Nicolas Kon Kam King

OBJECTIVE: Neurosurgery presents unique surgical challenges arising from delicate neural structures, limited accessibility, and the risk of CSF leakage that can lead to CNS infections. Sutures and staples may have limited applicability in the complex anatomical constraints of cranial and spinal surgeries, especially in trauma settings when time is of the essence. Surgical bioadhesives are emerging as attractive alternatives because they avoid traumatic application methods, provide a stress-distributed fixation, and provide good cosmesis and outcomes. This article presents the history of the development of surgical bioadhesives, and is also a review of current applications of commercial surgical bioadhesives within neurosurgical procedures and the unmet clinical needs that should be addressed in bioadhesives technologies. METHODS: A PubMed literature search was performed using the terms “(glue OR bioadhesive OR fibrin OR tisseel OR evicel OR tachosil OR cyanoacrylate OR duraseal OR bioglue) AND (neurosurgery OR spine OR spinal OR dural OR microvascular decompression OR transsphenoidal OR endovascular).” Of 2433 records screened, 168 studies were identified that described the use of bioadhesives in neurosurgical procedures. RESULTS: The greatest number of studies describing the use of bioadhesives in neurosurgery were identified for endovascular embolization, followed by dural closure and transsphenoidal surgeries. Other common areas of application were for microvascular decompression, skin closure, peripheral nerve repair, and other novel uses. Numerous case reports were also identified describing complications associated with bioadhesive use. CONCLUSIONS: Despite the paucity of approved indications, surgical bioadhesive use in neurosurgical procedures is prevalent. However, current bioadhesives still each have their own limitations and research is intense in the development of novel solutions.

Following the outbreak of coronavirus 2019 (COVID-19), there is strong evidence of neurological involvement in these patients. We aimed to determine the clinical characteristics of neurological manifestations in COVID-19. A systematic review of studies reporting neurological manifestations published between 1 December, 2019 and 11 May, 2020 was performed. Studies were grouped based on neurological manifestation. Pooled analyses of individual patient's clinical characteristics and olfactory and gustatory dysfunction prevalence were performed. Of 486 studies identified, 48 were included. 70 patients with 73 neurological manifestations were reported. 39 (53.4%) patients had stroke, 18 (24.7%) had Guillain-Barré syndrome and variants, 11 (15.1%) had meningitis, encephalitis, encephalopathy, or myelitis, and five (6.8%) had seizures. They had a mean age of 61.9 ± 17.7 years (60.6% male). Neurological disease occurred 8.1 ± 6.8 days from initial symptoms. Average mortality rate was 17.8%. Stroke has a mortality rate of 25.6%. Olfactory and gustatory dysfunction occurred in 59.9% and 57.5%, respectively. Stroke is the most frequently reported neurological manifestation in COVID-19 and has the highest mortality rate. Neurological manifestations tend to develop one to two weeks after the onset of respiratory disease. There is significant morbidity and mortality associated with COVID-19 neurological manifestations.

Introduction Deep brain stimulation of the subthalamic nucleus (STN DBS) has been shown to reduce antiparkinsonian medication in Parkinson’s disease. We aimed to investigate the changes in long-term medication profile with STN DBS. Methods Antiparkinsonian medication data for 56 patients were collected from as early as 3 years before STN DBS up to 10 years after. Cost spending on medication changes was analyzed. Mean levodopa equivalent daily dose (LEDD) was projected 10 years into the future based on preoperative data to create a comparator group wherein the patients did not undergo STN DBS. Use of neuroleptics and antidepressants was also recorded. Results LEDD requirement was significantly reduced by a mean of 31 ± 2% over 10 years after DBS, from 1049 ± 381 mg at pre-DBS baseline, to 713 ± 392 mg at 1 year post-DBS, and 712 ± 385 mg at 10 years post-DBS. This was associated with a mean reduction of 35 ± 3% in medicine cost. Modeled LEDD requirements for not having STN DBS were in the range of 1489 mg to 2721 mg at 10 years post-DBS (109–282% higher than the observed mean LEDD in DBS cohort). The proportion of patients increased from 5% before STN DBS to 14% at 10 year post-DBS for neuroleptics, and 11–23% for antidepressants. Conclusion STN DBS led to LEDD reduction and antiparkinsonian medication cost savings in our South-East Asian cohort. Medication reduction with STN DBS in our cohort over the 10-year period was comparable to those reported in Western populations.

This paper presents a robotic needle positioning approach with a novel 4-DoF parallel positioner, two back-driveable 2-channel linear/rotational driver, and a machine-body interface. Being more compact and flexible, Ni-Ti alloy wire-based Bowden cable transmission is introduced to connect the positioner and the drivers. For this new mechanism, forward and inverse kinematics are derived, and the workspace is analyzed. The mechanism's maximum incidence angle is 45°, and the stroke of the slider is 41 mm. The structural size of one positioner is ø70 mm×45 mm. The compact size and lightweight of the positioner makes it readily mountable on the skull or attached to other parts of the body. We fabricated a 3D printed proof-of-concept prototype of the system and tested its performance. The open-loop positioning accuracy of the slider and rotor is within ±1 mm and -0.8°to 1.5°, respectively. The trajectory tracking error of the system is within 1.71 mm. The stiffness of the positioner in x and y directions can be calculated as 9.03 N/mm and 11.91 N/mm, respectively. Finally, an image-guided navigation framework based on electromagnetic tracking demonstrates the feasibility of the proposed system on a phantom study.

Background: Gliomas consist of a heterogeneous group of tumors. This study aimed to report the incidences of O⁶-methylguanine-DNA-methyltransferase (MGMT) promoter methylation, 1p19q co-deletion, isocitrate dehydrogenase (IDH) gene mutations, and inactivating mutations of alpha-thalassemia/mental retardation syndrome X-linked (ATRX) in high-grade gliomas in an ethnically diverse population.Methods: Records of patients who underwent surgery for high-grade gliomas from January 2013 to March 2017 at our institution were obtained. The patients’ age, gender, ethnicity, Karnofsky Performance Scale (KPS) score, ability to perform activities of daily living (ADLs), tumor location and biomarkers status were recorded. Data were analyzed using chi-square and Mann-Whitney U tests, Kaplan-Meier estimates and log-rank test.Results: 181 patients were selected (56 with grade III gliomas, 125 with grade IV gliomas). In the grade III group, 55% had MGMT promoter methylation, 41% had 1p19q co-deletion, 35% had IDH1 mutation and none had ATRX loss. In the grade IV group, 30% had MGMT promoter methylation, 2% had 1p19q co-deletion, 15% had IDH1 mutation and 8% had ATRX loss. After adjusting for effects of age, surgery and pre-operative ADL statuses, only MGMT promoter methylation was found to be significantly associated with longer overall survival time in grade III (p = 0.024) and IV patients (p = 0.006).Conclusions: The incidences of MGMT promoter methylation and IDH1 mutation were found to be comparable to globally reported rates, but those of 1p19q co-deletion and ATRX loss seemed to be lower in our cohort. MGMT promoter methylation was associated with increased overall survival in our cohort and might serve as favorable prognostic factor.

Accurate localization of subthalamic nucleus (STN) is a key prior in deep brain stimulation (DBS) surgery for the patients with advanced Parkinson’s disease (PD). Microelectrode recordings (MERs) along with preplanned trajectories are often employed for the STN localization and it remains challenging task. These MER signals are nonstationary and multicomponent in nature. In this study, we propose a system based on time-frequency features of MERs to differentiate the STN and non-STN regions. We assessed the system with 50 MER trajectories from 26 PD patients who have undergone DBS surgery. The signals are pre-processed and subjected to six-level wavelet decomposition. Then, the entropy is computed from the detailed and approximate coefficients. These features are fed to the random forest classifier and the model is evaluated by leave one patient out cross-validation. The results show that entropy associated with detailed wavelet coefficients (D 1 and D 2 ) are higher in STN where as it is lower in other wavelet scales. All extracted features except entropy from approximate coefficients are found to have significant difference between non-STN and STN (p<0.05). The random forest classifier achieves about 83% accuracy and 87% precision in differentiating the STN and non-STN regions.