Three-dimensional course of the vestibular aqueduct.

Three-dimensional (3-D) reconstruction methods were employed to study the anatomy of the vestibular aqueducts (VAs) in ten postmortem temporal bone specimens obtained from ten individuals aged 4 months to 70 years at death. After reconstruction, the ten 3-D images of VAs were superimposed on one another and differences evaluated. The VA showed postnatal growth and variations in size and shape. However, the variations in angle at which the VA bends near the isthmus were not correlated with age. Furthermore, study of the superimposed images revealed that the 3-D course of the VA was essentially the same in individuals of all ages, despite its wide variability in size and shape. These results indicate that the basic course of the VA is determined before early infancy although the VA grows thereafter, suggesting that VA anomalies such as "large vestibular aqueduct syndrome" (in which the VA takes an abnormally straight and wide course) may be established prenatally.