Dual-floor Burr Hole Technique Optimized for Modern Burr Hole Caps with an Internal Electrode Locking Mechanism.

Insertion of a deep brain stimulating electrode is a commonly performed procedure. Burr hole caps play an important role in this procedure by immobilizing this electrode; however, burr hole caps could form scalp bumps, which can create further complications. The dual-floor burr hole technique could prevent the formation of scalp bumps. This technique has previously been used with older versions of burr hole caps and has proved to be successful. In recent years, modern burr hole caps with an internal electrode locking mechanism have become the mainstay for this procedure. However, modern burr hole caps differ considerably in diameter and shape from older burr hole caps. In the present study, a dual-floor burr hole technique was performed using modern burr hole caps. To accommodate the increase in diameters and changes in the shape of modern burr hole caps, a perforator with a 30-mm diameter was used for shaving the bone, and the bone shaving depth was altered. This surgical technique was applied to 23 consecutive deep brain stimulation surgeries without complications and was thus positively optimized for modern burr hole caps.

[Metabolic insult causing re-expression of old stroke (MICROS) presenting as stroke mimics].

BACKGROUND: Metabolic insult causing re-expression of old stroke (MICROS), one of the stroke mimics, is characterized by reappearance of impairment of past stroke and can be mistaken for a stroke recurrence. The aim of the present study was to identify the clinical characteristics of MICROS in emergency stroke care, and to investigate predictive factors for distinguishing MICROS from stroke recurrences. METHODS: In our Stroke Center, 519 consecutive patients admitted with suspected stroke in June 2016 to December 2017. MICROS was defined as an acute deterioration of neurological deficits of the previous stroke despite no evidence for stroke recurrences. Among the 70 patients with a past history of stroke, 14 were MICROS, 5 were transient ischemic attack, 15 were other stroke mimics, and 36 were stroke recurrences, respectively. We evaluated the clinical characteristics of MICROS and compared MICROS with stroke recurrences. RESULTS: The causes of MICROS were infectious disease (including influenza and pneumonia) in 4, transient somnolence after syncope in 4, hypo/hyperglycemia in 2, medication overdoses in 1, and anxiety in 3. Eight of the 14 MICROS patients were admitted within 4 hours after the symptom onset. In MICROS patients, fever (>37°C) was observed more frequently than those with stroke recurrences though the difference was not statistically significant. CONCLUSION: MICROS might be associated with fever, syncope, or serum glucose abnormality. MICROS patients sometimes visit the hospital emergency room within 4 hours, thus, distinction between MICROS and true stroke recurrences is important.

Training of Intra-Axial Brain Tumor Resection Using a Self-Made Simple Device with Agar and Gelatin.

INTRODUCTION: Self-made devices composed of agar and gelatin gel were used for resident training in intra-axial brain tumor resection. The mixture gel of agar and gelatin is retractable and can be suctioned. Hardness of the gel depends on the concentration of the solution. Therefore, by changing the concentration, it is easy to make gels of various hardness. METHODS: In this study, a mass of gel that looked like a tumor was placed into another gel that looked like the brain. A part of the "brain" was regarded as the eloquent area. Three types of "tumor" were prepared: hard, moderately hard, and soft tumors. Residents tried to remove the tumor entirely with minimal brain invasion. The training was repeated with 3 types of gel. After resection, the weight of the residual tumor, resected normal brain, and resected eloquent area were measured, and the time taken for removal was recorded. RESULTS: These data were compared between residents and neurosurgeons. We also analyzed how these data improved with repeated practice. In most cases, residual tumor, resected normal brain, resected eloquent area, and time taken for removal were less in neurosurgeons than in residents. Repeated training made residents more skillful. The responses of the trainees were almost all favorable. CONCLUSIONS: Our devices with "tumors" of various hardness appear to be suitable for resident training in each surgical skill. For the next step of this study, we will attempt to fabricate more practical 3-dimensional gel models for presurgical simulation.

Training in Cerebral Aneurysm Clipping Using Self-Made 3-Dimensional Models.

INTRODUCTION: Recently, there have been increasingly fewer opportunities for junior surgeons to receive on-the-job training. Therefore, we created custom-built three-dimensional (3D) surgical simulators for training in connection with cerebral aneurysm clipping. METHODS: Three patient-specific models were composed of a trimmed skull, retractable brain, and a hollow elastic aneurysm with its parent artery. The brain models were created using 3D printers via a casting technique. The artery models were made by 3D printing and a lost-wax technique. Four residents and 2 junior neurosurgeons attended the training courses. The trainees retracted the brain, observed the parent arteries and aneurysmal neck, selected the clip(s), and clipped the neck of an aneurysm. The duration of simulation was recorded. A senior neurosurgeon then assessed the trainee's technical skill and explained how to improve his/her performance for the procedure using a video of the actual surgery. Subsequently, the trainee attempted the clipping simulation again, using the same model. After the course, the senior neurosurgeon assessed each trainee's technical skill. The trainee critiqued the usefulness of the model and the effectiveness of the training course. RESULTS: Trainees succeeded in performing the simulation in line with an actual surgery. Their skills tended to improve upon completion of the training. CONCLUSION: These simulation models are easy to create, and we believe that they are very useful for training junior neurosurgeons in the surgical techniques needed for cerebral aneurysm clipping.

[Rapid 3-Dimensional Models of Cerebral Aneurysm for Emergency Surgical Clipping].

We developed a method for manufacturing solid models of cerebral aneurysms, with a shorter printing time than that involved in conventional methods, using a compact 3D printer with acrylonitrile-butadiene-styrene(ABS)resin. We further investigated the application and utility of this printing system in emergency clipping surgery. A total of 16 patients diagnosed with acute subarachnoid hemorrhage resulting from cerebral aneurysm rupture were enrolled in the present study. Emergency clipping was performed on the day of hospitalization. Digital Imaging and Communication in Medicine(DICOM)data obtained from computed tomography angiography(CTA)scans were edited and converted to stereolithography(STL)file formats, followed by the production of 3D models of the cerebral aneurysm by using the 3D printer. The mean time from hospitalization to the commencement of surgery was 242 min, whereas the mean time required for manufacturing the 3D model was 67 min. The average cost of each 3D model was 194 Japanese Yen. The time required for manufacturing the 3D models shortened to approximately 1 hour with increasing experience of producing 3D models. Favorable impressions for the use of the 3D models in clipping were reported by almost all neurosurgeons included in this study. Although 3D printing is often considered to involve huge costs and long manufacturing time, the method used in the present study requires shorter time and lower costs than conventional methods for manufacturing 3D cerebral aneurysm models, thus making it suitable for use in emergency clipping.

The Trans-Visible Navigator: A See-Through Neuronavigation System Using Augmented Reality.

INTRODUCTION: The neuronavigator has become indispensable for brain surgery and works in the manner of point-to-point navigation. Because the positional information is indicated on a personal computer (PC) monitor, surgeons are required to rotate the dimension of the magnetic resonance imaging/computed tomography scans to match the surgical field. In addition, they must frequently alternate their gaze between the surgical field and the PC monitor. OBJECTIVE: To overcome these difficulties, we developed an augmented reality-based navigation system with whole-operation-room tracking. METHODS: A tablet PC is used for visualization. The patient's head is captured by the back-face camera of the tablet. Three-dimensional images of intracranial structures are extracted from magnetic resonance imaging/computed tomography and are superimposed on the video image of the head. When viewed from various directions around the head, intracranial structures are displayed with corresponding angles as viewed from the camera direction, thus giving the surgeon the sensation of seeing through the head. Whole-operation-room tracking is realized using a VICON tracking system with 6 cameras. RESULTS: A phantom study showed a spatial resolution of about 1 mm. The present system was evaluated in 6 patients who underwent tumor resection surgery, and we showed that the system is useful for planning skin incisions as well as craniotomy and the localization of superficial tumors. CONCLUSIONS: The main advantage of the present system is that it achieves volumetric navigation in contrast to conventional point-to-point navigation. It extends augmented reality images directly onto real surgical images, thus helping the surgeon to integrate these 2 dimensions intuitively.

Training in Brain Retraction Using a Self-Made Three-Dimensional Model.

A hollow brain model was created using soft urethane. A tube passing through the hollow was attached for use as a water inlet and manometer. Water sufficient in quantity to realize the intended initial pressure was infused through the tube. The brain model was retracted with a brain spatula and the surgical corridor was opened. By measuring local force with a sensor set on the brain spatula, the model could be used for training in brain retraction. At the same time, the water column of the manometer was measured and the relationship with the force of the brain spatula was investigated. A positive correlation between the water column and local force was confirmed. This indicated that it was possible to use this model without a force sensor for the same training using water column measurements.

[Pre-surgical simulation of microvascular decompression for hemifacial spasm using 3D-models].

We have been performing pre-surgical simulations using custom-built patient-specific 3D-models. Here we report the advantageous use of 3D-models for simulating microvascular decompression(MVD)for hemifacial spasms. Seven cases of MVD surgery were performed. Two types of 3D-printers were used to fabricate the 3D-models:one using plaster as the modeling material(Z Printer®450, 3D systems, Rock Hill, SC, USA)and the other using acrylonitrile butadiene styrene(ABS)(UP! Plus 3D printer®, Beijing Tiertime Technology, Beijing). We tested three types of models. Type 1 was a plaster model of the brainstem, cerebellum, facial nerve, and the artery compressing the root exit zone of the facial nerve. Part of the cerebellum was digitally trimmed off to observe "the compressing point" from the same angle as that used during actual surgery. Type 2 was a modified Type 1 in which part of the skull was opened digitally to mimic a craniectomy. Type 3 was a combined model in which the cerebellum and the artery of the Type 2 model were replaced by a soft retractable cerebellum and an elastic artery. The cerebellum was made from polyurethane and cast from a plaster prototype. To fabricate elastic arteries, liquid silicone was painted onto the surface of an ABS artery and the inner ABS model was dissolved away using solvent. In all cases, the 3D-models were very useful. Although each type has advantages, the Type-3 model was judged extremely useful for training junior surgeons in microsurgical approaches.

Early diagnosis of cerebral ischemia in cerebral vasospasm by oxygen-pulse near-infrared optical topography.

PURPOSE: Early diagnosis of vasospasm is a key factor in the choice of treatment after subarachnoid hemorrhage (SAH). However, a noninvasive method of diagnosing delayed ischemic neurological deficit (DIND) has not been established. We therefore propose a new method of diagnosing cerebral ischemia using near-infrared optical topography (OT) with oxygen inhalation. MATERIALS AND METHODS: We used a 44-channel OT system that covers the bilateral front otemporoparietal areas to assess 29 patients who underwent surgery within 72 h of the onset of SAH. The patients inhaled room air followed by oxygen for 2 min, and then peripheral oxygen saturation (SpO2) was continuously monitored at the index fingertip. The patients were assessed by N-isopropyl-p-[¹²³I]iodoamphetamine (IMP)-SPECT and OT on the same day. Ischemic findings were confirmed using principal component analysis with reference to the systemic SpO2value. RESULTS: Seven of 29 patients developed DIND. Evidence of ischemia was identified by OT in all seven of these patients before the onset of DIND. The OT and SPECT findings agreed in 27 (93 %) of the 29 patients. DISCUSSION AND CONCLUSIONS: Our method might detect cerebral ischemia before the onset of DIND and thus be clinically useful for assessing cerebral ischemia with vasospasm.

Development of three-dimensional hollow elastic model for cerebral aneurysm clipping simulation enabling rapid and low cost prototyping.

OBJECTIVE: We developed a method for fabricating a three-dimensional hollow and elastic aneurysm model useful for surgical simulation and surgical training. In this article, we explain the hollow elastic model prototyping method and report on the effects of applying it to presurgical simulation and surgical training. METHODS: A three-dimensional printer using acrylonitrile-butadiene-styrene as a modeling material was used to produce a vessel model. The prototype was then coated with liquid silicone. After the silicone had hardened, the acrylonitrile-butadiene-styrene was melted with xylene and removed, leaving an outer layer as a hollow elastic model. RESULTS: Simulations using the hollow elastic model were performed in 12 patients. In all patients, the clipping proceeded as scheduled. The surgeon's postoperative assessment was favorable in all cases. This method enables easy fabrication at low cost. CONCLUSION: Simulation using the hollow elastic model is thought to be useful for understanding of three-dimensional aneurysm structure.

Detection of cerebral ischemia using the power spectrum of the pulse wave measured by near-infrared spectroscopy.

The diagnosis and medical treatment of cerebral ischemia are becoming more important due to the increase in the prevalence of cerebrovascular disease. However, conventional methods of evaluating cerebral perfusion have several drawbacks: they are invasive, require physical restraint, and the equipment is not portable, which makes repeated measurements at the bedside difficult. An alternative method is developed using near-infrared spectroscopy (NIRS). NIRS signals are measured at 44 positions (22 on each side) on the fronto-temporal areas in 20 patients with cerebral ischemia. In order to extract the pulse-wave component, the raw total hemoglobin data recorded from each position are band-pass filtered (0.8 to 2.0 Hz) and subjected to a fast Fourier transform to obtain the power spectrum of the pulse wave. The ischemic region is determined by single-photon emission computed tomography. The pulse-wave power in the ischemic region is compared with that in the symmetrical region on the contralateral side. In 17 cases (85%), the pulse-wave power on the ischemic side is significantly lower than that on the contralateral side, which indicates that the transmission of the pulse wave is attenuated in the region with reduced blood flow. Pulse-wave power might be useful as a noninvasive marker of cerebral ischemia.

Evaluation of cerebral ischemia using near-infrared spectroscopy with oxygen inhalation.

Conventional methods presently used to evaluate cerebral hemodynamics are invasive, require physical restraint, and employ equipment that is not easily transportable. Therefore, it is difficult to take repeated measurements at the patient's bedside. An alternative method to evaluate cerebral hemodynamics was developed using near-infrared spectroscopy (NIRS) with oxygen inhalation. The bilateral fronto-temporal areas of 30 normal volunteers and 33 patients with cerebral ischemia were evaluated with the NIRS system. The subjects inhaled oxygen through a mask for 2 min at a flow rate of 8 L/min. Principal component analysis (PCA) was applied to the data, and a topogram was drawn using the calculated weights. NIRS findings were compared with those of single-photon-emission computed tomography (SPECT). In normal volunteers, no laterality of the PCA weights was observed in 25 of 30 cases (83%). In patients with cerebral ischemia, PCA weights in ischemic regions were lower than in normal regions. In 28 of 33 patients (85%) with cerebral ischemia, NIRS findings agreed with those of SPECT. The results suggest that transmission of the changes in systemic SpO2 were attenuated in ischemic regions. The method discussed here should be clinically useful because it can be used to measure cerebral ischemia easily, repeatedly, and noninvasively.