Bilateral Otosclerosis and Revision Stapedectomy

Whether otosclerosis is unilateral or bilateral, the medical treatment is the same. The question that confronts otosclerosis surgeons is, rather, should both ears undergo stapedectomy? This is a controversial subject, with many experts for and others against (Porter et al 1995; Smyth et al 1975). It has been found that even with the best techniques, permanent cochlear hydrops can result from surgery on the second ear. Causse et al (1991) found that about one patient in 7000 develops profound sensorineural hearing loss.

RECOMMENDED INTERVAL OF TIME BETWEEN SURGERIES

Causse et al (1991) recommended that the second ear be operated on after a minimum period of 1 year only if the other ear is doing well in terms of hearing and vestibular symptoms. They reasoned that surgically induced severe cochlear deterioration usually occurs within the first year postoperatively. If any problem occurs after that time, it usually manifests itself as a conductive hearing loss.

CONTRAINDICATIONS FOR SECOND EAR STAPEDECTOMY

The two main contraindications for second ear stapedectomy are the following:

1. If the patient develops complications following the first surgery, then the second ear should not be operated on.

2. If the patient develops tinnitus and/or persistent vertigo following surgery upon the first ear, then stapedectomy should not be carried out on the second ear.

ARGUMENTS AGAINST SECOND EAR STAPEDECTOMY

The main arguments against second ear stapedectomy can be summarized in this way:

2. The second ear should be preserved in the event that the operated ear deteriorates.

3. The actual figures reported of sensorineural hearing loss may be higher than those reported because many patients are lost to follow-up.

4. An initial successful stapedectomy can fail many years later, resulting in profound sensorineural deafness.

5. Today there is a marked decrease in the number of patients undergoing stapedectomy, leaving younger surgeons with less experience in dealing with these complicated and technically challenging problems.

6. An inexperienced surgeon should never operate on the second ear.

FACTORS THAT INFLUENCE THE SUCCESSFUL OUTCOME OF SECOND EAR STAPEDECOTMY

Middle ear abnormalities, which are quite common, can adversely affect the success of stapedectomy (Daniels et al 2001). Very reasonable rates of success, however, can be achieved even in the presence of bilateral middle ear abnormalities.

In prognosticating success to patients who are to undergo surgery on the second ear, the surgeon should consider the following:

1. If the first ear was anatomically normal and the procedure was successful, there is a 95% chance that the procedure in the second ear will be successful too (Daniels et al 2001).

2. Most abnormalities occur at a bilateral rate of approximately 25% in the other ear. However, the incidence of bilateral obliterated footplate is 41%, and the bilateral success rate is approximately 60%.

3. The other abnormalities with reduced rates of bilateral success include promontory overhang, malleus fixation, and a dehiscent or overhanging facial nerve.

Abnormal middle ear findings during stapedectomy occur in a significant percentage of patients. Reasonable rates of success and overclosure can still be expected, but this is findings-specific. Understanding this, the percentage of bilateral abnormalities and its impact on predicting rates of success can help the surgeon counsel the patient correctly.

It should not be the patient’s request for second ear surgery that directs the surgeon regarding his or her decision to perform such surgery. Instead, it should be the surgeon’s opinion regarding the patient’s general and oto-logical health that should dictate his or her decision.

With this goal in mind, the surgeon should be familiar with all the nuances of stapedectomy, should be very experienced, and should have the best possible equipment for performing the surgery.

Horn et al (1998) stated that revision stapedectomy offers neither the safety nor the success that is usually associated with primary stapes surgery. The increased surgical variables encountered during revision stapedectomy adversely affect the outcome, resulting in overall decreased air-bone gap closure to approximately 50% and sensorineural hearing loss greater than 1% in most series where mechanical (i.e., where a laser has not been used) revision of primary stapes has been undertaken.

Histopathologic studies in stapedectomy patients conducted by Hohmann (1962), Linthicum (1971), and Schuknecht (1974) have shown adhesions between the prosthesis or the oval window neomembrane and the utricle and saccule. Surgical manipulation of the prosthesis or neomembrane could rupture these delicate inner ear structures, resulting in permanent profound sensorineural hearing loss accompanied by vertigo. Yet the surgeon must uncover the reason why a stapedectomy has failed; this will entail manipulating the various structures in the middle ear and running the risk of a permanent sensorineural hearing loss.

The introduction of lasers for revision stapedectomy has significantly contributed to improvement in hearing while lessening the incidence of complications. Argon, KTP, and carbon dioxide lasers have all been reported to be very useful in revision stapedectomy (Lesinski and Stein 1989; McGee et al 1993; Palva and Ramsey 1990).

CAUSES OF THE REAPPEARANCE OF A CONDUCTIVE HEARING LOSS FOLLOWING STAPEDECTOMY

Most authors (Ayache et al 2000; Fisch et al 2001) report that the most common causes for residual conductive hearing loss or the reappearance of a conductive hearing loss following stapedectomy include migration (displacement) of the stapes prosthesis, erosion of the incus, and bony or fibrous growth of the otosclerotic focus at the oval window. Ayache et al retrospectively reviewed a series of 26 revision stapedectomies. The leading cause of reappearance of a conductive hearing loss was prosthesis malfunction (migration) (42%), fibrous adhesions (37.5%), incus erosion (12.5%), and regrowth of the otosclerotic focus (12.5%). When revision was indicated because of cochleovestibular symptoms, middle ear exploration revealed three problems: oval window granuloma, excessively long prosthesis, and perilymph fistula.