3. Extensive adhesions between the membrane and inner wall may render it difficult to separate the shaft of the malleus without fracturing its neck.
4. In old-standing cases in which there is a large perforation of the membrane, the malleus may be so retracted as not only to be difficult to see but difficult to seize. In this particular case, division of the tensor tympani with Schwartze’s tenotome and then extraction of the malleus by means of Sexton’s forceps is a better procedure than trying to encircle its shaft with Delstanche’s ring-knife.
5. Removal of the incus by the ordinary instruments may be rendered impossible owing to the narrowness of the attic posteriorly from chronic thickening of its walls. In these cases a seeker, such as Schwartze uses in the mastoid operation ([Fig. 219]), may be employed with advantage. It is passed over the incus in the same manner as an incus hook.
Accidents. 1. Fracture of the handle of the malleus. This is the result of too forcible extraction. If a Delstanche’s ring-knife has been used, this may be due to the tensor tympani not having been cut through; this should now be done. The head of the malleus is then removed either by means of a small hook or some form of curette bent at right angles to its shaft, depending on what is most suitable for the case in question.
2. Failure to extract the incus. In the course of a chronic middle-ear suppuration, the incus may become exfoliated or gradually disappear as the result of caries. It does not therefore always follow that inability to extract the incus means that the surgeon has failed in his manipulations, although frequently this is the case, the instruments failing to extract the incus, or perhaps dislodging it into the mastoid antrum, a fact which is difficult to determine and may only be discovered if the subsequent performance of the complete mastoid operation becomes necessary.
3. Facial paralysis. This accident is usually due to the incus hook not being inserted high enough up, so that, instead of entering the attic, it presses on the inner upper border of the tympanic cavity, and on being rotated in a backward and downward direction, it follows the line of the facial canal (Fig. 208). If much force be employed the frail wall of the facial canal will be fractured or pressed in on the underlying facial nerve. It is very rarely, however, that the nerve is completely crushed or torn through, and therefore recovery almost invariably takes place.
The facial nerve may also be injured whilst curetting away granulations in the upper posterior part of the tympanic cavity.
| Fig. 208. Diagrammatic Section to show Correct and Wrong Positions of Incus Hook. A, Facial nerve canal; A', Facial nerve, in section; B, Antrum; C, External semicircular canal; D, Incus hook in its correct position in the attic, above facial canal; E, Incus hook in wrong position, about to press on facial canal; F, Promontory. |
4. Injury to or removal of the stapes. This very rarely occurs during the act of removal of the incus, but is generally the result of too violent curetting. If only the crura be broken off, it does not matter; but if the stapes itself be dislodged from the fenestra ovalis, the subsequent symptoms may be attacks of vertigo, nausea, and vomiting. As a rule these symptoms subside. If, however, the internal ear becomes infected (although judging from literature and my own experience this is of very rare occurrence), complete deafness or even meningitis may occur as the result of labyrinthine inflammation or suppuration.
Results. (a) With regard to arrest of the disease. If the disease be limited to the ossicles themselves and to the anterior and outer part of the attic, a favourable prognosis may be given. Complete cessation of the discharge and scarring over of the affected part may take place within a month, or after a much longer period.