black eye"), or to gravitation of blood from the forehead or temple. Sub-conjunctival ecchymosis also may occur independently of a fracture implicating the anterior fossa--for example, in a.s.sociation with an ordinary black eye, or with fracture of the orbital ridge or of the zygomatic (malar) bone.

Finally, paralysis of the cranial nerves may result from pressure of blood-clot, or from the nerves being torn without the skull being fractured.

#Fracture of the middle fossa# is usually the result of severe violence applied to the vault, as, for example, when a man falls from a height, or is thrown from a horse and lands on his head.

_Clinical features._--The most conclusive sign of fracture of the middle fossa is the escape of dark-coloured blood in a steady stream from the ear, followed by oozing of cerebro-spinal fluid. The bleeding from the ear may go on for days, the blood gradually becoming lighter in colour from admixture with cerebro-spinal fluid. Finally the blood ceases, but the clear fluid continues to drain away, sometimes for weeks, and in such quant.i.ty as to soak the dressings and the pillow.

In our experience, the escape of cerebro-spinal fluid is much less common than is generally supposed. In most cases, on examining the ear with a speculum, the tympanic membrane is found to be ruptured; when it is intact, the blood and cerebro-spinal fluid may pa.s.s down the Eustachian tube into the pharynx. The escape of brain matter from the ear is exceedingly rare. Emphysema of the scalp sometimes results when the fracture pa.s.ses through the mastoid cells. The facial and acoustic nerves and the maxillary and mandibular divisions of the trigeminal are frequently implicated. Deafness is a serious and not uncommon accompaniment of fracture of the middle fossa, as the fracture involves the labyrinth and is attended with haemorrhage and the formation of new bone.

_Diagnosis._--Care must be taken not to mistake blood which has pa.s.sed into the ear from a scalp wound, or which has its origin in a fracture of the wall of the external auditory meatus or a laceration of the tympanic membrane, for blood escaping from a fracture of the base. Under these conditions the blood is usually bright red, is not accompanied by cerebro-spinal fluid, and the flow soon stops. It is on record[4] that blood and cerebro-spinal fluid may escape along the sheath of the acoustic nerve without the bone being broken.

[4] Miles, _Edinburgh Medical Journal_, 1895.

#Fracture of the posterior fossa# is produced by the same forms of violence as cause fracture of the middle fossa; it is specially liable to result if the patient falls on the feet or b.u.t.tocks.

_Clinical Features._--Sometimes a comparatively limited fracture of the occipital bone results, and in the course of a few days blood infiltrates the scalp in the region of the occiput and mastoid, or may pa.s.s down in the deeper planes of the neck. As a rule, however, there is no immediate external evidence of fracture. The patient is generally unconscious, and shows signs of injury to the pons and medulla, causing interference with respiration, which soon proves fatal. The rapidly fatal issue of these cases usually prevents the manifestation of any injury to the posterior cranial nerves.

_Diagnosis of Basal Fractures._--In the diagnosis of fractures of the base, reliance is to be placed chiefly upon: (1) the nature of the injury; (2) the diffuse character of the cerebral symptoms; (3) the evidence of injury to individual cranial nerves; (4) the occurrence of persistent bleeding from the nose, mouth, or ear; (5) the extravasation of blood under the conjunctiva or behind the mastoid process; and (6) the presence of blood in the cerebro-spinal fluid withdrawn by lumbar puncture. In rare cases the diagnosis is made certain by the escape of cerebro-fluid or of brain matter from the nose, mouth, or ear.

It must be admitted, however, that in a large proportion of cases which end in recovery, the diagnosis of fracture of the base is little more than a conjecture. The external evidence of damage to the bone is so slight and so liable to be misleading, that little reliance can be placed upon it. The a.s.sociated cerebral and nervous symptoms also are only presumptive evidence of fracture of the bone. In all cases, however, in which there is reason to suspect that the base is fractured, the patient should be treated on this a.s.sumption. It is often found that, when there are no cerebral symptoms present, it is difficult to convince the patient of the necessity for undergoing treatment, and of the risk involved in his leaving his bed and resuming work.

_Prognosis in Basal Fractures._--The prognosis depends upon the severity of the cerebral lesions, and on the occurrence of traumatic dema or infective intra-cranial complications. Many cases prove fatal within a few hours from the a.s.sociated injury to the brain, the patient dying from cerebral compression due to haemorrhage. If the patient survives two days, the prognosis is more hopeful (Wagner). It is possible that the free escape of blood from the nose or ear may in some cases prevent compression, and to a certain extent render the prognosis more favourable. Punctured fractures are frequently fatal from infective complications--meningitis, sinus thrombosis, and cerebral abscess. These complications are also liable to occur in fractures rendered compound by opening into the nose, pharynx, or ear, but they are less common than might be expected.

_Treatment._--The general treatment includes that for all head injuries. In a number of cases attended with symptoms of compression, benefit has followed the relief of intra-cranial tension by a decompression operation. The withdrawal of 30 or 40 c.c. of cerebro-spinal fluid by lumbar puncture has also proved beneficial in the same way; Quenu strongly recommends repeated puncture in serious cases. In a few cases this procedure has been followed by sudden death.

Steps must be taken to prevent infection from the mucous surfaces implicated. This is exceedingly difficult in fractures opening into the pharynx and nose. Owing to the general condition of the patient, it is usually impossible to employ nasal douching or mouth washes, but spraying the cavities with peroxide of hydrogen or other antiseptics may be employed with benefit. In fractures of the middle fossa, the ear should be gently sponged out and the meatus plugged with gauze, retained in position by adhesive plaster or a bandage. When there is a persistent escape of blood or cerebro-spinal fluid, the dressing requires to be changed frequently.

In compound fractures of the anterior fossa due to perforation through the orbit, the frontal bone should be trephined to admit of the removal of loose fragments or of any foreign body that may have entered the skull and to provide for drainage.

CHAPTER XIV

DISEASES OF THE BRAIN AND MEMBRANES

Pyogenic diseases--Meningitis: _Varieties_--Abscess: _Varieties_--Sinus phlebitis--Intra-cranial tuberculosis.

Cephaloceles--_Meningocele_--_Encephalocele_-- _Hydrencephalocele_--Traumatic cephal-hydrocele--Hydrocephalus; _Varieties_--Micrencephaly. Cerebral tumours. Tumours of the pituitary body. Epilepsy--Hernia cerebri. Surgical affections of cranial nerves--Cervical sympathetic.

PYOGENIC DISEASES

The most important intra-cranial conditions that result from infection with pyogenic bacteria are: meningitis, abscess of the brain, and phlebitis of the venous sinuses.

The organisms most frequently a.s.sociated with these conditions are the staphylococcus aureus and the streptococcus, but it is not uncommon to meet with mixed infections in which other bacteria are present--particularly the pneumococcus, the bacillus ftidus, the bacillus coli, the bacillus pyocyaneus, and the diplococcus intracellularis.

By far the most common source of intra-cranial infection is chronic suppuration of the middle ear and mastoid antrum, the organisms pa.s.sing from these cavities to the interior of the skull directly through a perforation of the tegmen tympani or of the wall of the sigmoid groove, or being carried in the blood stream by the emissary veins. In some cases the infection travels along the sheaths of the facial and acoustic nerves.

Less frequently infective conditions of the nasal cavity and its accessory air sinuses, and compound fractures of the skull, particularly punctured fractures, are followed by intra-cranial complications; or infection is conveyed to the inside of the skull, by way of the emissary veins, from wounds of the scalp, or from such conditions as erysipelas of the face and scalp, malignant pustule, carbuncles, or boils.

At the bedside there is often difficulty in discriminating between the various pyogenic intra-cranial complications, because many of the symptoms are common to all the members of this group, and because more than one condition is frequently present. Thus a localised meningitis spreading to the brain may set up a cerebral abscess; a sinus phlebitis may give rise to a purulent lepto-meningitis; or a cerebral abscess bursting into the sub-arachnoid s.p.a.ce may produce meningitis.

MENINGITIS

#Pachymeningitis.#--This term is applied when the infection involves the dura mater--a condition which is usually due to the spread of infection from a localised osseous lesion, such as erosion of the tegmen tympani in chronic suppuration of the middle ear, of the wall of the sigmoid groove in mastoid disease, or of the posterior wall of the frontal sinus in suppuration of that cavity. It also occurs in relation to septic lesions of the cranial bones such as a broken-down gumma, after operations on the cranial bones, and in cases of compound fracture attended with a mild degree of infection and with imperfect drainage. In contusion of the skull without an external wound, the infection may take place through the blood stream.

The layer of the dura in contact with the affected portion of bone is inflamed, thickened, and covered with a layer of granulations--_external pachymeningitis_--and between it and the bone there is an effusion of fluid. Up to this point the process is largely protective in its effects, and gives rise to no symptoms, beyond perhaps some pain in the head.

In the majority of cases, however, suppuration occurs between the dura and the bone--_suppurative pachymeningitis_--and leads to the formation of an _extra-dural abscess_ (Fig. 192). When this happens in a.s.sociation with disease in the middle ear or frontal sinus, it is attended with severe headache referred to the seat of the abscess, a sudden rise of temperature preceded by shivering, and other evidence of the absorption of toxins. Over the situation of the abscess, the scalp becomes swollen and dematous--a condition which Percival Pott, in 1760, first observed to be characteristic of extra-dural suppuration, hence the name, _Pott's puffy tumour_, applied to it (Fig. 193). Under these circ.u.mstances the abscess is seldom of sufficient size to cause a marked increase in the intra-cranial tension, or to give rise to localised cerebral symptoms by pressing on the brain.

[Ill.u.s.tration: FIG. 192.--Diagram of Extra-Dural Abscess.]

[Ill.u.s.tration: FIG. 193.--Pott's Puffy Tumour in case of extra-dural abscess following compound fracture of orbital margin; infected with road-dust; operation; recovery. At the time of the photograph the man was unconscious.]

When a.s.sociated with a punctured wound implicating the skull, an extra-dural abscess may develop within a few days of the injury, or not till after the lapse of several weeks, and it may spread over a wide area and come to encroach on the cranial cavity sufficiently to raise the intra-cranial tension and cause symptoms of compression, or even to press upon cortical centres and produce localised paralyses.

As discharge can escape from the wound in the scalp, the puffy tumour does not necessarily form.

_Treatment._--When the abscess is secondary to middle ear disease, the mastoid must be opened, the eroded bone exposed, and sufficient of it removed with rongeur forceps to admit of free drainage. When the infection has spread from the frontal sinus, the skull is trephined in the frontal region, the precise site being indicated by the dematous area in the scalp, and the diseased bone is removed. In cases of compound fracture, drainage is established by enlarging the scalp wound, and removing loose, depressed, or inflamed portions of bone; if the bone is comparatively intact, it must be trephined, and further bone is removed with rongeur forceps over the entire area in which the dura has been separated.