Special Conditions and Complications in Otosclerosis Surgery

In this section we discuss common problems that could be encountered during stapedectomy surgery. Understanding these problems is helpful in providing a solution when dealing with these difficulties, especially when they are encountered during surgery. The occasional stapes surgeon as well as the experienced stapes surgeon could encounter these situations. The experienced stapes surgeon will be taxed when trying to restore hearing in the presence of various obstacles that are present.

CEREBROSPINAL FLUID GUSHER

This complication is also known as a perilymph gusher, although in fact it is cerebrospinal fluid (CSF) that escapes. A CSF gusher occurs when the vestibule is opened and CSF gushes out. It is thought to be due to an abnormal patency of the cochlear aqueduct (Shea 1963) or to a defect in the fundus of the internal auditory canal (Schuknecht and Reisser 1988). A CSF gusher occurs rarely; it was reported in only 0.03% of cases by Causse and Causse (1980). Most cases of CSF gushers are associated with congenital fixation of the footplate in the pediatric population rather than in adults. Suzuki (1960) and Wlodyka (1978), however, showed that as age increases, so does the incidence of patency of the cochlear aqueduct. Farrior and Endicott (1971) reported two convincing cases where ablation of the cochlea aqueduct was required to control a CSF gusher, although author Glasscock (1973) reported the need to pack the vestibule in a CSF gusher because of a defect in the fundus of the internal auditory canal. Schuknecht and Reisser (1988) postulated that a widely patent cochlear aqueduct may be the etiology of an “oozer,” whereas “gushers” are the result of defects in the fundus of the internal auditory canal.

Can the Surgeon Be Alerted Prior to Surgery about the Presence of a Possible CSF Gusher?

Management of a CSF Gusher

Management of a CSF gusher involves the following steps:

1. Elevation of the head

2. Lumbar spinal drain to remove as much CSF as possible

3. Small fenestra stapedotomy

4. Tissue seal over the fenestra is mandatory. Some experts recommend that a prosthesis be placed to keep the seal over the fenestra in place (Wiet et al 1993).

Complete control of the CSF gusher is necessary because this complication has the potential to cause meningitis. The patient’s hearing is likely to deteriorate following such a complication. Some surgeons recommend drilling a small control hole in the footplate prior to creating an actual fenestra for stapedotomy. This is done to avoid a “cork in a bottle” effect when the vestibule is suddenly opened.

MALLEUS FIXATION

Malleus fixation may result from ossification of the superior and anterior suspensory ligaments. The malleus head may be fixed congenitally. Approximately three fourths of malleus fixations are associated with stapedial oto-sclerosis. The incidence of malleus fixation is approximately 1%, as reported by most centers (Lippy and Schuring 1978; Powers et al 1967). Causse and Causse (1980), however, reported that malleus fixation occurs in as many as 10.6% of patients undergoing primary stapedectomy.

Can Malleus Fixation Be Diagnosed Prior to Surgery?

Moon and Hahn (1981) offered several clues to diagnose the presence of malleus fixation:

1. Lack of movement of the manubrium and umbo on pneumatic otoscopy

2. Palpation of the malleus (on occasion, this may prove to be painful, however)

3. Audiologic findings that seldom reveal an air-bone gap of more than 30 dB

4. Acoustic reflexes with isolation of the tensor tympani on impedance audiometry. A jet of air is blown across the cornea or the tragus is stroked; if no readings are detected or if they are faint, it is likely that malleus fixation is present.

Vincent et al (1999) presented the following features by which malleus ankylosis may be suspected:

2. Small air-bone gap predominantly in the low frequencies

3. Association with sensorineural impairment in the high frequencies

4. Acoustic reflex absent on the impaired side but present in the contra-lateral ear

Moon and Hahn (1981) described an atrophic tympanic membrane that becomes flaccid while continuing to function against a fixed malleus handle. Many of these tympanic membranes return to normal once the ankylosis is repaired. Primary malleus fixation occurs late in life, whereas otosclerosis occurs mainly in young or middle-aged adults. A conductive hearing loss of 10 to 15 dB is more commonly seen with isolated malleus fixation (Powers et al 1967). Carhart’s notch, which is typical of stapedial otosclerosis, can also be seen in malleus fixation as a result of ossicular inertia.

Management

If the ossified ligaments are fractured, it is likely that they will get refixed. An incus bypass procedure using either an incus replacement prosthesis (IRP) or a total ossicular replacement prosthesis (TORP) has been advocated. The treatment lies in amputating the head of the malleus after removing the incus. The tympanic membrane is dissected off the handle of the malleus; an IRP is crimped over the handle and placed into the fenestra of the footplate. Sheehy (1982) recommended a TORP in these situations; Fisch et al (2001), however, recommended malleostapedotomy and have reported good results with this technique.

Results

Sheehy (1982) reported that 64% of patients had closure to within 10 dB. Ninety-five percent of cases had a 20 dB or less residual conductive deficit. Results were the same whether an IRP or a TORP was used.

INCUS PROBLEMS ENCOUNTERED DURING PRIMARY STAPES SURGERY

Problems include fusion of the incus to the malleus, accidental dislocation of the incus during surgery, congenital anomalies, and incudal necrosis.

Incus malleus fixation has a 1% reported incidence in association with otosclerosis (Moon and Hahn 1981). Fused malleus and incus are seen in congenital abnormalities of the ear. Postinflammatory changes such as tympanosclerosis, fibrosis, and adhesions can lead to fixation of the incus. An abnormally short or malformed incus may make it difficult to attach the prosthesis to it. One study presenting such features reported that an incus bypass procedure was required (Sheehy 1982). Overall incus problems (fixation, dislocation, and congenital abnormalities) are common indications for a bypass technique. When a bypass technique is undertaken, an IRP or a TORP is most commonly used; it is therefore necessary for the otolaryngologist to be able to perform such bypass techniques. Sheehy (1982) found that such bypass techniques were needed in 2% of primary stapedectomies.

If the incus is accidentally dislocated, it can be replaced without further problems, and the stapedectomy can proceed as usual (Causse and Causse 1980). Alternatively, the incus can be removed and an incus bypass procedure undertaken. An IRP or a TORP can be used in this situation.

Necrosis of the Long Process of the Incus

Lippy and Schuring (1974) recommended a modified Robinson prosthesis, reporting excellent results with the use of this prosthesis.

POSTOPERATIVE REPARATIVE GRANULOMA

Postoperative reparative granuloma is known to cause sensorineural hearing loss following stapedectomy.

Incidence

Kaufman and Schuknecht (1967) found an incidence of 1.3% of cases that developed granuloma formation, and Harris and Weiss (1962) found an incidence of 5% in their series.

Clinical Presentation

Sudden deterioration in hearing 1 to 6 weeks following surgery is suggestive of reparative granuloma. On inspection, the tympanic membrane appears reddish in color, especially at the posterior superior quadrant. Bone conduction and speech discrimination scores are affected. Kaufman and Shuknecht (1967) reported that in the majority of cases symptoms occurred in the first 3 weeks following surgery, and Gacek (1970) reported similar findings. Hearing loss is a typical finding. Vertigo was found to occur in 20 to 35% of cases. In some patients, tinnitus was present.

Some granulomas may occupy the middle ear without invading the vestibule, and these usually heal without catastrophic sequelae. Even though they may extend into the vestibule, they generally are not adherent to the saccule or utricle and can be safely removed (Pratt and Winchester 1962). Those that invade the vestibule, however, are accompanied by sensorineural hearing loss. Serous labyrinthitis is usually an accompanying feature. Such invasive granulomas are usually associated with fat or gelatin sponge being used as a seal on the fenestra created by the surgeon. Reparative granulomas are often found to engulf the prosthesis and long process of the incus, often in direct contact with the tympanic membrane.

Audiological Findings

A pure tone threshold loss for bone conduction is a typical finding. A simultaneous conductive hearing loss may also be present; partly due to the mass effect of the granuloma and partly due to the fluid in the middle ear. There is a marked decrease of speech discrimination scores, usually with a score of 60% or less.

The tympanic membrane is thickened, especially in the posterior half. On occasion, the tympanic membrane may even be edematous.

Etiology