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Keisuke Ueki, Joseph E. Parisi, and Burton M. Onofrio

✓ The authors report a case of transverse myelitis caused by Schistosoma mansoni. Although this is a treatable disease if diagnosed in the early stage, it is very rarely seen in developed countries and can result in complications if diagnosis is delayed.

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Kazuo Tsutsumi, Keisuke Ueki, Akio Morita, and Takaaki Kirino

Object. Controversy still exists about the risk estimation for rupture of untreated saccular aneurysms presenting for causes other than subarachnoid hemorrhage (SAH). The object of this study was to address this issue.

Methods. Between January 1976 and December 1997 in the Aizu Chuou Hospital, 62 patients underwent observation for more than 6 months for saccular, nonthrombotic, noncalcified unruptured aneurysms at locations not related to the cavernous sinus, which were detected in cerebral angiography studies performed for causes other than SAH. Clinical follow-up data in those 62 patients were reviewed to identify the risk of SAH.

All patients were followed until July 1998, with the observation period ranging from 6 months to 17 years (mean 4.3 years). Seven patients (11.3%) developed SAH confirmed on computerized tomography (CT) scanning at a mean interval of 4.8 years, six of whom died and one of whom recovered with a major deficit. In addition, one patient died of the mass effect of the aneurysm, and another after sudden onset of headache and vomiting. The 5- and 10-year cumulative risks of CT-confirmed SAH calculated by the Kaplan—Meier method were 7.5% and 22.1%, respectively, for total cases, 33.5% and 55.9%, respectively, for large (> 10 mm) aneurysms, and 4.5% and 13.9%, respectively, for small (< 10 mm) aneurysms.

Conclusions. Although based on a relatively small, single-institution series, our data indicated that the risk of rupture from incidental, intradural, saccular aneurysms was higher than previously reported, and may support preventive surgical treatment of incidental aneurysms, considering the fatality rate of SAH.

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Tetsuhiro Nishihara, Akira Teraoka, Akio Morita, Keisuke Ueki, Keisuke Takai, and Takaaki Kirino

✓ The authors advocate the use of a transparent sheath for guiding an endoscope, a simple and unique tool for endoscopic surgery, and describe preliminary results of its application in the evacuation of hypertensive intracerebral hematomas. This sheath is a 10-cm-long tube made of clear acrylic plastic, which greatly improves visualization of the surgical field through a 2.7-mm nonangled endoscope inserted within. Between April 1997 and December 1998, the authors performed endoscopic evacuation of intracerebral hematomas by using this sheath inserted into the patients' heads through a burr hole. In nine consecutive cases in which the hematoma was larger than 40 ml in volume, nearly complete evacuation (86–100%) of the lesion was achieved without complication. Excellent visualization of the border between the brain parenchyma and the hematoma facilitated accurate intraoperative orientation, and also allowed easy identification of the bleeding point. Thus, this combination of sheath and endoscope achieves both minimal invasiveness and the maximum extent of hematoma removal with secure hemostasis. This tool will reduce the inherent disadvantage of endoscopic procedures and may expand their application in other areas of neurosurgical management.

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Roberto C. Heros

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Bruce E. Pollock

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Masahiro Shin, Akio Morita, Shuichiro Asano, Keisuke Ueki, and Takaaki Kirino

✓ Isolated fourth ventricle (IFV) is a rare complication in patients who undergo shunt placement, and it is not easily corrected by surgical procedures. The authors report a case of IFV that was successfully treated with an aqueductal stent placed under direct visualization by using a neuroendoscope. This 36-year-old suffered meningitis after partial resection of a brainstem pilocytic astrocytoma, and subsequently developed hydrocephalus for which a ventriculoperitoneal shunt was placed. Nine months later, the patient presented with progressive cerebellar ataxia, and magnetic resonance imaging revealed slitlike supratentorial ventricles and a markedly enlarged fourth ventricle, which were compatible with the diagnosis of IFV. The surgical procedure described was performed under visualization through a styletlike slim optic fiberscope inserted into a ventricular catheter. The catheter, with the endoscope inside it, was passed through the foramen of Monro and then through the aqueduct to reach the enlarged fourth ventricle, where membranous occlusion of the foramen of Magendie was clearly visualized. The tip of the catheter was placed in the fastigium of the fourth ventricle. After the procedure, the size of the fourth ventricle was reduced and the patient's symptoms improved. Thus, it is concluded that endoscopic aqueductal stent placement is a simple and safe surgical procedure for treatment of IFV.

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Fumi Higuchi, Shunsuke Kawamoto, Yoshihiro Abe, Phyo Kim, and Keisuke Ueki

Object

Gamma Knife surgery (GKS) has gained increasing relevance in the treatment of metastatic brain tumors, but many metastatic tumors contain a large cystic component and often exceed the size limit for GKS. For such lesions, the authors adopted a procedure in which stereotactic aspiration is first performed and followed immediately by GKS on the same day. In this paper, the authors describe this 1-day combined procedure and evaluate its efficacy.

Methods

Between 2005 and 2010, 25 cystic metastases in 25 patients were treated at Dokkyo Medical University. The patients first underwent MRI and stereotactic aspiration of the cyst while stationary in a Leksell stereotactic frame; immediately afterward, the patients underwent a second MR imaging session and Gamma Knife treatment. Tumor volume reduction, tumor control rate, and overall survival were examined.

Results

Tumor volume, including the cystic component, decreased from 8.0–64.2 cm3 (mean 20.3 cm3) to 3.0–36.2 cm3 (mean 10.3 cm3) following aspiration, and the volume of 24 of 25 lesions decreased to less than 16.6 cm3, which is equivalent to the volume of a 3.16-cm sphere. At least 20 Gy was delivered to the entire lesion in 24 of 25 cases. Good tumor control was obtained in 16 of 21 cases that could be evaluated during a median follow-up period of 11 months (range 1–27 months); however, reaccumulation of cyst contents was observed in 2 patients who required Ommaya reservoir placement.

Conclusions

The 1-day aspiration plus GKS procedure is an effective and time-efficient treatment for large cystic brain metastases.

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Masahiro Shin, Hiroki Kurita, Tomio Sasaki, Masao Tago, Akio Morita, Keisuke Ueki, and Takaaki Kirino

Object. The purpose of this study is to determine the efficacy of gamma knife radiosurgery (GKS) treatment of pituitary adenomas that have invaded the cavernous sinus.

Methods. Sixteen patients were treated with GKS: three with nonfunctional adenomas and 13 with hormone-secreting (seven growth hormone [GH] and six adrenocorticotropic hormone [ACTH]) adenomas. More than 16 Gy and 30 Gy were delivered to the tumor margin for nonfunctioning tumors and functioning tumors, respectively, keeping the dose to the optic pathways below 10 Gy. The median follow up was 3 years.

Tumor growth control was achieved in all cases. In GH-producing tumors, four of six cases evaluated were endocrinologically normalized (serum GH < 10 mIU/L, somatomedin C < 450 ng/ml), and the remaining two cases also showed a steady decrease in the GH and somatomedin level. In ACTH-producing tumors, three of six cases were endocrinologically normalized (24-hour urinary-free cortisol < 90 mg/day), two were unchanged, and one showed hormonal recurrence 3 years after radiosurgery. Notably, there were no cases of permanent hypopituitarism or visual symptoms caused by radiosurgery.

Conclusions. The authors data indicate that GKS can be a safe salvage therapy for invading pituitary adenomas, with effectiveness equivalent to conventional radiation therapy but with less risk of causing radiation-induced injury to the surrounding structures.

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Masahiro Shin, Nobutaka Kawahara, Keisuke Maruyama, Masao Tago, Keisuke Ueki, and Takaaki Kirino

Object. Radiosurgery has been widely adopted for the treatment of cerebral arteriovenous malformations (AVMs) in which the practical endpoint is angiographic evidence of obliteration, presumed to be consistent with elimination of the risk of hemorrhage. To test this unverified assumption, the authors followed 236 radiosurgery-treated AVMs between 1 and 133 months (median 77 months) after angiographic evidence of obliteration.

Methods. Four patients experienced hemorrhage between 16 and 51 months after angiographic confirmation of AVM obliteration, and two underwent resection. The histological findings in these patients showed occlusion of the AVM by thickening of the intimal layer with dense hyalinization as well as a small amount of residual AVM vessels and a tiny vasculature. The risks of hemorrhage from these presumaby obliterated AVMs were 0.3% for the annual bleeding risk and 2.2% for the cumulative risk over 10 years. Continuous enhancement of the nidus on computerized tomography (CT) or magnetic resonance (MR) imaging was the only significant factor positively associated with hemorrhage in the statistical analysis (p = 0.0212).

Conclusions. Because the study was based on limited follow-up data, its significance for defining predictive features of hemorrhage after angiographic evidence of obliteration is still indeterminable. Nevertheless, disappearance of the AVM on angiography after radiosurgery does not always indicate total elimination of the disease, especially when CT or MR imaging continues to demonstrate an enhancing lesion. The authors therefore recommend continual follow up even after evidence of AVM obliteration on angiography.