Extreme vascularity of the bone is not unusual after ligature of the jugular vein. In these cases the surgeon must rely on the cleverness of the a.s.sistants in keeping the field of operation clear by careful swabbing.

In exposure of the jugular vein there may be difficulty in finding the vessel, especially if the cervical glands are enlarged, or if there be matting together of the tissues in consequence of periphlebitis or cellulitis. In these cases the best plan is to identify the common facial vein and then trace it down to its entrance into the jugular vein.

With regard to the sinus, the chief danger is injury of its inner wall whilst curetting out its contents: this may afterwards give rise to meningitis or a cerebellar abscess. Accidental p.r.i.c.king of a non-thrombosed jugular vein may allow of entry of air into the vein and so cause death: this is a catastrophe I have not yet met with. Also, if the operator be careless or inexperienced, he may injure the carotid artery or vagus nerve; in the former case the only thing to do is to ligature the artery above and below the wound.

=Complications.= The chief intracranial complications are meningitis and cerebellar abscess; the former usually from extension of the septic thrombosis along the petrosal sinuses. If, at the time of operation, it be doubtful whether intracranial suppuration already exists or not, the surgeon should content himself with removing the septic thrombus from the sinus and await further symptoms. At the time of the operation, however, sufficient bone should be removed to expose the dura mater over the cerebellum. If, in addition to the clinical symptoms, the appearance of the dura mater, the increased intracranial tension, and the absence of palpation suggest the presence of an abscess, the cerebellum should then be exposed and explored (see p. 467). Before doing this, the wound should be made as aseptic as possible and a fresh set of sterilized instruments used.

The complications resulting from general septic infection are pyaemia and septicaemia.

=Prognosis.= The prognosis depends entirely on whether the septic focus can be completely removed or not. Failure to do this is frequently due to the operation not having been sufficiently extensive. It is a matter of experience that if a second operation has to be performed recovery seldom takes place. For this reason the first operation must be thorough.

If such cases could be operated on in the earliest stage whilst the infective thrombus was still limited, without doubt a higher percentage of recoveries would be obtained. Unfortunately, the surgeon may not be summoned until too late, owing to the seriousness of the condition not having been realized.

In any individual case it is impossible to tell for the first few days after the operation what the ultimate result will be. Without operation a fatal termination is practically certain. As a result of operation about one-third of the cases may be expected to recover.

CHAPTER X

OPERATIONS FOR INTRACRANIAL ABSCESS OF Ot.i.tIC ORIGIN

An intracranial abscess, the result of disease of the temporal bone, is usually situated close to the surface of the brain, and is in close relationship with the diseased area of bone through which the infection has taken place. The actual track of the infection can frequently be traced through the bone to the dura mater and brain substance itself; sometimes, indeed, a fistula is found to pa.s.s through the bone and to communicate with the intracranial abscess. On the other hand, though rarely, the surface of the bone to all appearances is normal and there are no adhesions between it and the dura mater and underlying brain substance, and the abscess may be situated deeply within the brain.

With regard to the comparative frequency of temporo-sphenoidal and cerebellar abscess, in 100 cases collected from the records of the London Hospital the writer found that in children under ten years of age temporo-sphenoidal abscess occurred in 87% and cerebellar only in 13%, whereas in adults cerebral abscess occurred in 65% and cerebellar in 35%; and that a cerebral and cerebellar abscess occurred together only in 5% of the cases.

These statistics are practically the same as Korner's (_Die ot.i.tischen Erkrankungen des Hirns, der Hirnhaute und der Blutleiter_). Ballance, on the other hand, considers cerebellar abscess a more frequent occurrence than temporo-sphenoidal.

Multiple abscesses may be met with, usually the result of pyaemia.

=Indications.= An intracranial abscess must always be opened and drained.

Indications pointing to such a condition are persistent headache, purposeless vomiting, a slow pulse, a subnormal temperature, and optic neuritis. With this there is usually some change in the mental condition, especially in the case of a temporo-sphenoidal abscess. In the early stages there may be attacks of simple forgetfulness or mental aberration, or, on the other hand, that of extreme mental excitement.

Owing to the intracranial pressure caused by the increase in size of the abscess, the mental state becomes impaired and the condition known as slow cerebration or the 'dream state' may be observed.

It must, however, not be forgotten that the same clinical picture may be produced by other conditions, such as an intracranial tumour: in the case of a middle-ear suppuration, however, an intracranial abscess may be diagnosed unless this can otherwise be excluded.

Before operation is decided on, the site of the lesion must be determined. This can only be done if certain localizing symptoms are present.

_In a temporo-sphenoidal abscess_, if the cortical region be affected, there may be paralysis or paresis of the opposite side, beginning with the face and then spreading to the arm and leg; or in the opposite order if the internal capsule be involved.

If the left temporo-sphenoidal lobe be the site of the lesion, aphasia may be met with, and if the abscess extends backwards, word-blindness may occur. If the centre of hearing be affected there may be complete deafness of the opposite side owing to its destruction; or tinnitus or hyperacusis if the centre be only irritated by the proximity of the abscess; or if the anterior extremity be involved anosmia or parosmia may be noticed. Another important sign, occurring in conjunction with the above symptoms, is a fixed pupil on the affected side.

_In a cerebellar abscess_ the symptoms are less marked, or may even be absent, so that the abscess may remain undiagnosed during life and only be discovered at the autopsy, which may perhaps have been performed on account of the sudden and unexpected death of the patient from rupture of the abscess itself. In walking, in addition to a peculiar staggering gait, there is a tendency for the patient to direct his course gradually towards the affected side. Lateral nystagmus, if present, is usually directed towards the affected side and has to be differentiated from that due to internal-ear disease. If a cerebellar abscess be a.s.sociated with a labyrinthine suppuration and the latter is explored by operation, the nystagmus will still remain directed to the affected side. If, however, no cerebellar abscess be present the labyrinthine operation will be followed by nystagmus strongly directed to the opposite side.

Optic neuritis and vomiting usually are more severe than in temporo-sphenoidal abscess. Headache, if present, may be referred to the occipital region, and there may also be slight retraction of the neck or pain behind the mastoid region as a result of localized and early meningitis of the posterior fossa. If the abscess be very large, there may be paresis or paralysis of the facial nerve and perhaps also of the upper extremity. The deep reflexes may also be altered, the knee-jerk being frequently absent on the affected side. The patient in the late stage usually lies curled up in bed on the side opposite to the lesion, with the knees flexed.

=Methods of operation.= Two methods may be employed:--

1. Trephining directly over the area of the abscess (rarely necessary).

2. First performing the mastoid operation and then following out the route of infection (usual method).

In the case of middle-ear suppuration, trephining has practically been abandoned, and rightly so, since it has become recognized that the intracranial abscess is due to direct extension of the pyogenic infection from the middle-ear and mastoid cavities.

The only circ.u.mstances in which trephining may be advised are--(1) If the diagnosis be certain and the operator has no experience of aural surgery. In a case of emergency he is wiser, perhaps, to trephine and drain the abscess, leaving the mastoid to be dealt with afterwards by someone competent to do so. (2) If, after performing the mastoid operation, the situation of the abscess be doubtful. In order to diminish the risk of infection of the brain by an exploratory puncture which may prove negative, the bone may be trephined a little beyond the mastoid wound, either above or behind, according as a temporo-sphenoidal or cerebellar abscess is suspected. If, however, it be considered advisable to make a fresh opening in the bone beyond the septic wound cavity, the aural surgeon will probably prefer to do so by means of the gouge and bone-forceps, to which he is more accustomed.

Trephining has also been advised if the patient is so ill that a prolonged operation is impossible; or if there is cessation of respiration during the operation itself, which may occur in a cerebellar abscess as a result of pressure on the medullary respiratory centres. To those accustomed to perform the mastoid operation, the opening of this cavity and the necessary removal of bone can be done more rapidly by the gouge or bone-forceps than by the trephine.

For whatever reason trephining is done, it is afterwards essential to perform the mastoid operation and to remove the primary focus of the disease, otherwise one of the fundamental principles of surgery will be neglected.

=Operation.= The preliminary preparation of the patient is the same as for the mastoid operation, only the head should be shaved over a wider area. The exposure of the field of operation is the same whether the brain is explored through a trephine opening or from an extension of the mastoid operation.

In the case of the temporo-sphenoidal lobe, it is necessary to extend the incision behind the auricle vertically upwards for an inch or more (Fig. 252); whereas if the cerebellum has to be explored, an incision is carried backwards at right angles to the post-aural incision, just below its mid-point (Fig. 253). In the former case, on reflecting the soft tissues from the underlying bone, the squamous portion of the temporal bone, immediately above the zygomatic ridge, will be exposed; in the latter, the base of the skull behind and below the mastoid process and lateral sinus will be laid bare.

1. =Trephining.= The trephine used should be three-quarters of an inch to one inch in diameter according as the patient is a child or an adult.

Either the hand trephine or Macewen's improved pattern mounted with a guard may be used. If available, the trephine may be worked by a motor, but in this case it should be remembered that the bone will be pierced more quickly than by the hand instrument.

_Trephining for a temporo-sphenoidal abscess._ The object of the operation is to expose the lowest portion of the middle fossa just above the roof of the antrum and tympanic cavity. The trephine, therefore, should be placed so that it is situated just above the suprameatal spine, its lowest margin being slightly above the zygomatic ridge (Fig.

251). After the disk of bone has been removed the exploration of the abscess is then carried out.

[Ill.u.s.tration: FIG. 251. TOPOGRAPHY OF THE AUDITORY REGION OF THE SKULL.

A, Point of trephining for a temporo-sphenoidal abscess; B, For a cerebellar abscess; C, Dotted line marking a portion of the lateral sinus.]

_Trephining for a cerebellar abscess._ The point at which the bone is trephined must be behind and below the curve formed by the transverse and sigmoid portion of the lateral sinus; that is, behind the mastoid process and below Reid's base-line.

If the mastoid operation has not been performed, the centre pin of the trephine should be placed at a point 1-1/4 to 1-1/2 inches behind the centre of the external auditory meatus, and an inch below Reid's base-line (Fig. 251). If, however, the mastoid has already been opened and the lateral sinus exposed, the trephine should be placed so that its anterior border is just behind the sinus and its upper border well below Reid's base-line.

2. =After performing the mastoid operation.= If this has been done already, the wound is reopened, and cleansed by filling it with hydrogen peroxide. After gently curetting away any granulations the wound cavity is irrigated and then packed in order to dry it. Under good illumination, careful inspection is made to see if a fistula or a tract of diseased bone extends in any direction. Whether the middle or posterior fossa should first be explored depends not only on the clinical symptoms but also on the condition found on opening the mastoid cavity.

=Opening of a temporo-sphenoidal abscess.= A temporo-sphenoidal abscess may be explored either through its lowest point, that is, through the roof of the antrum and floor of the middle fossa, or through its outer wall just above the zygomatic ridge. To obtain a view of the roof of the antrum and mastoid cavities, the head of the patient should lie almost flat on the operating table and be turned well over to the opposite side. The bony roof of the antrum and mastoid is removed by means of the gouge and mallet, and so expose the dura mater covering the floor of the middle fossa (Fig. 252). If a fistula communicates with the antrum cavity and the middle fossa, the bone surrounding it is first attacked.

In removing the bone, it must be remembered that the tegmen tympani is exceedingly thin, and unless care is taken pieces of bone may be pressed inwards on to the overlying dura mater. Sufficient bone should be removed to determine whether the dura mater is normal or not. To do this it may be necessary to chisel away the tegmen tympani outwards until the squamous portion of the temporal bone is reached, after which a pair of bone forceps may be used until a sufficient opening is obtained.

[Ill.u.s.tration: FIG. 252. EXPLORATION FOR A TEMPORO-SPHENOIDAL ABSCESS.

A, Above the tegmen tympani; B, Through the tegmen tympani. Occasionally these methods are combined; the bone between the openings being also removed.]

The condition found on examination of the dura mater varies. In many cases it is congested or covered with granulations at the site of the infection, and usually it is adherent to the underlying bone. At other times it seems normal.

Increase of the intracranial pressure, as shown by the bulging outwards of the dura mater, and absence of pulsation are suggestive of an abscess. These signs, however, are not conclusive, as on the one hand increased intracranial pressure may be due to other causes and on the other it is quite possible to have pulsation if the abscess be small and deeply placed.

If an extra-dural abscess be present, the intracranial cavity should not be explored at once unless this is absolutely necessary, but this step of the operation should be delayed for at least twenty-four hours. If, however, immediate operation be necessary, special precautions must be taken to render the part as aseptic as possible, and a fine layer of gauze should be packed between the margin of the bone and the dura mater in order to prevent further infection of the brain or meninges. In an uncomplicated case only sufficient bone should be removed to permit of the insertion of a large drainage tube; that is, the dura mater should not be exposed over a larger area than the size of a shilling.

If there be disease of the tegmen tympani and the symptoms point to a temporo-sphenoidal abscess, the brain should be explored through this opening in the bone (Fig. 252), as the abscess is thus not only drained through its most dependent part, but also through its stalk.

If, however, the diagnosis be doubtful, the temporo-sphenoidal lobe may be explored through a fresh opening, just above the tegmen tympani. This will diminish the risk of septic infection from the mastoid cavity.

After the dura mater has been exposed sufficiently a small incision is made in it, taking care to avoid wounding any of the vessels. With a pair of forceps the cut edge of the dura mater is drawn outwards and the incision is prolonged in each direction with a pair of blunt-pointed scissors. Similarly, the dura mater is cut through at right angles to the primary incision, so that four small flaps are made and turned back so as to expose the outer surface of the brain.

As a rule the dura mater, arachnoid, and pia mater are fused together by inflammatory adhesions, so that from a practical point of view they need hardly be considered as separate structures. Similarly, at the site of infection, the point of the so-called stalk of the abscess, the cerebral membranes are adherent to the underlying brain, especially if there has been any localized meningitis. For this reason it is sometimes necessary to peel away the dura mater from the brain, in order to expose the latter.