A Self-Developed Mobility Augmented Reality System Versus Conventional X-rays for Spine Positioning in Intraspinal Tumor Surgery: A Case-Control Study.

OBJECTIVE: To evaluate the efficacy of a self-developed mobile augmented reality navigation system (MARNS) in guiding spinal level positioning during intraspinal tumor surgery based on a dual-error theory. METHODS: This retrospective study enrolled patients diagnosed with intraspinal tumors admitted to Fujian Provincial Hospital between May and November 2023. The participants were divided into conventional x-rays and self-developed MARNS groups according to the localization methods they received. Position time, length of intraoperative incision variation, and location accuracy were systematically compared. RESULTS: A total of 41 patients (19 males) with intraspinal tumors were included, and MARNS was applied to 21 patients. MARNS achieved successful lesion localization in all patients with an error of 0.38±0.12 cm. Compared to x-rays, MARNS significantly reduced positioning time (129.00±13.03 seconds vs. 365.00±60.43 seconds, p<0.001) and length of intraoperative incision variation (0.14 cm vs. 0.67 cm, p=0.009). CONCLUSION: The self-developed MARNS, based on augmented reality technology for lesion visualization and perpendicular projection, offers a radiation-free complement to conventional x-rays.

Hemodynamic characteristics and mechanism for intracranial aneurysms initiation with the circle of Willis anomaly.

Clinically, circle of Willis (CoW) is prone to anomaly and is also the predominant incidence site of intracranial aneurysms (IAs). This study aims to investigate the hemodynamic characteristics of CoW anomaly, and ascertain the mechanism of IAs initiation from the perspective of hemodynamics. Thus, the flow of IAs and pre-IAs were analyzed for one type of cerebral artery anomaly, that is, anterior cerebral artery A1 segment (ACA-A1) unilateral absence. Three patient geometrical models with IAs were selected from Emory University Open Source Data Center. IAs were virtually removed from the geometrical models to simulate the pre-IAs geometry. For calculation methods, a one-dimensional (1-D) solver and a three-dimensional (3-D) solver were combined to obtain the hemodynamic characteristics. The numerical simulation revealed that the average flow of Anterior Communicating Artery (ACoA) is almost zero when CoW is complete. In contrast, ACoA flow increases significantly in the case of ACA-A1 unilateral absence. For per-IAs geometry, the jet flow is found at the bifurcation between contralateral ACA-A1 and ACoA, which exhibits characteristics of high Wall Shear Stress (WSS) and high wall pressure in the impact region. It triggers the initiation of IAs from the perspective of hemodynamics. The vascular anomaly that leads to jet flow should be considered as a risk factor for IAs initiation.

Quantitative Evaluation of Hemodynamic Changes After Multiple Intracranial Aneurysms Occlusion Using Computational Fluid Dynamics.

OBJECTIVE: Multiple intracranial aneurysms (MIA) are prevalent. This study conducted hemodynamic calculations on MIA to analyze the effects of occlusion of the internal carotid artery (ICA) and middle cerebral artery (MCA) aneurysms on the hemodynamics of other arteries, as well as the issue of the treatment order for these aneurysms. METHODS: The models of 9 patients with MIA were selected for the study. A computational fluid dynamics model combining 1-dimension and 3-dimension was used to obtain the vascular flow pattern and wall pressure. RESULTS: There was increased pressure at the MCA and anterior cerebral artery (ACA) after occlusion of the aneurysm at the ICA. However, the pressure at the ICA has hardly changed after the aneurysm occlusion at the MCA. Occlusion of the aneurysm of different sizes at the MCA had almost no impact on the pressure at the ICA and ACA. For small aneurysm, the pressure of the ACA and MCA increases with decreasing size of the aneurysm at the ICA. After occlusion of a large aneurysm at the ICA, the impact on the pressure of the ACA and MCA is almost the same as after occlusion of a medium-sized aneurysm. CONCLUSIONS: If the treatment order of ICA and MCA aneurysms cannot be determined based on patient factors and aneurysm characteristics, the MCA aneurysm should be treated as a priority.

A Low-Cost Mobile-Based Augmented Reality Neuronavigation System for Retrosigmoid Craniotomy.

BACKGROUND AND OBJECTIVES: The correct positioning of the transverse-sigmoid sinus junction (TSSJ) during retrosigmoid craniotomy (RC) is crucial for enhancing surgical efficiency and preventing complications. An augmented reality technology may provide low-cost guidance for the TSSJ position. The authors aimed to investigate the clinical application of a self-developed mobile augmented reality navigation system (MARNS) for TSSJ positioning during RC and present their findings. METHODS: This observational research enrolled patients who underwent RC at Fujian Provincial Hospital from May 2023 to June 2023. All patients had their TSSJs located by MARNS. The surgical incision and skull "keyhole" for drilling were determined separately based on the projections of TSSJ on the 3-dimensional model displayed by MARNS. This method was assessed using matching error, positioning time, integrity of the bone flap, incidence of transversal sigmoid sinus injury, and other complications. RESULTS: Seven patients diagnosed with acoustic neuroma, trigeminal neuralgia, and hemifacial spasm were enrolled in this study. The MARNS system exhibited a matching error with an average magnitude of 2.88 ± 0.69 mm. The positioning procedure necessitated an average duration of 279.71 ± 27.29 seconds. In every instance, the inner edge of the TSSJ was precisely identified and exposed while the bone flap was successfully formed and maintained an average integrity of 86.7%. CONCLUSION: This study demonstrated the efficacy of MARNS in the precise placement of the TSSJ during RC procedures. It offers advantages for convenience, cost-effectiveness, and reliability for neurosurgical navigation.

Cerebral venous sinus thrombosis caused by traumatic brain injury complicating thyroid storm: a case report and discussion.

INTRODUCTION: Cerebral venous sinus thrombosis (CVST) is an uncommon cerebrovascular disease with diverse predisposing factors. We report a case of CVST caused by a thyroid storm induced by traumatic brain injury. CASE PRESENTATION: A 29-year-old male patient with a history of Graves' disease with hyperthyroidism presented to our hospital with head trauma of cerebral contusion and laceration in both frontal lobes confirmed by admission CT scan. He received mannitol to lower intracranial pressure, haemostatic therapy, and antiepileptic treatment. Eight days later, he presented with signs of thyroid storms, such as tachycardia, hyperthermia, sweating and irritation, and his thyroid function tests revealed high levels of TPO-Ab, TR-Ab, TG-Ab, FT3 and FT4. Then, he entered a deep coma. His brain CT showed a thrombosis of multiple venous sinuses, along with the opening of peripheral collateral vessels, congestive infarction with haemorrhage and brain swelling. He regained consciousness after treatment with antithyroid drugs, anticoagulants, respiratory support and a regimen of sedation/analgesia. After a half-year follow-up, most of the patient's blocked cerebral venous sinuses had been recanalized, but there were still some sequelae, such as an impaired fine motor performance of the right hand and verbal expression defects. CONCLUSIONS: CVST can be induced by thyroid storms, and trauma-related thyroid storms can develop on the basis of hyperthyroidism. The purpose of this case report is to raise clinicians' awareness and improve their ability to diagnose CVST early in patients with traumatic brain injury complicating thyroid storms to improve the neurological prognosis among similar patients.

Marker-less augmented reality based on monocular vision for falx meningioma localization.

BACKGROUND: The existing augmented reality (AR) based neuronavigation systems typically require markers and additional tracking devices for model registration, which causes excessive preparatory steps. METHODS: For fast and accurate intraoperative navigation, this work proposes a marker-less AR system that tracks the head features with the monocular camera. After the semi-automatic initialization process, the feature points between the captured image and the pre-loaded keyframes are matched for obtaining correspondences. The camera pose is estimated by solving the Perspective-n-Point problem. RESULTS: The localization error of AR visualization on scalp and falx meningioma is 0.417 ± 0.057 and 1.413 ± 0.282 mm, respectively. The maximum localization error is less than 2 mm. The AR system is robust to occlusions and changes in viewpoint and scale. CONCLUSIONS: We demonstrate that the developed system can successfully display the augmented falx meningioma with enough accuracy and provide guidance for neurosurgeons to locate the tumour in brain.

Assessment of a 3D printed simulator of a lateral ventricular puncture in interns' surgical training.

PURPOSE: In this study, a simulator for training lateral ventricular puncture (LVP) was developed using three-dimensional (3D) printing technology, and its function of improving the skills of LVP in young interns was evaluated. METHODS: A virtual 3D craniocerebral simulator of a 51-year-old female patient with hydrocephalus was reconstructed with 3D printing technology. The anatomical and practical validity were assessed by all interns on a 13-item Likert scale. The usefulness of this simulator was evaluated once a week by two neurosurgeons, based on the performance of the interns, using the objective structured assessment of technical skills (OSATS) scale. RESULTS: The Likert scale showed that all participants agreed with the overall appearance of the simulator. Also, the authenticity of the skull was the best, followed by the lateral ventricles, analog generation system of intraventricular pressure, cerebrum, and the scalp. This simulator could help the participants' learning about the anatomy of the lateral ventricle, effective training, and repeating the steps of LVP. During training, the interns' ratio of success in LVP elevated gradually. At each evaluation stage, all mean performance scores for each measure based on the OSATS scale were higher than the previous. CONCLUSIONS: The 3D printed simulator for LVP training provided both anatomical and practical validity, and enabled young doctors to master the LVP procedures and skills.

A virtual reality-based data analysis for optimizing freehand external ventricular drain insertion.

PURPOSE: This work exploits virtual reality technique to analyse and optimize the preoperative planning of freehand external ventricular drain (EVD) insertion. Based on the three-dimensional (3D) virtual brain models, neurosurgeons can directly observe the anatomical landmarks and complete the simulated EVD insertion. Simulation data is used to optimize preoperative planning parameters to ensure the surgical performance. METHODS: We used the computed tomography (CT) scans to construct the 3D virtual brain models. A group of EVD insertions were simulated by inserting virtual catheters at different entry points. The key parameters including the location of entry point, the catheter orientation, the catheter tip position on lateral ventricles, and the insertion depth were recorded. A data analysis method was then applied to optimize these parameters, resulting in the optimal parameters for the EVD insertion. RESULTS: When the lateral distance of entry point ranged from 2.5 to 3 cm, the success rate of 204 cases was 97.79%, which was higher than that of the classic method (59.52%). The optimal insertion angle towards the sagittal plane ranged from 10.46° to 12.73°. To prevent penetrating the lateral ventricles, the insertion depth was optimized to be 3.28 to 4.58 cm. CONCLUSIONS: The proposed data analysis method is helpful to optimize the key parameters of the preoperative planning, and provides useful references for neurosurgeons to perform the freehand EVD insertion. The EVD insertion experiments on 3D printing model had a success rate of 93.75%, which verified the effectiveness of the data analysis.

Development and evaluation of a craniocerebral model with tactile-realistic feature and intracranial pressure for neurosurgical training.

OBJECTIVE: In this article, a craniocerebral model is introduced for neurosurgical training, which is patient-specific, tactile-realistic, and with adjustable intracranial pressure. METHODS: The patient-specific feature is achieved by modeling from CT scans and magnetic resonance images (MRI). The brain tissue model is built by the hydrogel casting technique, while scalp, skull, vasculature, and lateral ventricles are all-in-one fabricated by three-dimensional (3D) printing. A closed-loop system is integrated to monitor and control the intracranial pressure. 3D measurements, mechanical tests, and simulated external ventricular drain (EVD) placement procedures are conducted on the model. RESULTS: A neurosurgical training model is completed with high accuracy (mean deviation 0.36 mm). The hydrogel brain tissue has a stiffness more similar to that of a real brain than the common 3D printed materials. The elasticity modulus of hydrogel brain tissue model is E=25.71 kPa, compared with our softest 3D printed material with E=1.14×103 kPa. Ten experienced surgeons rate the tactile realness of the neurosurgical training model at an average point of 4.25 on a scale from 1 (strongly negative) to 5 (strongly positive). The neurosurgical training model is also rated to be realistic in size (4.82), anatomy (4.70), and effective as an aid to improve blind EVD placement skills (4.65). CONCLUSIONS: The neurosurgical training model can provide trainee surgeons with realistic experience in both tactile feedbacks and craniocerebral anatomy, improving their surgical skills.

Secondary headache due to aspergillus sellar abscess simulating a pituitary neoplasm: case report and review of literature.

Fungal sellar abscess is rare. A 42-year-old man was admitted with 2-month headache characterized by right peri-orbital pain. An intrasellar mass was found to be simulated a pituitary neoplasm after magnetic resonance imaging examination, and operated on via an endoscopic trans-sphenoidal approach. Milk-like pus and a mass of ash black mixed and necrotic material were found and removed. Histopathology revealed numerous aspergillus hyphae. Itraconazole was given on a dosage of 200 mg twice a day orally for 6 weeks. No recurrence was observed during follow-up. Complete surgical resection through endoscopic trans-sphenoidal approach combined with systemic anti-fungal therapy, should be considered as the optimal treatment.

Sympathetic nerves bridge the cross-transmission in hemifacial spasm.

The pathophysiologic basis of hemifacial spasm is abnormal cross-transmission between facial nerve fibers. The author hypothesized that the demyelinated facial nerve fibers were connected with the sympathetic nerve fibers on the offending artery wall, and thus the latter function as a bridge in the cross-transmission circuit. This hypothesis was tested using a rat model of hemifacial spasm. A facial muscle response was recorded while the offending artery wall was electrically stimulated. The nerve fibers on the offending artery wall were blocked with lidocaine, or the superior cervical ganglion, which innervates the offending artery, was resected, and meanwhile the abnormal muscle response was monitored and analyzed. A waveform was recorded from the facial muscle when the offending artery wall was stimulated, named as "Z-L response". The latency of Z-L response was different from that of abnormal muscle response. When the nerve fibers on the offending artery wall were blocked by lidocaine, the abnormal muscle response disappeared gradually and recovered in 2h. The abnormal muscle response disappeared permanently after the sympathetic ganglion was resected. Our findings indicate that cross-transmission between the facial nerve fibers is bridged by the nerve fibers on the offending artery wall, probably sympathetic nerve fibers.

Discovery of a new waveform for intraoperative monitoring of hemifacial spasms.

BACKGROUND: Surgeons often rely on intraoperative electrophysiological monitoring to determine whether decompression is sufficient during microvascular decompression surgery for hemifacial spasms. A new monitoring method is needed when an abnormal muscle response is occasionally not available or is unreliable. This study was an observational clinical trial exploring a new waveform recorded from the facial muscles while the offending artery wall was electrically stimulated. METHODS: Thirty-two patients with typical hemifacial spasm and 12 with trigeminal neuralgia as a control were included. The facial muscle response was recorded during microvascular decompression surgery while the offending artery wall was stimulated (2 mA × 0.2 ms). The latency, amplitude, and effective refractory period were analyzed. RESULTS: A waveform was recorded from the facial muscles of patients with hemifacial spasm when the offending artery wall was stimulated and was named the "Z-L response." The latency was 7.3 ± 0.8 ms, the amplitude was 0.08 ± 0.02 mV, and the effective refractory period was 3.5-4 ms. The Z-L response disappeared immediately after microvascular decompression. No waveform was recorded from the facial muscles of patients with trigeminal neuralgia while the anterior inferior cerebellar artery, which adheres to the facial nerve, was stimulated (2 mA × 0.2 ms). CONCLUSION: We found a new waveform for intraoperative monitoring of hemifacial spasm. The Z-L response was useful when the abnormal muscle response was absent before decompression or persisted after all vascular compressions were properly treated. Particularly, the Z-L response may help neurosurgeons determine the real culprit when multiple offending vessels exist.

Management of intraneural vessels during microvascular decompression surgery for trigeminal neuralgia.

OBJECTIVE: To present the authors' experience in surgical treatment of patients with trigeminal neuralgia (TN) with intraneural vessels. METHODS: The study included three patients with TN and an intraneural artery (superior cerebellar artery) and eight patients with TN and an intraneural vein. The patients underwent microvascular decompression (MVD) procedures. The intraneural arteries were wrapped by a thin piece of Teflon sponge. The intraneural veins all were coagulated and divided. Clinical outcomes and postoperative complications were analyzed. RESULTS: Eight patients were free of facial pain soon after surgery, achieving excellent outcomes; two patients had good outcomes; and one patient had a failed first operation but experienced pain relief after reoperation, achieving an excellent outcome. Three patients had postoperative facial numbness because the trigeminal nerves were impaired owing to coagulation or mechanical injury. However, no dense corneal numbness or loss of corneal reflex occurred. CONCLUSIONS: If the intraneural vessel is an artery, it can be decompressed by wrapping techniques. Otherwise, intraneural veins should be coagulated and divided. Most patients can achieve excellent or good pain relief with this approach; facial numbness is uncommon.

Clinical features and surgical treatment of trigeminal neuralgia caused solely by venous compression.

PURPOSE: To summarize our experience and lessons of microvascular decompression surgery for trigeminal neuralgia caused solely by venous compression. METHODS: Fifteen patients with idiopathic trigeminal neuralgia caused by venous compression only underwent microvascular decompression. The entire course of the trigeminal root was explored thoroughly; and coagulating and cutting techniques were preferred in decompressing the culprit veins. Their clinical features, outcomes and operative complications were analyzed. RESULTS: The compressing veins included the transverse pontine vein in five cases (33.3%), the transverse pontine vein and the vein of middle cerebellar peduncle in one (6.7%), the transverse pontine vein and the vein of cerebellopontine fissure in one (6.7%), the superior petrosal vein in three (20%), the pontotrigeminal vein in one (6.7%), the vein of the cerebellopontine fissure in two (13.3%), and the plexus venosus or venule in two (13.3%). After microvascular decompression, 11 cases (73.3%) had "excellent" or "good" pain relief. Four cases (26.7%) failed the first surgery; and two of them underwent re-operation and got "excellent" pain relief. Postoperative facial numbness appeared in four cases, due to injury to trigeminal nerve when coagulation. CONCLUSION: The transverse pontine vein is the most common offending vein. For this type of trigeminal neuralgia, coagulating and cutting techniques are preferred in decompressing the culprit veins. The entire course of the trigeminal root should be explored and decompressed. Following these principles, excellent or good pain relief could be achieved in most cases; and recurrence is rare. However, sometimes injury to the nerve is unavoidable when coagulating the culprit vein.

Re-operation for persistent hemifacial spasm after microvascular decompression with the aid of intraoperative monitoring of abnormal muscle response.

BACKGROUND AND OBJECTIVES: Microvascular decompression (MVD) is the only solution that can effectively control hemifacial spasm (HFS). Regarding treatment of the patients who failed the first operation, it is still controversial. We tried to evaluate the safety and efficiency of the early re-exploration for such kinds of patients. METHODS: Thirteen patients failed the first MVD and received a second MVD procedure. The spasm was not resolved at all or became even more severe after the first MVD. Abnormal muscle response (AMR) persisted during the first MVD operation or disappeared once but emerged again. The patient had a strong will to do the re-operation and was aware of the high risks of operative complications. RESULTS: All the 13 patients got good or excellent spasm resolution immediately after the re-operation, which involved whole-range exploration and intraoperative AMR monitoring; however, there were two cases (15.4%) of permanent facial weakness and three cases (23.0%) of transient facial weakness. CONCLUSIONS: Our experience on early repeat MVD is whole-range exploration and intraoperative AMR monitoring; in other words, re-operation cannot rely too much on experience.