✓ The case of a chronic subdural hematoma is presented in which the computerized tomography scan showed two parallel fluid-blood density levels. The authors emphasize the importance of this finding in the management of such cases.
Naoya Hashimoto, Takehiko Sakakibara, Kazuaki Yamamoto, Masahito Fujimoto and Tarumi Yamaki
Manabu Kinoshita, Mai Taniguchi, Masatoshi Takagaki, Nobuhisa Seike, Naoya Hashimoto and Toshiki Yoshimine
Neurosurgical patties are the most frequently used instruments during neurosurgical procedures, and their high performance is required to ensure safe operations. They must offer cushioning, water-absorbing, water-retaining, and non–tissue adherent characteristics. Here, the authors describe a revised neurosurgical patty that is superior in all respects to the conventional patty available in Japan. Patty characteristics were critically and scientifically evaluated using various in vitro assays. Moreover, a novel ex vivo evaluation system focusing on the adherent characteristics of the neurosurgical patty was developed. The proposed assay could provide benchmark data for comparing different neurosurgical patties, offering neurosurgeons objective data on the performance of patties. The newly developed patty was also evaluated in real neurosurgical settings and showed superb performance during various neurosurgical procedures.
Yukihiro Goto, Yuichi Furuno, Takuya Kawabe, Kei Ohwada, Kazunori Tatsuzawa, Hiroyasu Sasajima and Naoya Hashimoto
A 34-year-old man with a 1-week history of diplopia was referred to the authors' hospital. Neurological examination revealed left abducens nerve palsy. Computed tomography showed a lesion in the left sphenoid sinus involving the medial wall of the left internal carotid artery (ICA) and osteolytic change at the clivus bordering the lesion. Magnetic resonance imaging demonstrated an extensive soft-tissue mass occupying the left sphenoid sinus. Surgical intervention by the endoscopic transnasal method allowed most of the lesion to be removed. Only the portion attached to the medial wall of the ICA was not removed. Postoperatively, the lesion was diagnosed as a giant cell tumor (GCT) and the patient received 120 mg of subcutaneous denosumab every 4 weeks, with additional doses on Days 8 and 15 during the first month of therapy. MRI a week after starting denosumab revealed shrinkage of the initially fast-growing residual tumor. The patient was discharged upon completion of the third denosumab administration. GCT is an aggressive stromal tumor developing mainly in young adults. Complete resection is recommended for GCT in the literature. However, size and location of the CGT often limit this approach. Various adjuvant treatments for skull base GCTs have been reported, including radiation and chemotherapy. However, the roles of adjuvant therapies have yet to be clearly defined. Denosumab, a monoclonal antibody, was recently approved for GCT in several countries. Denosumab may permit less invasive treatments for patients with GCTs while avoiding deleterious outcomes, and may also limit disease progression and recurrence.
Ryuichi Hirayama, Yasunori Fujimoto, Masao Umegaki, Naoki Kagawa, Manabu Kinoshita, Naoya Hashimoto and Toshiki Yoshimine
Existing training methods for neuroendoscopic surgery have mainly emphasized the acquisition of anatomical knowledge and procedures for operating an endoscope and instruments. For laparoscopic surgery, various training systems have been developed to teach handling of an endoscope as well as the manipulation of instruments for speedy and precise endoscopic performance using both hands. In endoscopic endonasal surgery (EES), especially using a binostril approach to the skull base and intradural lesions, the learning of more meticulous manipulation of instruments is mandatory, and it may be necessary to develop another type of training method for acquiring psychomotor skills for EES. Authors of the present study developed an inexpensive, portable personal trainer using a webcam and objectively evaluated its utility.
Twenty-five neurosurgeons volunteered for this study and were divided into 2 groups, a novice group (19 neurosurgeons) and an experienced group (6 neurosurgeons). Before and after the exercises of set tasks with a webcam box trainer, the basic endoscopic skills of each participant were objectively assessed using the virtual reality simulator (LapSim) while executing 2 virtual tasks: grasping and instrument navigation. Scores for the following 11 performance variables were recorded: instrument time, instrument misses, instrument path length, and instrument angular path (all of which were measured in both hands), as well as tissue damage, max damage, and finally overall score. Instrument time was indicated as movement speed; instrument path length and instrument angular path as movement efficiency; and instrument misses, tissue damage, and max damage as movement precision.
In the novice group, movement speed and efficiency were significantly improved after the training. In the experienced group, significant improvement was not shown in the majority of virtual tasks. Before the training, significantly greater movement speed and efficiency were demonstrated in the experienced group, but no difference in movement precision was shown between the 2 groups. After the training, no significant differences were shown between the 2 groups in the majority of the virtual tasks. Analysis revealed that the webcam trainer improved the basic skills of the novices, increasing movement speed and efficiency without sacrificing movement precision.
Novices using this unique webcam trainer showed improvement in psychomotor skills for EES. The authors believe that training in terms of basic endoscopic skills is meaningful and that the webcam training system can play a role in daily off-the-job training for EES.
Amami Kato, Yasunori Fujimoto, Masaaki Taniguchi, Naoya Hashimoto, Azuma Hirayama, Manabu Kinoshita, Takahito Baba, Motohiko Maruno and Toshiki Yoshimine
Object. Controlling hemorrhage is crucial in the safe and efficient removal of large meningiomas. Intravascular embolization is not always a satisfactory means of accomplishing this goal because of the procedure's hemostatic effect and risk of complications. The authors in this study used a volumetric thermal ablation technique incorporating radiofrequency energy, image guidance, and local temperature control to devascularize tumor tissue.
Methods. Five patients with large meningiomas were treated. The target and orientation of the radiofrequency thermal ablation (RFTA) were simulated preoperatively to maximize devascularization of the lesion without thermal injury to adjacent critical structures. Image fusion, three-dimensional reconstruction, and image-guided methods provided for optimized trajectories and targets for insertion of the RFTA needle. During ablation, local temperatures of the tissue being cauterized were monitored continuously to limit the ablated lesion to within the target volume.
The effects of devascularization and the softening of the tumor parenchyma facilitated lesion removal. The intracranial ablated meningioma changed into necrotic tissue and shrank within a few months. Histopathological examination of the ablated lesion revealed sharply demarcated coagulation necrosis.
Conclusions. Volumetric thermal devascularization can be applied safely in the treatment of large meningiomas to facilitate surgical manipulation of the lesion as well as to reduce its size palliatively. The procedure's usefulness should be studied further in a larger number of cases with different tumor characteristics.
Ryuichi Hirayama, Manabu Kinoshita, Hideyuki Arita, Naoki Kagawa, Haruhiko Kishima, Naoya Hashimoto, Yasunori Fujimoto and Toshiki Yoshimine
In the present study the authors aimed to determine preferred locations of meningiomas by avoiding descriptive analysis and instead using voxel-based lesion mapping and 3D image-rendering techniques.
Magnetic resonance images obtained in 248 treatment-naïve meningioma patients with 260 lesions were retrospectively and consecutively collected. All images were registered to a 1-mm isotropic, high-resolution, T1-weighted brain atlas provided by the Montreal Neurological Institute (the MNI152), and a lesion frequency map was created, followed by 3D volume rendering to visualize the preferred locations of meningiomas in 3D.
The 3D lesion frequency map clearly showed that skull base structures such as parasellar, sphenoid wing, and petroclival regions were commonly affected by the tumor. The middle one-third of the superior sagittal sinus was most commonly affected in parasagittal tumors. Substantial lesion accumulation was observed around the leptomeninges covering the central sulcus and the sylvian fissure, with very few lesions observed at the frontal, parietal, and occipital convexities.
Using an objective visualization method, meningiomas were shown to be located around the middle third of the superior sagittal sinus, the perisylvian convexity, and the skull base. These observations, which are in line with previous descriptive analyses, justify further use of voxel-based lesion mapping techniques to help understand the biological nature of this disease.
Tetsuo Hashiba, Naoya Hashimoto, Shuichi Izumoto, Tsuyoshi Suzuki, Naoki Kagawa, Motohiko Maruno, Amami Kato and Toshiki Yoshimine
Due to advances in neuroimaging and the increasing use of imaging to screen for brain disease (“brain checkups”), meningiomas are now often detected as an incidental finding. The natural history of these asymptomatic meningiomas remains unclear, however. In this study, the authors investigated the natural history and growth pattern of incidentally detected meningiomas using serial volumetric assessment and regression analysis.
In 70 patients with incidentally discovered meningiomas who underwent follow-up for longer than 1 year, tumor volumes were calculated volumetrically at each follow-up visit, and tumor growth was determined. In patients with tumor growth, regression analysis was performed to determine the pattern of growth.
Forty-four tumors exhibited growth and 26 did not. In a regression analysis, 16 of the tumors that grew followed an exponential growth pattern and 15 exhibited linear growth patterns. The presence of calcification was the only imaging characteristic that significantly distinguished the group with tumor growth from that without, although no radiological characteristics significantly distinguished the exponential growth group from the linear growth group. Two patients with obvious tumor growth underwent surgical removal and the pathological specimens extracted showed a high proliferative potential.
The authors found that incidentally discovered meningiomas did not always follow an exponential growth pattern but often exhibited more complex patterns of growth. Serial monitoring of tumor volumes and regression analysis may reveal the growth pattern of incidental meningiomas and provide information useful for determining treatment strategy.
Manabu Kinoshita, Hideyuki Arita, Yoshiko Okita, Naoki Kagawa, Haruhiko Kishima, Naoya Hashimoto, Hisashi Tanaka, Yoshiyuki Watanabe, Eku Shimosegawa, Jun Hatazawa, Yasunori Fujimoto and Toshiki Yoshimine
Diffusion MRI is attracting increasing interest for tissue characterization of gliomas, especially after the introduction of antiangiogenic therapy to treat malignant gliomas. The goal of the current study is to elucidate the actual magnitude of the correlation between diffusion MRI and cell density within the tissue. The obtained results were further extended and compared with metabolic imaging with 11C-methionine (MET) PET.
Ninety-eight tissue samples from 37 patients were stereotactically obtained via an intraoperative neuronavigation system. Diffusion tensor imaging (DTI) and MET PET were performed as routine presurgical imaging studies for these patients. DTI was converted into fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps, and MET PET images were registered to Gd-administered T1-weighted images that were used for navigation. Metrics of FA, ADC, and tumor-to-normal tissue ratio of MET PET along with relative values of FA (rFA) and ADC (rADC) compared with normal-appearing white matter were correlated with cell density of the stereotactically obtained tissues.
rADC was significantly lower in lesions obtained from Gd-enhancing lesions than from nonenhancing lesions. Although rADC showed a moderate but statistically significant negative correlation with cell density (p = 0.010), MET PET showed a superb positive correlation with cell density (p < 0.0001). On the other hand, rFA showed little correlation with cell density.
The presented data validated the use of rADC for estimating the treatment response of gliomas but also caution against overestimating its limited accuracy compared with MET PET.
Masayuki Hirata, Tetsu Goto, Gareth Barnes, Yuka Umekawa, Takufumi Yanagisawa, Amami Kato, Satoru Oshino, Haruhiko Kishima, Naoya Hashimoto, Youichi Saitoh, Naoki Tani, Shiro Yorifuji and Toshiki Yoshimine
Event-related cerebral oscillatory changes reflect regional brain activation. In a previous study, the authors proposed a new method to determine language dominance: examine frontal oscillatory changes during silent reading by using synthetic aperture magnetometry (SAM). The authors' aims in the present study were to establish a normal template for this method, to confirm the results of their previous study with a larger patient population, and to evaluate their method with respect to language localization.
A statistical group analysis of 14 healthy volunteers was conducted to establish a normal control. Language dominance and localization were then evaluated in a larger population of 123 consecutive patients. Study participants were instructed to silently read 100 visually presented words. Using SAM, the spatial distribution of the oscillatory changes was obtained as the Student t statistic by comparing the current density for each voxel between 1 second before and 1 second after each word presentation. Group analyses of the healthy volunteers were performed using statistical nonparametric mapping. Language dominance in the patients was determined according to the laterality index (LI) calculated using peak t values of the left and right frontal desynchronizations. Language dominance was prospectively assessed, and the results were compared with those of the Wada test (63 patients). Language localization results were quantitatively compared with those of stimulation mapping (17 patients).
Group analysis of the healthy volunteers indicated β to low γ band desynchronization in the left frontal area and α to β desynchronization in the left parietotemporal areas. In patients, the frontal language areas were detected in 118 persons (95.9%). Lateralization of β or low γ desynchronization in the inferior or middle frontal gyri corresponded well with language dominance. The introduction of the LI resulted in a quantitative evaluation of language dominance, whose results were concordant with those of the Wada test in 51 (85.0%) of 60 cases. The distance between the estimated frontal language areas and stimulation-positive sites was 6.0 ± 7.1 mm (mean ± SD).
This study is the first in which magnetoencephalography (MEG) was used to determine language dominance in a large population, and the results were compared with those of the Wada test. Moreover, language localization results obtained using MEG were compared with those obtained by invasive mapping. The authors' method, which is based on neuromagnetic oscillatory changes, is a new approach for noninvasively evaluating the frontal language areas, a procedure that has been problematic using MEG dipole methods. Synthetic aperture magnetometry is a noninvasive alternative to Wada testing for language dominance and helps to determine stimulation sites for invasive mapping.