Stapedectomy is a surgical procedure in which the stapes bone is removed from the middle ear and replaced with a prosthesis. If the stapes footplate is fixed in position, rather than being normally mobile, the result is a conductive hearing loss. There are two major causes of stapes fixation. The first is a disease process of abnormal mineralization of the temporal bone called otosclerosis. The second is a congenital malformation of the stapes. In both of these situations, it is possible to improve hearing by removing the stapes bone and replacing it with a micro prosthesis – creating a small hole in the fixed stapes footplate and inserting a tiny, piston-like prosthesis. The results of this surgery are generally most reliable in patients whose stapes has lost mobility because of otosclerosis. Nine out of ten patients who undergo the procedure will come out with significantly improved hearing while less than 1% will experience worsened hearing acuity or deafness. Successful surgery usually provides an increase in hearing acuity of about 20 dB. However, most of the published results of success fall within the speech frequency of 500 Hz, 1000 Hz and 2000 Hz; poorer results are typically obtained in the high frequencies, but these are normally less hampered by otosclerosis in the first place.
Stapedectomy process and results Stapedectomy has success rates ranging from 80% to 95%. Stapedectomy closes what is called the "air bone gap" very efficiently, meaning it restores efficient conduction of sound coming through the air close to the level of the best ability of the nerve cells to perceive the sound. It takes 30 minutes to 90 minutes depending on skills and experience of the surgeon and the presence of difficult or easy anatomical access to the stapes. Stapedectomy is performed under either local or general anesthesia depending on the preference of the surgeon. Most surgeons do not make any skin incisions, especially when the surgery is performed with an endoscope. However, sometimes the ear canal is so small that an incision is needed.
Indications Indications of stapedectomy:
Conductive hearing loss (due to fixation of stapes). Air bone gap of at least 30 dB. Presence of Carhart's notch in the audiogram of a patient with conductive hearing loss (relative) Good cochlear reserve as assessed by the presence of good speech discrimination.
Contraindications Contraindications for stapedectomy:
Poor general condition of the patient. Only hearing ear. Poor cochlear reserve as shown by poor speech discrimination scores Patient with tinnitus and vertigo Presence of active otosclerotic foci (otospongiosis) as evidenced by a positive flemmingo sign. Conductive deafness due to Ehlers–Danlos Syndrome (EDS)
Complications Complications of stapedectomy:
Facial palsy Vertigo in the immediate post op period Vomiting Perilymph gush Floating foot plate Tympanic membrane tear Dead labyrinth Perilymph fistula Labyrinthitis Granuloma (Reparative) Tinnitus When a stapedectomy is done in a middle ear with a congenitally fixed footplate, the results may be excellent but the risk of hearing damage is greater than when the stapes bone is removed and replaced (for otosclerosis). This is primarily due to the risk of additional anomalies being present in the congenitally abnormal ear. If high pressure within the fluid compartment that lies just below the stapes footplate exists, then a perilymphatic gusher may occur when the stapes is removed. Even without immediate complications during surgery, there is always concern of a perilymph fistula forming postoperatively. In 1995, Glasscock et al. published a 25-year single-centre review of over 900 patients who underwent stapedectomy and stapedotomy and found complications rates as follows: reparative granuloma 1.3%, tympanic membrane perforation 1.0%, total sensorineural hearing loss 0.6%, partial sensorineural hearing loss 0.3%, and vertigo 0.3%. In this series, there was no incidence of facial nerve paralysis or tinnitus.
Stapedotomy A modified stapes operation, called a stapedotomy, is thought by many otologic surgeons to be safer and reduce the chances of postoperative complications. In stapedotomy, instead of removing the whole stapes footplate, a tiny hole is made in the footplate – either with a microdrill or with a laser, and a prosthesis is placed to touch this area, oval window. This procedure can be further improved by the use of a tissue graft seal of the fenestra, which is now common practice. Laser stapedotomy is a well-established surgical technique for treating conductive hearing loss due to otosclerosis. The procedure creates a tiny opening in the stapes (the smallest bone in the human body) in which to secure a prosthetic. The CO2 laser allows the surgeon to create very small, precisely placed holes without increasing the temperature of the inner ear fluid by more than one degree, whilst decreasing the risk of footplate fracture, making this an extremely safe surgical solution. The hole diameter can be predetermined according to the prosthesis diameter. Treatment can be completed in a single operation visit using anesthesia, normally followed by one or two nights' hospitalization with subsequent at-home recovery time a matter of days or weeks.
Stapedectomy vs. stapedotomy Comparisons have shown stapedotomy to yield either as good or better results than stapedectomy (measured by hearing improvement and reduction in the air-bone hearing gap, and especially at higher sound frequencies), and to be less prone to complications. In particular, stapedotomy procedure greatly reduces the chance of a perilymph fistula (leakage of cochlear fluid). Stapedotomy, like stapedectomy, can be successful in the presence of sclerotic adhesions (tissue growths abnormally linking the bones to the tympanic cavity), provided the adhesions are removed during surgery. However, the adhesions may recur over time. The stapedotomy method is not applicable in those relatively rare cases that involve sclerosis of the entire ossicular chain.
Because it is a simpler and safer procedure, stapedotomy is normally preferred to stapedectomy in the absence of predictable complications. However, the success rate of either surgery depends greatly on the skill and the familiarity with the procedure of the surgeon. Furthermore, a major success factor in both surgeries is correctly determining the length of the prosthesis.
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