A System of Operative Surgery Part 74

As a rule, very little fluid escapes: if present in considerable quant.i.ty, and if it escapes from between the dura mater and brain, it is an unfavourable sign, as it generally signifies early meningitis.

If meningitis be present, purulent lymph or secretion may be seen on the surface of the brain, either localized or spreading from the site of the infection.

If the intracranial pressure be great, the brain will bulge through the opening in the dura mater. If the abscess be very large and situated superficially, the thin layer of brain substance forming its outer wall may rupture as soon as an opening has been made in the dura mater.

Sometimes, indeed, the pus may be seen to ooze through an opening in the dura mater, which may be found to communicate with the abscess cavity.

The next step is to open the abscess. Formerly a trocar and canula were used. This method is no longer in favour for the following reasons:--If the wall of the abscess cavity be very thick, it may not be pierced; secondly, the trocar may pa.s.s through the abscess cavity and enter the brain substance beyond without draining it; and thirdly, even if the trocar enters the abscess cavity the pus may be so thick as to plug its lumen. For these reasons a fine pair of Lister's sinus-forceps or a narrow-bladed bistoury is recommended. In the ordinary case Lister's forceps can be used.

The direction in which the brain is explored depends upon the point at which this is done. Thus, if the procedure be carried out through the tegmen tympani, the brain is explored in an upward direction. The forceps are made to pierce the brain for about an inch; the blades are then slightly dilated and the forceps partly withdrawn. If a large abscess exists, the cavity is usually opened at once and pus flows out along the track of the forceps. If the abscess be small and deeply placed, its cavity may not be entered on the first thrust of the forceps. In this case they are closed and withdrawn. The brain is then explored by thrusting the forceps first upwards and forwards, then upwards and backwards, and finally upwards and inwards; in the latter case it is unwise to pierce the brain for more than an inch and a quarter for fear of entering the lateral ventricle.

If the brain be explored through the outer wall of the temporo-sphenoidal lobe, the first direction in which this is carried out is directly inwards. If this be not successful, the brain is further explored in a direction forwards, upwards, or backwards, the exploratory instrument at the same time pointing slightly inwards.

If exploration proves negative, it may also be necessary to explore the cerebellum. If, however, the surgeon be still convinced that a temporo-sphenoidal abscess exists, he may next pierce the brain with the bistoury, in case the forceps has failed to enter the abscess cavity, perhaps owing to its walls being very thick. If all efforts fail to find the abscess, the little finger may be inserted into the brain itself to see if the resistant wall of an abscess can be felt. This procedure, however, should be avoided if possible, as by doing so it causes destruction of a certain amount of brain tissue.

If an abscess be opened a varying quant.i.ty of pus escapes, usually evil smelling. In the more chronic cases it is thick and greenish; in the acute cases it may contain shreds of necrosed brain tissue or be intermixed with bubbles of gas. Sometimes there is also an escape of turbid cerebro-spinal fluid, which if excessive is suggestive either that the lateral ventricle has been opened inadvertently or that the abscess has already burst into it. In these cases the patient is usually comatose or in the state of muttering delirium at the time of the operation.

After the abscess has been opened, the forceps or bistoury should be retained in position until the pus has drained away. A large tube is then pushed into the abscess cavity along the line of the forceps or bistoury. It is only permissible to withdraw the instrument with which the abscess has been opened after the end of the tube is well within the cavity. The outer end of the tube should be flush with the surface of the wound. To prevent it slipping too far into the brain, it may be anch.o.r.ed to the edge of the skin wound by a silkworm-gut suture. If the abscess be drained through the tegmen tympani, it will be difficult to bring the tube out into the wound without kinking it. For this reason I prefer to incise the brain substance slightly outwards after the abscess cavity has been reached, so that a tube can be inserted obliquely upwards and inwards at a point corresponding to the angle between the tegmen tympani and the squamous portion of the temporal bone. If the exploratory puncture has been made above the tegmen tympani and an abscess discovered, the question arises whether another drainage tube should not also be inserted into the brain through an opening in the roof of the antrum so as to drain the abscess from below. This, however, I do not think necessary.

In addition to the rubber tube, many varieties of drainage tubes have been suggested, such as decalcified chicken bone, as originally used by Macewen, and gla.s.s or silver tubes; the object of the latter being to resist the pressure of the brain, which may compress a rubber tube. The rubber tube is the simplest form of drainage, and if sufficiently thick it should be employed. To make more certain of free drainage, some surgeons use two tubes placed side by side. I think, however, one large tube (half an inch in diameter) is better than two small ones.

Irrigation of the abscess cavity is still a matter of opinion. If the abscess be small and circ.u.mscribed, the best method is to open it with as little disturbance as possible to the surrounding parts, insert a large drainage tube, and to do nothing further.

If, however, the abscess be large and irregular in shape, so that the drainage is not free, and especially if it be very septic and contains necrosed brain tissue, irrigation is justifiable if gently carried out.

The best method is to insert a fine tube along the lumen of the large one and allow some warm saline solution to flow slowly along it into the abscess cavity, the fluid returning along the larger tube. If two tubes have already been inserted into the abscess cavity, the fluid injected through one will escape by the other. Whatever method is employed, care must be taken that there is free exit for the fluid, as otherwise the abscess cavity may become over-distended, and in consequence rupture of a portion of its wall may take place, especially the inner, which perhaps only consists of a thin layer of brain tissue separating the abscess from the lateral ventricle. During the act of irrigation there is a risk of some of the fluid, now loaded with septic particles, escaping between the surface of the brain and the dura mater and thus setting up a secondary meningitis.

[Ill.u.s.tration: FIG. 253. EXPLORATION FOR A CEREBELLAR ABSCESS. A behind, and C in front of the lateral sinus; B, Lateral sinus.]

=Opening of a cerebellar abscess.= The cerebellum may be explored from two different points, either in front or behind the lateral sinus. The posterior route is adopted if the abscess is superficial in the outer portion of the lateral lobe, usually the result of lateral sinus thrombosis or disease of the posterior mastoid cells. The anterior route is indicated if it is thought that the abscess is deeply placed in the anterior inferior portion of the cerebellum, that is, in those cases in which it is apparently a complication of labyrinthine suppuration, or the result of disease of the inner wall of the antrum and mastoid cavities (Fig. 253).

(_a_) _Behind the lateral sinus._ After exposure of the lateral sinus the bone is removed either by means of the gouge and mallet or by bone-forceps, until a considerable area of the dura mater is exposed behind and below the curve of the sinus (Fig. 253). The dura mater is then incised as already described.

The cerebellum is explored by thrusting the instrument inward for about an inch. As a rule the abscess is found at once. If it be not discovered at the first attempt, the instrument should be directed forwards, upwards, and inwards towards the posterior surface of the petrous bone.

Care, however, must be taken that it is not pushed in too far, otherwise it may pierce the anterior upper margin of the cerebellum, and if an abscess be present, the meninges may thus become infected. If the surgeon has exposed the dura mater by trephining, it is necessary to push the exploratory instrument at least two inches inwards and forwards in order to reach an abscess situated in the anterior inferior portion of the cerebellum. In such cases it is by no means difficult to miss a small abscess, and further, drainage is frequently incomplete when an abscess is discovered. For this reason, if the cerebellum be explored first behind the lateral sinus and no abscess is discovered, it should further be explored by the anterior route in front of the lateral sinus.

If the cerebellar abscess be secondary to lateral sinus thrombosis, and if there be no doubt as to the diagnosis, the inner wall of the sinus should be made as aseptic as possible, and the dura mater forming it incised freely; the cerebellum being thus explored through the site of infection.

(_b_) _In front of the lateral sinus._ The lateral sinus is first exposed (Fig. 253). The triangular area of bone situated in front of it, between it and the semicircular ca.n.a.ls, and forming the inner boundary of the antrum and mastoid cavities, is now removed with the gouge and mallet or with a suitable pair of forceps. If it be certain that internal-ear suppuration exists, or if the operation be secondary to opening of the labyrinth, the posterior wall of the petrous bone may be removed until the internal auditory meatus is almost reached. If, however, the labyrinth be intact, care must be taken not to chisel away too much bone for fear of encroaching on the posterior semicircular ca.n.a.l. On exposure of the dura mater an extra-dural abscess may be met with, usually the result of internal-ear suppuration. Even if no pus be seen, it is always a wise precaution, if internal-ear suppuration coexists, to separate the dura mater from the posterior wall of the petrous bone by means of an elevator in order to prevent any deeply situated extra-dural abscess being missed. After the dura mater has been exposed sufficiently it is opened by a crucial incision. In this region absence of increased tension within the brain and lack of bulging outwards of the cerebellar tissue do not necessarily imply the absence of an abscess; the cerebellum to all appearances may appear normal and flaccid, although a small abscess may be present.

The cerebellum is explored in various directions to a distance of not more than one inch. After the pus has been evacuated a tube is inserted as described above. In the majority of cases this method is far superior to opening the cerebellum behind the lateral sinus, especially as it is now recognized that the chief cause of cerebellar abscess is internal-ear suppuration.

=After-treatment.= This is similar to that of any ordinary abscess, but care must be taken that free drainage is maintained. The main part of the mastoid wound is lightly plugged with gauze, the tube inserted into the brain abscess being brought flush with the surface of the skin. The gauze filling the wound cavity should be arranged around the tube so that it rests comfortably within the wound and is not kinked. If the drainage tube be in its proper position, pus should be seen to ooze out of it.

Although the mastoid cavity itself need not be dressed daily, if necessary the outer dressings may be removed twice a day, in order to see that drainage of the abscess is continuous. After the first two or three days, the tube is gradually shortened. If the abscess be a recent one and not encapsuled, it becomes rapidly obliterated by pressure of the surrounding brain tissue, so that the tube may be forcibly ejected within a few days. On the other hand, if the abscess has existed for a considerable period and is bounded by a thick wall, which may be extremely resistant, the purulent discharge may continue for many days and necessitate the continuance of drainage. Generally speaking, the tube may be shortened every second or third day, and can usually be dispensed with by the end of the second week, if not before. It is, however, very necessary that the tube should not be withdrawn until it is certain that the abscess cavity has been obliterated completely.

The general treatment of the case in no way differs from that already described for the mastoid operation in which the wound has been left open posteriorly.

=Complications.= (i) On turning back the flaps of the dura mater, a hernia, consisting of friable congested brain tissue, may occur at once.

This is extremely rare as a result of a simple abscess of the brain, but is significant of encephalitis frequently a.s.sociated with meningitis (see p. 436). If an abscess be suspected, the brain should be explored as already described. If, however, no abscess be discovered, the treatment consists in removal of more bone and further incision of the dura mater, in order to permit of free drainage and to relieve tension.

(ii) Opening into the lateral ventricle. This may be due to rupture of its wall owing to the sudden diminution of pressure from too rapid drainage of the abscess cavity, or it may occur accidentally from thrusting in the exploratory instrument or drainage tube too deeply. Its occurrence is evidenced by the sudden gush of cerebro-spinal fluid. The ultimate danger is subsequent infection of the cavity, which, unfortunately, frequently occurs.

(iii) Cessation of breathing. This is more likely to occur in a cerebellar abscess in consequence of direct pressure on the medullary respiratory centres. The immediate treatment is to do artificial respiration and to open the cerebellar abscess by the quickest method possible. If this be successful, respiration probably will be restored.

=Prognosis and subsequent progress.= In an uncomplicated case a favourable prognosis may be expected, provided the abscess is successfully opened and drained without much disturbance of the surrounding parts. Many factors, however, may lead to a fatal result.

With regard to recovery: in 100 cases taken from the records of the London Hospital during the last ten years, recovery took place in 20% operated on for cerebral and 10% for cerebellar abscess. Other statistics give a much higher percentage of recovery, but it must be remembered that in hospital patients a large number of the cases are only seen by the surgeon at a very late stage, when the brain abscess is complicated by other intracranial or suppurative lesions, and the patient is in an almost moribund condition; so that the operation may only be undertaken as a forlorn hope.

If the operation is going to be successful, the head symptoms quickly disappear. Even if the patient was comatose before operation, the recovery may be so rapid that his mental condition may be almost normal within twenty-four hours. In many cases, if the abscess be a large one, convalescence will be tedious or prolonged; sometimes, indeed, complete restoration of the mental faculties, in spite of a most successful operation, will not be obtained. The chief relief to the patient is the cessation of the terrible headaches from which he has been suffering.

Unfavourable symptoms are the sudden onset of pyrexia accompanied by delirium usually the result of diffuse meningitis, or of infection of the lateral ventricles. In the latter case there is a rapid termination in drowsiness, coma, and death.

Although the brain abscess may be draining freely, the patient for some days may lie in a semi-comatose condition as a result of dema or inflammation of the surrounding brain tissue; in such cases prognosis is difficult, but hope of recovery may be entertained if the pulse and temperature keep practically normal.

=Recurrence of symptoms.= This may take place within the first few days after the operation as a result of infective cerebritis, the presence of another abscess, or faulty drainage; or at a much later period, owing to the formation of another abscess or to a cyst within the brain at the site of the former abscess.

1. If the recurrence of the symptoms appears immediately after the operation, the wound should be inspected carefully, if necessary under an anaesthetic. If drainage be not free, the tube should be removed and a pair of forceps inserted along the track leading into the abscess, their blades being then slightly opened and withdrawn. On doing this an acc.u.mulation of pus may escape. The cavity may then be irrigated gently with saline solution and a larger tube inserted.

If, however, this procedure does not give a satisfactory result, the finger may be inserted into the brain to feel if the abscess is loculated. By this means any existing septa may be broken through; or if a feeling of resistance suggests the presence of another abscess, this part of the brain can also be explored. It must also be remembered that although a temporo-sphenoidal abscess has been opened successfully and is draining well, the continuance of the symptoms may be due to a coexisting abscess of the cerebellum, or _vice versa_; in other cases, in spite of all care, the patient gradually sinks, partly from exhaustion and partly from general toxaemia, the result of infective cerebritis.

2. Recurrence of symptoms at a later period. The occurrence of a fresh abscess is usually owing to the fact that the primary focus of the disease has not been completely removed at the first operation; for instance, if the surgeon only trephined and drained the abscess without performing the mastoid operation.

A cyst is usually the result of the abscess having been encapsulated and its wall not having been removed at the first operation. If a cyst be discovered on exploring the brain in consequence of these symptoms, its wall should be removed if possible.

Apart from symptoms of intracranial pressure, the patient may suffer from attacks of Jacksonian epilepsy from time to time, presumably due to the post-operative adhesions. If they continue in spite of conservative treatment, it may become necessary to operate in order to remove this source of irritation (see Vol. III).

SECTION IV

OPERATIONS UPON THE LARYNX AND TRACHEA

BY

W. DOUGLAS HARMER, M.C. (Cantab.), F.R.C.S. (Eng.)

Surgeon to the Throat and Nose Department, St. Bartholomew's Hospital

CHAPTER I

ENDOLARYNGEAL OPERATIONS

=Indications.= (i) _Tumours._ Tumours of the larynx are more often innocent than malignant. Sir F. Semon[5] collected 12,297 cases seen between 1862 and 1888 by 107 laryngologists, and of these 10,747 (or 88%) were benign and 1,550 (or 12%) were malignant. Of the innocent forms, papilloma, either simple or multiple, occurred in 39%; fibroma, sessile or pedunculated, was next in frequency; cystic tumours were not nearly so common; and other forms, including myxoma, angeioma, adenoma, lipoma, and enchondroma, were rare. The period during which these tumours are most common is between the ages of 20 and 40 years, but they are also frequent during childhood.

[5] _Internat. Centralblatt fur Laryngol._, Jahrgang v u. vi, 1888-9, 'Die Frage des Ueberganges gutartiger Kehlkopfgeschwulste in bosartige, speciell nach intralaryngealen Operationen.'

Malignant growths occur at a later age, mostly between the ages of 40 and 60, and attack males more than females. Carcinoma is far more common than sarcoma, and is generally of the squamous-celled variety.