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Yoshikazu Okada, Takeshi Shima, Shuichi Oki and Tohru Uozumi

✓ The effects of microsurgical embolectomy were investigated clinicopathophysiologically in 60 dogs after occlusion of the middle cerebral artery (MCA) trunk with a silicone cylinder embolus. One group of animals served as a control (non-embolectomized group), and in the other two groups the embolus was removed 3 or 6 hours after occlusion (3-hour or 6-hour embolectomy group). In the non-embolectomized animals, major neurological deficits with deep cerebral infarction were observed. Regional cerebral blood flow (CBF) in the basal ganglia decreased most prominently. Sensory evoked potentials also declined to about 50% of the control level 3 hours after embolization. In the 3-hour embolectomy group, mild neurological deficits with minimal infarctions were found. One hour after embolectomy, CBF was restored to the original level in all regions, and the sensory evoked potentials surpassed the control level. In the 6-hour embolectomy group, most animals exhibited major neurological deficits and severe brain swelling with hemorrhagic infarction. This study suggests that early microsurgical embolectomy of the MCA trunk restores blood flow in the perforating arteries and prevents deep cerebral infarction.

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Yoshikazu Okada, Takeshi Shima, Noboru Yokoyama and Tohru Uozumi

✓ The authors produced occlusion of the middle cerebral artery (MCA) trunk in dogs by two methods: silicone cylinder embolization and trapping. Comparative analyses of the clinicopathological features in these models, extending from the acute to chronic stage, were performed.

Within 24 hours after embolization, the brain exhibited swelling without macroscopic infarction. Microangiograms revealed impaired filling in the deep areas of the brain with midline shift. At 4 to 7 days after embolization, the animals showed major neurological deficits, evident deep cerebral infarction, and poorly perfused areas in the deep cerebrum with prominent midline shift. At 3 to 4 weeks after embolization, the neurological deficits improved and the affected regions showed cavities or localized lesions. Microangiograms demonstrated hypervascular areas with abnormal vessels in the affected cerebrum. On the other hand, trapping of the MCA trunk produced mild neurological deficits, although there was no evidence of macroscopic lesions or impairment of filling. This study shows that silicone cylinder embolization in the MCA trunk produces a reliable and reproducible deep cerebral infarction in dogs.

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Yoshikazu Okada, Takeshi Shima, Mitsuo Yamamoto and Tohru Uozumi

✓ Regional cerebral blood flow (rCBF), sensory evoked potentials (SEP), and intracranial pressure (ICP) were investigated in dogs with focal cerebral ischemia produced by a silicone cylinder embolus in the middle cerebral artery (MCA) trunk as compared to that produced by trapping the same vessel. These variables were measured at intervals of 1 hour for a period of 6 hours after MCA occlusion.

In the embolized animals, rCBF decreased most extensively at the basal ganglia, from a control level of 53.9 ± 3.9 (mean ± SE) to 21.5 ± 2.7 ml/100 gm/min at the 6th hour. Sensory evoked potentials decreased progressively from the resting level of 100% to 53.0% ± 7.2% at the 3rd hour. Intracranial pressure, measured by epidural pressure on the occluded side, increased rapidly during the first 3 hours, from 10.6 ± 0.3 to about 30 cm H2O.

In the animals with trapping, the decreases in rCBF and declines of SEP were significantly less than those in the embolized animals, and no evident brain swelling was observed. This study demonstrates that MCA trunk occlusion by silicone cylinder embolization produces a more marked decrease in deep CBF, with diminution of SEP and increase in ICP, than that produced by trapping.

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Yoshikazu Okada, Takeshi Shima, Masahiro Nishida and Kanji Yamane

✓ The authors describe the application of a Dacron tube as a retroauricular subcutaneous tunnel in extracranial-intracranial autologous vein bypass graft.

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Takeshi Okada, Kiyoshi Saito, Masakatsu Takahashi, Yasuhisa Hasegawa, Yasushi Fujimoto, Akihiro Terada, Yuzuru Kamei and Jun Yoshida

Object

The aim of this study was to describe a method for resecting malignant tumors originating in the external auditory canal or middle ear and requiring en bloc resection of the petrous bone.

Methods

Between 1995 and 2005, the authors performed en bloc petrosectomy for 18 malignant tumors in 9 male and 9 female patients, ranging in age from 15 to 74 years. Fourteen tumors originated in the external ear, 2 in the middle ear, and 2 in the parotid gland. The pathological entities included 15 squamous cell carcinomas, 2 adenoid cystic carcinomas, and 1 rhabdomyosarcoma. Through an L-shaped temporosuboccipital craniotomy, a medial osteotomy was created through the inner ear for tumors without extension into the inner ear (14 cases) and through the tip of the petrous bone for tumors reaching the inner ear (4 cases). Temporal dura mater in 3 patients and the base of the temporal lobe in 2 patients were included in the en bloc resection.

Results

Surgical complications occurred in 5 patients (28%) with no deaths. During a mean follow-up period of 45 months, 3 patients died of tumor recurrence. Overall, 2- and 5-year survival rates were 86 and 78%, respectively. Two of three patients with dural extension and 1 of 2 with brain invasion remain alive. Two of four patients with tumor extension into the inner ear died.

Conclusions

En bloc petrosectomy is recommended for malignant tumors of the ear. It is safe and effective for lesions limited to the middle ear and may be the procedure of choice for tumors reaching the inner ear and those with dural or brain invasion.

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Takeshi Funaki, Jun C. Takahashi, Yasushi Takagi, Takayuki Kikuchi, Kazumichi Yoshida, Takafumi Mitsuhara, Hiroharu Kataoka, Tomohisa Okada, Yasutaka Fushimi and Susumu Miyamoto

OBJECT

Unstable moyamoya disease, reasonably defined as cases exhibiting either rapid disease progression or repeated ischemic stroke, represents a challenge in the treatment of moyamoya disease. Despite its overall efficacy, direct bypass for such unstable disease remains controversial in terms of safety. This study aims to reveal factors associated with unstable disease and to assess its impact on postoperative silent or symptomatic ischemic lesions.

METHODS

This retrospective cohort study included both pediatric and adult patients with moyamoya disease who had undergone 140 consecutive direct bypass procedures at Kyoto University Hospital. “Unstable moyamoya disease” was defined as either the rapid progression of a steno-occlusive lesion or repeat ischemic stroke, either occurring within 6 months of surgery. The extent of progression was determined through a comparison of the findings between 2 different MR angiography sessions performed before surgery. The clinical variables of the stable and unstable disease groups were compared, and the association between unstable disease and postoperative diffusion-weighted imaging (DWI)–detected lesion was assessed through univariate and multivariate analyses with generalized estimating equations.

RESULTS

Of 134 direct bypass procedures performed after patients had undergone at least 2 sessions of MR angiography, 24 (17.9%) were classified as cases of unstable disease. Age younger than 3 years (p = 0.029), underlying disease causing moyamoya syndrome (p = 0.049), and radiographic evidence of infarction (p = 0.030) were identified as factors associated with unstable disease. Postoperative DWI-defined lesions were detected after 13 of 140 procedures (9.3%), although only 4 lesions (2.9%) could be classified as a permanent complication. The incidence of postoperative DWI-detected lesions in the unstable group was notable at 33.3% (8 of 24). Univariate analysis revealed that unstable disease (p < 0.001), underlying disease (p = 0.028), and recent stroke (p = 0.012) were factors associated with DWI-detected lesions. Unstable disease remained statistically significant after adjustment for covariates in both the primary and sensitivity analyses (primary analysis: OR 6.62 [95% CI 1.79–24.5]; sensitivity analysis: OR 5.36 [95% CI 1.47–19.6]).

CONCLUSIONS

Unstable moyamoya disease, more prevalent in younger patients and those with underlying disease, is a possible risk factor for perioperative ischemic complications. Recognition of unstable moyamoya disease may contribute to an improved surgical result through focused perioperative management based on appropriate surgical risk stratification.

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Takeshi Funaki, Jun C. Takahashi, Kazumichi Yoshida, Yasushi Takagi, Yasutaka Fushimi, Takayuki Kikuchi, Yohei Mineharu, Tomohisa Okada, Takaaki Morimoto and Susumu Miyamoto

OBJECT

The authors’ aim in this paper was to determine whether periventricular anastomosis, a novel term for the abnormal collateral vessels typical of moyamoya disease, is reliably measured with MR angiography and is associated with intracranial hemorrhage.

METHODS

This cross-sectional study sampled consecutive patients with moyamoya disease or moyamoya syndrome at a single institution. Periventricular anastomoses were detected using MR angiography images reformatted as sliding-thin-slab maximum-intensity-projection coronal images and were scored according to 3 subtypes: lenticulostriate, thalamic, and choroidal types. The association between periventricular anastomosis and hemorrhagic presentation at onset was evaluated using multivariate analyses.

RESULTS

Of 136 eligible patients, 122 were analyzed. Eighteen (14.8%) patients presented with intracranial hemorrhage with neurological symptoms at onset. Intra- and interrater agreement for rating of the periventricular anastomosis score was good (κw = 0.65 and 0.70, respectively). The prevalence of hemorrhagic presentation increased with the periventricular anastomosis score: 2.8% for Score 0, 8.8% for Score 1, 18.9% for Score 2, and 46.7% for Score 3 (p < 0.01 for trend). Univariate analysis revealed that age (p = 0.02) and periventricular anastomosis score (p < 0.01) were factors tentatively associated with hemorrhagic presentation. The score remained statistically significant after adjustment for age (OR 3.38 [95% CI 1.84–7.00]).

CONCLUSIONS

The results suggest that periventricular anastomosis detected with MR angiography can be scored with good intra- and interrater reliability and is associated with hemorrhagic presentation at onset in moyamoya disease. The clinical utility of periventricular anastomosis as a predictor for hemorrhage should be validated in further prospective studies.

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Hiroaki Takei, Jun Shinoda, Soko Ikuta, Takashi Maruyama, Yoshihiro Muragaki, Tomohiro Kawasaki, Yuka Ikegame, Makoto Okada, Takeshi Ito, Yoshitaka Asano, Kazutoshi Yokoyama, Noriyuki Nakayama, Hirohito Yano and Toru Iwama

OBJECTIVE

Positron emission tomography (PET) is important in the noninvasive diagnostic imaging of gliomas. There are many PET studies on glioma diagnosis based on the 2007 WHO classification; however, there are no studies on glioma diagnosis using the new classification (the 2016 WHO classification). Here, the authors investigated the relationship between uptake of 11C-methionine (MET), 11C-choline (CHO), and 18F-fluorodeoxyglucose (FDG) on PET imaging and isocitrate dehydrogenase (IDH) status (wild-type [IDH-wt] or mutant [IDH-mut]) in astrocytic and oligodendroglial tumors according to the 2016 WHO classification.

METHODS

In total, 105 patients with newly diagnosed cerebral gliomas (6 diffuse astrocytomas [DAs] with IDH-wt, 6 DAs with IDH-mut, 7 anaplastic astrocytomas [AAs] with IDH-wt, 24 AAs with IDH-mut, 26 glioblastomas [GBMs] with IDH-wt, 5 GBMs with IDH-mut, 19 oligodendrogliomas [ODs], and 12 anaplastic oligodendrogliomas [AOs]) were included. All OD and AO patients had both IDH-mut and 1p/19q codeletion. The maximum standardized uptake value (SUV) of the tumor/mean SUV of normal cortex (T/N) ratios for MET, CHO, and FDG were calculated, and the mean T/N ratios of DA, AA, and GBM with IDH-wt and IDH-mut were compared. The diagnostic accuracy for distinguishing gliomas with IDH-wt from those with IDH-mut was assessed using receiver operating characteristic (ROC) curve analysis of the mean T/N ratios for the 3 PET tracers.

RESULTS

There were significant differences in the mean T/N ratios for all 3 PET tracers between the IDH-wt and IDH-mut groups of all histological classifications (p < 0.001). Among the 27 gliomas with mean T/N ratios higher than the cutoff values for all 3 PET tracers, 23 (85.2%) were classified into the IDH-wt group using ROC analysis. In DA, there were no significant differences in the T/N ratios for MET, CHO, and FDG between the IDH-wt and IDH-mut groups. In AA, the mean T/N ratios of all 3 PET tracers in the IDH-wt group were significantly higher than those in the IDH-mut group (p < 0.01). In GBM, the mean T/N ratio in the IDH-wt group was significantly higher than that in the IDH-mut group for both MET (p = 0.034) and CHO (p = 0.01). However, there was no significant difference in the ratio for FDG.

CONCLUSIONS

PET imaging using MET, CHO, and FDG was suggested to be informative for preoperatively differentiating gliomas according to the 2016 WHO classification, particularly for differentiating IDH-wt and IDH-mut tumors.