The Cochlear Cleft
Jon B. Chadwella,
Mark J. Halstedb,
Daniel I. Chooa,
John H. Greinwalda and
Corning Bentonb
a Department of Otolaryngology, Cincinnati Children’s Hospital Medical Center and the University of Cincinnati College of Medicine, Cincinnati, OH
b Departments of Radiology, and Pediatrics, Cincinnati Children’s Hospital Medical Center and the University of Cincinnati College of Medicine, Cincinnati, OH
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FIG 1. Large cochlear cleft in a 2-year-old child.
A. Axial CT. The cleft (arrowhead) measures 1.3 high and 0.3 mm wide.
B. Coronal CT. The cleft (arrowheads) is 3.4 mm high and 0.2–0.4 mm wide.
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FIG 2. Large cochlear cleft in a 7-year-old child.
A. Axial CT. The cleft (arrowhead) is in the otic capsule lateral to the middle turn of the cochlea. It measures 0.8 high and 0.4 mm wide.
B. Coronal CT. The cleft (arrowheads) is in the lateral part of the cochlear otic capsule. It measures 5.0 mm high and 0.2–0.3 mm wide
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FIG 3. Small cochlear cleft in an 8-year-old child.
A. Axial CT. The cleft (arrowhead) measures 0.9 mm high and 0.2 mm wide.
B. Coronal CT. The cleft (arrowheads) is 3.7 mm high and 0.2–0.4 mm wide.
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FIG 4. Plot of cochlear cleft occurrence versus age. The occurrence rate decreases from 62% in the youngest age group to 19% in the oldest.
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FIG 5. Illustration of the perilymphatic labyrinthine space, the fissula ante fenestram (label underlined) and fossula post fenestram (adapted from [8], permission pending). The endolymphatic spaces within the semicircular canals and cochlear duct are drawn as grooves in the perilymphatic surface. The outer surface of the perilymphatic space conforms to the bony labyrinth. The fissula ante fenestram arises from the lateral wall of the vestibule and nearby scala vestibulae, and it continues parallel to the adjacent cochlear turn.
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FIG 6. Temporal bone photomicrographs showing temporal bone structures in an axial plane. (Courtesy of Dr. Barbara A. Bohne at the Washington University in St. Louis School of Medicine)
A, A nonosseous cleft is in the lateral part of the cochlear otic capsule (arrow). Ear structures visible are the carotid artery (CA), cochlea (CO), eustachian tube (ET), facial nerve (FN), foot plate of the stapes (FP), internal auditory canal (IAC), tympanic membrane (TM), tensor tympani muscle (TT), and vestibule (VE).
B, Enlarged view of the cochlea. The cochlear cleft (CC) is in the middle layer of the otic capsule. The base turn (BT) and middle turn (MT) of the cochlea are adjacent to the cleft.
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