Stapedectomy

The goal of any stapes procedure is to restore the vibration of fluids within the cochlea; increasing communication secondary to increasing sound amplification, bringing hearing levels to acceptable thresholds. The stapedectomy procedure can be dated back to 1892, a time where Frederick L. Jack performed a double stapedectomy on a patient who was reportedly still hearing ten years after the procedure. John Shea, in the early 1950s, realized the significance of this procedure and birthed the idea of utilizing a prosthesis to mimic the stapes bone. On May 1, 1956, John J. Shea performed the first stapedectomy with the use of a Teflon stapes prosthesis in a female patient with otosclerosis - a complete success.

The primary goal when operating on the stapes is to re-establish sound transmission through an ossicular chain that has likely been stiffened through the disease process known as otosclerosis. Otosclerosis, an otic capsule disease that involves absorption of compact bone and the redeposition of spongy-appearing, or spongiotic, bone, is the most common cause of acquired conductive hearing loss (CHL) as a result of stapes fixation.

Otosclerosis will present in patients as an insidious onset of hearing loss that continues to progress. These patients will have difficulty with conversation, especially while chewing, and may hear better in noisy environments due to an occurrence known as the paracusis of Willis. On otoscopic examination, the provider may notice a red blush or discoloration over the promontory - a finding known as the Schwartze sign.

Many etiologic factors have been studied, but none have been widely accepted as a cause. As Markou and Goudakos detail in their review, the primary insult remains unknown, and otosclerosis is generally considered to be a complex disease state caused by both genetic and environmental factors. Autosomal dominant with incomplete penetrance remains the most accepted theory regarding genetic inheritance and is associated with nine possible chromosomal loci (COL1A1, and OTSC1 through OTSC8).

Otosclerosis has been found to primarily affect white individuals, reaching as much as 12% of the population, with 0.3 to 0.4% presenting with clinical symptoms. Disease prevalence is lower in African Americans, Asians, and Native Americans. Gender might play a role, showing a slight female predominance with 1.5 to 2 women affected for every one symptomatic man.

Stapedectomy can effectively treat the significant conductive hearing loss associated with otosclerosis through the reconstruction of the sound-conducting mechanism of the middle ear. Success rates of these procedures are routinely evaluated by observing the degree of closure of a patient’s air-bone gap (ABG) per audiometric evaluation. The ABG is calculated by subtracting the postoperative bone conduction from the postoperative air conduction. A pure-tone average (PTA), or an average of the four tones associated with speech (0.5, 1, 2, and 3kHz), is utilized in these calculations. The minimum ABG that would require surgery is an averaged 20 dB difference resulting from the measurements of the key speech frequencies (0.5, 1, 2, and 3kHz).

Many studies have compared stapedectomy to small fenestra stapedotomy, depicting no significant difference between the two techniques regarding the closure of the ABG, particularly when observing a patient’s PTA. The author defines a stapedectomy as the total or subtotal removal of the stapes footplate. In contrast, a small fenestra stapedotomy is defined as a small hole created by laser or micro drill large enough for the placement of a piston prosthesis. The strongest factor for achieving the desired surgical outcome is the experience of the surgeon who is utilizing the ever-changing techniques and technologies in this field.