Surgical Findings

''Prior to undertaking revision stapes surgery, it is helpful for the otologic surgeon to know what problems he may encounter.

The most common finding at revision surgery is related to prosthesis dysfunction, which is reported to occur in perhaps up to 80% of the cases. The most common intraoperative findings, as cited in the literature, are summarized in Table 16-1. But prosthesis dysfunction, like the other findings noted below, is unlikely to be the only problem detected at surgery. in more than 50% of the cases, it is typical to find more than one cause of failure.7 Within the category of prosthesis dysfunction are the reported findings of slipped, loose, too-long, too-short, bent, fractured, and displaced prostheses. of these, a displaced prosthesis is most commonly found, and is often seen with other problems including oval window adhesions, obliterative regrowth of otosclerosis, a lateralized neomembrane, and incus necrosis (Fig. 16-1).

The finding of a deficient incus is encountered in between 5 and 30% of revision surgeries.19 The spiculated, atrophic, or even absent long process has, at best, only limited contiguity with the stapes prosthesis (Fig. 16-2). Nadol20 notes in his series, though, that it is the only finding on histopathology in just 7% of the cases. There exist many theories as to the etiopathogenesis of this problem. The loss of incus integrity is thought to result from the disruption of an already tenuous vascularity, and can occur

Table 16—1 Findings at Revision Surgery: Causes of Failure

Author(s) and Published Year (No. of Cases)

Prosthesis Incus Adhesions Obliterative Oval Window

Dysfunction Necrosis (%) Regrowth Fistula

Lateral Ossicular

Chain Fixation (%)

Prosthesis Incus Adhesions Obliterative Oval Window

Dysfunction Necrosis (%) Regrowth Fistula

Sheehy et al 198124 (n =1 258)

48

17

5

9

16

2

Derlacki 198518 (n =1 217)

82

30

8

10

10

0.5

Glasscock et al 198725 (n =1 79)

38

19

8

9

4

Farrior and Sutherland 199126

43

28

8

12

3

(n =/ 109)

Langman and Lindeman 199327

49

41

9

6

6

6 )

McGee et al 199322 (n =1185)

20

5

9

6

1

Cokkeser et al 199428 (n =52)

32

34

23

16

10

14

Silverstein et al 19947 (n =1 76)

53

29

29

13

12

6

Peter 199529 (n =1 39)

67

8

13

5

Pedersen 199630 (n =1186)

38

11

19

16

0.3

Han et al 199731 (n =1 74)

58

43

18

24

5

1

Somers et al 19971 (n =1 332)

33

28

13

5

7

2

Hammerschlag et al 199832

39

14

14

5

2

0.8

(n = / 250)

De La Cruz and Fayad 200033

53

26

14

2

0.8

(n = / 356)

Chapter 16 Revision Stapes Surgery

Long Process Incus
FIGURE 16 — 1 Appearance of the middle ear. Upon elevating the tympanomeatal flap, it is common to find the long and lenticular processes of the incus (I), along with the stapes prosthesis, engulfed in scar tissue. The region of the lenticular process is indicated by the arrow. M, malleus.

with any type of prosthesis.19,20 Medial fixation of the prosthesis, a loose crimping, postoperative inflammation, and fixation of the prosthesis (i.e., from adhesions or otosclerotic regrowth) creating friction at the point of incudal-prosthetic contact are postulated causes of the avascular necrosis and resorptive osteitis.20 Management of this problem may be accomplished with recrimping more proximally on the long process (which is associated with a high rate of re-erosion19) or as discussed below.

Patients may present with fluctuant hearing, especially evident with changes in middle ear aeration. The loose-wire syndrome occurs in cases where the attachment of the prosthesis to the incus is via a crimped wire. It consists of a triad of one or more symptoms that are improved with middle ear insufflation. These symptoms include an increase in auditory acuity, an improvement in sound distortion, or an improvement in speech discrimination.21,22 With middle ear insufflation, the tympanic membrane is displaced laterally, tensing the prosthesis wire crimp against the similarly lateralized ossicular chain, and thereby improving mechanical sound conduction. During middle ear exploration, the wire crimp is typically found somewhat loosely secured around the long process rather than solidly connected. The wire may be recrimped or the prosthesis replaced.

Middle Ear Crimper

FIGURE 16-2 Resorptive osteitis of the incus (I). The loss of incus integrity can often be recognized, as in this illustration, by a spiculated long process with the loop of the prosthesis nearly free. The arrow points to the limited area of contact between the prosthesis and the long process of incus. M, malleus.

FIGURE 16-2 Resorptive osteitis of the incus (I). The loss of incus integrity can often be recognized, as in this illustration, by a spiculated long process with the loop of the prosthesis nearly free. The arrow points to the limited area of contact between the prosthesis and the long process of incus. M, malleus.

Although quite rare nowadays, the presence of a reparative granuloma still must be considered a cause when sensorineural hearing loss and dizziness occur shortly after stapes surgery. Hearing loss, vertigo, and a dull, erythematous, tympanic membrane typically herald the occurrence of a reparative granuloma. It may occur with any type of prosthesis or grafting material but is seen to occur less frequently with the stapedotomy-blood sealant technique. Upon entering the middle ear, the surgeon commonly finds a brawny-red mass of granulation tissue that engulfs the prosthesis and incus and extends from the tympanic membrane down into the fossa ovalis. The prosthesis must be removed, the granuloma vaporized or removed, and a tissue sealant placed over the oval window fenestration.

An important cause for middle ear exploration following stapes surgery is the persistence of a perilymphatic leak. A perilymphatic fistula may account for up to 10% of all stapedectomy failures.23 The association of a fluctuant sensorineural hearing level, typically within the low frequencies, along with vertigo often implicates a perilymphatic fistula. However, the symptoms may be quite variable and instead consist of mixed or purely conductive hearing losses, dysequilibrium, and/or tinnitus.23 Fistulas have been identified radiographically by an aggregate of tiny air bubbles at the end of the prosthesis on high-resolution thin-cut CT.16 The presence of a perilymphatic fistula may be confirmed at surgery by the accumulation of clear fluid within or around the oval window during a Valsalva maneuver. To close a fistula the adjacent mucosa should be gently scored. Then either small pledgets of adipose tissue or a larger pressed piece of fat or fascia may be widely laid over the fistula site and this seal augmented with a drop of fibrin glue.

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