Journal of Otology & RhinologyISSN: 2324-8785

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Case Report, J Otol Rhinol Vol: 4 Issue: 5

Endoscopic Stapedotomy for Congenital Absence of Stapes

Jiun Fong Thong, Willis SS Tsang and Michael CF Tong*
Department of Otorhinolaryngology-Head and Neck Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
Corresponding author : Prof. Michael Tong, FAMS
Department of Otorhinolaryngology-Head and Neck Surgery, 6th Floor, LuiChe Woo Clinical Sciences Building, Prince of Wales Hospital, The Chinese University of Hong Kong 30-32, NganShing Street, Shatin, Hong Kong, China
Tel: +8522632628
E-mail: [email protected]
Received: August 07, 2015 Accepted: October 09, 2015 Published: October 14, 2015
Citation: Thong JF, Tsang WSS, Tong MCF (2015) Endoscopic Stapedotomy for Congenital Absence of Stapes. J Otol Rhinol 4:5. doi:10.4172/2324-8785.1000252

Abstract

Objective: To describe our experience with endoscope-assisted stapedotomy in a patient with congenital absence of stapes.

Patient: Female patient with bilateral congenital absence of stapes.

Intervention: Endoscopic stapedotomy.

Results: The patient recovered well with closure of air-bone gap on pure-tone audiogram postoperatively.

Conclusion: A rare case of congenital absence of stapes managed by endoscopic-assisted surgery is presented. The aetiology of this condition and the relative benefits of using the endoscope in such cases of congenital middle ear malformation are discussed.

Keywords: Endoscopic Stapedotomy; Congenital Absence; Stapes

Case Report

A 32 year old lady was diagnosed with bilateral conductive hearing loss since childhood and was on bilateral hearing aids. Previous right tympanotomyto improve the hearing was attempted in another unitbut the surgery was abandoned. Pure-tone audiogram showed bilateral moderate to severe conductive hearing loss (hearing thresholds 50 to 85 decibels).Computed tomography (CT) scan of the temporal bones was performed and this revealed bilateral congenital absence of the stapes and abnormal facial nerve anatomy (Figure 1). The tympanic segment of the facial nerve was inferior to the oval window bilaterally. The patient underwent left stapedotomy with the conventional assistance of the microscope and surgery was successful with improvement of hearing. However this was complicated by temporary left facial palsy.
Figure 1: Computed tomography (CT) scan of the right temporal bone in coronal view showing absence of stapes suprastructure (*) and the dehiscent tympanic segment of facial nerve abnormally located inferior to the oval window (arrow).
A few years later, the patient was keen for surgery to the other ear. This time, endoscopic-assisted ear surgery was performed. As previous tympanotomy was done in the right ear, the scutum was already removed and the chorda tympani were found to be severed. Adhesions between the tympanic membrane and middle ear were broken down. Visualisation with the endoscope was superior to the microscope and the anatomy of the middle ear was clearly visualised (Figure 2). The malleus and long process of incus were seen and found to be in continuity and mobile. The stapes suprastructure was absent. A depressed bony area corresponding to the region of the oval window was easily identified superior to the dehiscent tympanic facial nerve. The stapes footplate over the oval window was fixed. Skeeter drill was used to fenestrate the footplate under endoscopic visualisation and a platinum-fluoroplastic stapes piston was crimped onto the long process of the incus (Figures 3 and 4). There was good ossicular chain mobility at the end of surgery. The patient recovered well postoperatively and had closure of air-bone gap on pure-tone audiometry.
Figure 2: Endoscopic view of middle ear structures following elevation of tympanomeatal flap (I- incus, OW- oval window, FN- facial nerve, RW- round window niche).
Figure 3: Endoscopic view showing drilling of the fixed stapes footplate with the Skeeter drill (I- incus, SD- Skeeter drill).
Figure 4: Endoscopic view showing a platinum-fluroplasticstapes piston (red arrow) crimped onto the long process of the incus (I- incus, FN- facial nerve, RW- round window).

Discussion

Endoscopic ear surgery is becoming increasingly popular as it allows minimally invasive transcanal access to the middle ear with excellent visualisation [1]. The endoscope allows the surgeon to clearly visualise areas not so easily seen with the microscope which only allows a straight line of vision. The wide-angle zero-degree HOPKINS® II endoscopes provide high-definition magnification and the ability to see around corners because of its wide view. In addition, angled (30 degree and 45 degree) endoscopes are also available and enable even better visualisation of ‘hidden spaces’ in the middle ear.
Congenital absence of stapes is rare and was first reported in 1955 [2]. As in our case, the facial nerve was dehiscent and found to be abnormally located inferior to the oval window. This congenital malformation is believed to be related to abnormal facial nerve development, whereby displacement of the facial nerve from the fallopian canal during the fifth to sixth week of gestation causes disruption of contact between the otic capsule’s footplate and the stapes blastema. As a result, the stapes suprastructure fails to develop [3,4].
In congenital cases of conductive hearing loss, as such presented, the middle ear structures and facial nerve anatomy are frequently abnormal. The oval and round windows may be abnormally located (or even absent) and may be difficult to identify with the microscope. Hence, the potential for injury to the facial nerve and inner ear structures is high especially to the undiscerning surgeon. With the introduction of endoscope-assisted ear surgery, superior visualisation may help to minimise inadvertent surgical complications and allow surgeries to be completed where they may previously have been abandoned. Using the endoscope, the area corresponding to the oval window was clearly visualised above the dehiscent facial nerve in our patient, allowing safe drilling of the fixed stapes footplate under direct vision.

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