[Surgical Simulation Using a Three-Dimensional Printer].

3D printers have been applied in bone-based surgeries, including craniofacial, plastic, oral, and orthopedic surgeries. The improved capabilities of diagnostic imaging equipment and 3D printers have enabled the development of more precise models, and research on surgical simulations and training in the field of neurosurgery is increasing. This review outlines the use of 3D printers in neurosurgery at our institution in terms of modeling methods and surgical simulations. Modeling with the powder-sticking lamination method using plaster as the material allows drilling, which is a surgical procedure. Therefore, it is useful for simulating skull base tumors, such as petrosectomy in a combined transpetrosal approach or anterior clinoidectomy in an orbitozygomatic approach. The color coding of each part of the model facilitates anatomical understanding, and meshed tumor modeling allows deep translucency. As shown above, the 3D printer's modeling ingenuity allows for useful surgical simulations for each case.

Metastasis infiltrating tumor to meningioma: a case report.

BACKGROUND: There have been many reports of tumor-to-tumor metastasis, in which cancer metastasizes directly into meningiomas. However, metastasis infiltrating tumors in which cancer metastasizes around meningiomas are rare. Therefore, we report a case of metastasis originating from lung cancer that infiltrated meningioma. CASE PRESENTATION: A 79-year-old Japanese woman underwent head magnetic resonance imaging for brain metastasis screening before lung cancer surgery. At that time, asymptomatic meningioma of the left frontal region was accidentally found. Magnetic resonance imaging 6 months later revealed a lesion suspected to be a metastatic brain tumor close to the meningioma. Brain tumor resection was performed, and histopathological diagnosis was meningioma and metastatic brain tumor. Metastatic cancer had invaded the meningioma at the boundary between the brain tumor and metastasis. CONCLUSIONS: A sudden change in imaging findings on routine examination of meningiomas in patients with lung carcinoma may indicate a metastatic brain tumor. The form of cancer metastasis to meningioma is not limited to tumor-to-tumor metastasis, but also includes metastasis infiltrating tumors near the meningioma.

Local and systemic factors associated with quantitative stiffness of carotid plaque.

PURPOSE: Plaque stiffness in carotid artery stenosis is a clinically important factor involved in the development of stroke and surgical complications. The purpose of this study was to clarify which local and systemic factors are associated with the quantitatively measured stiffness of plaque. METHODS: The subjects were 104 consecutive patients who underwent carotid endarterectomy at our institution. To measure quantitative stiffness of plaque, we used an industrial hard meter in the operating room within 1 h after removal of plaque. Local factors related to carotid plaque hardness were evaluated, including maximum intima-media thickness (max IMT), degree of stenosis using the European Carotid Surgery Trial (ECST), presence of ulceration or calcification, and echo brightness on preoperative carotid ultrasound. The degree of stenosis was also evaluated using the North American Symptomatic Carotid Endarterectomy Trial method in digital subtraction angiography. Age, sex, and presence or absence of hypertension, diabetes, and dyslipidemia (low-density lipoprotein cholesterol and triglyceride [TG] levels) served as systemic factors and were compared with the quantitative stiffness of carotid plaque. RESULTS: In multivariate analysis, ECST stenosis degree, calcification, and IMT max as local factors affected plaque stiffness. As a systemic factor, plaque stiffness was statistically significantly negatively correlated with TG values in multivariate analysis (p < 0.05). CONCLUSION: The quantitative stiffness of the plaque was negatively correlated with TG levels as a systemic factor in addition to local factors. This might suggest that reducing high TG levels is associated with plaque stabilization.

Differentiation between Anterior and Posterior Roots Using Compound Muscle Action Potential in Intradural Extramedullary Spinal Tumor Surgery.

This study aims to determine the cutoff values for the compound muscle action potential (CMAP) stimulus in anatomically identified anterior (motor nerve) and posterior roots (sensory nerve) during cervical intradural extramedullary tumor surgery. The connection between CMAP data from nerve roots and postoperative neurological symptoms in thoracolumbar tumors was compared with data from cervical lesions. The participants of the study included 22 patients with intradural extramedullary spinal tumors (116 nerve roots). The lowest stimulation intensity to the nerve root at which muscle contraction occurs was defined as the minimal activation intensity (MAI) in the CMAP. In cervical tumors, the MAI was measured after differentiating between the anterior and posterior roots based on the anatomical placement of the dentate ligament and nerve roots. The MAIs for 20 anterior roots in eight cervical tumors were between 0.1 and 0.3 mA, whereas those for 19 posterior roots were between 0.4 and 2.0 mA. The cutoff was <0.4 mA for both the anterior and posterior roots, and sensitivity and specificity were both 100%. In thoracolumbar tumors, the nerve root was severed in 12 of 14 cases. All MAIs were determined to be at the dorsal roots as their scores were higher than the cutoff and did not indicate motor deficits. The MAIs of the anatomically identified anterior and posterior root CMAPs were found to have a cutoff value of <0.4 mA in the cervical lesions. Similar MAI cutoffs were also applicable to thoracolumbar lesions. Thus, CMAP may be useful in detecting anterior and posterior roots in spinal tumor surgery.

Relationship Between Quantitative Tumor Consistency and Pathological Factors in Intracranial Meningioma.

BACKGROUND: The consistency of intracranial meningiomas is an important clinical factor because it affects the success of surgical resection. This study aimed at identifying and quantitatively measuring pathological factors that contribute to the consistency of meningiomas. Furthermore, we investigated the relationship between these factors and preoperative neuroradiological imaging. METHODS: We analyzed 42 intracranial meningioma specimens, which had been removed at our institution between October 2012 and March 2018. Consistency was measured quantitatively after resection using an industrial stiffness meter. For pathological evaluation, we quantitatively measured the collagen-fiber content through binarization of images of Azan-Mallory-stained section. We assessed calcification and necrosis semi-quantitatively using images acquired of Hematoxylin and Eosin stained samples. The relationship between collagen-fiber content rate and imaging findings was examined. RESULTS: The content of collagen fibers significantly positively correlated with meningioma consistency (p < 0.0001). Collagen-fiber content was significantly higher in low- and iso-intensity regions compared with high-intensity regions on the magnetic resonance T2-weighted images (p = 0.0148 and p = 0.0394, respectively). Calcification and necrosis showed no correlation with tumor consistency. CONCLUSIONS: The quantitative hardness of intracranial meningiomas positively correlated with collagen-fiber content; thus, the amount of collagen fibers may be a factor that determines the hardness of intracranial meningiomas. Our results demonstrate that T2-weighted images reflect the collagen-fiber content and are useful for estimating tumor consistency preoperatively and non-invasively.

Academic Activities of Female Neurosurgeons in All Branch Meetings of the Japan Neurosurgical Society.

This study aims to evaluate the academic activities of female neurosurgeons at all branch meetings of the Japan Neurosurgical Society and identify related issues they encountered. The programs of all seven branch meetings of the Japan Neurosurgical Society (Hokkaido, Tohoku, Kanto, Chubu, Kinki, Chugoku/Shikoku, and Kyushu) were used to determine the number of presentations and chairpersons by sex. The covered period was from January 2008 to December 2020, which was available for viewing during the survey. Of note, only the Kinki branch used data from January 2008 to December 2019. The Neurologia Medico-chirurgica (NMC), the journal of the Japan Neurosurgical Society, was also reviewed to identify publication achievements during the same period. In all seven branches, the percentage of presentations given by female physicians increased from 7.9% in 2008 to 9.6% in 2020 (p < 0.05).Conversely, the percentage of female chairpersons in all branch meetings did not change over time and it was significantly lower (1.1%) than that of female presenters (7.9%) for all branch meetings combined in over 13 years (p < 0.01). In the NMC, the number of articles with female physicians as first authors did not increase or decrease over the years. We conclude that efforts to smoothly promote female neurosurgeons as chairpersons and increase the number of female first authors are necessary to facilitate their academic activities.

Diagnosis and treatment of vertebral artery injuries due to blunt trauma: A case series.

Blunt traumatic vertebral artery injuries are rare, but they cause rapid secondary strokes with worsening prognoses. We report four blunt traumatic vertebral artery injury cases that were diagnosed before developing stroke and successfully treated with coil embolization. All four patients were male, aged between 45 and 71 years (mean 57 years). The injuries were caused by road accidents in 2 cases and falls in 2 cases. The GCS at initial examination was 15, except for one case of hypoxic encephalopathy associated with pulmonary contusion (11 points). The vertebral arteries were completely occluded (Denver grade IV). Before treatment, only one patient had a mild right cerebellar hemispheric stroke, but three patients were asymptomatic. All patients underwent coil embolization (2 on 0 days, 1 on 7 days, and 1 on 17 days), and the postoperative course was uneventful. The neuroradiological imaging studies should be performed as early as possible in vertebral artery injuries due to blunt neck trauma. Moreover, endovascular coil embolization is a safe, effective treatment for blunt traumatic vertebral artery injuries.

Intraperitoneal hemorrhage due to segmental arterial mediolysis associated with cerebral vasospasm after subarachnoid hemorrhage.

A man in his 50s with no significant past medical history developed subarachnoid hemorrhage due to ruptured left middle cerebral artery aneurysm. On the ninth hospital day, he had a ruptured visceral aneurysm with segmental arterial mediolysis, and we successfully treated with transarterial embolization using metallic coils.

A Case of Lateral Ventricular Subependymoma with Intratumoral Hemorrhage via Neuroendoscopic Surgery.

Subependymoma (SE) is a rare, usually asymptomatic, brain tumor predominantly affecting older adults and occurring in the fourth and lateral ventricles. We report a rare case of SE with intratumoral hemorrhage that could be removed by neuroendoscopy. The 81-year-old patient had been followed as an outpatient for 10 years due to an intraventricular tumor. It did not grow over the patient's lengthy follow-up. The patient was transferred to our hospital after he fainted near his home; at the time of admission, he had mild consciousness disturbance, and his Glasgow Coma Scale score was 10 points (E3V3M4). Computed tomography showed intratumoral hemorrhage and slight ventricular enlargement. Magnetic resonance (MR) imaging showed a 4 cm-sized tumor in the anterior horn of the right lateral ventricle. The lesion appeared as a mixed-intensity solid tumor and showed irregular enhancement with gadolinium. The patient underwent neuroendoscopic tumor resection on the 30th day of the patient's hospital stay. A histopathological examination revealed small tumor cells with round nuclei scattered in the glial fibrillary background. Immunostaining was positive for glial fibrillary acidic protein; these findings are consistent with an SE diagnosis. The patient in this study had hypertension and used anticoagulants, risk factors for intratumoral hemorrhage. For intraventricular tumors with bleeding-particularly in older or more physically frail patients-minimally invasive neuroendoscopic surgery should be considered an option for tumor resection.

Quantitative comparison between carotid plaque hardness and histopathological findings: an observational study.

BACKGROUND: Plaque hardness in carotid artery stenosis correlates with cerebral infarction. This study aimed to quantitatively compare plaque hardness with histopathological findings and identify the pathological factors involved in plaque hardness. METHODS: This study included 84 patients (89 lesions) undergoing carotid endarterectomy (CEA) at our institution. Plaque hardness was quantitatively measured immediately after excision using a hardness meter. Collagen and calcification were evaluated as the pathological factors. Collagen was stained with Elastica van Gieson stain, converted to a gray-scale image, and displayed in a 256-step histogram. The median gray-scale median (GSM) was used as the collagen content. The degree of calcification was defined by the hematoxylin-eosin stain as follows: "0:" no calcification, "1:" scattered microcalcification, or "2:" calcification greater than 1 mm or more than 2% of the total calcification. Carotid echocardiographic findings, specifically echoluminance or the brightness of the narrowest lesion of the plaque, classified as hypo-, iso-, or hyper-echoic by comparison with the intima-media complex surrounding the plaque, and clinical data were reviewed. RESULTS: Plaque hardness was significantly negatively correlated with GSM [Spearman's correlation coefficient: -0.7137 (p < 0.0001)]: the harder the plaque, the higher the collagen content. There were significant differences between plaque hardness and degree of calcification between "0" and "2" (p = 0.0206). For plaque hardness and echoluminance (hypo-iso-hyper), significant differences were found between hypo-iso (p = 0.0220), hypo-hyper (p = 0.0006), and iso-hyper (p = 0.0015): the harder the plaque, the higher the luminance. In single regression analysis, GSM, sex, and diabetes mellitus were significant variables, and in multiple regression analysis, only GSM was extracted as a significant variable. CONCLUSIONS: Plaque hardness was associated with a higher amount of collagen, which is the main component of the fibrous cap. Greater plaque hardness was associated with increased plaque stability. The degree of calcification may also be associated with plaque hardness.

A Case of a Ruptured Aneurysm at the Supracallosal Portion (A4-A5) of the Bihemispheric Anterior Cerebral Artery Treated with Endovascular Surgery.

Objective: To report our experience on a rare case of a ruptured aneurysm at the supracallosal portion (A4-A5) of the bihemispheric anterior cerebral artery (ACA), an ACA anomaly, and present that endovascular surgery was a good treatment even for peripheral cerebral aneurysm. Case Presentation: A 53-year-old woman experienced a sudden onset of severe headache and vomiting. Plain CT scan revealed subarachnoid hemorrhage and hematoma in the supracallosal area. Cerebral angiography showed that the left pericallosal artery supplied blood to the bilateral parietal lobes through the bihemispheric artery. A saccular aneurysm was found at the supracallosal portion of the left bihemispheric ACA. Coil embolization of the cerebral aneurysm was performed completely. Conclusion: Several reports have demonstrated an aneurysm with bihemispheric ACA, all treated by neck clipping. In this case, endovascular treatment for intracranial peripheral cerebral aneurysms becomes possible, and treatment indications are said to expand.

The diagnostic value of 123I-IMP SPECT in ocular adnexal lymphoma.

BACKGROUND: N-isopropyl- (123I) p-iodoamphetamine (123I-IMP) is specifically accumulated in primary central nervous system lymphoma (PCNSL) during single-photon emission tomography (SPECT) and contributes to its diagnostic imaging. However, whether 123I-IMP is accumulated in ocular adnexal lymphoma (OAL), one of the malignant intraorbital tumors, remains unclear. This study aimed to evaluate the diagnostic value of 123I-IMP SPECT in OAL. METHODS: Between August 2005 and June 2020, 26 patients with intraorbital tumors underwent neurosurgery at the tertiary care center. Of these, 15 patients who underwent 123I-IMPSPECT before surgery were retrospectively examined. The region of interest was set in the cerebellum ipsilateral to the intraorbital tumor on 123I-IMP SPECT, and the tumor-to-cerebellum ratio (T/C ratio) was calculated using the following formula: T/C ratio = [accumulation of tumor (count/pixel)]/[accumulation of ipsilateral normal cerebellar hemisphere (count/pixel)]. RESULTS: Six patients were included in the OAL group, who were pathologically diagnosed with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), diffuse large B-cell lymphoma (DLBCL), and plasmacytoma. The T/C ratio in the OAL group was statistically higher than that in the non-OAL group (p < 0.01). The optimal cutoff values for both groups were between 0.76 and < 0.93. The sensitivity and specificity were 1.00, respectively. CONCLUSIONS: 123I-IMP SPECT is useful as one of the examinations in the differential diagnoses of OAL, because it showed a significantly higher accumulation in OAL group than in non-OAL group.

Repeated intracranial empyema following cranioplasty in a patient with atopic dermatitis: a case report.

BACKGROUND: Atopic dermatitis is a chronic inflammatory skin disease associated with pruritus. Skin affected by atopic dermatitis not only shows a high percentage of Staphylococcus aureus colonization, but corneal barrier dysfunction is also known to occur. It is considered a risk factor for bacterial infections in various areas of the body. However, the relationship between atopic dermatitis and bacterial infection following neurological surgery has not yet been reported. Here, we present a case of atopic dermatitis in which the surgical site became infected twice and finally resolved only after the atopic dermatitis was treated. CASE PRESENTATION: A 50-year-old Japanese woman with atopic dermatitis underwent cerebral aneurysm clipping to prevent impending rupture. Postoperatively, she developed repeated epidural empyema following titanium cranioplasty. As a result of atopic dermatitis treatment with oral antiallergy medicines and external heparinoids, postoperative infection was suppressed by using an absorbable plastic plate for cranioplasty. The patient's postoperative course was uneventful for 16 months. CONCLUSIONS: Atopic dermatitis is likely to cause surgical-site infection in neurosurgical procedures, and the use of a metal implant could promote the development of surgical-site infection in patients with dermatitis.

Relationship between Preoperative Neuroradiological Findings and Intraoperative Bulbocavernosus Reflex Amplitude in Patients with Intradural Extramedullary Tumors.

The current study aimed to evaluate the relationship between preoperative neuroradiological findings and intraoperative bulbocavernosus reflex (BCR) amplitude in patients with intradural extramedullary tumors. A total of 24 patients with lesions below the 12th thoracic vertebra were included in the analysis. Objective and subjective urinary symptoms were investigated using data obtained from medical records and the core lower urethral symptom score (CLSS) questionnaire. The lesion compression rate was evaluated with MRI. In the epiconus-to-conus medullaris (Epi-CM) group, BCR amplitude changes were found to be correlated with the compression rate (p <0.05). The preoperative CLSS of the group with a BCR amplitude of <50% was worse than that of the group with ≥50% (p <0.01). The group did not experience symptom improvement 6 months postoperatively based on the CLSS. The preoperative CLSS of the group with compression rate of ≥80% on imaging was worse than that of the group with <80% (p <0.05). In the group with preoperative compression rate of ≥80%, CLSS at 1 month and 6 months postoperatively was improved as compared to preoperative CLSS (p <0.01, p <0.05). Hence, BCR amplitude changes are associated with the degree of lesion compression on preoperative images and pre- and postoperative urinary symptoms. Patients with intradural extramedullary Epi-CM lesions with strong compression are likely to present with low BCR amplitude and worsened postoperative symptoms. It is considered that the risk of postoperative urinary symptoms increases even with careful surgical manipulation under these conditions.

Effects of Enhanced Intracranial Pressure on Blood Pressure and the Cardio-Ankle Vascular Index in Rabbits.

AIM: Stroke is well known to lead to hypertension; nevertheless, the role of vascular function in hypertension remains unclear. In this study, we aimed to clarify the mechanism underlying increased arterial stiffness following stroke. METHODS: The cardio-ankle vascular index (CAVI) was measured in five New Zealand White rabbits. Under general anesthesia, intracranial pressure (ICP) was increased by injecting saline (15 mL) into the cisterna magna. ICP was monitored using a catheter inserted into the subarachnoid space via right frontal bone craniotomy. Blood pressure (BP), CAVI, and common carotid flow (CCF) were evaluated, and the responses of these parameters to increased ICP were analyzed. RESULTS: Saline injection into the cisterna magna increased the ICP by over 20 mmHg. Both BP and CAVI increased from 63.2±4.84 to 128.8±14.68 mmHg and from 4.02±0.28 to 4.9±0.53, respectively. Similarly, BP and CCF increased. When hexamethonium was administered before the increase in ICP, the increase in BP (132.2±9.41 mmHg with 10 mg/kg hexamethonium vs. 105.6±11.01 mmHg with 100 mg/kg hexamethonium) and CAVI (5.02±0.64 with 10 mg/kg hexamethonium vs. 4.82±0.42 with 100 mg/kg hexamethonium) were suppressed in a dose-dependent manner. CONCLUSION: Increased ICP causes an increase in BP and CAVI, suggesting that enhanced stiffness of the muscular arteries contributes to high BP. Blocking the autonomic nervous system with hexamethonium suppresses the increase in BP and CAVI, indicating that these increases are mediated by activation of the autonomic nervous system.

[A Case of Mature Teratoma in the Third Ventricle with Holmes Tremor].

Intracranial teratoma is a rare disease that frequently occurs in children and young adults. It comprises of approximately 0.1% of the brain tumors. We report a case of a large mature teratoma in the third ventricle with Holmes tremor. A 5-year-old boy presented with tremors 2 years ago. CT showed a 56×48 mm tumor in the third ventricle and hydrocephalus. The tumor was well demarcated from the surrounding brain tissue and contained calcification. MRI indicated a partially high-intensity signal on T1-weighted and T2-weighted images. The preoperative diagnosis was teratoma. Initially, the tumor was biopsied using neuroendoscopy and the Ommaya reservoir was set. The pathological results showed fat-like tissues and fibroblasts. Subsequently, the tumor was completely removed using the interhemispheric transcallosal transchoroidal approach. The tumor included fat and hair tissues. It also included calcification similar to that observed in a tooth. It was strongly adhered near the pineal gland. Pathologically, the diagnosis was a mature teratoma. Postoperatively, the tremor disappeared and the patient was discharged from the hospital without neurological deficits. We believe that compression of the Guillain-Mollaret triangle was relieved by removal of the tumor. Hence, the tremor disappeared after the operation.

Utility of Schwann/2E and Sox10 in distinguishing CD57-negative olfactory groove schwannoma from olfactory ensheathing cell tumor: A case report and review of the literature.

We herein report a patient who was diagnosed as having olfactory groove schwannoma (OGS) which was negative for CD57 (Leu7) but positive for Schwann/2E and Sox10. A 13-year-old female with a chief complaint of headache was referred to our department due to a tumor lesion in the anterior skull base identified by magnetic resonance imaging (MRI). At the first visit, she did not exhibit altered consciousness, motor palsy, anosmia, seizures, or café au lait spots. On contrast-enhanced computed tomography (CT), a heterogeneously enhanced tumor, 50 × 45 × 50 mm in size, was observed at the anterior skull base. The left cribriform plate was thinner on bone window CT. The tumor exhibited strong, heterogeneous gadolinium enhancement on MRI as well. Slight tumor staining was observed by angiography of the left internal carotid artery but not the left external carotid artery. The patient was preoperatively diagnosed as having meningioma and underwent gross tumor resection via the basal interhemispheric approach. The tumor was strongly positive for S-100 protein and negative for epithelial membrane antigen and CD57 by immunostaining. The tumor was positive for both Schwann/2E and Sox10, which aided in the differential diagnosis between OGSs and olfactory ensheathing cell (OEC) tumors, and the definitive diagnosis was OGS. The assessment of immunoreactivities for Schwann/2E and Sox10 might be necessary to differentiate CD57-negative Schwannomas from OEC tumors.

A Questionnaire to Assess the Challenges Faced by Women Who Quit Working as Full-Time Neurosurgeons.

OBJECTIVE: To analyze why women quit full-time employment as neurosurgeons and to discuss the conditions required for their reinstatement. METHODS: We asked 94 core hospitals providing training programs in the board certification system adopted by the Japan Neurosurgical Society to indicate the total number and present status of women in their department and to send our anonymous questionnaire to women who had formerly worked as full-time neurosurgeons. The questionnaire consisted of closed and open questions on their reasons for quitting as full-time neurosurgeons. RESULTS: Among 427 women evaluated, 72 (17%) had quit full-time employment as neurosurgeons. Twenty-one women who had quit 3-21 years after starting their neurosurgery careers responded to the questionnaire, including 17 board-certified neurosurgeons, 11 individuals with master's degrees, and 16 mothers. Their main reasons for quitting full-time work were difficulty in balancing their neurosurgical career and motherhood (52%) and the physical burden (38%). At the time of quitting, only 2 units (5%) had a career counseling system for women. Two thirds of participants might resume full-time work as neurosurgeons in the future. Their support system during pregnancy and the child-raising period, and understanding of male bosses and colleagues were identified as the key themes. CONCLUSIONS: The Japan Neurosurgical Society could facilitate supportive environments for women in neurosurgery by enhancing adequate childcare services, changing the work style of full-time neurosurgeons to incorporate diverse working styles, shorter working hours, understanding of their bosses and colleagues, and a career counseling system.

Comparison of quantitative measurements of central nervous system tumour consistency and the associated preoperative imaging findings.

Purpose: Central nervous system (CNS) tumour consistency is one of the factors determining the difficulty of surgery for such lesions. We measured the consistency of surgically excised CNS tumour specimens using a hardness meter. The purpose of this study was to identify imaging parameters that reflect tumour consistency by comparing preoperative imaging findings with CNS tumour consistency measurements. Material and methods: Of 175 consecutive patients with CNS tumours who underwent surgery at our hospital between October 2012 and October 2018, 127 were included in this study (those whose specimens were difficult to measure were excluded). CNS tumour consistency was measured immediately after surgical excision using a hardness meter and compared with preoperative T1-weighted, T2-weighted (T2WI), fluid attenuated inversion recovery (FLAIR), diffusion-weighted imaging, gadolinium-enhanced magnetic resonance imaging, plain computed tomography (CT), and contrast-enhanced CT findings. Tumour consistency was also subjectively classified by the surgeon into soft, hard, or very hard. Results: The intracranial meningiomas were harder than the metastatic tumours and gliomas (p = 0.03 and p = 0.03, respectively). Among the intracranial meningiomas, the tumours that exhibited high intensity on T2WI were softer than those that displayed isointensity or low intensity (p < 0.001 and p < 0.001, respectively), and the isointense tumours were softer than the low intensity tumours (p = 0.02). Among the metastatic tumours, the tumours that exhibited high intensity on T2WI were softer than those that displayed isointensity or low intensity (p < 0.001 and p < 0.001, respectively). Among the intracranial meningiomas and metastatic tumours, significant correlations were detected between the T2WI findings and subjective tumour consistency according to the surgeon or quantitative tumour consistency (p = 0.01 and p = 0.03, respectively). Conclusions: The preoperative T2WI findings of intracranial meningiomas and metastatic tumours were significantly correlated with quantitatively measured tumour consistency and subjectively evaluated tumour consistency. Therefore, we concluded that T2WI findings are useful for preoperatively predicting the consistency of such tumours.

Three-Dimensional Printed Model for Surgical Simulation of Combined Transpetrosal Approach.

BACKGROUND: The combined transpetrosal approach is a complicated skull base surgery with a high degree of difficulty. Herein, we made a 3-dimensional (3D) printed petrous bone with color-coded anatomic sites and evaluated its usefulness as a model to practice drilling associated with combined transpetrosal surgery. METHODS: To design a 3D model of the petrous bone, we chose a representative epidermoid petroclival tumor case who underwent combined transpetrosal surgery at our hospital. A 3D image of the petrous bone embedded with color-coded anatomic sites, including cranial nerves, brainstem, and internal carotid and vertebrobasilar arteries, was created based on preoperative computed tomography scan, magnetic resonance, and digital subtraction angiography images and was then 3D printed. Thirteen neurosurgeons from our department evaluated the anatomic reproducibility and estimated distance between each anatomic site of the 3D image and model and the usefulness of the model for drilling practice. RESULTS: The anatomic reproducibility of both the 3D image and model was high, and the 3D model was considered good for drilling practice (P < 0.05). The error in the estimated distance between anatomic sites in the 3D model was significantly smaller than that of the 3D image (P < 0.0001). CONCLUSIONS: These results indicate that our 3D printed model is very useful for practice with craniotomy and petrosectomy drilling, necessary in the combined transpetrosal approach.