[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.

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.

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.

Endoscopic Contralateral Interhemispheric Transfalcine Keyhole Approach for Large Falcine Meningiomas.

OBJECTIVE: Falcine meningioma is usually approached ipsilaterally, and the technique for tumor removal has traditionally been performed under microscopy. We report a surgical procedure for large falcine meningioma by an endoscopic contralateral interhemispheric transfalcine keyhole approach. METHODS: The study period was from September 2019 to March 2021. Study participants were patients with World Health Organization grade I meningioma showing falx attachment, excluding neurofibromatosis, who underwent initial surgery at our institution. The surgical procedure begins with a small contralateral craniotomy of about 3 cm, followed by insertion of an endoscope. The tumor attachment to the falx is excised, exposing the tumor. Internal decompression is performed, and the lesion is dissected from the surrounding brain before removal through the falx. RESULTS: An endoscopic contralateral interhemispheric transfalcine keyhole approach was used to resect 4 cases of large falcine meningioma. The mean operation time was 265 minutes (range: 216-294 minutes), achieving Simpson grade I removal in all cases. No evidence of cerebral infarction, cerebral edema, or new neurological complaints related to impaired venous return was seen using this surgical method. CONCLUSIONS: In the case of falcine meningioma, the endoscopic keyhole contralateral technique allows detachment of the tumor from the falx and safe manipulation in a minor field of view. In addition, because the craniotomy is smaller and the operation time is shorter, this procedure offers a less-invasive approach for the patient. This technique is thus, in our opinion, quite advantageous.

Osaka Sliding Knot Seals Dural Defect Simply in Extended Endoscopic Endonasal Approach.

An extended endoscopic endonasal approach (EEA) has become standard for parasellar and midline skull base lesions. However, postoperative leakage of cerebrospinal fluid (CSF) can result from dural defects after lesion removal. We present a simple and effective technique, the Osaka sliding knot, to prevent CSF leakage. Between November 2018 and March 2021, a total of 41 patients underwent reconstruction of skull base defects with intraoperative high-flow CSF leaks after extended EEA by using this closure technique, of whom only 1 patient experienced postoperative CSF leakage. This technically simple and efficient method seals the dural defect to prevent CSF leakage after surgeries using an extended EEA.

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.

[Acute Changes in the Computed Tomography Findings of Mucocele Combined with Pituitary Adenoma:A Case Report].

INTRODUCTION: We report a rare case in which a pituitary tumor co-occurred with a giant mucocele. The mucocele's computed tomography(CT)values fell markedly when it collapsed, and we report the associated considerations. CASE: This case involved a 42-year-old male patient. For 20 years, his visual acuity had progressively declined, and it suddenly rapidly worsened over a month. Cranial CT revealed a massive tumor in the sphenoid sinus and a pituitary tumor. A region of high absorption extended from the paranasal sinus to the skull base. Two days after the patient's initial presentation, he experienced a sudden loss of vision. Therefore, we performed an urgent re-examination. The CT value of the paranasal lesion was found to have sharply declined. The sinus lesion was diagnosed as a mucocele. Emergent endoscopic surgery was performed. Actinomyces meyeri was detected in the samples cultures. DISCUSSION: The causes of mucocele exhibiting abnormally high signal intensity on CT include the accumulation of hemosiderin due to repeated bleeding in the cyst. Furthermore, we inferred that the Actinomyces meyeri had been taking up metallic elements in vivo for a long time. The marked reduction in the lesion's CT value was considered to have been due to the destruction of the mucocele. The contents of the mucocele flowed out and were replaced with newly produced mucus, which exhibits low absorption values. CONCLUSION: We treated a patient with a giant mucocele involving distraction of the frontal base and a pituitary adenoma. In such cases, surgery should be performed when visual acuity deteriorates suddenly.

Clinical Characteristics of Subarachnoid Hemorrhage with an Intracerebral Hematoma and Prognostic Factors.

BACKGROUND: Subarachnoid hemorrhage (SAH) with an intracerebral hematoma (ICH) shows an unfavorable prognosis. In the present study, we examined the characteristics of SAH with ICH and its prognosis. METHODS: Subjects comprised 218 patients with SAH who underwent surgery between January 2007 and December 2015. We compared age, sex, the location of the aneurysm, treatment procedures, medical history (hypertension, diabetes, and heart disease), the Glasgow Coma Scale (GCS) score on admission, rerupture rate, hydrocephalus, the diameter of the aneurysm, cerebral vasospasm, perioperative cardiopulmonary complications, and the Glasgow Outcome Scale (GOS) score after 2 months between patients with SAH with and without ICH. The interval from the onset of SAH until surgery, the location of ICH, and hematoma volume were investigated as prognostic factors for SAH with ICH. RESULTS: Among all subjects, 82 had SAH with ICH. GCS scores on admission were poorer in patients with SAH with ICH than in those without ICH (P < .001), and middle cerebral artery aneurysms were more likely to form hematomas (P < .001). GOS scores after 2 months were also poorer in patients with SAH with ICH (P < .01). The size of aneurysms was larger in the 82 patients with SAH with ICH than in those without ICH (P < .001), and the rerupture rate was higher (P < .001). The unfavorable prognosis of patients with SAH with ICH was associated with age and GCS score on admission. CONCLUSIONS: A young age and a favorable GCS score on admission may be associated with a favorable prognosis for patients with SAH with ICH, and SAH with ICH may easily rerupture.

A neurosurgical simulation of skull base tumors using a 3D printed rapid prototyping model containing mesh structures.

BACKGROUND: Deep regions are not visible in three-dimensional (3D) printed rapid prototyping (RP) models prepared from opaque materials, which is not the case with translucent images. The objectives of this study were to develop an RP model in which a skull base tumor was simulated using mesh, and to investigate its usefulness for surgical simulations by evaluating the visibility of its deep regions. METHODS: A 3D printer that employs binder jetting and is mainly used to prepare plaster models was used. RP models containing a solid tumor, no tumor, and a mesh tumor were prepared based on computed tomography, magnetic resonance imaging, and angiographic data for four cases of petroclival tumor. Twelve neurosurgeons graded the three types of RP model into the following four categories: 'clearly visible,' 'visible,' 'difficult to see,' and 'invisible,' based on the visibility of the internal carotid artery, basilar artery, and brain stem through a craniotomy performed via the combined transpetrosal approach. In addition, the 3D positional relationships between these structures and the tumor were assessed. RESULTS: The internal carotid artery, basilar artery, and brain stem and the positional relationships of these structures with the tumor were significantly more visible in the RP models with mesh tumors than in the RP models with solid or no tumors. CONCLUSIONS: The deep regions of PR models containing mesh skull base tumors were easy to visualize. This 3D printing-based method might be applicable to various surgical simulations.