Posterior semicircular canal dehiscence: a histopathologic human temporal bone study.
BACKGROUND
Posterior semicircular canal dehiscence has been shown to cause ear symptoms.


OBJECTIVE
To evaluate the incidence of dehiscence of the posterior semicircular canal, thin bone overlying the posterior semicircular canal, and the normal development of the distance between the posterior semicircular canal and posterior cranial fossa.


METHODS
The shortest distance between the posterior semicircular canal and posterior cranial fossa was measured in 1,051 adult human temporal bones (557 cases), and temporal bones with a distance less than 0.1 mm were evaluated. The shortest distance also was measured in 4 fetal temporal bones (2 cases) and 110 temporal bones from children.


RESULTS
Of the 1,051 temporal bones, 23 temporal bones (2.2%) had a distance less than 0.1 mm between the posterior semicircular canal and posterior cranial fossa. Two temporal bones (0.2%) had posterior semicircular canal dehiscence, and 2 temporal bones had microfractures in the thin bone; however, related clinical symptoms were not confirmed. In children, the distance between the posterior semicircular canal and the posterior cranial fossa increased with age (rho = 0.68, p < 0.01).


CONCLUSIONS
The histopathologic incidence of posterior semicircular canal dehiscence was lower than the previous radiographic reports. The dehiscence of the posterior semicircular canal may be due to a developmental anomaly. In our study, none of the cases with a distance less than 0.1 mm had apparent symptoms related to canal dehiscence syndrome. Other factors, in addition to thinning of the bone, may be required to cause the clinical manifestations.
Nomiya
Shigenobu
S
Department of Otolaryngology, University of Minnesota, Minneapolis, Minnesota 55455, U.S.A.
Cureoglu
Sebahattin
S
Kariya
Shin
S
Morita
Norimasa
N
Nomiya
Rie
R
Schachern
Patricia A
PA
Nishizaki
Kazunori
K
Paparella
Michael M
MM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001344:Autopsy; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000473:pathology; D005260:Female; D050723:Fractures, Bone / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007759:Labyrinth Diseases / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D012016:Reference Values; D012665:Semicircular Canals / Q000254:growth & development / Q000473:pathology*; D012727:Sex Characteristics; D013701:Temporal Bone / Q000254:growth & development / Q000473:pathology*; D055815:Young Adult