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Abstract
Background Pituitary adenoma coexists with intracranial aneurysms in 2.3 to 3.6% of cases, and intracranial aneurysms are thought to be incidental. On the other hand, older age and cavernous sinus invasion are reported to increase the rate of coexistence, so these two diseases may be related.
Methods Ten males and 14 females with the coexistence of pituitary adenomas and intracranial aneurysms were retrospectively investigated among 923 patients (2.6%). Patients were subdivided into two groups: those with direct attachment of cerebral aneurysms to the pituitary adenomas and those without direct attachment. The clinical characteristics, therapeutic strategies, and possible effects of vascular remodeling factors were investigated.
Results Twelve patients had functioning pituitary adenomas, and cavernous sinus invasion was identified in 7 of 24 patients. Five of these 7 patients were treated with priority for the cerebral aneurysm until 2007, whereas 14 of 17 patients without involvement of the aneurysm tip in the tumor were treated with priority for the pituitary adenoma in the later period. Among vascular remodeling factors, strong expression of vascular endothelial growth factor (VEGF) was significantly associated with the coexistence of pituitary adenoma and cerebral aneurysm (p < 0.05).
Conclusion Intracranial aneurysms were found to coexist in 2.6% of cases of surgically treated pituitary adenomas. VEGF-induced arterial wall remodeling may be part of the mechanism of association between pituitary adenomas and cerebral aneurysms, suggesting possible causative mechanism.

Background Intracranial chondromas are extremely rare and represent only 0.2% of all intracranial primary neoplasms. The histologic appearance lacks nuclear atypism and mitoses, and it usually shows low growth potential, although these benign features do not necessarily imply a good prognosis.
Case Description A 44-year-old man was referred to our institution with a subarachnoid hemorrhage (SAH). He had a history of SAH 5 years previously that was diagnosed as unknown etiology at another hospital. Head magnetic resonance imaging showed a large tumor located in the prepontine cistern and extending up to the interpeduncular cistern, and the tumor was irregularly enhanced with contrast medium. Retrospective analysis of the original computed tomography of 5 years earlier identified a small contrast enhancing defect behind the dorsum sellae. Tumor removal was planned to prevent repeated SAH and control the apparently growing tumor. An extended transsphenoidal approach was performed. The pituitary gland was dissected from the bottom of the sellar floor and transposed forward to the prechiasmatic cistern with preservation of the pituitary stalk and its blood supply, and subtotal removal of the tumor was achieved. Postoperative diabetes insipidus disappeared within a few days, and the patient was discharged without neurologic or endocrinologic deficits. Histologic examination established the diagnosis as chondroma without a sarcomatous component. Follow-up examination 3 months after surgery showed a re-enlargement of the residual tumor, and gamma knife surgery was performed.
Conclusions Intracranial chondroma sometimes manifests as intracranial hemorrhage and grows comparatively rapidly in a short period despite the benign histologic features. A long and careful follow-up period is essential.

AbstractReactivation of the hepatitis B virus (HBV) is a risk in the 350 million HBV carriers worldwide. HBV reactivation may cause hepatocellular carcinoma, cirrhosis, and fulminant hepatitis, and HBV reactivation accompanied with malignant tumor and/or chemotherapy is a critical problem for patients with chronic HBV infection. Multiple risk factors causing an immunosuppressive state can also induce HBV reactivation.We present a case of HBV reactivation during an immunosuppressive state caused by Cushing disease and physical and psychological stress after a disaster. A 47-year-old Japanese woman was an inactive HBV carrier until the Great East Japan Earthquake occurred and follow-up was discontinued. One year after the earthquake she had intractable hypertension, and her visual acuity gradually worsened. Head magnetic resonance imaging showed a sellar tumor compressing the optic chiasm, and hepatic dysfunction with HBV reactivation was identified. Endocrinologic examination established the diagnosis as Cushing disease. After normalization of hepatic dysfunction with antiviral therapy, transsphenoidal tumor removal was performed that resulted in subtotal removal except the right cavernous portion. Steroid hormone supplementation was discontinued after 3 days of administration, and gamma knife therapy was performed for the residual tumor. Eighteen months after the operation, adrenocorticotropic hormone and cortisol values returned to normal. The patient has been free from tumor regrowth and HBV reactivation throughout the postoperative course.Accomplishment of normalization with intrinsic steroid value with minimization of steroid supplementation should be established. Precise operative procedures and careful treatment planning are essential to avoid HBV reactivation in patients with this threatening condition.

Abstract
Background Modern imaging techniques can identify adverse factors for tumor removal such as cavernous sinus invasion before surgery, but surgeries for giant pituitary adenomas often reveal discrepancies between preoperative imaging and intraoperative findings because pituitary adenomas have feeding arteries with narrow diameters. Current imaging methods are not suitable for tumors with not only large vascular beds but also slow arterial filling.
Patients and Methods This prospective study recruited 13 male subjects and 9 female subjects with giant pituitary adenomas between November 2011 and 2018. All the patients were investigated with three-dimensional magnetic resonance (MR) imaging, bone image computerized tomography (CT), and digital subtraction angiography (DSA) using a C-arm cone-beam CT scanner with a flat-panel detector and 50% diluted contrast medium. Fine angioarchitecture was evaluated and the tumor blush was quantified using newly developed region of interest (ROI) analysis to establish surgical strategies.
Results Seven patients demonstrated no or very faint tumor blushes. In these patients, feeding arteries run centripetally from the surface of the tumor. Fifteen patients showed significant tumor blushes, and the feeding arteries penetrated centrifugally from the inferoposterior pole to the upper pole of the tumor. All the patients were treated according to the angiographic information with successful hemostasis. The patients showed improvement and/or disappearance of the neurologic deficits. The faint and significant blush groups showed significant differences in intraoperative bleeding (p < 0.01) and operation time (p < 0.05).
Conclusion Specialized evaluation focused on vascularization is required for successful therapy of giant pituitary adenomas.

Abstract
Background The World Health Organization (WHO) classification of tumors of the endocrine organs was revised in 2017. The term atypical adenoma is no longer recommended, and tumors with rapid growth, radiologic invasion, and high Ki-67 labeling index are defined as high-risk adenomas. In this article, we present the case of an aggressive pituitary adenoma not fulfilling the new high-risk criteria with extraordinary rapid progression after very long stable disease, and discuss the remaining problem of the new criteria in terms of a complicated balance between pathologic findings and clinical features.
Case Description A 67-year-old man was admitted with sellar tumor. Serum prolactin concentration was high at 4,552.2 ng/mL. Transsphenoidal surgery achieved subtotal removal. Histologic diagnosis was lactotroph cell adenoma, and Ki-67 labeling index was 2.6%. Postoperatively, magnetic resonance imaging revealed no evidence of tumor regrowth, but terguride or cabergoline administration was continued for slight hyperprolactinemia. Second surgery was performed 18 years after initial surgery because the tumor showed extraordinary rapid regrowth and hyperprolactinemia of 969 ng/mL. Histologic diagnosis was lactotroph cell adenoma with Ki-67 labeling index of 28.9% and positive immunoreactivity for p53. This case could be diagnosed as a high-risk adenoma from the beginning of treatment based on the WHO 2017 criteria, but the clinical course was unusually long and the indication of aggressive adjuvant therapy after initial surgery remained unsolved.
Conclusion Pathologic confirmation for the present definition would be expected to assess the cutoff between typical adenomas and aggressive tumors.

AbstractWe report a case of a 66-year-old woman with a malignant transformation of a growth hormone (GH)-producing pituitary adenoma that was mainly located in the clivus. The patient originally presented with left oculomotor and abducens nerve palsies. Magnetic resonance imaging revealed a clival tumor separated from the normal pituitary gland, and the patient subsequently underwent transsphenoidal surgery. Analysis of the resected clival tissue revealed proliferation of tumor cells with slightly irregular nuclei but no mitosis. Although the Ki-67 labeling index was as high as 8.7%, p53 was negative. Histologic analysis confirmed the diagnosis of a GH-producing pituitary adenoma. Two months after the first operation, the tumor acutely enlarged and caused a subarachnoid hemorrhage. Pathologic findings of the second surgical specimen showed significant nuclear atypia. The Ki-67 labeling index increased to 27.7% and the p53 was positive; there was no GH immunoreactivity. Following the second surgical intervention, the patient was diagnosed with an atypical pituitary adenoma and underwent postoperative local radiotherapy (50 Gy in 25 fractions). Twenty months after the first surgery, multiple bone metastases were detected that led to the diagnosis of pituitary carcinoma. This is the first report of a clival pituitary adenoma undergoing malignant transformation. Because neuroimaging may underestimate local invasiveness in ectopic pituitary tumors, it is essential to conduct a histologic examination to evaluate it. Further analysis of similar cases is necessary to improve clinical management for this confused diagnostic criterion.

Abstract
Background Endoscopic hematoma evacuation is one of the most promising procedures for the treatment of intracerebral hemorrhage (ICH) to avoid severe outcomes, such as death or dependency. However, the effect of the procedure on the functional outcome remains controversial. Thus, standardization and sophistication are required to enhance the surgical results. This study aimed to evaluate the potential efficacy of ultrasonography (US) in endoscopic hematoma evacuation.
methods This study included 39 consecutive patients with spontaneous supratentorial ICH who underwent endoscopic hematoma evacuation between April 2019 and July 2021. The patients were divided into two groups, namely, surgery with or without US assistance. Rebleeding and evacuation rate were set as the primary endpoints, and operation time, requirement for repeat puncture, and modified Rankin scale at discharge were set as the secondary endpoints. During surgery, the burr hole was placed, and the dura mater was widely opened. The US probe was applied on the brain surface via the burr hole to detect the depth and direction of the hematoma cavity. With US assistance, the hematoma cavity was punctured with a cannula, and the transparent port was introduced into the hematoma cavity along the tract. The hematoma was gently evacuated with the irrigation–suction instrument.
Results Of the 39 cases, 9 underwent endoscopic hematoma evacuation with US assistance. Rebleeding was noted in 0 and 2 (6.7%) patients with and without US assistance, respectively (p = 0.43). The mean hematoma evacuation rates were 78.6 and 80.6% in patients with and without US assistance, respectively (p = 0.80). In all cases with US assistance, the cavity could be reached with a single tap. However, repeat puncture was required in 20 (66.7%) cases without US assistance (p = 0.04). In one case, an unexpected residual hematoma was detected using US, which was applied after hematoma evacuation and before wound closure. The operation time was not extended even if US was used during the surgery.
Conclusions US-assisted hematoma evacuation is an effective procedure that can assist in the precise insertion of the puncture cannula and exclusion of the residual hematoma. US might contribute toward improving the accuracy of each step of the procedure, thus leading to better clinical outcomes.

Nonobstructive hydrocephalus in patients with craniopharyngiomas is uncommon. We describe our surgical series of 25 consecutive patients with craniopharyngioma who presented with hydrocephalus. Obstructive hydrocephalus was evident in most cases, and nonobstructive hydrocephalus was revealed in three cases. Even after improvement of cerebrospinal fluid (CSF) pathway obstruction by tumor removal, 10 patients (40%) required CSF diversion. Preoperative imaging study revealed thin intraventricular hemorrhage or superficial siderosis in five cases, and CSF examination revealed hemosiderin-laden phagocytes in one case. These findings indicate continuous bleeding into the CSF that might be associated with CSF malabsorption. We also describe a representative case of craniopharyngioma associated with nonobstructive hydrocephalus due to continuous minor bleeding from the tumor surface in a 62-year-old man with a complaint of disorientation and a decline in daily living activity.Our study demonstrated that minor bleeding into the CSF is a possible mechanism of the development of nonobstructive hydrocephalus in patients with craniopharyngiomas.

Background The piezo actuator-driven pulsed water jet (ADPJ) system is a novel surgical instrument that enables dissection of tissue without thermal damage. Using the ADPJ system in epilepsy surgery requires prediction of the tissue breaking strength of the epileptic brain. The aim of this study was to elucidate whether magnetic resonance imaging T2 relaxometry could predict the breaking strength.
Methods A total of 12 patients with drug-resistant temporal lobe epilepsy who received surgical treatment were included in the study. All the patients qualified for surgery after a comprehensive preoperative evaluation for the treatment of epilepsy. T2 relaxation time, breaking strength of the hippocampus, and an anterior temporal lobe specimen obtained from surgery with dissection depth determined by the ADPJ system were examined.
Results Preoperative T2 relaxation times of the anterior temporal lobe and hippocampus showed mild positive correlation with breaking strength (R2 = 0.60). The hippocampus showed higher T2 relaxation time than the temporal lobe. Hippocampal sclerosis seemed to have higher breaking strength than other pathologies, suggesting the correlation depends on the anatomical location and histopathology. The dissection depth of the extirpated lesion was negatively correlated with the breaking strength at input voltages of 10 V (R2 = − 0.34) and 20 V (R2 = − 0.20).
Conclusions T2 relaxometry may be useful to predict tissue breaking strength in the epileptic brain that allows safe application of the ADPJ system in epilepsy surgery.

Objective Maximum resection with minimum damage to normal structures is required for a better clinical outcome. Several efficient surgical devices such as the Cavitron ultrasonic surgical aspirator are available. Our group developed the actuator-driven pulsed water jet (ADPJ) to dissect soft tissue with vessel preservation. Although these devices are very effective for resection, tumor seeding is a potential risk. The present study investigated the control of splashing during ADPJ use. We demonstrate the effect of additional water flow around the instrument tip to veil the splashing.
Methods Pulsed water jet was ejected from the tip of the ADPJ nozzle. Effects of ADPJ parameters such as input voltage, suction pressure, and distance between the nozzle and the target (standoff distance) on the amount of splashing were analyzed. Methylene blue solution was ejected on photo paper, gelatin brain phantom, and porcine brain harvested and subsequently immersed into physiologic saline to quantify the amount of splashing.
Results High-input voltage and a long standoff distance had significant correlations with large amounts of splashing (r > 0.5; p < 0.01). However, suction pressure had no correlation (r = 0.23). Additional water flow combined with the ADPJ decreased the amount of splashing. A high-speed camera recording revealed that the additional water flow formed a water veil that prevented droplet dispersion, as confirmed with experiments using the brain phantom and porcine brain, in which the irregularity and elasticity are specific.
Conclusions The veil effect of additional water flow is important to reduce splashing during ADPJ use and can minimize the potential risk of dissemination and enhance the safety of the ADPJ.

Background and Study Aims Various minimally invasive approaches are used in neurosurgery. Surgeons must perform nondynamic fine movements in a narrow corridor, so specially designed surgical devices are essential. Unsophisticated instruments may pose potential hazards. The purpose of this study was to assess the factors associated with muscle fatigue during minimally invasive neurosurgery and to investigate whether physical stress can be reduced by refining the devices used.
Material and Methods Four physical aspects of a handpiece were investigated: torque of conduits (0.20, 0.28, and 0.37 kgf*cm), shape of hand grip (five types), angle of the nozzle (0, 20, and 40 degrees), and weight balance (neutral, proximal, and distal). To evaluate muscle fatigue, surface electromyography was recorded from the extensor carpi radialis muscle and flexor carpi radialis muscle during a geometric tracing task. The maximum voluntary contraction (MVC) of each muscle and %MVC (muscle contraction during a task/MVC × 100) were used as the indexes of muscle fatigue.
Results The shape of the hand grip significantly reduced %MVC, which is associated with muscle fatigue. The torque of conduits and angle of the nozzle tended to reduce muscle fatigue but not significantly. Weight balance did not affect muscle fatigue. Based on these results, we made two refined models: model α (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9 × 2.0-cm oval section with angled finger rest), and model β (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9-cm round section with a curved finger rest). The %MVC was significantly decreased with both types (p < 0.05 and p < 0.01, respectively), indicating reduction of muscle fatigue.
Conclusions The geometrically refined surgical device can improve muscle load during surgery and reduce the surgeon's physical stress, thus minimizing the risk of complications.

Object Pulsed water jet is an emerging surgical instrumentation intended to achieve both maximal lesion resection and functional maintenance through preservation of fine vessels and minimal damage to the surrounding tissue. The piezo actuator-driven pulsed water jet (ADPJ) is a new technology that can deliver a precisely controlled uniform and efficient pulsed water jet with minimum water flow. The present study evaluated the ADPJ system in preclinical animal studies in the swine brain, and investigated breaking strength, one of the parameters for mechanical properties, to elucidate the mechanism of tissue selectivity for tissue dissection by the water jet.
Methods This system consisted of a pump chamber driven by a piezo actuator, a stainless steel tube, and a nozzle (internal diameter: 0.15 mm). The water was supplied at 6 ml/min. The relationship between input voltage (3-25 V at 400 Hz) and peak pressure was measured using a pressure sensor through a sensing hole. Temporal profile of dissection depth during moving application was evaluated using gelatin brain phantom and swine brain. The dissected specimens were evaluated histologically. The mechanical property (breaking strength) of swine brain was measured by a compact table-top universal tester.
Results Peak pressure increased linearly with increase in the input voltage, which reflected dissection depth in both the gelatin brain phantom and swine brain. Small arteries were preserved, and minimum damage to surrounding tissues occurred. The breaking strength of arachnoid membrane (0.12 ± 0.014 MPa) was significantly higher compared to gray matter (0.030 ± 0.010 MPa) and white matter (0.056 ± 0.009 MPa) (p < 0.05). The breaking strength of gray matter corresponded to that of 3 wt% gelatin, and that of white matter corresponded to a value between those of 3.5 and 4 wt% gelatin, and the dissection depth seemed to be estimated by 3-4 wt% gelatin.
Conclusion The present study suggests that the ADPJ system has the potential to achieve accurate tissue dissection with preservation of blood vessels in neurosurgery. The difference in breaking strength may explain the tissue selectivity between brain parenchyma and tissue protected by the arachnoid membrane.