Search Results

You are looking at 1 - 10 of 23 items for

  • Author or Editor: Yutaka Sawamura x
Clear All Modify Search
Restricted access

Yutaka Sawamura and Hiroshi Abe

✓ This report describes a new surgical technique to improve the results of conventional hypoglossal—facial nerve anastomosis that does not necessitate the use of nerve grafts or hemihypoglossal nerve splitting.

Using this technique, the mastoid process is partially resected to open the stylomastoid foramen and the descending portion of the facial nerve in the mastoid cavity is exposed by drilling to the level of the external genu and then sectioning its most proximal portion. The hypoglossal nerve beneath the internal jugular vein is exposed at the level of the axis and dissected as proximally as possible. One-half of the hypoglossal nerve is transected: use of less than one-half of the hypoglossal nerve is adequate for approximation to the distal stump of the atrophic facial nerve. The nerve endings, the proximally cut end of the hypoglossal nerve, and the distal stump of the facial nerve are approximated and anastomosed without tension. This technique was used in four patients with long-standing facial paralysis (greater than 24 months), and it provided satisfactory facial reanimation, with no evidence of hemitongue atrophy or dysfunction.

Because it completely preserves glossal function, the hemihypoglossal—facial nerve anastomosis described here constitutes a successful approach in patients with long-standing facial paralysis who do not wish to have tongue function compromised.

Full access

Yutaka Sawamura and Hiroshi Abe

This report describes a new surgical technique to improve the results of conventional hypoglossal-facial nerve anastomosis that does not necessitate the use of nerve grafts or hemihypoglossal nerve splitting.

Using this technique, the mastoid process is partially resected to open the stylomastoid foramen and the descending portion of the facial nerve in the mastoid cavity is exposed by drilling to the level of the external genu and then sectioning its most proximal portion. The hypoglossal nerve beneath the internal jugular vein is exposed at the level of the axis and dissected as proximally as possible. One-half of the hypoglossal nerve is transected: use of less than one-half of the hypoglossal nerve is adequate for approximation to the distal stump of the atrophic facial nerve. The nerve endings, the proximally cut end of the hypoglossal nerve, and the distal stump of the facial nerve are approximated and anastomosed without tension. This technique was used in four patients with long-standing facial paralysis (greater than 24 months), and it provided satisfactory facial reanimation, with no evidence of hemitongue atrophy or dysfunction.

Because it completely preserves glossal function, the hemihypoglossal-facial nerve anastomosis described here constitutes a successful approach in patients with long-standing facial paralysis who do not wish to have tongue function compromised.

Restricted access

Yutaka Sawamura, Yoku Nakagawa, Toshio Ikota and Hiroshi Abe

✓ Neurinomas arising from the peripheral branch of the acoustic nerve distal to the internal auditory canal in the temporal bone are rare. Two advanced skull-base neurinomas are described which were situated mainly in the temporal petrous bone, and extended to the parapharyngeal space anteriorly, to the lateral cervical portion inferiorly, into the sphenoidal sinus medially, and into the middle and posterior cranial fossae compressing the brain stem. Both patients had been deaf for several years without other neurological deficits. The operative findings revealed that the fifth, seventh, and caudal cranial nerves were intact; therefore, it was suspected that these neurinomas originated primarily within the cochlea or the vestibule in the temporal bone. The tumors were completely removed via an extradural approach, with good results. Since the surgical treatment of such advanced skull-base neurinomas is difficult, the operative infratemporal fossa approach is described in detail.

Restricted access

Yutaka Sawamura, Hiroshi Abe, Toshimitsu Aida, Masuo Hosokawa and Hiroshi Kobayashi

✓ The present investigation was conducted in order to examine the feasibility of isolating and growing gliomainfiltrating lymphocytes in vitro as possible effector cells for use in new adoptive immunotherapy. Eight surgical specimens obtained from patients with malignant astrocytomas were treated by enzyme dispersion; the cells were separated on a density gradient and grown in the presence of human recombinant interleukin-2. The cultured lymphocytes were tested for cell-surface markers by using monoclonal antibodies in a flow cytometric analysis. In all cases the glioma-derived lymphocytes were grown in culture for several weeks with substantial increases in cell numbers (at least 5 × 108 cells). The mature T cell population (CD3, 89%) was found to have an increased proportion of the cytotoxic/suppressor phenotype CD8 (55%) as compared to peripheral blood lymphocytes (PBL's). Eighty-six percent of the cultivated lymphocytes expressed HLA-DR. The IL-2 receptor was predominantly expressed on the helper subset (CD4-positive). Otherwise, anti-CD16, which specifically reacts with natural killer (NK) cells, did not stain significantly more of the cultured glioma-derived lymphocytes compared with lymphocyte-activated PBL's. These results corroborate the observations made with conventional immunohistochemical examination. It has been demonstrated that T lymphocytes isolated from human cancers are enriched for specific reactivity to their autochthonous tumor cells. These experiments support the possible use of glioma-infiltrating lymphocytes as a new treatment for patients with malignant glioma.

Restricted access

Yuuta Kamoshima, Yutaka Sawamura, Motoyuki Iwasaki, Yoshinobu Iwasaki and Kazuhiko Sugiyama

The authors report a metachronous germ cell tumor with different histological type occurring 12 years after resection of a pineal germinoma. Histological examination of the original tumor revealed germinoma without any other component of germ cell tumor, and the patient underwent chemotherapy followed by 24 Gy of localized irradiation. Twelve years later, follow-up MR imaging showed a round mass in the genu of the corpus callosum. Two courses of chemotherapy were administered, but the tumor size remained stable. A second operation was performed and this second tumor was completely removed. The histological diagnosis was mature teratoma. The second tumor was considered as a metachronous mature teratoma rather than a recurrence of the original germinoma. To the authors' knowledge, this combination of metachronous germ cell tumor has not previously been reported in the literature

Restricted access

Katsuyuki Asaoka, Yutaka Sawamura, Masabumi Nagashima and Takanori Fukushima

Object. In this study the authors investigated the histomorphometric background and microsurgical anatomy associated with surgically created direct hypoglossal—facial nerve side-to-end communication or nerve “anastomosis.”

Methods. Histomorphometric analyses of the facial and hypoglossal nerves were performed using 24 cadaveric specimens and three surgically obtained specimens of severed facial nerve. Both the hypoglossal nerve at the level of the atlas and the facial nerve just distal to the external genu were monofascicular. The number of myelinated axons in the facial nerve (7228 ± 950) was 73.2% of those in the normal hypoglossal nerve (9778 ± 1516). Myelinated fibers in injured facial nerves were remarkably decreased in number. The cross-sectioned area of the normal facial nerve (0.948 mm2) accounted for 61.5% of the area of the hypoglossal nerve (1.541 mm2), whereas that of the injured facial nerve (0.66 mm2) was less than 50% of the area of the hypoglossal nerve. Surgical dissection and morphometric measurements were performed using 18 sides of 11 adult cadaver heads. The length of the facial nerve from the pes anserinus to the external genu ranged from 22 to 42 mm (mean 30.5 ± 4.4 mm). The distance from the pes anserinus to the nearest point on the hypoglossal nerve ranged from 14 to 22 mm (mean 17.3 ± 2.5 mm). The former was always longer than the latter; the excess ranged from 6 to 20 mm (mean 13.1 ± 3.4 mm). Surgical anatomy and procedures used to accomplish the nerve connection are described.

Conclusions. The size of a half-cut end of the hypoglossal nerve matches a cut end of the injured facial nerve very well. By using the technique described, a length of facial nerve sufficient to achieve a tensionless communication can consistently be obtained.

Restricted access

Yutaka Sawamura, Nicolas de Tribolet, Nobuaki Ishii and Hiroshi Abe

✓ Because intracranial germinomas are readily curable with radiation and chemotherapy or radiation therapy alone, the role of radical surgery has become debatable. This study assesses the optimum degree of surgical resection for intracranial germinomas.

Twenty-nine patients who underwent surgery for germinoma were retrospectively analyzed (male/female ratio 27:2, median age 18 years). Among these 29 patients there were 10 solitary pineal, seven solitary neurohypophyseal/hypothalamic, and 12 multifocal or disseminated tumors. Biopsy samples were obtained in 16 patients (stereotactically in eight, transsphenoidally in four, and via frontotemporal craniotomy in four). Partial resection was attained in five patients (via a frontotemporal approach in three and occipitotranstentorially in two). Gross-total resection was achieved via an occipitotranstentorial route in eight patients with pineal masses. After surgery, 10 patients were treated with radiotherapy alone, and 19 received radiation and chemotherapy; complete remission was achieved in all 29 patients. The overall tumor-free survival rate was 100% at a median follow-up period of 42 months. There was no significant difference in outcome related to the extent of surgical resection. Postoperative neurological improvement was seen in only two patients, whereas transient postoperative complications, mainly upgaze palsy, were observed in six. One patient experienced a slight hemiparesis, bringing the surgical morbidity rate to 3% (one of 29).

It is concluded that radical resection of intracranial germinomas offers no benefit over biopsy. The primary goal of surgery should be to obtain a sufficient volume of tumor tissue for histological examination. If there is strong evidence of germinoma on radiological studies, biopsy samples should be obtained. When a perioperative histological diagnosis of pure germinoma is made during craniotomy, no risk should be taken in continuing the resection.

Restricted access

Katsuyuki Asaoka, Mitsuhiro Tada, Yutaka Sawamura, Jun Ikeda and Hiroshi Abe

Object. Recombinant adenovirus is used as a competent vector in a wide spectrum of cancer gene therapies because of its high efficiency in gene delivery. To study the feasibility of gene therapy in malignant gliomas, the authors examined the antiproliferative effect of the adenovirally transduced wild-type p53 tumor suppressor gene by using 15 different high-grade glioma cell lines.

Methods. Although growth suppression in association with a high adenoviral p53 transduction efficiency was seen in five of 15 cell lines, it was not observed in the remaining 10 cell lines. To clarify the underlying mechanism, we examined the expression levels of the Coxsackievirus and adenovirus receptor (CAR), which is the primary receptor for adenovirus, and of the integrins αvβ3 and αvβ5, which promote adenoviral internalization. The expression level of the CAR gene showed a close correlation to adenoviral gene transduction efficiency in the tested cell lines, whereas the expression levels of the integrins did not. The CAR expression was decreased by wild-type p53 transduction in U251MG cells harboring mutant p53 and increased by antisense inhibition of p53 in LN443 cells with endogenous wild-type p53.

Conclusions. The results of this study indicate that CAR expression is a critical determinant of transduction efficiencies in adenovirus-based gene therapy for human malignant gliomas.