Part ii, p. 495).

EXPOSURE OF THE JUGULAR BULB

This may be performed either by following the sinus downwards or through the floor of the auditory canal and tympanic cavity. The former method was first described by Grunert (_Archiv für Ohrenheilkunde_, 1902, vol. liii, p. 287); the latter by Piffl (_Archiv für Ohrenheilkunde_, 1903, vol. lviii, p. 76).

=Indications.= The object of the operation is to remove the septic clot situated within the jugular bulb in the hope of preventing extension of the infection along the veins leading into it, more especially the inferior petrosal sinus. This indeed has been known to occur even after the lateral sinus has been curetted out, the jugular vein ligatured, and the venous channel syringed through.

=Grunert’s operation.= After free opening of the mastoid process and exposure of the outer wall of the lateral sinus, the skin incision is extended downwards beyond the tip of the mastoid. The soft tissues are then separated from the bone forwards and backwards so as to expose completely not only the mastoid process, but also the digastric fossa and base of the skull immediately behind it, up to the outer bony margin of the jugular foramen. Unless care is taken, the forcible traction forwards of the soft tissues necessary to expose the field of operation may injure or tear the facial nerve as it emerges from the stylo-mastoid foramen.

The tip of the mastoid process is removed first. The lateral sinus is then freely exposed to its lowest possible limit by removing the overlying bone. In doing this it must be remembered that the sinus becomes horizontal just before it ends in the jugular fossa, so that at this point the skull forms its floor instead of its outer wall.

After having exposed the sinus as freely as possible, the ‘bridge’ of bone separating it from the outer wall of the jugular foramen is removed in small pieces by nipping it away with narrow biting forceps until the jugular bulb is exposed from its outer surface. The facial nerve should not be injured, as it lies in front and external to the portion of the bone to be removed.

In performing the later stages of the operation, the patient’s head should be turned well over to the opposite side in order to get a good view of the parts lying behind and beneath the mastoid process; and in tracking the sinus downwards, the probe should be used carefully in order to try and define the exact position of the jugular fossa.

=Piffl’s operation.= Owing to the anatomical difficulty of reaching the jugular bulb by following the sigmoid sinus downwards, especially in those cases in which the sinus lies far forwards and in which, at the same time, there is a very well-developed jugular fossa, Piffl recommends exposure of the jugular bulb from above through the auditory canal. The object of this method is to prevent injury to the facial nerve, which he states is almost certain to occur in Grunert’s operation, if carried out in cases such as those just mentioned.

After the complete mastoid operation has been performed, the skin incision is extended downwards and forwards in order that the soft tissues may be freed from the floor and anterior surface of the bony portion of the auditory canal as far forward as the Glaserian fissure. The soft tissues are pulled forward with a blunt hook to give sufficient room. The lower portion of the tip of the mastoid is removed by means of the gouge, as far as can be done without injuring the facial nerve, which in this operation is pulled backwards with the soft tissues at the posterior inferior margin of the wound. The lower bony margin of the auditory canal, now freely exposed, is removed by means of a pair of fine biting forceps until the floor of the tympanic cavity is reached. If there be not sufficient room, the bone may be clipped away as far as the styloid process, which also may be removed by bone-forceps after the muscles attached to it have been dissected off.

In freeing the styloid process, its posterior surface must be approached with caution for fear of injuring the facial nerve, which here lies in close connexion with it. In the front of the wound the capsule of the temporo-maxillary joint may be exposed, but must not be interfered with.

After removal of the styloid process, the uppermost portion of the external jugular vein should be seen emerging from the jugular fossa. This is followed upwards by careful removal of the bone between it and the floor of the auditory canal and tympanic cavity, until the jugular bulb is brought into view. This part of the operation must be proceeded with very cautiously, the bone being nibbled away in small fragments with gouge forceps which are of sufficient strength to nip through the bone without having to wrench it away. The amount of bone to be removed and the difficulty of the operation depend largely on the anatomical condition found.

Whether Grunert’s or Piffl’s operation has been employed, the operation may be completed either by incising the outer wall of the sinus and jugular bulb, then curetting out the thrombus, and finally washing through the lower portion of the vein from above downwards, or by the more radical method of also exposing the upper portion of the jugular vein throughout its whole length. To do this the post-aural incision is continued downwards until it joins the one previously made in the neck. To obtain room, the neck must be somewhat extended and the jaw pulled well forward and the sterno-mastoid muscle backwards. The jugular vein is then dissected upwards towards the bulb.

The nearer the jugular fossa is approached the deeper and more difficult becomes the exposure of the vein. Passing in front of it may be found the stylo-pharyngeal, stylo-hyoid, and digastric muscles. In Grunert’s operation they need not be cut through as the vein will lie posterior to them. In Piffl’s operation these muscles probably have been already reflected forward, after removal of the styloid process.

Particular care must be taken not to injure the nerve trunks, which are in such close relationship with the vein. Lying immediately behind the vein is the vagus nerve; the spinal accessory passes downwards and outwards behind it, and the glosso-pharyngeal and hypoglossal nerves forwards between the vein and the internal carotid artery.

After the vein, the jugular bulb, and the sigmoid sinus have been exposed throughout their course, their outer wall is cut through with a pair of blunt-pointed scissors along its whole length, so as to convert the venous canal into an open gutter. The thrombus is then curetted out and the dissected portion of the jugular vein cut off as high up as possible. Any bleeding from the inferior petrosal sinus or condyloid veins, which may not be thrombosed, should be arrested by direct pressure of a strip of gauze over the bleeding points. The wound cavity is then washed out with a weak biniodide solution and dried.

The lower portion of the incision in the neck may be closed with sutures and a small drainage tube inserted at its lower angle. The upper portion of the wound, now directly continuous with that of the mastoid cavity, is left open and packed lightly with gauze, which is inserted into the remains of the venous channel.

=Comparison of operations for lateral sinus thrombosis.= Except when the thrombus is limited to the upper part of the sigmoid sinus, it is undoubtedly wiser to tie the jugular vein than to be content with curetting out the clot after obstructing the sinus above and below by means of gauze plugs. Exposure of the jugular bulb is so difficult an operation and requires so much time, especially if the whole length of the upper portion of the jugular vein is also dissected out, that it is seldom advisable to perform it; nor will it often be justifiable owing to the condition of the patient, who is seldom strong enough to undergo such a prolonged operation. The records of this particular operation are so few that it is impossible as yet to determine its value.

If the sinus be exposed as low down as possible, and the jugular vein dissected out and brought out into the neck, and the venous channel afterwards syringed through, the chances of recovery should be almost as good as in the case of free exposure of the jugular bulb.

If the inferior petrosal sinus be already infected before the operation, it does not matter whether the operation performed is that of syringing through the jugular bulb or freely exposing it, as in either case the inferior petrosal sinus cannot be followed out.

Curetting of the lower portion of the sinus without previous ligature of the jugular vein should never be done.

=Difficulties and dangers of the operation.= The chief difficulty in these operations is anatomical; the chief danger is hæmorrhage.

If the hæmorrhage be due to accidental tearing of the wall of the sinus in the earlier part of the operation, and if it be impossible to obliterate the sinus below this point by pressing in gauze between its wall and the underlying bone, then the jugular vein should be tied before anything else is done.

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 assistants 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 pricking 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 pyæmia and septicæmia.

=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.