Modern surgical treatment of otosclerosis - Helda - Helsinki.fi

Review of the literature
is positively correlated with conductive hearing loss, but cochlear involvement and extent
of SNHL do not correlate (Derks et al. 2001, Nauman et al. 2005). Although the CT is the
most valuable radiological examination, magnetic resonance imaging (MRI) is also
effective in the detection of especially active otospongiotic lesions. Lesions in the lateral
wall of the labyrinth are sometimes more visible with MRI than with CT, where a partialvolume
effect can be troublesome (Ziyeh et al. 1997). In cochlear otosclerosis, a mild to
moderate enhancement after gadoliniun administration is frequently seen on T1-weighted
images, but an increased signal might also be seen in T2-images (Ziyeh et al. 1997, Goh et
al. 2002). In a recent case report on the three-dimensional fluid attenuated inversion
recovery MRI of a patient with SNHL, an enhancement of the inner ear fluid after
gadolinium administration was noted. This suggests a breakdown of the blood-labyrinth
barrier, which is a potential reason for SNHL (Sugiura et al. 2008).
2.7 Surgical treatment
Modern surgical treatment of otosclerosis began in 1956, when Shea reported the
successful total removal of stapes (stapedectomy) and replacement with a Teflon
prosthesis after sealing the opening with a tissue graft. In 1958, he presented a surgical
treatment rationale for otosclerosis, in which a polyethylene tube was placed over the vein
graft and the other end was stretched to the head of the long process of the incus. He also
demonstrated the possibility of using the posterior crus as a prosthesis over the vein graft.
In this technique, the incudostapedial joint was left intact, but the stapedius tendon was cut
and the posterior crus repositioned to the centre of the sealed oval window (Shea 1958).
Schuknecht (1960) introduced a technique in which he used a wire-adipose tissue
prosthesis with a shaft made of stainless steel or tantalum and adipose tissue to seal the
oval window. The prosthesis was prepared during the surgery and contained a loop that
attached to the long process of the incus. A wire-loop prosthesis is still in use today with a
different sealing material (vein, fascia, perichondrium, fat), but polyethylene tubes are no
longer used owing to the frequency of incus erosion and occasional slippage of the
prosthesis into the vestibule (Rizer and Lippy 1993). The operative technique has evolved
during recent decades towards stapedotomy, where the piston prosthesis is inserted into
the small fenestra of the stapes footplate, performed with a micro-drill or laser. This was
preceded by partial stapedectomy, where only part of the stapes footplate was removed
together with the superstructure. At present, all techniques (total/partial stapedectomy and
stapedotomy) are used successfully (Rizer and Lippy 1993, House et al. 2002, Aarnisalo et
al. 2003). The operation can be done using either local or general anaesthesia. According
to the national guidelines in Finland, surgical treatment is indicated if the patient has a
mean conductive hearing loss of 15 dB (0.5-2.0 kHz) or more, and at the same frequencies
the mean air conduction threshold is 30 dB or more. The Rinne test should be negative.
The patient should be expected to reach a mean postoperative hearing threshold of 30 dB
or better or at least a mean threshold within 15 dB of that of the better hearing ear
(Laitakari et al. 2005). In this section, the technical aspects of surgical treatment and their
effect on outcomes are discussed.
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