Facial nerve herniation.A 61-year-old man presented to the office with a 3-month history of right-sided hearing loss that caused him difficulty in his normal environment. He denied any history of associated illness, including otitis media. He had no complaints of dizziness or disequilibrium. Microscopic examination of the right ear revealed an atrophic collapse of the posterior tympanic membrane with retraction under the malleus and adherence to an eroded incus and stapes capitulum capitulum /ca·pit·u·lum/ (kah-pit´u-lum) pl. capi´tula [L.] a small eminence on a bone, as on the distal end of the humerus, by which it articulates with another bone. . A perforation with associated granulation tissue was noted inferiorly. The appearance of the left ear was normal, without significant retraction or effusion. No mass or lesion was seen on nasopharyngoscopy. An audiogram au·di·o·gram n. A graphic record of hearing ability for various sound frequencies. Audiogram A chart or graph of the results of a hearing test conducted with audiographic equipment. demonstrated a mild conductive hearing loss Conductive hearing loss A type of medically treatable hearing loss in which the inner ear is usually normal, but there are specific problems in the middle or outer ears that prevent sound from getting to the inner ear in a normal way. in the right ear. The speech discrimination scores in both ears were identical (96%), the speech reception threshold on the right was 30 dB, and the pure-tone average was 30 dB. In view of the depth of the retraction pocket under the malleus, high-resolution computed tomography high-resolution computed tomography Imaging CT at slice–collimation scan interval widths of ≤ 4 mm, which is narrower than the usual 1-3 cm interval 'slices' obtained in conventional CT imaging. Cf Spiral computed tomography. (CT) was ordered to look for the presence of a cholesteatoma. CT demonstrated a large retraction pocket with erosion of the incus and soft-tissue attenuation between the tympanic portion of the right facial nerve and the incudostapedial articulation. The patient underwent a right tympanoplasty tympanoplasty /tym·pa·no·plas·ty/ (tim´pah-no-plas?te) surgical reconstruction of the tympanic membrane and establishment of ossicular continuity from the tympanic membrane to the oval window. and middle ear exploration via a postauricular approach with continuous facial nerve monitoring. A 2 x 2-mm mucosa-like mass was encountered in the region of the tympanic segment of the facial nerve superior to the stapes (figure). The mass stimulated at 0.1 mA and activated both the upper and lower divisions of the facial nerve, as evidenced by the tracings on the facial nerve monitor. The tympanoplasty was completed without further manipulation of the mass. No postoperative facial weakness was demonstrated. Postoperative magnetic resonance imaging magnetic resonance imaging (MRI), noninvasive diagnostic technique that uses nuclear magnetic resonance to produce cross-sectional images of organs and other internal body structures. demonstrated no enhancement of the tympanic course of the facial nerve and no evidence of facial nerve neuroma. The intraoperative findings were consistent with facial nerve herniation herniation /her·ni·a·tion/ (her?ne-a´shun) abnormal protrusion of an organ or other body structure through a defect or natural opening in a covering, membrane, muscle, or bone. . Nathan Hales, MD; Wayne Berryhill, MD |
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