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Naokatsu Saeki and Albert L. Rhoton Jr.

✓ The microvascular anatomy of the posterior part of the circle of Willis, important in surgery of pituitary tumors and basilar aneurysms, was defined in 50 cadaver brains. Significant findings were as follows: 1) Anomalies of the posterior half of the circle of Willis were found in 46% of cases. 2) Hypoplastic P-1 (posterior cerebral segment) and posterior communicating segments gave origin to the same number and size of perforating arteries, having the same termination as normal-sized segments. Thus hypoplastic segments should be handled with care and divided to aid in exposure of the basilar bifurcation only after careful consideration. 3) An average of four perforating branches arose from P-1; most from the superior and posterior surfaces. No branches arose from the anterior surface of the basilar bifurcation. The most proximal P-1 branch originated 2 to 3 mm distal to the basilar bifurcation. It was most commonly a thalamoperforating artery. The largest P-1 branch was usually a thalamoperforating or a posterior choroidal artery. 4) An average of seven branches emerged from the superior and lateral surfaces of the posterior communicating artery. The anterior half was a richer source of perforators than the posterior half. The largest communicating branch in 80% of specimens supplied the premamillary area. 5) The anterior choroidal artery originated from the carotid artery on both sides in all cases. A double anterior choroidal artery was present in 4% of cases.

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Akira Yamaura, Yoshiro Watanabe and Naokatsu Saeki

✓ Among 86 patients with aneurysms arising from the vertebral artery or its branches, 24 had dissecting aneurysms. The patients with dissecting aneurysms were characteristically relatively young males. Twenty-one patients presented with subarachnoid hemorrhage (SAH) and three with ischemia. Severe headache or neck pain occurred in all three patients with ischemia. Five of the 21 patients with SAH and all three patients with ischemia experienced recurrent episodes. Angiography typically showed fusiform dilatation and proximal and/or distal narrowing of the affected artery. The difficulty of diagnosing this disorder is pointed out. Surgery was performed in 19 patients, the most common technique being clip-occlusion of the proximal vertebral artery. There were no postoperative deaths or rebleeding; a lateral medullary syndrome developed in three patients. The observation at surgery of intramural clot with characteristic discoloration was limited to the cases operated on within 36 days after the ictus. After this period, the aneurysm was whitish gray in color and had become firm. Of 36 other cases of vertebral dissecting aneurysm reported in the literature, 20 were operated on. The indications for surgery are discussed.

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Eiichi Kobayashi, Naokatsu Saeki, Hiromichi Oishi, Shinji Hirai and Akira Yamaura

Object. The purpose of this study was to delineate the long-term natural history of hemorrhagic moyamoya disease (MMD).

Methods. A retrospective review was conducted among 42 patients suffering from hemorrhagic MMD who had been treated conservatively without bypass surgery. The group included four patients who had undergone indirect bypass surgery after an episode of rebleeding. The follow-up period averaged 80.6 months. The clinical features of the first bleeding episode and repeated bleeding episodes were analyzed to determine the risk factors of rebleeding and poor outcome.

Intraventricular hemorrhage with or without intracerebral hemorrhage was a dominant finding on computerized tomography scans during the first bleeding episode in 29 cases (69%). During the follow-up period, 14 patients experienced a second episode of bleeding, which occurred 10 years or longer after the original hemorrhage in five cases (35.7%). The annual rebleeding rate was 7.09%/person/year. The second bleeding episode was characterized by a change in which hemisphere bleeding occurred in three cases (21.4%) and by the type of bleeding in seven cases (50%). After rebleeding the rate of good recovery fell from 45.5% to 21.4% and the mortality rate rose from 6.8% to 28.6%. Rebleeding and patient age were statistically significant risk factors of poor outcome. All four patients in whom there was indirect revascularization after the second bleeding episode experienced a repeated bleeding episode within 8 years.

Conclusions. The occurrence of rebleeding a long time after the first hemorrhagic episode was not uncommon. Furthermore, the change in which hemisphere and the type of bleeding that occurred after the first episode suggested the difficulty encountered in the prevention of repeated hemorrhage.

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Motoo Kubota, Naokatsu Saeki, Akira Yamaura, Yoshiaki Yamamoto, Yuko Nemoto and Toshio Fukutake

✓ Cervical spondylolysis is a rare clinical entity and occurs predominantly at the C-6 level. The authors describe a patient with congenital spondylolysis of the axis that caused myelopathy. The patient was a 57-year-old woman with long-standing gait disturbance. Plain cervical radiography revealed a radiolucent defect across the pedicle of the axis. Magnetic resonance imaging of the cervical spine in the neutral, flexion, and extension neck positions as well as a computerized tomography myelography in the neutral neck position failed to demonstrate any spinal cord compression. When she rotated her neck, however, the spinal cord was caught between the hypertrophic anterior arch of the atlas and posterior part of the slipped pedicle of the axis on the contralateral side. The spinal cord was transformed into a pear shape. Mechanical injury to the spinal cord seemed to explain her neurological presentation. This is, to the authors' knowledge, the 15th case of axial spondylolysis and the sixth case of spinal cord involvement of the cervical spondylolysis. No cases involving myelopathy secondary to such a unique mechanism have been reported previously in the literature.

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Toru Serizawa, Yoshinori Higuchi, Osamu Nagano, Tatsuo Hirai, Junichi Ono, Naokatsu Saeki and Akifumi Miyakawa

Object

The authors conducted validity testing of the 5 major reported indices for radiosurgically treated brain metastases— the original Radiation Therapy Oncology Group's Recursive Partitioning Analysis (RPA), the Score Index for Radiosurgery in Brain Metastases (SIR), the Basic Score for Brain Metastases (BSBM), the Graded Prognostic Assessment (GPA), and the subclassification of RPA Class II proposed by Yamamoto—in nearly 2500 cases treated with Gamma Knife surgery (GKS), focusing on the preservation of neurological function as well as the traditional endpoint of overall survival.

Methods

The authors analyzed data from 2445 cases treated with GKS by the first author (T.S.), the primary surgeon. The patient group consisted of 1716 patients treated between January 1998 and March 2008 (the Chiba series) and 729 patients treated between April 2008 and December 2011 (the Tokyo series). The interval from the date of GKS until the date of the patient's death (overall survival) and impaired activities of daily living (qualitative survival) were calculated using the Kaplan-Meier method, while the absolute risk for two adjacent classes of each grading system and both hazard ratios and 95% confidence intervals were estimated using the Cox proportional hazards model.

Results

For overall survival, there were highly statistically significant differences between each two adjacent patient groups characterized by class or score (all p values < 0.001), except for GPA Scores 3.5–4.0 and 3.0. The SIR showed the best statistical results for predicting preservation of neurological function. Although no other grading systems yielded statistically significant differences in qualitative survival, the BSBM and the modified RPA appeared to be better than the original RPA and GPA.

Conclusions

The modified RPA subclassification, proposed by Yamamoto, is well balanced in scoring simplicity with respect to case number distribution and statistical results for overall survival. However, a new or revised grading system is necessary for predicting qualitative survival and for selecting the optimal treatment for patients with brain metastasis treated by GKS.

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Toru Serizawa, Yoshinori Higuchi, Junichi Ono, Shinji Matsuda, Osamu Nagano, Yasuo Iwadate and Naokatsu Saeki

Object

The authors analyzed the effectiveness of Gamma Knife surgery (GKS) for metastatic brain tumors without adjuvant prophylactic whole-brain radiotherapy (WBRT). Salvage GKS was performed as the sole treatment for new distant lesions.

Methods

Among 1127 patients in whom new brain metastases had been diagnosed, 97 who met one or more of the following three criteria were excluded from the study: any surgically inaccessible huge (≥ 35 mm) lesion; tumor number and size requiring an internal skull dose exceeding 10 J; or symptomatic carcinomatous meningitis. Thus, 1030 consecutive patients formed the basis for this study. Huge tumors were totally removed, whereas smaller lesions were treated with GKS. No adjuvant WBRT was given prior to GKS, and new distant lesions were appropriately retreated with GKS. Overall, neurological and new lesion–free survival curves were calculated and the prognostic values of covariates were obtained. In total, 1853 separate GKS sessions were required to treat 10,163 lesions.The patients' median overall survival period was 8.6 months. Neurological survival and new lesion–free rates at 1 year were 89.1 and 49.3%, respectively. In a multivariate analysis, the significant factors for poor prognosis were the development of more than four new brain metastases and active extracranial disease.

Conclusions

In meeting the goal of preventing neurological death and maintaining activities of daily living for patients with brain metastases, GKS alone provides excellent palliation without prophylactic WBRT. New distant lesions were quite well controlled with GKS salvage treatment alone.

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Toru Serizawa, Toshihiko Iuchi, Junichi Ono, Naokatsu Saeki, Katsunobu Osato, Masaru Odaki, Osamu Ushikubo, Shinji Hirai, Motoki Sato and Shinji Matsuda

Object. The purpose of this retrospective study was to compare the effectiveness of gamma knife radiosurgery (GKS) for multiple cerebral metastases with that of whole-brain radiation therapy (WBRT).

Methods. Ninety-six consecutive patients with cerebral metastases from nonsmall cell lung cancer were treated between 1990 and 1999. The entry criteria were the presence of between one and 10 multiple brain lesions at initial diagnosis, no surgically inaccessible tumors with more than a 30-mm diameter, no carcinomatous meningitis, and more than 2 months of life expectancy. The patients were divided into two groups: the GKS group (62 patients) and the WBRT group (34 patients).

In the GKS group, large lesions (> 30 mm) were removed surgically and all other small lesions (≤ 30 mm) were treated by GKS. New distant lesions were treated by repeated GKS without prophylactic WBRT. In the WBRT group, the patients were treated by the traditional combined therapy of WBRT and surgery. In both groups, chemotherapy was administered according to the primary physician's protocol. The two groups did not differ in terms of age, sex, initial Karnofsky Performance Scale (KPS) score, type, lesion number, and size of lesion, systemic control, and chemotherapy.

Neurological survival and qualitative survival of the GKS group were longer than those of the WBRT group. In multivariate analysis, significant poor prognostic factors were systemically uncontrolled patients, WBRT group, and poor initial KPS score.

Conclusions. Gamma knife radiosurgery without prophylactic WBRT could be a primary choice of treatment for patients with as many as 10 cerebral metastases from nonsmall cell cancer.

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Osamu Nagano, Yoshinori Higuchi, Toru Serizawa, Junichi Ono, Shinji Matsuda, Iwao Yamakami and Naokatsu Saeki

Object

The authors prospectively analyzed volume changes in vestibular schwannomas (VSs) after stereotactic radiosurgery.

Methods

One hundred consecutive patients with unilateral VS treated with Gamma Knife surgery (GKS) at Chiba Cardiovascular Center between 1998 and 2006 were analyzed in this study. For each lesion the Gd-enhanced volume was measured serially every 3 months in the 1st year, then every 6 months thereafter, using volumetric software. The frequency and degree of transient tumor expansion were documented and possible prognostic factors were analyzed. Concurrently, neurological deterioration involving trigeminal, facial, and cochlear nerve functions were also assessed.

Results

The mean observation period was 65 months (range 25–100 months). There were 32 men and 68 women, whose mean age was 59.1 years (range 29–80 years). Tumor volumes at GKS averaged 2.7 cm3 (range 0.1–13.2 cm3), and the lesions were irradiated at the mean 52.2% isodose line for the tumor margin (range 50–67%), with a mean dose of 12.2 Gy (range 10.5–13 Gy) at the periphery. The tumor volume was increased by 23% at 3 months and 27% at 6 months. Tumors shrank to their initial size over a mean period of 12 months. The maximum volume increase was < 10% (no significant increase) in 26 patients, 10–30% in 23, 30–50% in 22, 50–100% in 16, and > 100% in 13. The peak tumor expansion averaged 47% (range 0–613%). A high-dose (≥ 3.5 Gy/min) treatment appears to be the greatest risk factor for transient tumor expansion, although the difference did not reach statistical significance. Transient facial palsy and facial dysesthesia correlated strongly with tumor expansion, but only half of the hearing loss was coincident with this phenomenon.

Conclusions

Transient expansion of VSs after GKS was found to be much more frequent than previously reported, strongly suggesting a correlation with deterioration of facial and trigeminal nerve functions.

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Toru Serizawa, Yoshinori Higuchi, Osamu Nagano, Shinji Matsuda, Kyoko Aoyagi, Junichi Ono, Naokatsu Saeki, Yasuo Iwadate, Tatsuo Hirai, Shinya Takemoto and Yuta Shibamoto

OBJECTIVE

The neurological prognostic score (NPS) was recently proposed as a means for predicting neurological outcomes, such as the preservation of neurological function and the prevention of neurological death, in brain metastasis patients treated with Gamma Knife radiosurgery (GKRS). NPS consists of 2 groups: Group A patients were expected to have better neurological outcomes, and Group B patients were expected to have poorer outcomes. NPS robustness was tested in various situations.

METHODS

In total, 3040 patients with brain metastases that were treated with GKRS were analyzed. The cumulative incidence of the loss of neurological function independence (i.e., neurological deterioration) was estimated using competing risk analysis, and NPS was compared between Groups A and B by employing Gray's model. NPS was tested to determine if it can be applied to 5 cancer categories—non–small cell lung cancer, small cell lung cancer, gastrointestinal tract cancer, breast cancer, and other cancers—as well as if it can be incorporated into the 5 major grading systems: recursive partitioning analysis (RPA), score index for stereotactic radiosurgery (SIR), basic score for brain metastases (BSBM), graded prognostic assessment (GPA), and modified-RPA (M-RPA).

RESULTS

There were 2263 patients in NPS Group A and 777 patients in Group B. Neurological deterioration was observed in 586 patients (19.2%). The cumulative incidences of neurological deterioration were 9.5% versus 21.0%, 14.1% versus 25.4%, and 17.6% versus 27.8% in NPS Groups A and B at 1, 2, and 5 years, respectively. Significant differences were detected between the NPS groups in all cancer categories. There were significant differences between NPS Groups A and B for all classes in terms of the BSBM, GPA, and M-RPA systems, but the differences failed to reach statistical significance in terms of RPA Class I and SIR Class 0 to 3.

CONCLUSIONS

The NPS was verified as being highly applicable to all cancer categories and almost all classes for the 5 grading systems in terms of neurological function independence. This NPS system appears to be quite robust in various situations for brain metastasis patients treated with GKRS.

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Natsuki Shinozaki, Yoshio Uchino, Kyosan Yoshikawa, Tomoo Matsutani, Azusa Hasegawa, Naokatsu Saeki and Yasuo Iwadate

Object

The diagnostic usefulness of 11C-methionine PET scans in gliomas is still controversial. The authors investigated the clinical significance of 11C-methionine PET findings in preoperative diagnosis of histological type and grade.

Methods

The tissue uptake of 11C-methionine was assessed using PET in 70 patients with histologically confirmed intracerebral gliomas. The ratio of maximum standard uptake values in tumor areas to the mean standard uptake values in the contralateral normal brain tissue (tumor/normal tissue [T/N] ratio) was calculated and correlated with tumor type, histological grade, contrast enhancement on MR imaging, Ki 67 labeling index, and 1p/19q status.

Results

The T/N ratio was significantly increased as tumor grade advanced in astrocytic tumors (WHO Grade II vs Grade III, p = 0.0011; Grade III vs Grade IV, p = 0.0007). Among Grade II gliomas, the mean T/N ratio was significantly higher in oligodendroglial tumors than in diffuse astrocytomas (DAs) (p < 0.0001). All T/N ratios for oligodendroglial tumors were ≥ 1.46, and those for DA were consistently < 1.46, with the exception of 2 cases of gemistocytic astrocytoma. The Ki 67 labeling index significantly correlated with T/N ratio in astrocytic tumors, but not in oligodendrogliomas. Oligodendroglial tumors without 1p/19q deletion had a significantly higher T/N ratio than those with the codeletion. In combination with Gd-enhanced MR imaging, 67% of nonenhanced tumors with a T/N ratio of ≥ 1.46 were proved to be Grade II oligodendrogliomas.

Conclusions

These results clearly show that 11C-methionine PET T/N ratios in Grade II oligodendrogliomas were higher than those in DAs independently of their proliferative activity. This information contributes to preoperative differential diagnoses of histological type, especially in suspected low-grade gliomas.