Three-Dimensional CT Studies of Inner Ear Anomalies. Cases with Residual Hearing.

DOI 6 Citations 17 References

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  • 内耳奇形の３次元ＣＴ所見　　聴力残存例を中心に
  • -Cases with Residual Hearing-
  • ―聴力残存例を中心に―

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Abstract

Up to now the diagnosis of inner ear anomalies has been largely dependent on pathohistological studies. In clinical practice, however, imaging diagnostics are inevitably used to characterize inner ear anomalies. Imaging diagnostics has evolved through a number of steps: simple roentgenography, tomography, computed tomography (CT), high resolution CT and magnetic resonance imaging (MRI). Over the course of development of MRI and imaging diagnostics, pros and cons of these methods have been discussed. We have applied three-dimensional helical CT scanning (3D-CT), which has recently been put to use in clinical diagnosis, to observe shortening of the cochlear turn, which could not be visualized with conventional two-dimensional CT scanning (2D-CT). Case #1, a 17-year-old male, had an inner ear anomaly of the Mondini type, with hearing of 40dB HL in the frequency range for conversation. 2D-CT indicated an anomaly of the cochlea, but failed to reveal its detailed structure. On the contrary, 3D-CT clearly indicated that a part of the cochlear turn was missing. Case #2, a 35-year-old female, had fluctuating hearing levels in the left ear and hearing of 80-40dB HL in the frequency range for conversation. While 2D-CT suggested only a relatively minor anomaly of the inner ear without showing the developmental status of the cochlea in detail, 3D-CT pointed out a shortened cochlear turn. In this way, 3D-CT permitted identification of the cause of deafness, which could not be defined by 2D-CT. These observations suggest that 3D-CT is useful as a method of diagnosing inner ear anomalies and deafness of unknown cause.

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