Part 50 (1/2)

In this operation the bony outer wall of the orbit is divided above and below, and turned outwards so as to expose the orbital contents without interfering with the globe; the bony wall, being kept attached to the overlying tissue, can be replaced subsequently without fear of necrosis.

=Indications.= The operation is performed in cases of a suspected tumour of the orbit, which, if small and non-malignant, can be removed, the eye being left _in situ_. If doubt exists as to the nature of the tumour a piece can be removed and examined microscopically, either at the time of the operation or later. It is especially suitable for tumours of the optic nerve and for orbital cysts behind the globe.

=Instruments.= Scalpel, dissecting forceps, artery forceps, scissors, periosteum detacher, chisel and hammer, or preferably, a motor rotary saw, and retractors.

=Operation.= Performed under a general anaesthetic.

_First step._ A slightly curved incision with the convexity forwards is made so as to expose the outer margin of the orbit and carried down to the bone. The periosteum is separated from the inner surface of the outer wall of the orbit by means of a periosteum detacher and divided horizontally, the finger is inserted, and the orbit explored. If a small tumour or cyst be found it can sometimes be sh.e.l.led out through this incision without enlarging the wound further.

_Second step._ The eye and orbital contents are carefully protected with a large flat retractor. The bone is first divided above, by means of either a chisel or a saw. The upper incision should pa.s.s through the base of the external angular process of the frontal bone, and run backwards and slightly downwards to the posterior end of the spheno-maxillary fissure. The lower incision should run directly backwards from the lower orbital margin into the spheno-maxillary fissure. The triangular wedge of bone attached by its outer surface to the soft tissues in the temporal fossa is then forced outwards. In doing this care must be taken not to fracture the orbital wall anteriorly, otherwise the s.p.a.ce to work in will be much reduced.

_Third step._ Consists in the removal of the tumour. Care must be taken to displace the external rectus to one side so as to avoid injury to it as much as possible. If the case should be one of an optic nerve tumour, for which the operation is most frequently performed, the optic nerve is divided close behind the globe. The tumour is freed from the surrounding ciliary nerves and the ophthalmic artery and brought up into the wound as much as possible. The optic nerve is then divided at the apex of the orbit and the tumour removed. The wound in the periosteum of the outer wall of the orbit is closed with a catgut suture, the bone, together with the soft parts, replaced in position and the skin wound closed by sutures. A drainage tube should be inserted for at least twenty-four hours.

=Complications.= 1. _Proptosis._ The operation is liable to be followed by great proptosis as the result of haemorrhage into the orbit. If the optic nerve has been removed, the globe may be dislocated forwards between the lids and come in contact with the dressings.

2. _Corneal ulceration._ As the cornea is frequently anaesthetic from division of the ciliary nerves, ulceration is very liable to follow. It is, therefore, desirable in many cases to st.i.tch the lids together after closing the skin wound.

3. _Defective outward movement in the globe_ is of frequent occurrence, owing either to injury of the external rectus or the sixth nerve, or to involvement of them in the scar tissue. St.i.tching the periosteum together obviates the latter to a certain extent.

4. As the wound cicatrizes a certain amount of _enophthalmos_ is very liable to result.

EVISCERATION OF THE ORBIT

=Indications.= This operation is usually performed for some form of new growth originating either in the eye or the orbit.

=Operation.= This may be modified (1) according to the _position_ of the growth. In severe cases of rodent ulcer and sarcomatous growths, which involve the lids, it is desirable that the lids should be removed with the tumour; but in cases of tumour of the optic nerve, or disease situated far back in the orbit, and not involving the lids or conjunctiva, these structures may be retained, since a much better socket is thus obtained. (2) The _nature_ of the growth. In simple tumours, such as naevi and some cases of arterio-venous aneurism which have failed to yield to other treatment, the incomplete method, in which the lids are retained, is all that is necessary, but in malignant cases they should be removed.

_The Complete Method._ An incision down to the bone is first made, completely encircling the orbital margin and including any growth that may be involving the skin. The periosteum is then separated completely, as near to the optic foramen as possible. Care must be taken in dealing with the periosteum over the lachrymal bone, as the bone is liable to be fractured and an opening made into the nose if undue force be used. The apex of the cone formed by the periosteum is divided, as far back as possible, with curved scissors, and the whole orbital contents are removed. The wound is packed with gauze, and skin-grafting is subsequently performed when the bone has become covered with granulations; this usually occurs about the end of the second week.

_The Incomplete Method._ The globe is first enucleated and the outer canthus divided. The lids are well retracted and an incision is carried down to the bone along the orbital margins. The periosteum is then stripped up from the walls of the orbit and the apex of the cone divided as far back as possible, as in the previous operation. The conjunctiva and outer canthus are then united with sutures. As a rule, skin-grafting is not necessary after this operation.

OPENING AN ORBITAL ABSCESS

Orbital abscesses should be incised where they point. In the upper lid care should be taken not to divide the levator palpebrae muscle; the incision should be placed well to one side. In making an incision over the inner side of the orbit care should be taken not to detach the pulley of the superior oblique. The cause of the abscess should be ascertained if possible. Suppuration in the ethmoidal sinuses coming through from the nose is the commonest cause, and should be treated appropriately (see Section V).

SECTION III

OPERATIONS UPON THE EAR

BY HUNTER F. TOD, M.A., M.D. (Cantab.), F.R.C.S. (Eng.) Aural Surgeon to the London Hospital

CHAPTER I

EXAMINATION OF THE EAR: GENERAL CONSIDERATIONS WITH REGARD TO OPERATIONS

In order to perform successfully the various operations upon the ear, it is essential that the surgeon should be familiar with the technique of its examination, which, for the sake of convenience, will first be briefly described.