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Clinical characteristics of patients with narrow bony cochlear nerve canal

Is the bilateral case just a duplicate of the unilateral case?

Authors

  • Sung-Woo Cho MD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
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  • Seong Il Kang MD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
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  • Sung Joon Park MD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
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  • Ah Reum Kim BA,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
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  • Ja Won Koo MD, PhD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
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  • Chong Sun Kim MD, PhD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
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  • Jun Ho Lee MD, PhD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
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  • Sun O Chang MD, PhD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
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  • Seung-Ha Oh MD, PhD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
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  • Byung Yoon Choi MD, PhD

    Corresponding author
    • Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
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  • This study was supported by the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare and Family Affairs, Republic of Korea (Nos. A080588 and A111377) and the Seoul National University Bundang Hospital research fund 04-2010-003 (to b.y.c.).

  • The authors have no other funding, financial relationships, or conflicts of interest to disclose.

Send correspondence to Byung Yoon Choi, MD, Assistant Professor, Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam 463-707, South Korea. E-mail: choiby@snubh.org

Abstract

Objectives/Hypothesis

To evaluate whether there is a genetic contribution to the development of narrow bony cochlear nerve canal and analyze the differences between unilateral and bilateral narrow bony cochlear nerve canal.

Study Design

Retrospective review.

Methods

Patients diagnosed with unilateral (n=44) or bilateral (n=13) sensorineural hearing loss with narrow bony cochlear nerve canals from October 2004 to July 2011 were evaluated. The segregation ratio of hearing loss among siblings of probands was calculated. The differences in segregation ratio and other clinical characteristics were also compared.

Results

The segregation ratio of hearing loss in siblings of patients with unilateral narrow bony cochlear nerve canal was close to zero, whereas the ratio in siblings of patients with bilateral canals was 20%. Internal auditory canal narrowing was significantly more frequently combined in unilateral than bilateral narrow bony cochlear nerve canal cases. Cochlear nerve deficiency based on magnetic resonance imaging was found in 63.6% of bilateral narrow bony cochlear nerve canal cases. Milder hearing loss was exclusively detected in bilateral cases.

Conclusions

Narrow bony cochlear nerve canal is not likely to have a simple Mendelian inheritance pattern, especially in unilateral cases. The contribution of a Mendelian genetic etiology to bilateral narrow bony cochlear nerve canals remains elusive. More frequent coexistence of internal auditory canal narrowing among unilateral narrow bony cochlear nerve canal cases suggests that bilateral narrow bony cochlear nerve canals are not just a duplicate of the unilateral narrow bony cochlear nerve canal.

Level of Evidence

4. Laryngoscope, 123:1996–2000, 2013

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