Nobuhisa Matsumura

Intracranial Germinoma Associated with Down’s Syndrome

It is well known that Down’s syndrome is sometimes associated with leukemia. However, there have been only a few case reports of a relationship between Down’s syndrome and brain tumors. We report 2 cases with histological diagnoses of germinoma. The 1st case was a 10-year-old boy with Down’s syndrome complaining of seizure and left hemiparesis. Computed tomographic (CT) scan and magnetic resonance imaging (MRI) showed a mass lesion in the right basal ganglia and thalamus. Histological examination indicated two cell pattern germinomas. The 2nd case was a 20-year-old man with Down’s syndrome complaining of headache and vomiting. CT scan and MRI showed a pineal region tumor with marked hydrocephalus. Surgical specimens showed typical germinoma. Only 13 cases of brain tumors associated with Down’s syndrome have been reported. A higher incidence of germ cell tumors seems to be related to chromosomal abnormalities.

Intramedullary spinal teratoma with spina bifida

Abstract Spinal intramedullary teratoma is a rare tumor. We report a case of intramedullary teratoma of the conus medullaris with spina bifida. A 5-year-old boy was admitted to our hospital for removal of a lumbosacral tumor sited in an intramedullary location at the conus medullaris, which was totally resected with neuroendoscopic assistance. The pathological diagnosis was mature teratoma consisting of three germ cell layers. The pathogenesis of spinal intramedullary teratoma is discussed with special reference to spina bifida.

A newly designed training tool for microvascular anastomosis techniques: Microvascular Practice Card.

BACKGROUND We report a newly designed training card (Microvascular Practice Card) that is a non-animal practice tool for surgical training and practicing the skills for microvascular anastomosis techniques. METHODS The Microvascular Practice Card is a pocketbook-sized card that has silicone tubes affixed to it. On the card, 6 small-diameter, 4-cm-long tubes side by side are arranged in 4 directions with both ends secured. The tubes are available in diameters of 2.0, 1.0, 0.5, and 0.3 mm. The thickness of the tube wall is 0.05 or 0.1 mm. The card includes a record area that allows records to be written. Four directional tubes are arranged on one card, making it possible to practice various directional suturing and anastomosing. RESULTS Beginners begin to practice suturing with larger diameter tubes (2.0 mm) and refine their skills using 1.0 mm diameter tubes as they get used to the practice. For vascular anastomosis, the card provides for end-to-end anastomosis, end-to-side anastomosis, and side-to-side anastomosis. Furthermore, superfine diameter tubes (0.5 and 0.3 mm) help microsurgeons to gain experience at higher magnifications. Training on this card is performed through a plastic box with a small hole using long microinstruments. CONCLUSION Microvascular Practice Card is a new training tool for repeatedly practicing microvascular anastomosis in various situations. This non-animal practice tool would help trainees practice under safe and hygienic conditions and reduce the number of laboratory animals used during technical training.

Multiple aneurysms arising from the origin of a duplication of the middle cerebral artery

Duplication of the middle cerebral artery is an anomalous vessel arising from the internal carotid artery. There have only been 14 reports of aneurysms arising from the origin of a duplication of the middle cerebral artery and 5 of these patients had multiple aneurysms. Aneurysms at this site have a high rupture rate compared to aneurysms in other locations and aggressive management is indicated.

Basic training model for supermicrosurgery: a novel practice card model.

Supermicrosurgery has been developed and reported the anastomosis of vessels with diameters of about 0.5 mm or less. The anastomosis of vessels of about 0.5 mm or less in diameter is technically more difficult than 1.0 mm or larger. This article describes a novel practice card model for acquiring basic supermicrosurgical techniques. A practice card is composed of very small-caliber silicone tubes simulating very small-caliber vessels and a thick paper. The silicone tube external diameters are 0.3, 0.5, or 0.7 mm. The thickness of the tube wall is 0.05 mm. Microsurgeons can easily begin to practice and warm up the supermicrosurgical suturing and anastomosing techniques using this nonvital practice card under a personal desk stereomicroscope in the office and an operating microscope in the operating room. This training model is a simple system for practicing basic supermicrosurgical techniques repeatedly and for warming up before a supermicrosurgical operation. This article also describes basic training regarding its use at high magnifications. This training-based supermicrosurgical skill may become a valuable technique for microsurgeons in many specialties.

Vertebrobasilar artery dissection presenting with simultaneous subarachnoid hemorrhage and brain stem infarction: case report.

BACKGROUND Intracranial dissecting aneurysms have been associated with subarachnoid hemorrhage (SAH) or cerebral ischemia. We encountered a patient presenting with simultaneous subarachnoid hemorrhage and brainstem infarction caused by a dissecting aneurysm of the vertebrobasilar artery, which was diagnosed by magnetic resonance imaging (MRI) but did not show abnormal findings on cerebral angiography. CASE DESCRIPTION A 55-year-old man had sudden onset of headache and left abducens palsy. Computed tomography revealed a subarachnoid hemorrhage localized in the left prepontine cistern and the left cerebellomedullary fissure. Cerebral angiography showed neither a saccular aneurysm nor fusiform dilatation causing the subarachnoid hemorrhage. MRI demonstrated a small infarction in the left dorsal pons, and an intramural hematoma of the left vertebral artery and lower basilar artery. CONCLUSION This is a rare case of a vertebrobasilar dissecting aneurysm that simultaneously caused both SAH and brain stem infarction. MRI should be performed in the acute phase of SAH of unknown origin to determine the possible coexistence of a dissecting aneurysm, as occurred in this case.

An operating microscope with higher magnification and higher resolution for cerebral aneurysm surgery: preliminary experience-technical note.

We describe a higher magnifying power operating microscope system to improve one method of high-quality microsurgical clipping for cerebral aneurysm in some cases. This higher magnification is achieved by a new lens design in the optical system, which makes the image of the object very clear at high magnifications (distinctiveness of 7 μm). This higher-resolution operating microscope system provides the surgeon with higher-magnified images (at the maximum of more than 30× magnifications as each working distance) in the operating field. The magnifications can be changed from low power (2.9×) to high power (62.0×) depending on the circumstances in a given procedure. We have used this operating microscope system on 11 patients with microsurgical clipping for cerebral aneurysms. Microsurgical treatment could be performed safely and precisely. All aneurysms were treated without any technical complications. We think that the use of this microscope would have potential benefits for microsurgical treatment for cerebral aneurysms because of better visualization.

A new bayonet spring microsurgical instrument handle with a bar for microneurosurgery.

Background: The bayonet-shaped spring surgical instrument is essential and perhaps the most important tool in microneurosurgery. It is needed to be handled gently, and so stable handling to the spring tension of the long instrument handle is necessary for fine action in narrow and deep operative fields under an operating microscope. Methods: A bayonet spring microsurgical instrument handle with a bar as a stabilizer is presented for facilitating delicate microsurgical manipulations stably in microneurosurgery. The bar with the handle is a metric projection. The grip of this instrument is a modified writing grasp, which is composed of writing grasp and sandwiching a lateral-projected bar with handle between the medial side of the index finger and the lateral side of the middle finger. Then, this bar as a stabilizer of the instrument is suitable to fix it. Results: Microneurosurgical operations using this instrument system were performed. This was advantageous to stabilize the instrument in deep and narrow operative fields, to be sensitive to move its functional tips by fingertips, and to reduce unwanted movements under an operating microscope. This was disadvantageous to limit the rotational movement within fingers. There were no complications. Conclusion: This handle would provide a steady and balanced grip to ensure precise manipulation of the functional tips of the bayonet instrument for microneurosurgery. It may be useful particularly for the beginners or for the non-dominant hand of microsurgeons.

Microvascular anastomosis at 30-50× magnifications (super-microvascular anastomosis) in neurosurgery.

Background: We report a safe and precise technique of microvascular anastomosis at higher magnifications (30 – 50 ×) in neurosurgery and evaluate our experiences to examine the utility of this method for cerebral revascularization in various situations. Methods: A retrospective review was carried out of patients who underwent microvascular anastomosis using a high-magnified operating microscope. This method was performed in 30 patients with 35 microvascular anastomoses in various situations. This microscope has two optical systems, a standard zooming system and a newly developed high magnification system. High resolution and good depth of focus are achieved by a new lens design in the optical system, which makes the image of the object very clear at higher magnifications. In this operating microscope, the combination of a 10 × eyepiece and the 200, 250, and 300-mm objective lens enables a range of final magnifications from 2.9 × to 50.4 ×. Results: This method enabled one to pay attention to performing atraumatic manipulations of small vessels and correct suturing, intima-to-intima, of vessel walls. Microvascular anastomoses were performed safely and precisely at higher magnifications. All anastomoses were patent. Conclusion: It is obvious that practical final magnifications of more than 30 × in neurosurgery would be super-magnified operative views. Microvascular anastomosis at 30 – 50 × magnifications (super-microvascular anastomosis) can help neurosurgeons to improve their skills, with good visualization, and to be safe and accurate when conducting cerebral revascularization in various situations.

Task-Dependent and Independent Synchronous Activity of Monkey Hippocampal Neurons in Real and Virtual Translocation

Previous neurophysiological and behavioral studies relate hippocampal functions to place learning and memory, and encoding of task (or context)-specific information. Encoding of both task-specific information and own location is essential for episodic memory and for animals to navigate to reward-related places. It is suggested that different neural circuits with different assemblies of different hippocampal neurons are created in different environments or behavioral contexts for the hippocampal formation (HF) to encode and retrieve episodic memory. To investigate whether synchronous activity of hippocampal neurons, suggesting functional connectivity between those neurons, is task and position dependent, multiple single unit activities were recorded during performance of real and virtual translocation (VT) tasks. The monkey moved to one of four reward areas by driving a cab (real translocation) or by moving a pointer on a monitor. Of 163 neuron pairs, significant peaks in cross-correlograms (CCGs) were observed in 98 pairs. Most CCGs had positive peaks within 50 ms. Task-dependent cross-correlations (CCRs) were observed in 44% of the neuron pairs, and similarly observed in both the real and VT tasks. These CCRs were frequently observed in pyramidal vs. pyramidal neuron pairs with positive peak and peak shift. However, no consistent patterns of peak polarity, peak shift, and neuronal types were seen in task-independent CCRs. There was no significant difference in frequency of CCG peaks between real and VT tasks. These results suggest that the task-dependent information may be encoded by interaction among pyramidal neurons, and the common information across tasks may be encoded by interaction among pyramidal neurons and interneurons in the HF. These neuronal populations could provide a neural basis for episodic memory to disambiguously guide animals to places associated with reward in different situations.