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Kazuhiro Hongo

Publications and source records attributed to Kazuhiro Hongo.

At least 55 records · Page 3Linked to original sources
PubMed2003

Growth pattern and rate in residual nonfunctioning pituitary adenomas: correlations among tumor volume doubling time, patient age, and MIB-1 index.

OBJECT: Surgical cure can be achieved in pituitary adenomas when they are completely removed. It is controversial whether postoperative radiation therapy should be given to prevent recurrence, and whether an early reoperation should be performed for residual adenomas, because we have little information about the natural history of postoperative residual adenomas. METHODS: The residual tumor volume was serially measured in 40 nonfunctioning pituitary adenomas (NFPAs) and the tumor volume doubling time (TVDT) was calculated. Correlations between the patients' age, tumor volume, log TVDT, and MIB-1 index were examined. Other factors including the patient's sex, cavernous sinus (CS) invasion by the tumor, or presence of an intratumoral cyst were analyzed to assess their influence on the TVDT. Values are expressed as the means +/- standard deviations. Thirty-eight adenomas increased in volume and two decreased during a follow-up period ranging from 4 to 141 months (mean 52.5 months). Exponentially linear tumor growth was observed in the 38 growing adenomas regardless of the residual tumor volume, with the TVDT ranging from 506 to 5378 days (mean 1836 days). The patients' age was 57.1 +/- 15.7 years (range 15-79 years), the tumor volume at the beginning of the magnetic resonance imaging observation period was 2.5 +/- 2.2 cm3 (range 0.07-14.5 cm3), and the MIB-1 index was 0.73 +/- 0.68% (range 0.1-2.9%). There was a correlation between the log TVDT and patient age (R = 0.73), an inverse correlation between the log TVDT and MIB-1 index (r = -0.49), and an inverse correlation between the MIB-1 index and patient age (r = -0.61). A significant difference (p = 0.0001) was noted between the TVDT (1,106 days) in the 19 patients younger than 61 years of age and the TVDT (2566 days) in the 19 patients who were 61 years of age or older. There was also a significant difference (p = 0.0002) between the age (50.8 +/- 15.3 years) of the patients with rapidly growing tumors (TVDT < 1,836 days, 24 patients) and the age (69.1 +/- 7.6 years) of the patients with slowly growing tumors (TVDT> 1836 days, 14 patients). Other factors including the patients' sex, CS invasion, and intratumoral cyst formation did not affect the TVDT of residual NFPAs. CONCLUSIONS: The tumor growth rate of residual NFPAs is strongly influenced by the patient's age. The TVDT in elderly patients is much longer than that previously reported. Treatment strategies that take into consideration the natural history of residual adenomas should be established especially in the elderly population.

Adenoma↗
PubMed2003

"Real" three-dimensional constructive interference in steady-state imaging to discern microneurosurgical anatomy. Technical note.

Three-dimensional (3D) neuroimages are generally considered useful for neurosurgical practice. Nevertheless, neuroimaging modalities such as 3D digital subtraction angiography and 3D computerized tomography angiography are still insufficient because the resulting images fail to delineate neural structures. Complex neurosurgical procedures are mostly performed in the cerebrospinal fluid (CSF) space of the basal cistern, where vessels and neural structures are present along with the lesion. The magnetic resonance (MR) imaging-derived 3D constructive interference in steady-state (CISS) imaging displays the margin between the CSF and neural structures, vessels, and dura mater in detail, in a two-dimensional fashion. The authors know that volume-rendered 3D CISS images would be more useful for surgery than conventional ones. Although the usefulness of "virtual MR image endoscopy" was reported previously, the endoscopic view is different from the operative field because of the perspective being emphasized. Therefore, to simulate surgical views, the authors made 3D neuroimages from a 3D CISS MR sequence by using an advanced computer workstation. After generating volume images, a cutting method was used in the desired plane to visualize the lesion with reference to a multiplanar reformatted image. The authors call these "real" 3D CISS images, and they are more comparable to the operative field. This newly developed method of producing a real 3D CISS image was used in 30 cases and contributed to the understanding of the relationship between a lesion and surrounding structures before attempting neurosurgical procedures, with minimal invasiveness to the patient.

Basilar Artery↗
PubMed2003

Microvascular pathological features of immediate perinidal parenchyma in cerebral arteriovenous malformations: giant bed capillaries.

OBJECT: The behavior of brain tissue in cases of arteriovenous malformations (AVMs) is a matter of debate. The authors believe that the local microvascular environment in the AVM bed shares the hemodynamic changes influencing that behavior in one way or another. The purpose of this study was to investigate the microvascular pathological features in the immediate perinidal brain tissue. METHODS: This retrospective study was conducted using excised AVM specimens obtained in 35 patients, from which the authors selected 20 specimens that fulfilled the criteria for sufficient brain tissue around the excised nidus. Specimens were stained with hematoxylin and eosin, and the immediate perinidal microvascular environment was examined using light microscopy. CONCLUSIONS: Eighty-five percent of the AVMs studied showed the presence of huge, dilated capillaries, and 65% showed severe congestion of these capillaries. The authors have named these capillaries "giant bed capillaries." In this study capillary bleeding was shown in AVMs, and a pericapillary space was seen around some vessels. The brain parenchyma containing AVMs with these findings proved to be significantly ischemic.

Adolescent↗
PubMed2003

Clinical and neuroimaging characteristics of hydrocephalus associated with vestibular schwannoma.

OBJECT: The clinical and neuroimaging characteristics of hydrocephalus associated with vestibular schwannoma were retrospectively analyzed to improve the perioperative management of the circulation of cerebrospinal fluid. METHODS: A retrospective analysis was performed in 236 patients with unilateral vestibular schwannomas. The patients' ages ranged from 17 to 83 years (mean 53.6 +/- 13.2 years), and the diameters of the tumors the patients harbored ranged from 5 to 60 mm (mean 30.5 +/- 12.7 mm). Hydrocephalus was present before tumor resection in 33 patients (14%) and in six of these patients focal dilation of the sylvian fissures was noted. There was a significant correlation between the incidence of hydrocephalus and tumor size. The incidence of preoperative hydrocephalus among elderly patients (> or = 65 years of age) was 28.6% and that among younger patients (< 65 years of age) was 10.8%. Tumors in elderly patients with hydrocephalus (mean tumor diameter 32.8 +/- 11.7 mm; 12 patients) were significantly smaller than those in younger patients (mean tumor diameter 41.7 +/- 10.9 mm; 21 patients). Among patients with tumors smaller than 30 mm (114 patients), the incidence of hydrocephalus in elderly patients (25%) was 12-fold higher than that in younger patients (2.1%). Six patients with hydrocephalus who had focal dilation of the sylvian fissures were significantly older than 27 patients with hydrocephalus in whom there was no focal dilation. The dilated sylvian fissures collapsed in two patients spontaneously after tumor resection and in the other four patients after shunt placement. CONCLUSIONS: The incidence of associated hydrocephalus is higher in older patients. Communicating hydrocephalus tends to occur in elderly patients. Enlargement of the ventricles with focal dilation of the sylvian fissures should not be misinterpreted as physiological brain atrophy.

Adolescent↗
PubMed2003

Aneurysmal subarachnoid hemorrhage in young adults: a comparison between patients in the third and fourth decades of life.

OBJECT: Aneurysmal subarachnoid hemorrhage rarely occurs in young adults. The aim of this work was to clarify the clinical characteristics of ruptured aneurysms in young adults in the third and fourth decades of life and to compare these two age groups. METHODS: The authors retrospectively investigated 2493 patients who underwent surgical repair for ruptured cerebral aneurysms during a 14-year period (1988-2001). There were 25 patients (1%) in the third decade of life and 106 patients (4.3%) in the fourth decade. In general, favorable outcome was achieved in both groups. There were significant differences in the sizes and locations of aneurysms between the two age groups. Among patients in the fourth decade of life, the aneurysm was large and was located more often on the anterior cerebral artery. CONCLUSIONS: In this study the authors summarize the clinical characteristics of a large series of 131 young adult patients with ruptured cerebral aneurysms. Congenital factors as well as hemodynamic stress may contribute to differences in aneurysm size and location between the two age groups.

Adolescent↗
PubMed2003

Clinical application of robotic telemanipulation system in neurosurgery. Case report.

The NeuRobot is a telecontrolled microscopic micromanipulator system designed for neurosurgical procedures. The unit houses a three-dimensional endoscope and three robot arms that the surgeon operates without direct contact with the patient. The authors have successfully performed robotics-assisted neurosurgical procedures by using the NeuRobot in a 54-year-old man who had a recurrent atypical meningioma. Following the usual preparation of craniotomy and opening of the dura mater, a portion of the tumor was removed using the NeuRobot with the aid of microscopic observation. No complication related to the use of the NeuRobot was encountered and the patient's postoperative course was uneventful. Although various kinds of robots have been developed for use in neurosurgery in recent years, a robotic telemanipulation system capable of performing several surgical tasks has not previously been introduced to clinical neurosurgery. This is the first case report in which neurosurgical manipulation by a robotics system is described.

Humans↗
PubMed2002

Chronic subdural hematoma after transsphenoidal surgery.

Chronic subdural haematoma has not been reported as a complication of transsphenoidal surgery. We present a case of pituitary adenoma which was gross-totally removed by transsphenoidal surgery with the enlarged sellar opening. Postoperative serial imaging showed massive air accumulation in both frontal subdural spaces followed by subdural fluid collection and subsequent chronic subdural haematomas 2 months later. We conclude that close follow up imaging study is required to avoid overlooking chronic subdural haematoma when massive air is introduced into the subdural space by the transsphenoidal surgery.

Adenoma↗
PubMed2002

Aneurysm originating from the fenestration of the posterior cerebral artery: case report.

OBJECTIVE AND IMPORTANCE: A rare case of an aneurysm arising at the fenestration of the P2 segment of the posterior cerebral artery is reported. CLINICAL PRESENTATION: A 37-year-old man presented with severe headache and disturbance of consciousness. Computed tomographic scanning showed diffuse subarachnoid hemorrhage. Cerebral angiography revealed an aneurysm at the fenestration of the P2 segment of the right posterior cerebral artery. The aneurysm was located at the middle portion of the lower trunk of the fenestration. An unruptured arteriovenous malformation was incidentally found in the right thalamus. INTERVENTION: A right frontotemporal craniotomy with orbitozygomatic osteotomy was made, and the aneurysm was successfully clipped. One year after the operation, gamma knife surgery was performed for the right thalamic arteriovenous malformation. CONCLUSION: This is the first reported case of an aneurysm originating from the middle portion of a fenestrated posterior cerebral artery.

Adult↗
PubMed2002

NeuRobot: telecontrolled micromanipulator system for minimally invasive microneurosurgery-preliminary results.

OBJECTIVE: Microneurosurgery can be performed less invasively with the recent advances in neuronavigation and neuroendoscopy. For even less invasive microneurosurgery, we have developed a telecontrolled micromanipulator system. METHODS: The NeuRobot telecontrolled micromanipulator system was developed. With the use of this system, surgical simulations were performed with a human cadaveric head. RESULTS: The system consists of four main parts, i.e., a micromanipulator (slave manipulator), a manipulator-supporting device, an operation-input device (master manipulator), and a three-dimensional display monitor. Three 1-mm forceps and a three-dimensional endoscope, which could be remotely controlled with three degrees of freedom (rotation, neck swinging, and forward/backward motion), were installed in the slave manipulator. All surgical procedures were accurately performed with this system. CONCLUSION: The use of telecontrolled manipulator systems in neurosurgery is very promising, and we are convinced that this system will facilitate more accurate, less invasive microneurosurgery. The details of the NeuRobot system and preliminary results are presented.

Cadaver↗
PubMed2002

Modified, multipurpose, radiolucent sugita head frame for intraoperative cerebral angiography.

OBJECTIVE: Although several radiolucent head-fixation devices have been developed to allow intraoperative cerebral angiography, no device provides satisfactory freedom to obtain the most suitable head position. We recently designed a multipurpose radiolucent Sugita head frame (modified radiolucent Sugita frame) with satisfactory degrees of freedom and rigidity for intraoperative head positioning and head holding, respectively. DESCRIPTION OF INSTRUMENTATION: A short arm and a ring joint, made of engineering plastic, were added to the prototype radiolucent Sugita frame, to permit side-tilting movements of the frame. The shape of all handles at the joints was also changed and the size was enlarged, to facilitate adjustment of the head position. EXPERIENCE AND RESULTS: We used this modified radiolucent Sugita frame in 20 cases involving aneurysms or arteriovenous malformations. The frame performed satisfactorily in all cases, in terms of firm head fixation and unrestrained freedom of head positioning at the surgeon's request. The modified radiolucent Sugita frame was evaluated with respect to its resistance to physical forces. The physical strength of the modified radiolucent Sugita frame is almost equivalent to that of the metallic Sugita frame and is considered sufficient for clinical usage. CONCLUSION: With its rigidity, satisfactory degrees of freedom, and ease of handling, the clinical applicability of the dramatically improved radiolucent head frame enables us to obtain satisfactory intraoperative angiograms.

Cerebral Angiography↗
PubMed2002

Three-dimensional contrast medium-enhanced computed tomographic cisternography for preoperative evaluation of surgical anatomy of intradural paraclinoid aneurysms of the internal carotid artery: technical note.

OBJECTIVE AND IMPORTANCE: Precise preoperative evaluation is especially important when internal carotid artery aneurysms in the paraclinoid region are clipped, because these vascular structures are located in close proximity to various important structures such as the optic nerve and anterior clinoid process. We report a new method for "simultaneously" describing the interrelationships among the aneurysm, internal carotid artery, optic nerve, and bony structures with three-dimensional contrast medium-enhanced computed tomographic (3-D CMECT) cisternography. METHODS: Informed consent was obtained from the patient. An 8-ml injection of iotrolan (Isovist; Schering, Berlin, Germany) (240 mg I/ml) was administered into the lumbar intrathecal space. A computed tomographic scan of the head was obtained 2 hours later with a multislice Asteion computed tomographic scanner (Toshiba, Inc., Tokyo, Japan). An Alatoview workstation (Silicon Graphics, Mountain View, CA) was used to reconstruct the three-dimensional images. RESULTS: These images, as generated by 3-D CMECT cisternography, were found to accurately demonstrate the interrelationships of the internal carotid artery, aneurysm, and surrounding structures preoperatively. The findings obtained from these images proved to be quite similar to the intraoperative findings. 3-D CMECT cisternography clarified whether the paraclinoid aneurysm was intradural or extradural. CONCLUSION: 3-D CMECT cisternography was found to provide a useful means for preoperative evaluation of lesions in the paraclinoid area.

Aged↗
PubMed2002

Mechanism of extracellular K+-induced local and conducted responses in cerebral penetrating arterioles.

BACKGROUND AND PURPOSE: Extracellular concentration of potassium ion ([K+]o) may have a significant influence on the cerebral circulation in health and disease. Mechanisms of [K+]o-induced conducted vasomotor responses in cerebral arterioles, possibly linking microvascular regulation to neuronal activity, have not been examined. METHODS: We analyzed vascular responses to small increases of [K+]o (up to 5 mmol/L) in isolated, cannulated, and pressurized rat cerebral arterioles (36.5+/-1.4 micro m). [K+]o was elevated globally through extraluminal application or locally through micropipette, while arteriolar diameter was measured online. RESULTS: Elevation of [K+]o (5 mmol/L) produced dilation that was inhibited by ouabain but not BaCl2. Locally applied [K+]o (3 to 5 mmol/L) produced a biphasic response (initial constriction followed by dilation), both of which were conducted to the remote site (distance 1142+/-68 microm). Endothelial impairment inhibited conducted but not local biphasic responses. Extraluminal ouabain attenuated local and conducted secondary dilation but not initial constriction. The local biphasic response was unaffected by extraluminal or intraluminal BaCl2. Extraluminal but not intraluminal BaCl2 impaired both conducted constriction and dilation. CONCLUSIONS: In rat penetrating arteriole, (1) [K+]o (3 to 5 mmol/L) strongly regulates arteriolar tone and causes conducted vasomotor responses; (2) local responses to elevated [K+]o are endothelium independent but conducted responses are dependent on an intact endothelium; (3) smooth muscle Na+-K+-ATPase activation is the generator of conducted dilation; and (4) smooth muscle inward rectifier potassium channels sustain conduction. Our findings suggest that potassium-induced conducted vasomotor responses may link local neuronal activity to microvascular regulation, which may be attenuated in pathological conditions.

Animals↗
PubMed2002

Role of endothelial nitric oxide and smooth muscle potassium channels in cerebral arteriolar dilation in response to acidosis.

BACKGROUND AND PURPOSE: Potassium channels or nitric oxide or both are major mediators of acidosis-induced dilation in the cerebral circulation. However, these contributions depend on a variety of factors such as species and vessel location. The present study was designed to clarify whether potassium channels and endothelial nitric oxide are involved in acidosis-induced dilation of isolated rat cerebral arterioles. METHODS: Cerebral arterioles were cannulated and monitored with an inverted microscope. Acidosis (pH 6.8 to 7.4) produced by adding hydrogen ions mediated dilation of the cerebral arterioles in a concentration-dependent manner. The role of nitric oxide and potassium channels in response to acidosis was examined with several specific inhibitors and endothelial damage. RESULTS: The dilation was significantly inhibited by potassium chloride (30 mmol/L) and glibenclamide (3 micromol/L; ATP-sensitive potassium channel inhibitor). We found that 30 micromol/L BaCl2 (concentration-dependent potassium channel inhibitor) also affected the dilation; however, an additional treatment of 3 micromol/L glibenclamide did not produce further inhibition. Tetraethylammonium ion (1 mmol/L; calcium-activated potassium channel inhibitor) and 4-aminopyridine (100 micromol/L; voltage-dependent potassium channel inhibitor) as well as ouabain (10 micromol/L; Na-K ATPase inhibitor) and N-methylsulphonyl-6-(2-proparglyloxyphenyl) hexanamide (1 micromol/L; cytochrome P450 epoxygenase inhibitor) did not alter acidotic dilation. N(omega)-Monomethyl-L-arginine (10 micromol/L) and N(omega)-nitro-L-arginine (10 micromol/L) as nitric oxide synthase inhibitor blunted the dilation. Furthermore, the dilation was significantly attenuated after the endothelial impairment. Additional treatment with glibenclamide (3 micromol/L) further reduced the dilation in response to acidosis. CONCLUSIONS: Endothelial nitric oxide and smooth muscle ATP-sensitive potassium channels contribute to acidosis-induced dilation of rat cerebral arterioles. Endothelial damage caused by pathological conditions such as subarachnoid hemorrhage or traumatic brain injury may contribute to reduced blood flow despite injury-induced cerebral acidosis.

Acidosis↗
PubMed2002

Endoscopic telerobotics for neurosurgery: preliminary study for optimal distance between an object lens and a target.

To overcome limited maneuverability and procedures in the endoscopic neurosurgery, and to utilize its maximum potential ability, the HUMAN (hyper-utility mechatronic assistant) system has been developed. The system has a rigid three-dimensional endoscope with built-in three guiding-manipulators completely controlled as a slave robot by a surgeon in a remote place. To use this system most efficiently, we investigated the suitable distance between an object lens of the endoscope and a target. Actual working territory (AWT) and actual working angle (AWA) of the forceps in the endoscopical operative field (EOF) were measured by changing the distance between the lens and the target. AWT ratio (AWT/EOF) and AWA ratio (AWA/360) decreased from 58% to 12% and increased from 39% to 85% respectively as the distance became longer. When the distance exceeds 13 mm, AWA did not increase more than 85%, and AWT kept decreasing. For the effective use of the system, the optimal distance between the lens and the target should be within 13 mm, and the system will demonstrate its ability to the maximum at the distance of 8mm.

Endoscopes↗
PubMed2002

Disturbed spatial learning of rats after intraventricular administration of transforming growth factor-beta 1.

Patients with subarachnoid hemorrhage (SAH) who later suffer hydrocephalus show persistently high levels of transforming growth factor-beta 1 (TGF-beta 1) in the cerebrospinal fluid after the onset of SAH. Recombinant TGF-beta 1 induces hydrocephalus in mice. This study examined the spatial learning ability of rats after intraventricular administration of TGF-beta 1. Thirteen-week-old Wistar rats were treated with 0.8 or 8.0 micrograms of human recombinant TGF-beta 1 by direct injection or via osmotic pump. Three months later, their spatial learning ability was evaluated with a Morris water maze. Ventricular size, ultrastructural features, and sodium-potassium-adenosine triphosphatase (Na+, K(+)-ATPase) activity of the subarachnoid space were examined. All three TGF-beta 1-treated groups clearly exhibited impaired spatial learning ability, but they did not exhibit ventricular dilation. Histological examination revealed subarachnoid fibrosis and deactivation of Na+, K(+)-ATPase in the arachnoid cells. These findings are similar to those of our previous experiments involving injection of TGF-beta 1 in mice. The present and previous studies suggest that subarachnoid fibrosis is an important factor in the disturbance of the spatial learning ability of rats, whereas ventricular size is less important.

Animals↗
PubMed2002

Radiometric analysis of paraclinoid carotid artery aneurysms.

OBJECT: Classification of paraclinoid carotid artery (CA) aneurysms based on their associated branching arteries has been confusing because superior hypophyseal arteries (SHAs) are too fine to appear opacified on cerebral angiograms. The authors performed a retrospective radiometric analysis of surgically treated paraclinoid aneurysms to elucidate their angiographic and anatomical characteristics. METHODS: A retrospective analysis was made of 85 intradural paraclinoid aneurysms in which the presence or absence of branching arteries had been determined at the time of surgical clipping. The lesions were classified as supraclinoid, clinoid, and infraclinoid aneurysms based on their relation to the anterior clinoid process on lateral angiograms of the CA. The direction of the aneurysms were measured according to angles formed between the medial portion of the horizontal line crossing the aneurysm sac and the center of the aneurysm neck on anteroposterior angiograms. Branching arteries were associated with 68 aneurysms, of which 28 were ophthalmic artery (OphA) lesions (32.9%) and 40 were SHA ones (47.1%); associated branching arteries were absent in 17 aneurysms (20%). Twenty-five aneurysms (29.4%) were located at the supraclinoidal level, 46 (54.1%) at the clinoidal, and 14 (16.5%) at the infraclinoidal. The majority of aneurysms identified at the supraclinoidal level were OphA lesions (44%) or those unassociated with branching arteries (48%), with mean directions of 57 degrees or 67 degrees, respectively. At the clinoidal level, the mean directions of aneurysms were 76 degrees in six lesions unassociated with branching arteries (13%), 43 degrees in 16 OphA lesions (35%), and -11 degrees in 24 SHA ones (52%). All aneurysms at the infraclinoidal level arose at the origin of the SHAs, with a mean direction of -29 degrees, and most of these were embedded in the carotid cave. CONCLUSIONS: Aneurysms arising from the SHA can be distinguished from those not located at an arterial division by cerebral angiography, because SHA lesions are usually located at the medial or inferomedial wall of the internal carotid artery at the clinoidal or infraclinoidal level. Their distribution correlates well with the reported distribution of SHA origins. The carotid cave aneurysm is a kind of SHA lesion that originates at the most proximal intradural CA.

Adult↗