Dorsal location of the cochlear nerve on vestibular schwannoma: Preoperative evaluation, frequency, and functional outcome

Akira Nakamizo, Toshiyuki Amano, Masahiro Mizoguchi, Koji Yoshimoto, Tomio Sasaki

研究成果: ジャーナルへの寄稿記事

抄録

The cochlear nerve is most commonly located on the caudoventral portion of the capsule of vestibular schwannomas and rarely on the dorsal portion. In such a condition, total removal of the tumor without cochlear nerve dysfunction is extremely difficult. The purpose of our study was to identify the frequency of this anatomical condition and the status of postoperative cochlear nerve function; we also discuss the preoperative radiological findings. The study involved 114 patients with unilateral vestibular schwannomas operated on via a retrosigmoid (lateral suboccipital) approach. Locations of the cochlear nerve on the tumor capsule were ventral, dorsal, caudal, and rostral. Ventral and dorsal locations were further subdivided into rostral, middle, and caudal third of the tumor capsule. The postoperative cochlear nerve function and preoperative magnetic resonance (MR) findings were reviewed retrospectively. In 56 patients that had useful preoperative hearing, useful hearing was retained in 50.0 % (28 of 56) of patients after surgery. The cochlear nerve was located on the dorsal portion of the tumor capsule in four patients (3.5 %), and useful hearing was preserved in only one of these patients (25 %) in whom the tumor had been partially resected. This tumor-nerve anatomical relationship was identified in all tumors of <2 cm at preoperative MR cisternography. MR cisternography has the potential to identify the tumor-nerve anatomical relationship, especially in small-sized tumors that usually require therapeutic intervention that ensures hearing preservation. Hence, careful evaluation of the preoperative MR cisternography is important in deciding the therapeutic indications.

元の言語英語
ページ(範囲)39-43
ページ数5
ジャーナルNeurosurgical Review
36
発行部数1
DOI
出版物ステータス出版済み - 1 1 2013

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Cochlear Nerve
Acoustic Neuroma
Neoplasms
Hearing
Capsules
Magnetic Resonance Spectroscopy

All Science Journal Classification (ASJC) codes

  • Surgery
  • Clinical Neurology

これを引用

Dorsal location of the cochlear nerve on vestibular schwannoma : Preoperative evaluation, frequency, and functional outcome. / Nakamizo, Akira; Amano, Toshiyuki; Mizoguchi, Masahiro; Yoshimoto, Koji; Sasaki, Tomio.

:: Neurosurgical Review, 巻 36, 番号 1, 01.01.2013, p. 39-43.

研究成果: ジャーナルへの寄稿記事

Nakamizo, Akira ; Amano, Toshiyuki ; Mizoguchi, Masahiro ; Yoshimoto, Koji ; Sasaki, Tomio. / Dorsal location of the cochlear nerve on vestibular schwannoma : Preoperative evaluation, frequency, and functional outcome. :: Neurosurgical Review. 2013 ; 巻 36, 番号 1. pp. 39-43.
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abstract = "The cochlear nerve is most commonly located on the caudoventral portion of the capsule of vestibular schwannomas and rarely on the dorsal portion. In such a condition, total removal of the tumor without cochlear nerve dysfunction is extremely difficult. The purpose of our study was to identify the frequency of this anatomical condition and the status of postoperative cochlear nerve function; we also discuss the preoperative radiological findings. The study involved 114 patients with unilateral vestibular schwannomas operated on via a retrosigmoid (lateral suboccipital) approach. Locations of the cochlear nerve on the tumor capsule were ventral, dorsal, caudal, and rostral. Ventral and dorsal locations were further subdivided into rostral, middle, and caudal third of the tumor capsule. The postoperative cochlear nerve function and preoperative magnetic resonance (MR) findings were reviewed retrospectively. In 56 patients that had useful preoperative hearing, useful hearing was retained in 50.0 {\%} (28 of 56) of patients after surgery. The cochlear nerve was located on the dorsal portion of the tumor capsule in four patients (3.5 {\%}), and useful hearing was preserved in only one of these patients (25 {\%}) in whom the tumor had been partially resected. This tumor-nerve anatomical relationship was identified in all tumors of <2 cm at preoperative MR cisternography. MR cisternography has the potential to identify the tumor-nerve anatomical relationship, especially in small-sized tumors that usually require therapeutic intervention that ensures hearing preservation. Hence, careful evaluation of the preoperative MR cisternography is important in deciding the therapeutic indications.",
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