Kiyoshi Saito

Long-term control of clival chordoma with initial aggressive surgical resection and gamma knife radiosurgery for recurrence

PurposeChordomas are locally destructive tumors with high rates of recurrence, and therapeutic strategies remain controversial. This study analyzed long-term outcomes for clival chordomas after initial aggressive surgical resection and gamma knife radiosurgery for recurrence and investigated clinical factors predicting recurrence.MethodsClinical records were reviewed for 19 consecutive patients (11 men, 8 women; mean age, 43.1xa0years) with clival chordoma who underwent initial surgical resection using skull base approaches (mean follow-up after surgical resection, 87.2xa0months). All tumors were aggressively removed, along with the surrounding bone. Four patients were treated with radiotherapy after surgical resection. Recurrent lesions were treated with gamma knife radiosurgery or reoperation. Factors predicting tumor recurrence were analyzed, including age, tumor extension, extent of resection and MIB-1 labeling index. Patient status was evaluated using the Karnofsky performance scale (KPS).ResultsTumor resection was total, subtotal and partial in 14, 4 and 1 patients, respectively. Tumors recurred in 11 patients. Overall, 2- and 5-year progression-free survival rates were 77.9% and 47.9%, respectively. The MIB-1 labeling index was independently associated with recurrence. The optimum cutoff point for the MIB-1 labeling index was 3.44%. All recurrent tumors were totally resected or controlled by gamma knife (mean follow-up after recurrence, 71.2xa0months). All patients survived and were active (mean KPS at final follow-up, 89.5%).ConclusionLong-term control of clival chordomas was achieved. Recurrent tumors were controlled with gamma knife radiosurgery, since lesions were localized and small after initial aggressive resection. The MIB-1 labeling index can provide important information for predicting tumor recurrence.

Epigenetic subclassification of meningiomas based on genome-wide DNA methylation analyses

Meningiomas are among the most common intracranial tumors and are mostly curable by surgical resection. However, some populations of meningiomas with benign histological profiles show malignant behavior. The reasons for this inconsistency are yet to be ascertained, and novel diagnostic criteria other than the histological one are urgently needed. The aim of the present study is to subclassify meningiomas from the viewpoint of gene methylation and to determine the subgroup with malignant characteristics. Thirty meningiomas were analyzed using microarrays for 6157 genes and were classified into three clusters on the basis of their methylation status; these were found to be independent of the histological grading. One of the clusters showed a high frequency of recurrence, with a marked accumulation of methylation in a subset of genes. We hypothesized that the aggressive meningiomas universally share characteristic methylation in certain genes; therefore, we chose the genes that strongly contributed to cluster formation. The quantified methylation values of five chosen genes (HOXA6, HOXA9, PENK, UPK3A and IGF2BP1) agreed well with microarray findings, and a scoring system consisting of the five genes significantly correlated with a high frequency of recurrence in an additional validation set of 32 patients. Of particular note is that three cases with malignant transformation already showed hypermethylation at histologically benign stage. In conclusion, a subgroup of meningiomas is characterized by aberrant hypermethylation of the subset of genes in the early stage of tumorigenesis, and our findings highlight the possibility of speculating potential malignancy of meningiomas by assessing methylation status.

Intradural cranial chordoma

BACKGROUNDnIntradural chordomas are rare and have been considered benign owing to the feasibility of complete resection and the display of lesser aggressive biologic behavior than typical chordomas.nnnCASE DESCRIPTIONnWe herein reported 2 cases of intradural cranial chordoma with aggressive biologic behavior. A tumor (anti-Ki-67 monoclonal antibody [MIB-1], 13.9%) in a 59-year-old woman was strongly adherent to the brainstem and involved the basilar artery and its branches. After subtotal removal, the remnant tumor was treated with stereotactic radiotherapy. A tumor (MIB-1, 6.2%) in a 75-year-old woman repeatedly recurred even after initial gross total removal. The recurrent chordomas were treated with γ-knife radiosurgery.nnnCONCLUSIONnThe cases presented in this study indicate that intradural chordomas can also be aggressive such as typical chordomas. Long-term follow-ups with a large number of patients with this condition are essential for elucidating the prognosis of intradural chordomas.

Neural Basis of Language: An Overview of An Evolving Model

The neural basis of language had been considered as a simple model consisting of the Broca’s area, the Wernicke’s area, and the arcuate fasciculus (AF) connecting the above two cortical areas. However, it has grown to a larger and more complex model based upon recent advancements in neuroscience such as precise imaging studies of aphasic patients, diffusion tensor imaging studies, functional magnetic resonance imaging studies, and electrophysiological studies with cortical and subcortical stimulation during awake surgery. In the present model, language is considered to be processed through two distinct pathways, the dorsal stream and the ventral stream. The core of the dorsal stream is the superior longitudinal fasciculus/AF, which is mainly associated with phonological processing. On the other hand, semantic processing is done mainly with the ventral stream consisting of the inferior fronto-occipital fasciculus and the intratemporal networks. The frontal aslant tract has recently been named the deep frontal tract connecting the supplementary motor area and the Broca’s area and it plays an important role in driving and initiating speech. It is necessary for every neurosurgeon to have basic knowledge of the neural basis of language. This knowledge is essential to plan safer surgery and preserve the above neural structures during surgery.

Magnetically guided 3-dimensional virtual neuronavigation for neuroendoscopic surgery: technique and clinical experience.

OBJECTIVE The authors have developed a novel intraoperative neuronavigation with 3-dimensional (3D) virtual images, a 3D virtual navigation system, for neuroendoscopic surgery. The present study describes this technique and clinical experience with the system. METHODS Preoperative imaging data sets were transferred to a personal computer to construct virtual endoscopic views with image segmentation software. An electromagnetic tracker was used to acquire the position and orientation of the tip of the neuroendo-scope. Virtual endoscopic images were interlinked to an electromagnetic tracking system and demonstrated on the navigation display in real time. Accuracy and efficacy of the 3D virtual navigation system were evaluated in a phantom test and on 5 consecutive patients undergoing neuroendoscopic surgery. RESULTS Virtual navigation views were consistent with actual endoscopic views and trajectory in both phantom testing and clinical neuroendoscopic surgery. Anatomic structures that can affect surgical approaches were adequately predicted with the virtual navigation system. The virtual semitransparent view contributed to a clear understanding of spatial relationships between surgical targets and surrounding structures. Surgical procedures in all patients were performed while confirming with virtual navigation. In neurosurgery with a flexible neuroscope, virtual navigation also demonstrated anatomic structures in real time. CONCLUSION The interactive method of intraoperative visualization influenced the decision-making process during surgery and provided useful assistance in identifying safe approaches for neuroendoscopic surgery. The magnetically guided navigation system enabled navigation of surgical targets in both rigid and flexible endoscopic surgeries.

Skull base reconstruction using various types of galeal flaps.

BackgroundFailure of skull base reconstruction is a life-threatening issue. This study describes surgical techniques utilising various types of galeal flaps and reports on outcome of these procedures for skull base reconstruction.MethodClinical records of 136 patients (75 men, 61 women; mean age, 50.0xa0years) who required skull base reconstruction with galeal flaps were reviewed retrospectively. Patients had undergone skull base surgeries with simultaneous reconstruction for benign tumours in 77 patients, malignant tumours in 53, and other lesions in 6. We repaired dural defects using a fascial patch, and covered the skull base defects using various types of galeal flap according to the size and location of the skull base defects. Routine spinal drainage was not used in any patients.FindingsReconstruction was performed as planned in all patients. We utilised a galea frontalis flap in 17 patients, temporoparietal galeal flap in 95, temporoparietal galeal flap with calvarial bone in 9, and bipedicled temporoparietal galeal flap in 15. Postoperative complications included scalp wound necrosis in 8 patients (5.9%), transient leakage of cerebrospinal fluid in 3 (2.2%), and intracranial infection in 2 (1.5%). Necrosis of the galeal flaps was not encountered.ConclusionsGalea is a well-vascularised tissue with homogenous thickness. Since the galeal layer covers the entire head area, various types of galeal flap can be elevated to cover any size and location of skull base defect.

Development of and Clinical Experience with a Simple Device for Performing Intraoperative Fluorescein Fluorescence Cerebral Angiography: Technical Notes

To perform intraoperative fluorescence angiography (FAG) under a microscope without an integrated FAG function with reasonable cost and sufficient quality for evaluation, we made a small and easy to use device for fluorescein FAG (FAG filter). We investigated the practical use of this FAG filter during aneurysm surgery, revascularization surgery, and brain tumor surgery. The FAG filter consists of two types of filters: an excitatory filter and a barrier filter. The excitatory filter excludes all wavelengths except for blue light and the barrier filter passes long waves except for blue light. By adding this FAG filter to a microscope without an integrated FAG function, light from the microscope illuminating the surgical field becomes blue, which is blocked by the barrier filter. We put the FAG filter on the objective lens of the operating microscope correctly and fluorescein sodium was injected intravenously or intra-arterially. Fluorescence (green light) from vessels in the surgical field and the dyed tumor were clearly observed through the microscope and recorded by a memory device. This method was easy and could be performed in a short time (about 10 seconds). Blood flow of small vessels deep in the surgical field could be observed. Blood flow stagnation could be evaluated. However, images from this method were inferior to those obtained by currently commercially available microscopes with an integrated FAG function. In brain tumor surgery, a stained tumor on the brain surface could be observed using this method. FAG could be performed with a microscope without an integrated FAG function easily with only this FAG filter.