The location of the mastoid portion of the facial nerve in patients with congenital aural atresia

Abstract

In order to investigate the location of the mastoid portion of the facial nerve in patients with congenital aural atresia and to assess its effect on the round window middle ear implant (MEI) transducer implantation approach, 70 patients with unilateral congenital aural atresia were examined by computer tomography (CT). The patients were divided into two groups based on their ages: 44 patients in Group A (2-12 years) and 26 patients in Group B (13-29 years). CT scans were reviewed for each patient. Based on the CT findings, the mastoid portion of the facial nerve's spatial configuration with respect to the oval and round windows was qualitatively recorded. Additionally, the exact location of the facial nerve was measured quantitatively. The results suggested that of the 70 deformed ears, 57 had facial nerves located at the round window, six at the oval window, and seven at the normal site. Of the 70 normal opposite ears, 63 had facial nerves located at the normal site, and the other seven had facial nerves located at the round window. Based on the quantitative measurements, the mastoid portion of the facial nerve was more anteriorly positioned in the deformed ears: 3.44-6.09 mm more anteriorly located in Group A and 4.35-7.41 mm more anteriorly located in Group B. In conclusion, in patients with congenital aural atresia, the dislocation of the facial nerve could have significant effects on the surgical approach to round window MEI transducer implantation.

Seltene Erkrankungen des Mittelohres und der lateralen Schädelbasis

“…Minderentwicklung von Mastoid und Gehörgang können den Verlauf des Nervus fazialis im Fallop'schen Kanal beeinflussen. Es kommt zu einer Vorverlagerung des Nerven im tympanalen und mastoidalen Verlauf, was zu einer Lokalisation im ovalen Fenster oder in der Rundfensternische führt [7]. Die Inzidenz der großen Ohrfehlbildung liegt zwischen 1:8'000-1:10'000 [2,8].…”

“…Eine Vorverlagerung des Sinus sigmoideus, ein Hochstand des Bulbus Venae jugularis oder der Arteria carotis interna können zu Problemen in der chirurgischen Versorgung der kleinen und großen Ohrfehlbildungen führen. Dies spielt insbesondere bei der Neuanlage eines Gehörgangs, bei der Ossikuloplastik oder bei der Anlage implantierbarer Hörgeräte eine Rolle [1,7,15,21]. Weiter kann eine nicht wie üblicherweise zurückgebildete Arteria stapedia (▶abb.…”

A Novel Classification: Anomalous Routes of the Facial Nerve in Relation to Inner Ear Malformations

“…FN canal ossification from Reichert's cartilage is completed at the fifth gestational week; however, the mastoid segment canal is formed postnatally, along with the growth and pneumatization of the mastoid bone. 22 Surgically, the mastoid segment is crucially important, as the FR is drilled out to expose the round window niche or promontorium for cochlear implantation. In the present study, the FR was measured in axial HRCT sections and did not differ significantly according to IEM type.…”

A meta-analysis of the long-term hearing outcomes and complications associated with atresiaplasty

“…The anatomic variability, such as ectopic facial nerve or absence of the stapes, in aural atresia makes surgical correction more challenging [4]. The Jahrsdoerfer grading scale, proposed in 1992, assigns an anatomical score for the atretic ear based on the presence or absence of 9 structures.…”