Intraoperative Monitoring

Facial nerve injuries are the most feared untoward consequence of cholesteatoma surgery. The necessity of intraoperative facial nerve monitoring when performing cholesteatoma surgery remains controversial. A survey of practicing otologists performed in 1990 showed that most experienced otologists do not believe that facial nerve monitoring is obligatory, and many experienced otologists use it only occasionally.12 They do not believe the extra expense and time required to use the technique is justified and expressed concern that the device can be misleading. "Silent" transections do occur, and the use of a facial nerve monitor does not ensure against facial nerve injury. They recognize that intraoperative monitoring can be begun in the middle of a case when difficult circumstances that justify its use are encountered.

Other surgeons argue that one can never predict the cases in which facial nerve monitoring may be useful and that the expense and time required to set it up is justified in every case. They see it as a "safety net," much like electrocardiographic (ECG) monitoring, that is always potentially useful.13 Most surgeons who use facial nerve monitoring do not feel compelled to do so by medical/legal considerations. However, they would feel uncomfortable about a case in which the facial nerve was injured and monitoring was omitted.13 An effective use of facial nerve monitoring techniques requires experience. Some surgeons justify routine use of the facial nerve monitor as a method of developing and retaining

experience in its use.

Some surgeons pursue an intermediate course and do not use facial nerve monitoring on a regular basis, but only for selected cases. These cases may include revision operations, circumstances in which the patient had previous postoperative facial nerve paralysis, or, for patients who have preoperative facial nerve involvement, either paresis or hyperirritability, or cases in which preoperative scanning shows anomalies or dehiscence of the fallopian canal.14

REFERENCES

Roland—CHAPTER 37

1. Mancuso A, Harnsberger H, Dillon W. MRI and CT of the head and neck. 2nd Ed. Baltimore: Williams & Wilkins; 1989

2. Sheehy J, Brackmann D, Graham M. Complications of cholesteatoma: a report of 1024 cases. In: McCabe B SJ, Abramson M, eds. Cholesteatoma, First International Conference. Birmingham, AL: Aesclapius, 1977:420

3. Sheely J. Mastoidectomy: the intact canal wall procedure. In: Brackmann D, Shelton C, Arriaga M, eds. Otologic Surgery. Philadelphia: WB Saunders; 1997

4. Paparella M, Meyerhoff W, Morris M, DaCosta S. Mastoidectomy and tympanoplasty. In: Parparella MM, Shumrick DA, Gluckman JL, Meyerhoff WL, eds. Otolaryngology. Vol 2. Philadelphia: WB Saunders, 1991:1405-1439

5. Smyth G, Tower J. Mastoidectomy: canal wall down techniques. In: Brackmann D, Shelton C, Arriago M, eds. Oto-logic surgery. Philadelphia: WB Saunders, 1997

6. Cook J, Krishnan S, Fagan P. Hearing results following modified radical versus canal-up mastoidectomy. Ann Otol Rhinol Laryngol 1996;105:379-383

7. Whittemore K Jr, Merchant S, Rosowski J. Acoustic mechanisms: canal wall-up versus canal wall-down mastoidectomy. Otolaryngol-Head Neck Surg 1998;118:751-761

8. Dodson E, Hashisaki G, Hobgood T, Lambert P. Intact canal wall mastoidectomy with tympanoplasty for cholesteatoma in children. Laryngoscope 1998;108:977-983

9. Bhatia S, Karmarkar S, DeDonato G, et al. Canal wall down mastoidectomy: causes of failure, pitfalls, and their management. J Laryngol Otol 1995;109:583-589

10. Law K, Smyth G, Kerr A. Fistula of the labyrinth treated by staged combined approach tympanoplasty. J Laryngol Otol 1975;89:471-478

11. Sheehy J, Shelton C. Tympanoplasty: to stage or not to stage. Otolaryngol Head Neck Surg 1991;104:399-407

12. Roland PS, Meyerhoff WL. Intraoperative facial nerve monitoring: what is its appropriate role? (Editorial.) Am J Otol 1993;14:I

13. Pensak M, Willging J, Keith R. Intraoperative facial nerve monitoring in chronic ear surgery: a resident training experience. Am J Otol 1994;15:108-110

14. Silverstein H, Rosenberg S. Intraoperative facial nerve monitoring. Otolaryngol Clin North Am 1991;24:709-725

The primary objectives of management of chronic otitis media with and without cholesteatoma include (1) elimination of infection or cholesteatoma; (2) prevention of recurrent disease; and (3) reconstruction of the tympanic membrane and ossicular chain to minimize the postoperative air bone gap. As judged by published success rates in achieving a dry, safe ear over time and in reconstruction of the middle ear, surgical management of the chronic ear remains one of the more challenging disease processes in otology. In chronic otitis media with cholestea-toma, combined rates of either residual or recurrent cholesteatoma occur in up to 50% of patients.1-3 In general, most series suggest a lower recidivism rate for cholesteatoma in cases managed by canal wall-down technique as compared with canal wall-up.3-6 However, even without recurrent cholesteatoma, the canal wall-down technique appears to predispose the patient to persistent or recurrent intermittent drainage requiring revision surgery7-9 in up to 60% of cases.

Hearing results have been likewise disappointing in chronic otitis media as compared with other middle ear reconstructive problems. Thus, postoperative air bone gaps > 20 dB were reported in 38%,10 and > 30 dB in 30%.n In 400 second-stage procedures of chronic otitis media, closure of the air bone gap to < 20 dB occurred in 68% of patients with intact stapes. In general, postoperative air bone gaps are even larger when the stapes superstructure is not intact.5'12-14

Although some authors a priori prefer either the canal wall-up technique2,15 or canal wall-down technique,16 it is this author's opinion that each case should be individualized to minimize recurrence of disease.

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