Stapedectomy Periprocedural Care

Updated: Oct 24, 2018
  • Author: Rodney C Diaz, MD, FACS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Periprocedural Care

Pre-Procedure Planning

Preoperative evaluation

A thorough preoperative evaluation including a comprehensive physical exam should be performed to identify conditions that may present similarly to otosclerosis or may occur in conjunction with otosclerosis. For example, a history suggestive of a congenital dysplasia, as in the case of an enlarged vestibular aqueduct, or autophony, with accompanied sound induced vertigo, would be more suggestive of a semicircular canal dehiscence.

Otoscopy

Preoperative binocular microscopy should be performed and with inspection of the tympanic membrane to rule out evidence of atelectasis or cholesteatoma. Close inspection for the presence of myringosclerosis can point towards fixation of any of the ossicles.

Tuning fork testing

Rinne and Weber testing should be performed with 512 Hz (and optionally 1024 Hz and 2048 Hz) tuning forks to document conductive hearing loss.

Audiometry

Preoperative audiometry should be performed in all patients undergoing stapedectomy. Pure tone thresholds should be confirmed with tuning-fork tests prior to surgery for documentation of true hearing loss. Speech audiometry is important to document integrity of speech discrimination.

Immittance testing is necessary for all patients undergoing stapedectomy surgery. Acoustic reflex testing is a requirement, as the presence of intact acoustic reflexes must compel the surgeon to search for other causes of conductive hearing loss, such as superior semicircular canal dehiscence or other third-window fistulae

The usual pattern of otosclerosis is a normally shaped tympanogram with a large air-bone gap with absent stapedial muscle reflexes for both ipsilateral and contralateral stimulation. Occasionally, an A subtype S tympanogram may be identified, signifying normal tympanometry with decreased compliance in ossicular chain mobility. A Carhart notch, decreased bone conduction threshold at 2000 Hz, is typical and is indicative of otosclerosis. 

Preoperative imaging

Temporal bone CT can sometimes be used in preoperative analysis of oval window width and facial promontory angle to predict operative difficulty. [15]

However, in general, for primary procedures, preoperative imaging is not required for patients with a typical presentation of otosclerosis. Occasionally, CT scanning of the temporal bone can be useful for identifying anatomical variants (ie, dysplasia of the IAC or cochlea consistent with X linked gusher) that could pose problems during surgery or for possible factors that could explain surgical failure in revision operations.  

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Equipment

Necessary equipment for stapedectomy includes a full set of middle-ear instruments with multiple sizes of otologic specula. Some surgeons use a speculum holder for steadying the speculum and freeing the hands for other instruments. Various blades, including a sickle knife and round knife, must also be available.

An operating microscope with a 200- to 250-mm objective is used for the entire procedure. Various microscopes are available with both fixed and adjustable focal lengths. The microscope is typically covered with a sterile drape for the procedure.

Recently, the endoscope has been used as an alternative approach to visualization during stapedectomy/stapedotomy. However, the mainstay of stapes surgery remains the transcanal approach utilizing the operating microscope. One study analyzed the audiological outcomes achieved by endoscopic surgery versus those with the microscope and showed similar hearing outcomes. However, the endoscopic approach required longer initial operative times. Challenges to stapes surgery with the endoscope include instrument limitation, single-handed work, lack of stereoscopic view, and a potentially high surgeon learning curve. [16, 17, 18]

Various methods are used for creating the fenestration in the stapes footplate. A Skeeter drill or microdrill has been used by some surgeons. Other authors suggest using a laser to minimize the vibrations caused by the drill on the stapes footplate, with a possible drop in bone conduction thresholds from sensorineural hearing loss at high frequencies due to acoustic trauma at the basal turn. [19] Multiple types of lasers have been advocated, including argon, KTP, and CO2 lasers. [20, 21, 22] Reports have shown no apparent difference between microdrill and the various laser techniques regarding drop in bone conduction thresholds. [23, 24, 25, 22, 26] Various modifications, including hand-held laser delivery devices (eg, Omniguide), are also available.

Potential damage to the membranous labyrinth due to the different absorptive properties of the various laser wavelengths in relation to the inner ear structures has caused some stapes surgeons to advocate for specific laser modalities over others. There are theoretical advantages to the use of the CO2 laser, due to its high reflectance off of the perilymph, versus the KTP and argon laser, which due to their lower wavelengths allow greater penetration into the perilymph and potentially greater energy absorption by the pigmented tissues of the membranous labyrinth in the line of laser fire at the base of the vestibule (ie, the saccule). [27]

When patients are under general anesthesia for the procedure, a facial nerve monitor is often used during the case. It is important to realize that the use of the facial nerve monitor does not eliminate the risk of facial nerve injury during stapedectomy. There is no substitute for a thorough knowledge of the middle-ear anatomy in order to avoid complications. The monitor can provide the surgeon with feedback while microdissection in the area of the facial nerve is performed, allowing the surgeon to modify technique to minimize risk of injury to the nerve. Electrodes are usually applied above the eye on the operative side within the orbicularis oculi muscle and above or below the lip on the operative side within the orbicularis oris. Grounding electrodes are placed in the forehead, upper chest, or shoulder.

Types of prostheses

Many types of prostheses exist for reconstruction in stapes surgery. Prostheses can be categorized as either hooked or handled prostheses.

Hook prostheses have shepherd’s crook–type open loops that hook around and are mechanically crimped or self-crimp around the incus, whereas handled prostheses have an articulating handle that swings above the incus to secure the incus lenticular process into a bucket-shaped hollow within the prosthesis shaft.

Self-crimping prostheses are made from nitinol. The wire of the prosthesis is made to the diameter of the incus; this will be stretched to the appropriate size for placement during surgery. When heated with a laser during surgery, it will return to its original diameter allowing for circumferential crimping of the hook without having to squeeze the incus with a manual crimper. [28]  

There have been few studies comparing the many available prostheses, and a true comparison of outcomes is not feasible due to outcomes being heavily dependent on experience of the operating surgeon. 

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Patient Preparation

Anesthesia

Stapedectomy procedures are performed under either local monitored anesthesia care (MAC) or general anesthesia. Long-acting paralytics are not recommended owing to the inability to monitor facial nerve function.

The planned posterior canal skin incision area is typically infiltrated with lidocaine or bupivacaine (Marcaine) with diluted epinephrine. Some surgeons use diluted epinephrine (ie, 1:100,000) without anesthetic since injected solution sometimes migrates into the middle ear in the vicinity of the facial nerve, with resultant inability to monitor facial nerve function. Currently, however, no published literature supports the necessity of this practice. [29]

In patients who undergo surgery under MAC anesthesia, routine facial nerve monitoring is not required.

Approximately 2.5–3 mL of the anesthetic of choice is used. Injection is also performed at the vascular strip in order to reduce bleeding during the incision. Some surgeons also include an incision just anterior to the helical crus for improved exposure for the procedure. [30] If this is to be included, additional anesthetic should also be injected into this area.

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Positioning

The patient is placed in the supine position on the operating table with the head turned to the opposite side from the operative ear, to about 30–45°. The head is held in place by tape placed across the patient’s forehead, securing him or her to the bed. The bed is almost uniformly turned 180° and the patient’s head positioned as close to the operating side as possible. The patient’s arms are tucked to his or her sides with adequate padding. Additionally, the patient is secured to the table with a waist band in case the bed must be rotated during the procedure.

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Monitoring & Follow-up

Typically, patients are discharged home the same day following surgery.

Some patients experience vertigo or dysequilibrium after stapes surgery and should be counseled for this possibility during their preoperative evaluation. This is typically present for only several hours but may last up to several days and is almost always self-limited. Patients should be instructed not to blow their nose after surgery and to sneeze with an open mouth. They also should not strain themselves for a total of 2–4 weeks after surgery.

Patients are generally able to remove the cotton ball and Band-Aid from their ear after surgery the following day. If a Shaw disk is used, it is removed at their first follow-up, in one week following the procedure.

An audiogram is usually performed 3 weeks to one month after surgery, after most patients have regained their hearing. In the subset of patients in whom recovery is more slow, an audiogram repeated at 3–4 months can also be performed.

If the patient requires a revision surgery, it is usually not performed until 3–6 months have passed to allow time for full recovery. Hearing loss with a persistent ABG > 25 dB, persistent intractable vertigo, or facial nerve complication requiring intervention are the main indications for revision surgery. [12]

Patients should undergo annual audiography for the first 5 years after the procedure to ensure stability in hearing improvement.

The failure rate is approximately 5%–10% overall with stapedectomy, which most commonly results from prosthesis malposition. The second most common cause of failure is necrosis of the incus. Recent reports also suggest that patients with otosclerosis are at a higher risk of sensorineural hearing loss than hearing loss due to presbycusis. [8] The authors of this article suggest continued follow-up, as most patients who undergo this procedure ultimately require auditory rehabilitation or hearing aids.

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