Diagnostic Accuracy and Field for Improvement of Frameless Stereotactic Brain Biopsy: A Focus on Nondiagnostic Cases.

BACKGROUND: The diagnostic accuracy of frameless stereotactic brain biopsy has been reported, but there is limited literature focusing on the reasons for nondiagnostic cases. In this study, we evaluate the diagnostic accuracy of frameless stereotactic brain biopsy, compare it with the current international standard, and review the field for improvement. METHODS: This is a retrospective analysis of consecutive, prospectively collected frameless stereotactic brain biopsies from 2007 to 2020. We evaluated the diagnostic accuracy of the frameless stereotactic brain biopsies using defined criteria. The biopsy result was classified as conclusive, inconclusive, or negative, based on the pathologic, radiologic, and clinical diagnosis concordance. For inconclusive or negative results, we further evaluated the preoperative planning and postoperative imaging to review the errors. A literature review for the diagnostic accuracy of frameless stereotactic biopsy was performed for the validity of our results. RESULTS: There were 106 patients with 109 biopsies performed from 2007 to 2020. The conclusive diagnosis was reached in 103 (94.5%) procedures. An inconclusive diagnosis was noted in four (3.7%) procedures and the biopsy was negative in two (1.9%) procedures. Symptomatic hemorrhage occurred in one patient (0.9%). There was no mortality in our series. Registration error (RE) and inaccurate targeting occurred in three trigonal lesions (2.8%), sampling of the nonrepresentative part of the lesion occurred in two cases (1.8%), and one biopsy (0.9%) for lymphoma was negative due to steroid treatment. The literature review suggested that our diagnostic accuracy was comparable with the published literature. CONCLUSION: The frameless stereotactic biopsy is a safe procedure with high diagnostic accuracy only if meticulous preoperative planning and careful intraoperative registration is performed. The common pitfalls precluding a conclusive diagnosis are RE and biopsies at nonrepresentative sites.

Solar-Powered Switch of Antiferromagnetism/Ferromagnetism in Flexible Spintronics.

The flexible electronics have application prospects in many fields, including as wearable devices and in structural detection. Spintronics possess the merits of a fast response and high integration density, opening up possibilities for various applications. However, the integration of miniaturization on flexible substrates is impeded inevitably due to the high Joule heat from high current density (1012 A/m2). In this study, a prototype flexible spintronic with device antiferromagnetic/ferromagnetic heterojunctions is proposed. The interlayer coupling strength can be obviously altered by sunlight soaking via direct photo-induced electron doping. With the assistance of a small magnetic field (±125 Oe), the almost 180° flip of magnetization is realized. Furthermore, the magnetoresistance changes (15~29%) of flexible spintronics on fingers receiving light illumination are achieved successfully, exhibiting the wearable application potential. Our findings develop flexible spintronic sensors, expanding the vision for the novel generation of photovoltaic/spintronic devices.

Deterministic Magnetization Reversal in Synthetic Antiferromagnets using Natural Light.

Traditional current-driven spintronics is limited by localized heating issues and large energy consumption, restricting their data storage density and operation speed. Meanwhile, voltage-driven spintronics with much lower energy dissipation also suffers from charge-induced interfacial corrosion. Thereby finding a novel way of tuning ferromagnetism is crucial for spintronics with energy-saving and good reliability. Here, a visible light tuning of interfacial exchange interaction via photoelectron doping into synthetic antiferromagnetic heterostructure of CoFeB/Cu/CoFeB/PN Si substrate is demonstrated. Then, a complete, reversible magnetism switching between antiferromagnetic (AFM) and ferromagnetic (FM) states with visible light on and off is realized. Moreover, a visible light control of 180° deterministic magnetization switching with a tiny magnetic bias field is achieved. The magnetic optical Kerr effect results further reveal the magnetic domain switching pathway between AFM and FM domains. The first-principle calculations conclude that the photoelectrons fill in the unoccupied band and raise the Fermi energy, which increases the exchange interaction. Lastly, a prototype device with visible light control of two states switching with a 0.35% giant magnetoresistance ratio change (maximal 0.4%), paving the way toward fast, compact, and energy-efficient solar-driven memories is fabricated.

Manipulations of Spin Waves by Photoelectrons in Ferromagnetic/Non-Ferromagnetic Alloyed Film.

Spin waves are considered to be an alternative carrier with great promise for information sensing. The feasible excitation and low-power manipulation of spin waves still remain a challenge. In this regard, natural light enablings spin-wave tunability in Co60 Al40 -alloyed film is investigated. A reversible shift of the critical angle (from 81° in the dark to 83° under illumination) of the body spin-wave is achieved successfully Meanwhile, an eye-catching shift (817 Oe) of the ferromagnetic resonance (FMR) field is obtained optically, leading to changes in magnetic anisotropy. Based on the modified Puszkarski's surface inhomogeneity model, the control of spin-wave resonance (SWR) by sunlight can be understood by an effective photoelectron-doping-induced change of the surface magnetic anisotropy. Furthermore, the body spin wave is modulated stably with natural light illumination, confirming a non-volatile, reversible switching behavior. This work has both practical and theoretical importance for developing future sunlight-tunable magnonics/spintronics devices.

Frameless versus frame-based stereotactic radiosurgery for intracranial arteriovenous malformations: A propensity-matched analysis.

Objective: The frameless linear accelerator (LINAC) based stereotactic radiosurgery (SRS) has been evolving with a reduction in patient discomfort. However, there was limited evidence comparing frame-based and frameless SRS for intracranial arteriovenous malformations (AVM). We aimed to compare the treatment outcomes between frame-based and frameless LINAC SRS. Materials and Methods: This retrospective cohort compared the outcomes of frame-based LINAC SRS (1998-2009) with frameless LINAC SRS (2010-2020). The primary outcome was the obliteration rate. The other outcomes included the neurological, radiological, and functional outcomes after SRS. A matched cohort was identified by propensity scores for further comparisons. Results: A total of 65 patients were included with a mean follow-up time of 13.2 years (158.5 months). There were 40 patients in the frame-based group and 25 patients in the frameless group. The overall obliteration rate was comparable (Frame-based 82.5% vs Frameless 80.0%, p = 0.310) and not significantly different over time (log-rank p = 0.536). The crude post-SRS hemorrhage rate was 1.5% and the incidence was 0.3 per 100 person-years. There were 67.7% of patients with AVM obliteration without new persistent neurological deficits at the last visit and 56.9% of patients with AVM obliteration without any deficits (transient or persistent) during the entire follow-up period. Four patients (8.0%) developed late onset persistent adverse radiation effects (more than 96 months after SRS) among 50 patients with more than 8-year surveillance. In the propensity-matched cohort of 42 patients, there was no significant difference in AVM obliteration (Frame-based vs Frameless, log-rank p = 0.984). Conclusion: Frameless and frame-based LINAC SRS have comparable efficacy in intracranial AVM obliteration. A longer follow-up duration may further characterize the rate of late adverse radiation effects in frameless SRS.

Deterministic Magnetic Switching in Perpendicular Magnetic Trilayers Through Sunlight-Induced Photoelectron Injection.

Finding an energy-efficient way of switching magnetization is crucial in spintronic devices, such as memories. Usually, spins are manipulated by spin-polarized currents or voltages in various ferromagnetic heterostructures; however, their energy consumption is relatively large. Here, a sunlight control of perpendicular magnetic anisotropy (PMA) in Pt (0.8 nm)/Co (0.65 nm)/Pt (2.5 nm)/PN Si heterojunction in an energy-efficient manner is proposed. The coercive field (HC ) is altered from 261 to 95 Oe (64% variation) under sunlight illumination, enabling a nearly 180° deterministic magnetization switching reversibly with a 140 Oe magnetic bias assistant. The element-resolved X-ray circular dichroism measurement reveals different L3 and L2 edge signals of the Co layer with or without sunlight, suggesting a photoelectron-induced redistribution of the orbital and spin moment in Co magnetization. The first-principle calculations also reveal that the photo-induced electrons shift the Fermi level of electrons and enhance the in-plane Rashba field around the Co/Pt interfaces, leading to a weakened PMA and corresponding HC decreasing and magnetization switching accordingly. The sunlight control of PMA may provide an alternative way for magnetic recording, which is energy efficient and would reduce the Joule heat from the high switching current.

Minimally Invasive Tubular Retractor Surgery for Intradural Extramedullary Spinal Tumor Reduces Postoperative Degeneration of Paraspinal Muscle.

Background Minimally invasive surgery (MIS) using a tubular retractor has been increasingly utilized in spinal surgery for degenerative conditions with the benefit of paraspinal muscle preservation. This benefit has not been previously reported for intradural extramedullary tumors using the MIS approach. In this study, we aimed to compare the degree of postoperative fatty degeneration in paraspinal muscle between MIS with tubular retractor (MIS) and open laminectomy (Open) for intradural extramedullary spinal tumors. Methods This was a retrospective review conducted in a tertiary neurosurgical center from 2015 to 2019. The degree of paraspinal muscle fatty degeneration, as measured by Goutallier grade on postoperative magnetic resonance imaging (MRI), was analyzed, and the degree of excision, tumor recurrence rate, and chronic pain were compared between the two surgical approaches. Results Among 9 patients in the MIS group and 33 patients in the Open group, the rate of gross total resection was comparable (MIS: 100.0%, Open: 97.0%, p = 1.000). The degree of paraspinal muscle fatty degeneration was significantly reduced in the MIS group (median Goutallier grade 1 in MIS group vs. median Goutallier grade 2 in Open group, p = 0.023). There was no significant difference in the tumor recurrence rate, complication rate, and chronic pain severity. A consistent trend of reduced analgesic consumption was observed in the MIS group, though not statistically significant. Conclusions Minimally invasive tubular retractor surgery is an effective approach for appropriately selected intradural extramedullary spinal tumors with significantly reduced postoperative fatty degeneration in paraspinal muscle.

Multidimensional Outcomes of Selective Dorsal Rhizotomy for Children With Spastic Cerebral Palsy: Single-Level Laminectomy vs Multiple-Level Laminotomy Techniques.

BACKGROUND: Selective dorsal rhizotomy (SDR) reduces lower limb spasticity, improves gait patterns, and restores normal physical and social activity in children with spastic cerebral palsy. Single-level laminectomy (SLL) and multiple-level laminotomy (MLL) are 2 surgical approaches for SDR with limited clinical data comparing their postoperative outcomes. OBJECTIVE: To compare the differences in multidimensional outcomes after SDR between SLL and MLL for children with spastic cerebral palsy. METHODS: We retrospectively reviewed children who underwent SDR in our hospital from 1997 to 2016. The multidimensional outcomes in spasticity, joint range of motions, gait kinetics, gross motor activities, functional outcomes, and urological outcomes were assessed 1 year postoperatively. Hip dysplasia and scoliosis rate were compared as long-term outcomes. RESULTS: Sixty children underwent SDR, including 34 SLL patients and 26 MLL patients. Most improvements in multidimensional outcomes were comparable between SLL and MLL. Patients in the SLL group had larger improvements in ankle dorsiflexion in the midstance phase (SLL 7.59° ± 11.48° vs MLL 0.29° ± 11.30°, P = .027). The rate of scoliosis was similar between the 2 surgical approaches (SLL 12.1% vs MLL 15.4%, P = .722). CONCLUSION: SDR for children with spastic cerebral palsy could provide physical, functional, and urological improvements. SLL achieved a higher degree of improvement in ankle dorsiflexion in the midstance phase. The rate of scoliosis was not significantly increased by multiple-level laminotomy.

Radiological Latency in Pineal Germinoma: A Case Report and Literature Review.

Suprasellar germinomas can present with non-diagnostic, or even normal results on imaging. The spectrum of reported cases ranges from normal imaging, thickened pituitary stalks, to discrete tumour growths. This similar phenomenon is less commonly seen in the pineal region, or bifocal germinomas, and the literature is sparse with only a few case series or reports mentioning a similar presentation of signs and symptoms preceding radiological evidence of diagnosis. We report a case of pineal germinoma presenting with dorsal midbrain syndrome with no evidence of tumour growth on initial imaging despite symptoms. For patients presenting with this clinical radiological latent period, follow-up imaging is useful to identify interval development of germinomas. This applies to patients with dorsal midbrain syndrome, or even other unexplained ophthalmoplegia, as the initial sign of pineal region germinoma, despite normal imaging.

Tracheostomy decannulation outcomes in 131 consecutive neurosurgical patients.

OBJECTIVES: This study was a retrospective study to investigate factors related to difficult tracheostomy decannulation, and to evaluate outcomes of tracheostomized neurosurgical patients. METHODS: All consecutive tracheostomized neurosurgical patients in the Prince of Wales Hospital between 1st September 2016 and 31st August 2019 were reviewed retrospectively. Patients were grouped into easy decannulation and difficult decannulation groups using 3 months as cut-off time. Risk factors were analysed and outcomes were compared. RESULTS: One hundred thirty-one patients were included. In univariate analyses, male gender, GCS less than or equal to 8 on admission, the presence of vocal cord palsy at 3 months, and pneumonia within 1-month post-tracheostomy were associated with difficult decannulation. In multivariable logistic regression for difficult decannulation, GCS on admission, the presence of vocal cord palsy at 3 months, and the presence of pneumonia within 1-month post-tracheostomy remained statistically significant. The easy decannulation group had a shorter length of in-patient stay, higher survival rate, and more favourable neurological outcome (GOS 4-5) than the difficult decannulation group at both 6 months and 1 year. The majority of easy decannulation group patients (54%) were discharged to home, while the majority of the difficult decannulation group (42%) of patients were discharged to the infirmary. CONCLUSION: GCS less than or equal to 8 on admission, the presence of vocal cord palsy, and the presence of pneumonia were associated with difficult tracheostomy decannulation in neurosurgical patients. Difficult decannulation is associated with a longer length of in-patient stay and poor neurological outcomes.

Predictive factors for bleeding carotid artery pseudoaneurysms in patients with previous radiations for head and neck cancers.

BACKGROUND: Bleeding from carotid artery pseudoaneurysms is an emergency condition with high morbidity and mortality. We aimed to identify risk factors predicting pseudoaneurysmal bleeding as the cause of profuse epistaxis in irradiated head and neck cancer patients with suspect carotid blowout or pseudoaneurysms. METHODS: We retrospectively reviewed consecutive patients with history of radiation therapy for head and neck cancers and with nasal, oral or ear bleeding requiring in-patient treatment from hospital database. Pseudoaneurysms were subgrouped into internal carotid artery (ICA) pseudoaneurysms, and external carotid artery (ECA) pseudoaneurysms. The treatment outcomes were evaluated using 30-day mortality rate, recurrent bleeding, and cerebral infarction. RESULTS: There were 41 admissions for suspected carotid blowout or pseudoaneurysms from 1 July 2016 to 30 June 2020 with 17 bleeding pseudoaneurysms identified, including 11 internal carotid arteries (ICA) pseudoaneurysms and 6 external carotid arteries (ECA) pseudoaneurysms. Among ICA pseudoaneurysms, six patients passed Balloon occlusion test with embolization and parent artery occlusion (trapping) of ICA performed, and all ECA pseudoaneurysms were embolized with parent artery occlusion (trapping). Baseline hypertension and hypotension on arrival were predictive for pseudoaneurysmal bleeding. The degree of haemoglobin drop was not significantly different between pseudoaneurysmal bleeding and non-pseudoaneurysmal bleeding (2.1 ± 1.4 g/dL vs. 1.6 ± 1.4 g/dL, p = 0.234). CONCLUSIONS: We identified baseline hypertension and hypotension on arrival as predictive factors for pseudoaneurysmal bleeding in patients with irradiated head and neck cancer. Presence of these risk factors should alert the clinicians to the possibility of carotid pseudoaneurysms.

Newly-Diagnosed, Histologically-Confirmed Central Nervous System Tumours in a Regional Hospital in Hong Kong : An Epidemiological Study of a 21-Year Period.

OBJECTIVE: To investigate the epidemiology of newly-diagnosed, histologically-confirmed (NDHC) central nervous system (CNS) tumours and its changes over a 21-year period in a regional hospital in Hong Kong. METHODS: This is a single-institute retrospective descriptive study of patients undergoing surgery for CNS tumours in a regional hospital of Hong Kong in the period from January 1996 to December 2016. The histological definition of CNS tumours was according to the World Health Organization classification, while the site definition for case ascertainment of CNS tumours was as set out by the Central Brain Tumour Registry of the United States. Patients of any age, who had NDHC CNS tumours, either primary or secondary, were included. The following parameters of the patients were retrieved : age at diagnosis, gender, tumour location, and histological diagnosis. Population data were obtained from sources provided by the Government of Hong Kong. The incident rate, estimated by the annual number of cases per 100000 population, for each histology grouping was calculated. Statistical analyses, both including and excluding brain metastases, were performed. Statistical analysis was performed with Microsoft Excel, 2016 (Microsoft, Redmond, WA, USA). RESULTS: Among the 2134 cases of NDHC CNS tumours, there were 1936 cases of intracranial tumours and 198 cases of spinal tumours. The annual number of cases per 100000 population of combined primary intracranial and spinal CNS tumours was 3.6 in 1996, and 11.1 in 2016. Comparing the 5-year average annual number of cases per 100000 population of primary CNS tumours from the period 1996-2000 to 2011-2015, there was an 88% increase, which represent an increase in the absolute number of cases by 4.52 cases/100000 population. This increase was mainly contributed by benign histologies. In the aforementioned periods, meningiomas increased by 1.45 cases/100000 population; schwannomas by 1.05 cases/100000 population, and pituitary adenomas by 0.91 cases/100000 population. While gliomas had a fluctuating 5-year average annual number of cases per 100000 population, it only had an absolute increase of 0.51 cases/100000 population between the 2 periods, which was mainly accounted for by the change in glioblastomas. CONCLUSION: This retrospective study of CNS tumour epidemiology revealed increasing trends in the incidences of several common CNS tumour histologies in Hong Kong, which agrees with the findings in large-scale studies in Korea and the United States. It is important for different geographic locations to establish their own CNS tumour registry with well-defined and structured data collection and analysis system to meet the international standards.

Epidural multi-slitted microporous non-absorbable patch in decompressive craniectomy to facilitate cranioplasty: a preliminary study.

Developing a surgical plane between the temporalis muscle and the dura is the most technically challenging step when performing cranioplasty for post-decompressive craniectomy defects. The authors report a simple technique to demarcate this surgical plane by laying a multi-slitted, microporous polyesterurethane (MPU) patch during decompressive craniectomy. Specifically, they tried to avoid creating potential spaces around the patch, which is the inherent drawback of published anti-adhesive techniques. In 21 patients undergoing decompressive craniectomy, and in 11 of them subsequently undergoing cranioplasty, there was no wound related complications. During cranioplasty, no epidural fluid collection was found; the patch could be separated from the temporalis muscle and the dura with blunt dissection leaving the muscle intact. They conclude that their epidural MPU patch technique is a safe technique, and appears useful to facilitate cranioplasty by helping the surgeon in developing the surgical plane between the temporalis muscle and the dura during cranioplasty.

Systemic treatment for inoperable pancreatic adenocarcinoma: review and update.

There have been many clinical trials conducted to evaluate novel systemic regimens for unresectable pancreatic cancer. However, most of the trial results were negative, and gemcitabine monotherapy has remained the standard systemic treatment for years. A number of molecular targeted agents, including those against epidermal growth factor receptor and vascular endothelial growth factor receptors, have also been tested. In recent years, there have been some breakthroughs in the deadlock: three regimens, namely gemcitabine-erlotinib, FOLFIRINOX, and gemcitabine-nab-paclitaxel, have been shown to prolong the overall survival of patients when compared with gemcitabine monotherapy. In addition, emerging data suggested that the membrane protein human equilibrative nucleotide transporter 1 is a potential biomarker with which to predict the efficacy of gemcitabine. Here we review the literature on the development of systemic agents for pancreatic cancer, discuss the current choices of treatment, and provide future directions on the development of novel agents.