Endoscopic Stapedectomy

Abstract 

The evolution of stapes surgery for otosclerosis has undergone several advancements to reach its current form. Although the microscopic approach to stapes surgery is still the current treatment standard for otosclerosis, endoscopic stapedectomy is a relatively new approach that has been gaining traction as a minimally invasive option. Endoscopic stapedectomy includes several important steps including incudostapedial joint separation, downfracture and removal of the stapes suprastructures, and prosthesis placement. These steps require a high level of technical skill and present a steep learning curve. However, this approach includes several technical advantages to decrease morbidity and support patient outcomes. Here, we present the endoscopic approach to repair otosclerosis and ultimately improve conductive hearing loss. 

Case Overview

Background

Otosclerosis is a disease of abnormal bone remodeling in the middle ear which causes the bony otic capsule and stapes footplate to be replaced by irregular spongy bone and eventually dense, sclerotic bone.¹ This results in changes to conductive hearing and balance based on disease progression and affected areas. Endoscopic stapedectomy is a surgical treatment option to restore the mechanical transmission of vibrations and sound within the middle ear. Although traditionally performed using microscopes, the endoscopic approach has been gaining traction with key benefits including superior increased visualization of the operative field, minimally invasive approach, and higher preservation rates of the chorda tympani nerve.² This video highlights the surgical steps to perform an endoscopic stapedectomy.

Focused History of the Patient

This patient presented with gradual, progressive hearing loss and ringing in the left ear. An audiogram demonstrated a conductive hearing loss and she had no history of ear infections, surgery, drainage, pain, or other concerning symptoms such as vertigo. 

Physical Exam

On physical exam, most patients present with gradual conductive hearing loss that usually starts in one ear before involving the other ear for bilateral hearing loss. Other symptoms may include tinnitus and vertigo. Otoscopic examination may not reveal significant findings but active otosclerosis may rarely show reddish discoloration of the promontory vascularity through the eardrum, known as the Schwartz sign in 10% of patients.^3, 4

Imaging

Although primarily diagnosed by history and audiometric testing, imaging plays a supportive role in diagnosis, staging/grading, prognosis, surgical planning, outcomes, and complications.⁵ High-resolution computed tomography (HRCT) is the standard imaging for diagnosis of otosclerosis, mainly to rule out other pathology and causes of hearing loss. Active otosclerotic foci may appear as hypolucent areas at the fissula ante fenestram or the cochlea (halo sign).⁴ Although the sensitivity of HRCT in diagnosis ranges from 34–95%, detection rates over 90% have been reported for fenestral otosclerosis. The specificity of HRCT for otosclerosis detection is much higher, up to 100%.⁶

Natural History

Otosclerosis is a multifactorial disease with genetic and environmental factors. Most people are diagnosed between the ages of 10 and 45, and most commonly in their 30s. This disease primarily affects the white population and is twice as likely in women compared to men.⁷ Hearing loss typically begins in the third decade, usually beginning in one ear before progressing to the other in 70–85% of patients.⁸ Although traditionally affecting the middle area, disease progression may also include the inner ear, causing mixed or pure sensorineural hearing loss.⁸ The course of this disease is variable and there is a current lack of validated evidence for specific risk factors and disease modifiers. Some proposed factors include different genes including COL1A1, TGF-β, angiotensin II, and class I major histocompatibility complex.^9, 10  Additional potential risk factors include measles virus, puberty, pregnancy, and menopause hormonal factors.^9, 10  

Options for Treatment

Otosclerosis may be treated through surgical management or more conservative medical management. Surgical treatment options include stapedectomy, the removal of the stapes footplate and crura and replacement with a prosthesis, and stapedotomy, where a small hole is made in the stapes footplate and placement of a prosthesis.^11, 12 Stapedectomy is the surgical treatment of choice with a high level of safety and efficacy. For endoscopic and traditional stapedectomy, the rate of air-bone gap (ABG) closure to less than 10 dB is 76.6% and 72–94%, respectively.¹³ Stapedotomy is also a viable option with comparable results and reduced postoperative complications.  Vincent reported a postoperative ABG closed to 10 dB in 94.2% of cases in 3,050 stapedotomies.¹⁴

Although the efficacy of medical management including amplification is controversial, there are several therapies that may play a role in slowing down disease progression, preventing disease progression, or managing symptoms. Sodium fluoride may slow progression by neutralizing hydrolytic and proteolytic enzymes causing stapedial fixation.¹⁵ Bisphosphonates act to counteract bone resorption and turnover to prevent osteolytic lesions with good efficacy in patients with positive Schwartz signs.¹⁵ Another conservative option may be the use of hearing aids, which does not alter disease progression, but improves conductive hearing.¹⁵

Rationale for Treatment

The goals of treatment are to restore hearing levels to an acceptable threshold. Without surgical intervention, disease progression may cause significant hearing loss, impairing daily activities and quality of life. Some patients with severe or long-term otosclerosis may experience severe mixed hearing loss or even deafness.

Discussion

This case includes several key steps that are similar to the microscopic approach and stapedotomy as follows: 1) Slow local anesthetic injection for optimal hemostasis and minimal blistering, 2) Tympanomeatal flap elevation to the level of the annulus with scutum removal, 3) Incudostapedial joint separation with downfracture of the stapes superstructure, 4) Stapes footplate removal, and 5) Graft and prosthesis placement. Notably, this case was converted from a stapedotomy to a stapedectomy due to adhesions requiring removal of the stapes footplate. 

Stapes surgery had four major eras: the pre-antibiotic era, the fenestration era, the mobilization era, and the current stapedectomy era.¹⁶ The first stapes surgery is credited to Johannes Kessel in 1876, and further advanced by Julius Lempert in 1938 with the single-stage fenestration operation. Eventually John Shea described the first stapedectomy procedure in 1956, which has remained the current standard for otosclerosis therapy.¹⁶ Currently, microscopic assisted stapedectomy remains the most common technique, however the use of endoscopes has been gaining traction after Tarabichi described his experience with endoscopic middle ear procedures in 1999.¹⁷ While stapes surgery has been well developed with high safety and efficacy, there some potential complications. Complications of stapedectomy may include tympanic membrane perforation while elevating the tympanomeatal flap, chorda tympani damage, sensorineural hearing loss, perilymph fistula, vertigo, facial nerve injury, tinnitus, and necrosis of the incus and granuloma formation.^7, 12, 13 

Endoscopic stapedectomy is comparable and even superior in some aspects to the microscopic approach. Audiological outcomes of the endoscopic approach are comparable to the microscopic approach with studies showing the ABG closure within 10 dB in 76.6% of cases and within 20 dB for 95.3% of cases, with shorter operative times and low complication rates including chorda tympani nerve injury, facial nerve injury, tympanic membrane perforation, and vertigo.^13,18,20 A randomized clinical trial found that compared to microscope assisted stapedectomy, the endoscopic approach has decreased operative time, decreased post-operative pain, similar ABG closure, less bone removal, superior chorda tympani handling, and better visibility of the footplate area.²¹ In this case, the chorda tympani nerve is clearly visualized with the endoscope and unnecessary stretching and damage was avoided. Additionally, the scar tissue on specific areas of otosclerosis are visualized, allowing for more accurate perioperative disease evaluation. 

Some potential drawbacks of the endoscopic approach include decreased depth perception compared to microscopes, which may require special attention when working with the footplate area. In this case, the stapes footplate was fractured, and the case was converted from an endoscopic stapedotomy to a stapedectomy. Significant bleeds or perilymph gush may also require a conversion to a microscope approach or procedure failure due to the inherent requirements of a clear working field with endoscopes.²¹

The endoscopic stapedectomy represents a surgical treatment option for otosclerosis with comparable safety and efficacy outcomes to microscopic approaches. Benefits of this approach include superior field of view (particularly with difficult or variant anatomy), minimal invasiveness, and decreased complications. Limitations include decrease depth perception, single-handed technique, and learning curve. 

Equipment

Endoscope (0-3 mm)
KTP Laser 
Rosen needle/footplate hook
Hough Hoe-Style elevator

Disclosures

C. Scott Brown serves as Editor for the Otolaryngology Section of the Journal.

Statement of Consent

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.