Enhanced Dural Repair Using Biodegradable Sealants Based on Photocurable Hyaluronic Acid.

Cerebrospinal fluid (CSF) leakage is a common complication of intradural surgery or incidental durotomy in neurosurgery. Dural suturing is a common method for durotomy repair, but this technique requires a long operation time and includes the risk of CSF leakage by incomplete sealing. Glue-type sealants are effective for watertight dural closure. However, unresolved shortcomings include insufficient sealing performance, poor biocompatibility, and excessive swelling. Here, a dural sealant using light-activated hyaluronic acid (HA) with multi-networks (HA photosealant) that provides fast sealing performance and high biocompatibility is reported. The HA photosealants form a watertight hydrogel barrier with multilength networks under low-energy visible light exposure (405 nm, <1 J cm-2) for 5 s and allow firm tissue adhesion on the wet dural surface. In a rabbit model of craniectomy and durotomy, HA photosealants exhibit the faster sealing performance of dural tears and enhance dural repair with accelerated bone formation compared to commercial surgical glues, with no degenerative changes, such as inflammation or necrosis, in histopathological evaluation. This biocompatible HA photosealant can be applied in a variety of clinical settings that require fast wound closure as a promising potential.

Exoskeleton-assisted Gait Training in Spinal Disease With Gait Disturbance.

Objective: Gait impairment reduces a patient's quality of life. Exoskeletons and wearable robotics enable patients with gait disturbance to stand up and walk. An exoskeleton was developed for use in patients with stroke and spinal cord injuries. This study aimed to evaluate the effectiveness of overground exoskeleton-assisted gait training (OEGT) in spine diseases with gait disturbance. Methods: This was a single-group preliminary study. Five participants with gait disorders because of root dysfunction accompanying spinal stenosis were included in this study. All participants underwent surgical treatment and an exoskeleton training protocol scheduled for 2 or 3 days per week for 4 weeks. Each session was 60 minutes. Clinical tests were performed before (T1) and at the end of the training (T2). Results: One patient dropped out of the study because of medical issues that were not associated with the exoskeleton. Exoskeleton-assisted rehabilitation was feasible for all participants. All participants showed positive changes in gait performance, balance, proximal muscle strength, psychological state, and satisfaction with the rehabilitation. However, there was no significant improvement in neurological deficits. Conclusion: OEGT is a feasible rehabilitation method for patients with gait disorders caused by degenerative spinal disease.

Imaging Characterization of Non-Rheumatoid Retro-Odontoid Pseudotumors: Comparison with Atlantoaxial Manifestation of Rheumatoid Arthritis.

Backgroundand Objectives: To date, imaging characterization of non-rheumatic retro-odontoid pseudotumors (NRROPs) has been lacking; therefore, NRROPs have been confused with atlantoaxial joint involvement of rheumatoid arthritis (RA). It is important to differentiate these two disease because the treatment strategies may differ. The purpose of this study is to characterize imaging findings of NRROPs and compare them with those of RA. Material and Methods: From January 2015 to December 2019, 27 patients (14 women and 13 men) with NRROPs and 19 patients (15 women and 4 men) with RA were enrolled in this study. We evaluated various imaging findings, including atlantoaxial instability (AAI), and measured the maximum diameter of preodontoid and retro-odontoid spaces with magnetic resonance imaging (MRI) and computed tomography (CT). Results: Statistical significance was considered for p < 0.05. AAI was detected in eight patients with NRROPs and in all patients with RA (p < 0.0001). Seventeen patients with NRROPs and six patients with RA showed spinal cord compression (p = 0.047). Compressive myelopathy was observed in 14 patients with NRROPs and in 4 patients with RA (p = 0.048). Subaxial degeneration was observed in 25 patients with NRROPs and in 9 patients with RA (p = 0.001). Moreover, C2-3 disc abnormalities were observed in 11 patients with NRROPs and in 2 patients with RA (p = 0.02). Axial and longitudinal diameter of retro-odontoid soft tissue and preodontoid and retro-odontoid spaces showed significant differences between NRROP and RA patients (p < 0.0001). Furthermore, CT AAI measurements were differed significantly between NRROP and RA patients (p < 0.05). Conclusions: NRROPs showed prominent retro-odontoid soft tissue thickening, causing compressive myelopathy and a high frequency of subaxial and C2-3 degeneration without AAI.

In vitro and in vivo assessment of squeeze-cast Mg-Zn-Ca-Mn alloys for biomedical applications.

Squeeze casting of biodegradable Mg-4Zn-0.5Ca-xMn (x = 0, 0.4 or 0.8 all in weight %) alloys is a process intended to improve mechanical properties (i.e., strength and ductility), corrosion performance (i.e., resistance), and biocompatibility (i.e., little to no cytotoxicity). In this study, we found that an increased Mn content causes the dendritic microstructure of squeeze-cast Mg-4Zn-0.5Ca-xMn to become more refined and uniform, while the volume fraction of the Ca2Mg6Zn3 phase simultaneously increases. Squeeze-cast Mg-4Zn-0.5Ca-0.8Mn presents the best yield strength, ultimate tensile strength, and elongation of the alloys tested. An electrochemical corrosion test in Hanks' solution at 36.5°C demonstrates that the corrosion resistance of squeeze-cast Mg-4Zn-0.5Ca-xMn alloys show improvement at higher Mn levels. Additionally, squeeze-cast Mg-4Zn-0.5Ca alloys containing Mn exhibit favorable biocompatibility, as evidenced by cell viability studies with MC3T3-E1 cells and a local lymph node assay test. Squeeze-cast alloy specimens implanted into the skull and spine of Sprague-Dawley rats for four weeks showed no serious cytotoxicity or foreign body response; however, swelling was observed in the implantation areas of Mn-free squeeze-cast Mg-4Zn-0.5Ca alloy, while no swelling was observed in rats implanted with Mn-containing Mg-4Zn-0.5Ca alloy. These findings indicate potential applications of biodegradable, Mn-containing, squeeze-cast Mg-4Zn-0.5Ca specimens in bone-reconstruction devices given their biocompatibility, mechanical properties, and degradation profiles. STATEMENT OF SIGNIFICANCE: Bioresorbable magnesium alloys have recently gained attention as viable biomaterials for skeletal reconstruction implants. Extensive research on biodegradable Mg alloy design, synthesis, and as-cast versus post-processed material properties useful for medical applications have been reported. The squeeze-casting technique used in this study can improve the mechanical properties (i.e., strengthening) and corrosive performance (reduced rate) of bioresorbable Mg-Zn-Ca-Mn alloys. Squeeze-casting of these alloys is also expected to improve specimen microstructure, near-net-shape manufacturing, and cost (i.e., reduced). This study provides an in vitro and in vivo assessment of squeeze-cast Mg-Zn-Ca-Mn alloys for biomedical applications.

Conversational Artificial Intelligence for Spinal Pain Questionnaire: Validation and User Satisfaction.

OBJECTIVE: The purpose of our study is to develop a spoken dialogue system (SDS) for pain questionnaire in patients with spinal disease. We evaluate user satisfaction and validated the performance accuracy of the SDS in medical staff and patients. METHODS: The SDS was developed to investigate pain and related psychological issues in patients with spinal diseases based on the pain questionnaire protocol. We recognized patients' various answers, summarized important information, and documented them. User satisfaction and performance accuracy were evaluated in 30 potential users of SDS, including doctors, nurses, and patients and statistically analyzed. RESULTS: The overall satisfaction score of 30 patients was 5.5 ± 1.4 out of 7 points. Satisfaction scores were 5.3 ± 0.8 for doctors, 6.0 ± 0.6 for nurses, and 5.3 ± 0.5 for patients. In terms of performance accuracy, the number of repetitions of the same question was 13, 16, and 33 (13.5%, 16.8%, and 34.7%) for doctors, nurses, and patients, respectively. The number of errors in the summarized comment by the SDS was 5, 0, and 11 (5.2%, 0.0%, and 11.6 %), respectively. The number of summarization omissions was 7, 5, and 7 (7.3%, 5.3%, and 7.4%), respectively. CONCLUSION: This is the first study in which voice-based conversational artificial intelligence (AI) was developed for a spinal pain questionnaire and validated by medical staff and patients. The conversational AI showed favorable results in terms of user satisfaction and performance accuracy. Conversational AI can be useful for the diagnosis and remote monitoring of various patients as well as for pain questionnaires in the future.

Erratum: Transiting Nerve Rootlet Abnormalities on MRI after Lumbar Laminectomy: Associations with Persistent Postoperative Pain.

This corrects the article on p. 225 in vol. 22, PMID: 32901462.

User perception of medical service robots in hospital wards: a cross-sectional study.

BACKGRUOUND: Recently, there have been various developments in medical service robots (MSRs). However, few studies have examined the perceptions of those who use it. The purpose of this study is to identify user perceptions of MSRs. METHODS: We conducted a survey of 320 patients, doctors, and nurses. The contents of the survey were organized as follows: external appearances, perceptions, expected utilization, possible safety accidents, and awareness of their responsibilities. Statistical analyses were performed using t-test, chi-square test, and analysis of variance. RESULTS: The most preferred appearance was the animal type, with a screen. The overall average score of positive questions was 3.64±0.98 of 5 points and that of negative questions was 3.24±0.99. Thus, the results revealed that the participants had positive perceptions of MSR. The overall average of all expected utilization was 4.05±0.84. The most expected utilization was to guide hospital facilities. The most worrisome accident was exposure to personal information. Moreover, participants thought that the overall responsibility of the robot user (hospital) was greater than that of the robot manufacturer in the case of safety accidents. CONCLUSION: The perceptions of MSRs used in hospital wards were positive, and the overall expected utilization was high. It is necessary to recognize safety accidents for such robots, and sufficient attention is required when developing and manufacturing robots.

Preclinical mouse model of optical coherence tomography for subcortical brain imaging without dissection.

The purpose of this study was to investigate the feasibility of using optical coherence tomography (OCT) to identify internal brain lesions, specifically intracerebral hemorrhage, without dissection. Mice with artificially injected brain hematomas were used to test the OCT system, and the recorded images were compared with microscopic images of the same mouse brains after hematoxylin and eosin staining. The intracranial structures surrounding the hematomas were clearly visualized by the OCT system without dissection. These images reflect the ability of OCT to determine the extent of a lesion in several planes. OCT is a useful technology, and these findings could be used as a starting point for future research in intraoperative imaging.

Imaging characteristics of intradural disc herniation: A comparison with large disc extrusion.

OBJECTIVE: To compare the computed tomography (CT) and magnetic resonance imaging (MRI) findings of lumbar intradural disc herniation (IDH) and disc extrusion mimicking IDH. MATERIALS AND METHODS: Between January 2015 and August 2018, 32 with surgically confirmed IDH or disc extrusion mimicking IDH were included. Age, sex, symptoms, herniated disc level, history of discectomy at the same site, and operative findings were investigated through the medical records. We evaluated the direction, type, migration, margin, and shape of disc herniation, the presence of an abrupt discontinuity of the posterior longitudinal ligament (PLL), Y-sign of ventral dura, disc material beyond the PLL, and disc calcification or ossification. In addition, maximum herniated disc diameter to central canal diameter (MHDD/CCD) ratios were calculated. RESULTS: Twelve patients (8 males, 4 females; mean age 53.3 [21-83] years) were surgically confirmed to have lumbar IDH and 20 (11 males, 9 females; mean age 52 [19-78] years) had disc extrusion mimicking lumbar IDH. Margins and beak-like shapes of herniated discs, abrupt discontinuity of the PLL, Y-sign of ventral dura, disc material beyond the PLL, calcification or ossification of herniated discs, and MHDD/CCD ratios were significantly different in the IDH and non-IDH groups (p < 0.05). CONCLUSION: Imaging findings of an ill-defined margin, a beak-like shape, herniated disc calcification or ossification, abrupt PLL discontinuity, Y-sign of ventral dura, disc material beyond the PLL and a high MHDD/CCD ratio were found to predict the presence of IDH.

Successful Motor Evoked Potential Monitoring in Cervical Myelopathy : Related Factors and the Effect of Increased Stimulation Intensity.

OBJECTIVE: Intraoperative neurophysiological monitoring (IONM) has been widely used during spine surgery to reduce or prevent neurologic deficits, however, its application to the surgical management for cervical myelopathy remains controversial. This study aimed to assess the success rate of IONM in patients with cervical myelopathy and to investigate the factors associated with successful baseline monitoring and the effect of increasing the stimulation intensity by focusing on motor evoked potentials (MEPs). METHODS: The data of 88 patients who underwent surgery for cervical myelopathy with IONM between January 2016 and June 2018 were retrospectively reviewed. The success rate of baseline MEP monitoring at the initial stimulation of 400 V was investigated. In unmonitorable cases, the stimulation intensity was increased to 999 V, and the success rate final MEP monitoring was reinvestigated. In addition, factors related to the success rate of baseline MEP monitoring were investigated using independent t-test, Wilcoxon rank-sum test, chi-squared test, and Fisher's exact probability test for statistical analysis. The factors included age, sex, body mass index, diabetes mellitus, smoking history, symptom duration, Torg-Pavlov ratio, space available for the cord (SAC), cord compression ratio (CCR), intramedullary increased signal intensity (SI) on magnetic resonance imaging, SI length, SI ratio, the Medical Research Council (MRC) grade, the preoperative modified Nurick grade and Japanese Orthopedic Association (JOA) score. RESULTS: The overall success rate for reliable MEP response was 52.3% after increasing the stimulation intensity. No complications were observed to be associated with increased intensity. The factors related to the success rate of final MEP monitoring were found to be SAC (p<0.001), CCR (p<0.001), MRC grade (p<0.001), preoperative modified Nurick grade (p<0.001), and JOA score (p<0.001). The cut-off score for successful MEP monitoring was 5.67 mm for SAC, 47.33% for the CCR, 3 points for MRC grade, 2 points for the modified Nurick grade, and 12 points for the JOA score. CONCLUSION: Increasing the stimulation intensity could significantly improve the success rate of baseline MEP monitoring for unmonitorable cases at the initial stimulation in cervical myelopathy. In particular, the SAC, CCR, MRC grade, preoperative Nurick grade and JOA score may be considered as the more important related factors associated with the success rate of MEP monitoring. Therefore, the degree of preoperative neurological functional deficits and the presence of spinal cord compression on imaging could be used as new detailed criteria for the application of IONM in patients with cervical myelopathy.

Validation of a gyroscope-based wearable device for real-time position monitoring of patients in a hospital.

BACKGROUND: Monitoring patients' position is important, but there have been few studies related to validation. OBJECTIVE: The objective of this study was to assess the validity of position monitoring measured using a wearable device by comparing the device's measurements to a patient's actual position. METHODS: We constructed a wearable device with a three-axis gyroscope and applied it to 10 patients who were unable to change their position independently. We compared the actual angle of the position and the angle transmitted from the wearable device using a Bland-Altman plot and a receiver operating characteristic curve. RESULTS: We compared the actual angle of the position and the angle transmitted from the wearable device using a Bland-Altman plot, but it was difficult to observe statistical similarity. The angles transmitted from the wearable device in the lateral and supine positions showed significant differences. The cutoff value separating the lateral and supine positions was found to be 27.1∘ (sensitivity = 100%, specificity = 99.9%). CONCLUSIONS: Through our method, the measured values from the gyroscope-based wearable device did not accurately reflect the patient's actual position. However, the wearable device was able to distinguish the lateral position from the supine position.

Transiting Nerve Rootlet Abnormalities on MRI after Lumbar Laminectomy: Associations with Persistent Postoperative Pain.

OBJECTIVE: To determine whether changes in the transiting nerve rootlet or its surroundings, as seen on MRI performed after lumbar hemilaminectomy, are associated with persistent postoperative pain (PPP), commonly known as the failed back surgery syndrome. MATERIALS AND METHODS: Seventy-three patients (mean age, 61 years; 43 males and 30 females) who underwent single-level partial hemilaminectomy of the lumbar spine without postoperative complications or other level spinal abnormalities between January 2010 and December 2018 were enrolled. Two musculoskeletal radiologists evaluated transiting nerve rootlet abnormalities (thickening, signal alteration, distinction, and displacement), epidural fibrosis, and intrathecal arachnoiditis on MRI obtained one year after the operations. A spine surgeon blinded to the radiologic findings evaluated each patient for PPP. Univariable and multivariable analyses were used to evaluate the association between the MRI findings and PPP. RESULTS: The presence of transiting nerve rootlet thickening, signal alteration, and ill-distinction was significantly different between the patients with PPP and those without, for both readers (p ≤ 0.020). Conversely, the presence of transiting nerve rootlet displacement, epidural fibrosis, and intrathecal arachnoiditis was not significantly different between the two groups (p ≥ 0.128). Among the above radiologic findings, transiting nerve rootlet thickening and signal alteration were the most significant findings in the multivariable analyses (p ≤ 0.009). CONCLUSION: On MRI, PPP was associated with transiting nerve rootlet abnormalities, including thickening, signal alterations, and ill-distinction, but was not associated with epidural fibrosis or intrathecal arachnoiditis. The most relevant findings were the nerve rootlet thickening and signal alteration.

Synthesis and formation mechanism of bone mineral, whitlockite nanocrystals in tri-solvent system.

Whitlockite (WH, Ca18Mg2(HPO4)2(PO4)12) is the second most abundant bone mineral and has attracted attention as one of the novel bone regenerative materials. It has proven to enhance growth and promote osteogenesis of stem cells. However, investigating the mechanism of formation of pure phase WH nanocrystals remains a challenge. In this study, we introduced an interesting synthesis approach of WH nanocrystals using a tri-solvent system for the solid-liquid-solution (SLS) process. The ratio of precursor and reaction solvent composition was optimized to generate WH nanocrystals with tunable size, morphology (nanoplates, nanospheres), and surface properties (hydrophobic, hydrophilic), which is impossible to achieve using the traditional precipitation method. Molecular dynamics (MD) simulations revealed that the growth direction of nanoplates is highly related to the surfactant and its binding affinity. Finite element method (FEM) simulations elucidated that the ratio of ethanol/water plays an important role in defining the crystallinity and morphology of WH. In this study, we demonstrated that the cell proliferation of human bone marrow-derived mesenchymal stem cells (hBMSCs) is enhanced upon treatment with WH. The results of quantitative real-time polymerase chain reaction (qPCR) revealed that WH can positively accelerate the osteogenic differentiation in hBMSCs. The as-synthesized WH has a great potential in the future to be used in osteogenic tissue engineering. This study opens a new horizon for the synthesis and application of WH.

Hounsfield Units on Lumbar Computed Tomography for Predicting Regional Bone Mineral Density.

OBJECTIVE: Bone mineral density (BMD) is a very important factor in spinal fusion surgery using instrumentation. Our aim was to investigate the utility of Hounsfield units (HU) obtained from preoperative lumbar computed tomography (CT) to predict osteoporosis coupling with data of quantitative computed tomography (QCT) and dual X-ray absorptiometry (DEXA). METHODS: We reviewed 180 patients that underwent both QCT and lumbar CT for spine surgery. HU was retrospectively calculated on the lumbar CT of 503 lumbar vertebrae from L1 to L3. Femur DEXA was performed in all patients and spine DEXA was tested in 120 patients (331 vertebrae). BMD was grouped as osteoporosis (QCT<80mg/cm3, DEXA T score≤-2.5) and non-osteoporosis (QCT≥80mg/cm3, DEXA T score>-2.5) for comparison of HU value. RESULTS: HU value and BMD showed significant correlations. The optima cut-off value based on QCT was higher than that of DEXA scans which had the best correlation for predicting osteoporosis. ROC curve analysis demonstrated that HU value with QCT of 146 has a sensitivity of 94.3% and a specificity of 87.5% for osteoporosis. CONCLUSIONS: Significant correlation was found between HU measurement and BMD value. These findings provide evidence that HU measurement can be established as a means for predicting osteoporosis before spine fusion surgery with reduced radiation hazard.

The Usefulness of a Wearable Device in Daily Physical Activity Monitoring for the Hospitalized Patients Undergoing Lumbar Surgery.

OBJECTIVE: Functional outcomes have traditionally been evaluated and compared using subjective surveys, such as visual analog scores (VAS), the Oswestry disability index (ODI), and Short Form-36 (SF-36), to assess symptoms and quality of life. However, these surveys are limited by their subjective natures and inherent bias caused by differences in patient perceptions of symptoms. The Fitbit Charge® (Fitbit Inc., San Francisco, CA, USA) provides accurate and objective measures of physical activity. The use of this device in patients after laminectomy would provide objective physical measures that define ambulatory function, activity level, and degree of recovery. Therefore, the present study was conducted to identify relationships between the number of steps taken by patients per day and VAS pain scores, prognoses, and postoperative functional outcomes. METHODS: We prospectively investigated 22 consecutive patients that underwent laminectomy for spinal stenosis or a herniated lumbar disc between June 2015 and April 2016 by the same surgeon. When patients were admitted for surgery and first visited after surgery, preoperative and postoperative functional scores were recorded using VAS scores, ODI scores, and SF-36. The VAS scores and physical activities were recorded daily from postoperative day (POD) 1 to POD 7. The relationship between daily VAS scores and daily physical activities were investigated by simple correlation analysis and the relationship between mean number of steps taken and ODI scores after surgery was subjected to simple regression analysis. In addition, Wilcoxon's signed-rank test was used to investigate the significance of pre-to-postoperative differences in VAS, ODI, and SF-36 scores. RESULTS: Pre-to-postoperative VAS (p<0.001), ODI (p<0.001), SF-36 mental composite scores (p=0.009), and SF-36 physical composite scores (p<0.001) scores were found to be significantly different. Numbers of steps taken from POD 1 to POD 7 were negatively correlated with daily VAS scores (r=-0.981, p<0.001). In addition, the mean number of steps from POD 3 to POD 7 and the decrease in ODI conducted one month after surgery were statistically significant (p=0.029). CONCLUSION: Wearable devices are not only being used increasingly by consumers as lifestyle devices, but are also progressively being used in the medical area. This is the first study to demonstrate the usefulness of a wearable device for checking patient physical activity and predicting pain and prognosis after laminectomy. Based on our experience, the wearable device used to provide measures of physical activity in the present study has the potential to provide objective information on pain severity and prognosis.

Machine Learning Model to Predict Osteoporotic Spine with Hounsfield Units on Lumbar Computed Tomography.

OBJECTIVE: Bone mineral density (BMD) is an important consideration during fusion surgery. Although dual X-ray absorptiometry is considered as the gold standard for assessing BMD, quantitative computed tomography (QCT) provides more accurate data in spine osteoporosis. However, QCT has the disadvantage of additional radiation hazard and cost. The present study was to demonstrate the utility of artificial intelligence and machine learning algorithm for assessing osteoporosis using Hounsfield units (HU) of preoperative lumbar CT coupling with data of QCT. METHODS: We reviewed 70 patients undergoing both QCT and conventional lumbar CT for spine surgery. The T-scores of 198 lumbar vertebra was assessed in QCT and the HU of vertebral body at the same level were measured in conventional CT by the picture archiving and communication system (PACS) system. A multiple regression algorithm was applied to predict the T-score using three independent variables (age, sex, and HU of vertebral body on conventional CT) coupling with T-score of QCT. Next, a logistic regression algorithm was applied to predict osteoporotic or non-osteoporotic vertebra. The Tensor flow and Python were used as the machine learning tools. The Tensor flow user interface developed in our institute was used for easy code generation. RESULTS: The predictive model with multiple regression algorithm estimated similar T-scores with data of QCT. HU demonstrates the similar results as QCT without the discordance in only one non-osteoporotic vertebra that indicated osteoporosis. From the training set, the predictive model classified the lumbar vertebra into two groups (osteoporotic vs. non-osteoporotic spine) with 88.0% accuracy. In a test set of 40 vertebrae, classification accuracy was 92.5% when the learning rate was 0.0001 (precision, 0.939; recall, 0.969; F1 score, 0.954; area under the curve, 0.900). CONCLUSION: This study is a simple machine learning model applicable in the spine research field. The machine learning model can predict the T-score and osteoporotic vertebrae solely by measuring the HU of conventional CT, and this would help spine surgeons not to under-estimate the osteoporotic spine preoperatively. If applied to a bigger data set, we believe the predictive accuracy of our model will further increase. We propose that machine learning is an important modality of the medical research field.

Symptomatic Pneumocephalus After Spinal Intradural-Extramedullary Tumor Surgery.

OBJECTIVE: Durotomy is a necessary procedure for resection of spinal intradural-extramedullary (IDEM) tumor. The purpose of this study was to investigate the prevalence and clinical implications of pneumocephalus after spinal IDEM tumor surgery and also the association between pneumocephalus and postoperative headache. METHODS: This prospective study was conducted in a cohort of 20 patients who were diagnosed with a spinal IDEM tumor and underwent surgical resection. The mean patient age was 53.6 years (range, 29-75 years). Histological findings revealed schwannoma in 16 cases (80.0%) and meningioma in 4 cases (20.0%). Brain computed tomography scan was performed immediately after surgery. The prevalence and severity were analyzed based on the classification into 4 groups according to the extension of pneumocephalus: absence, mild, moderate, and severe. A visual analog scale (VAS; range 0-10) for headache was reported daily for the first postoperative week. Headache-related pneumocephalus was defined as a VAS score of ≥5 points at least once in that 1-week period. RESULTS: The prevalence of pneumocephalus was 90.0% (18 patients). Five patients (25.0%) had severe pneumocephalus extending to the extra-axial space. Seven of the 20 patients (38.9%) complained of significant headache. Five of these patients had severe pneumocephalus, 1 patient had moderate pneumocephalus, and 1 patient had moderate pneumocephalus. A statistically significant association was observed between the severity of pneumocephalus and headache (P = 0.001). CONCLUSIONS: Pneumocephalus is a common complication after spinal IDEM tumor surgery. This report is the first study to investigate the prevalence of pneumocephalus and analyze its association with headache after spine surgery. The severity of pneumocephalus was significantly related to postoperative headache.

Internet of Things, Digital Biomarker, and Artificial Intelligence in Spine: Current and Future Perspectives.

Recent interest in medical artificial intelligence (AI) has increased with onset of the fourth industrial revolution. Real-time monitoring of patients is an important research area of medical AI. The medical AI is very closely related to the Internet of Things (IoT), a core element of the fourth industrial revolution. Attempts to diagnose and treat patients using IoT have been already applied to patients with chronic disease such as hypertension and arrhythmia. However, in the spine, research on IoT and digital biomarkers are still in the early stages. The digital biomarker obtained by IoT devices is objective and could represent real-time, real-world, and abundant data. Based on its characteristics, IoT and digital biomarkers can also be useful in the spine. Currently, research on real-time monitoring of physical activity or spinal posture is ongoing. Therefore, the authors introduce the basic concepts of IoT and digital biomarkers, their relationship to AI, and recent trends. Current and future perspectives of IoT and digital biomarker in spine are also discussed. In the future, it is expected that IoT, digital biomarkers, and AI will lead to a paradigm shift in the diagnosis and treatment of spinal diseases.

Cervical Pedicle Screw Placement Using Medial Funnel Technique.

OBJECTIVE: Cervical pedicle screw (CPS) placement is very challenging due to high risk of neurovascular complications. We devised a new technique (medial funnel technique) to improve the accuracy and feasibility of CPS placement. METHODS: We reviewed 28 consecutive patients undergoing CPS instrumentation using the medial funnel technique. Their mean age was 51.4 years (range, 30-81 years). Preoperative diagnosis included degenerative disease (n=5), trauma (n=22), and infection (n=1). Screw perforations were graded with the following criteria: grade 0 having no perforation, grade 1 having <25%, grade 2 having 25%-50% and grade 3 having >50% of screw diameter. Grades 0 and 1 were considered as correct position. The degree of perforation was determined by 2 junior neurosurgeons and 1 senior neurosurgeon. RESULTS: A total of 88 CPSs were inserted. The rate of correct placement was 94.3%; grade 0, 54 screws; grade 1, 29 screws; grade 2, 4 screws; and grade 3, 1 screw. No neurovascular complications or failure of instrumentation occurred. In perforated screws (34 screws), lateral perforations were 4 and medial perforations were 30. CONCLUSION: We performed CPS insertion using medial funnel technique and achieved 94.3% (83 of 88) of correct placement. And it can decrease lateral perforation.

Spontaneous Epidural Hematoma Associated with Venous Phlebolith in Cervical Spine and Possible Pathogenesis.

Although the etiology of spontaneous spinal epidural hematoma (SSEH) is unclear, SSEH is known to be associated with anticoagulants, coagulopathy, vascular malformation, hypertension, and pregnancy. However, no report has been issued on the relation between SSEH and venous phlebolith. Here, the authors present an extremely rare case of SSEH associated with phlebolith in the cervical spine and suggest a possible pathogenesis. A 36-year-old man without any relevant medical history presented with neck pain and numbness and severe radiating pain on the left arm. Magnetic resonance imaging showed epidural hematoma at the C5-7 level, and computed tomography revealed a calcified nodule in the left epidural hemorrhage at C6 level. During left partial laminectomy, epidural venous plexus, and thick epidural hematoma were found, and hematoma removal revealed a white, ovoid, smooth, hard mass of diameter 3 mm. Histopathologic examination confirmed the mass as a venous phlebolith. The presence of a calcified solitary nodule in dorsal epidural space indicates the presence of phlebolith and the risk of SSEH. In such cases, the authors recommend spine surgeons should take into consideration the possibility of epidural hemorrhage.