Distal-scanning common path probe for optical coherence tomography

In this paper,we present a distal-scanning common path probe for optical coherence tomography(OCT)equipped with a hollow ultrasonic motor and a simple and specially designed beam-splitter.This novel probe proves to be able to effectively circumvent polarization and dispersion mismatch caused by fiber motion and is more robust to a variety of interfering factors during the imaging process,experimentally compared to a conventional noncommon path probe.Furthermore,our design counteracts the attenuation of backscattering with depth and the fall-off of the signal,resulting in a more balanced signal range and greater imaging depth.Spectral-domain OCT imaging of phantom and biological tissue is also demonstrated with a sensitivity of∼100dB and a lateral resolution of∼3μm.This low-cost probe offers simplified system configuration and excellent robustness,and is therefore particularly suitable for clinical diagnosis as one-off medical apparatus.

Engineering neuroregenerative microenvironment via aligned hydrogel-assisted magnetic stimulation for complete spinal cord injury repair

Utilizing biomaterials in tissue engineering has shown considerable promise for tissue regeneration,particularly through delivering multimodel cell-regulatory signals,including the material-related signals and extrinsic stimuli.In this research,we developed a magnetic-responsive aligned nanofiber fibrin hydrogel(MAFG),integrating the structured alignment of nanofibers and the pliability of fibrin hydrogel with an external magnetic field.This design aimed to enhance the regenerative response in spinal cord injury treatment.A medium-strength magnetic field,aligned with the spinal cord,was applied to aid motor function recovery in rats with spinal cord injuries.The use of MAFG in this context not only intensified the effect of the magnetic field but also encouraged the activation and differentiation of native neural stem cells.Furthermore,this method effectively steered macrophage polarization towards a beneficial M2 phenotype,addressing immune dysregulation at the injury site.The parallel application of magnetic field stimulation through MAFG in a spinal cord injury model contributed to the concurrent promotion of neurogenesis,angiogenesis,and immunomodulation,resulting in marked improvement in motor function in rats.This investigation underscores the therapeutic potential of magnetic field stimulation and highlights how aligning this stimulation with the spinal cord can significantly enhance the regenerative milieu at the injury site.

Voluntary walking related joint movement training with targeted epidural electrical stimulation enabled neural recovery for individuals with spinal cord injury

Spinal cord injury(SCI)poses a substantial medical and social challenge,frequently leading to partial or complete loss of motor function below the site of injury[1].The disruption of descending neural pathways and the consequent loss of neural connectivity impair voluntary movement and interfere with sensory and autonomic functions.Traditional therapeutic strategies have primarily centered on compensatory methods,helping individuals with SCI adapt to their impairments[2].However,recent advances in neurorehabilitation are shifting the paradigm toward restorative treatments that seek to re-establish neural connections and promote functional recovery.

3D bio-printed living nerve-like fibers refine the ecological niche for long-distance spinal cord injury regeneration

3D bioprinting holds great promise toward fabricating biomimetic living constructs in a bottom-up assembly manner.To date,various emergences of living constructs have been bioprinted for in vitro applications,while the conspicuous potential serving for in vivo implantable therapies in spinal cord injury(SCI)has been relatively overlooked.Herein,living nerve-like fibers are prepared via extrusion-based 3D bioprinting for SCI therapy.The living nerve-like fibers are comprised of neural stem cells(NSCs)embedded within a designed hydrogel that mimics the extracellular matrix(ECM),assembled into a highly spatial ordered architecture,similar to densely arranged bundles of the nerve fibers.The pro-neurogenesis ability of these living nerve-like fibers is tested in a 4 mm-long complete transected SCI rat model.Evidence shows that living nerve-like fibers refine the ecological niche of the defect site by immune modulation,angiogenesis,neurogenesis,neural relay formations,and neural circuit remodeling,leading to outstanding functional reconstruction,revealing an evolution process of this living construct after implantation.This effective strategy,based on biomimetic living constructs,opens a new perspective on SCI therapies.

N‑Cadherin‑Functionalized Nanofiber Hydrogel Facilitates Spinal Cord Injury Repair by Building a Favorable Niche for Neural Stem Cells

The inhospitable niche at the injury site after spinal cord injury(SCI)brings several challenges to neural stem cell(NSC)therapy,such as limited NSC retention and neuronal differentiation.Biomaterial-based stem cell transplantation has become a promising strategy for building a favorable niche to stem cells.Herein,an aligned fibrin nanofiber hydrogel modified with N-Cadherin-Fc(AFGN)was fabricated by electrospinning and biochemical conjugation to deliver NSCs for SCI repair.The AFGN hydrogel provides multimodal cues,including oriented nanofibrous topography,soft stiffness,and specific cell binding ligand,for directing NSC functions and nerve regeneration.The conjugated N-Cadherin-Fc recapitulated the homo-philic cell-cell interaction for NSCs’adhesion on AFGN and modulated cellular mechanosensing in response to AFGN for NSC differentiation.In addition,the AFGN hydrogel carrying exogenous NSCs was implanted in a rat 2 mm-long complete transected SCI model and significantly promoted the grafted NSCs retention,immunomodulation,neuronal differentiation,and in vivo integration with inherent neurons,thus finally achieved renascent neural relay formation and an encouraging locomotor functional recovery.Altogether,this study represents a valuable strategy for boosting NSC-based therapy in SCI regeneration by engineering an NSC-specific niche.

White matter regeneration induced by aligned fibrin nanofiber hydrogel contributes to motor functional recovery in canine T12 spinal cord injury

A hierarchically aligned fibrin hydrogel(AFG)that possesses soft stiffness and aligned nanofiber structure has been successfully proven to facilitate neuroregeneration in vitro and in vivo.However,its potential in promoting nerve regeneration in large animal models that is critical for clinical translation has not been sufficiently specified.Here,the effects of AFG on directing neuroregeneration in canine hemisected T12 spinal cord injuries were explored.Histologically obvious white matter regeneration consisting of a large area of consecutive,compact and aligned nerve fibers is induced by AFG,leading to a significant motor functional restoration.The canines with AFG implantation start to stand well with their defective legs from 3 to 4 weeks postoperatively and even effortlessly climb the steps from 7 to 8 weeks.Moreover,high-resolution multi-shot diffusion tensor imaging illustrates the spatiotemporal dynamics of nerve regeneration rapidly crossing the lesion within 4 weeks in the AFG group.Our findings indicate that AFG could be a potential therapeutic vehicle for spinal cord injury by inducing rapid white matter regeneration and restoring locomotion,pointing out its promising prospect in clinic practice.

Accuracy of pedicle screw placement in the thoracic and lumbosacral spines using O-arm-based navigation versus conventional freehand technique

The accuracy and safety of pedicle screw insertion was markedly improved with the introduction of intraoperative three-dimensional navigation system during the last decade. This study aimed to evaluate the accuracy of pedicle screw placement using O-arm-based navigation system versus conventional freehand technique. Methods: We reviewed the accuracy of 341 thoracic (n = 173) and lumbosacral (n = 168) pedicle screws placed in 60 consecutive patients using either O-arm-based navigation or freehand technique in the Department of Neurosurgery of Beijing Tsinghua Changgung Hospital between January 2015 and June 2018. Patient-specific characteristics, treatment-related characteristics, and screw-specific accuracy were analyzed. The accuracy of pedicle screw placement was measured by Gertzbein-Robbins scale and screw grades A and B were clinically acceptable. Results: One hundred ninety-one screws were inserted in the O-arm-based navigation group and 150 in the freehand group. One hundred eighty-three (95.81%) clinically acceptable screws were placed in the navigation group and 135 (90.00%) in the freehand group (p = 0.034). Twenty-three (6.74%) screw revisions were performed in the two groups (8 screws in the navigation group and 15 screws in the freehand group) and significant difference was observed in thoracic spine (p = 0.018), while no statistical significance was presented in lumbosacral spine (p >0.05). Twenty-four (12.57%) screws in the navigation group and 24 (16.00%) in the freehand group violated the cortex (p > 0.05). Medial screw deviation was the most common problem in the two groups. Conclusion: The O-arm-based navigation exhibits higher accuracy for pedicle screw insertion than the freehand insertion technique.

Diffuse midline glioma treated with epigenetic agent-based immunotherapy

Dear Editor,Diffuse midline glioma,H3K27-altered(DMG),is a pediatric-type high-grade diffuse glioma that preferentially localizes to the brainstem or pons,thalamus,and spinal cord.Surgical resection is challenging and biopsy is often performed in most cases.To date,no conventional,targeted or immune therapy has been convincingly shown to improve patients’overall survival(OS).

Application of intraoperative O-arm-assisted real-time navigation technique for spinal fixation

This study explored the combined use of the O-arm and real-time navigation during spinal fixation. The clinical data for 60 patients undergoing spinal fixation, at Beijing Tsinghua Chang Gung Hospital between May 5, 2015 and May 1, 2017, were retrospectively analyzed. Pre-, intra-, and postoperative imaging findings were assessed. The patients were classified into the occipitocervical fusion(32 cases) and thoracic/lumbar/sacral spine fixation(28 cases, including 6 cases of percutaneous pedicle screw) groups. Lesion resections were performed microscopically. An O-arm, combined with real-time navigation, was used to assess spinal fixation. Efficacy was evaluated using operative times, X-ray times, screw positioning, and complications. Within the occipitocervical fusion group, 182 screws were placed in the cervical spine and 96 in the occipital bone. However, 6 screws penetrated the bone cortex and were adjacent to the vertebral arteries, based on O-arm three-dimensional imaging; therefore, the precision rate was 96.7%. Within the thoracic/lumbar/sacral spine fixation group, 148 pedicle screws were implanted, with 4 initially outside the vertebral body,yielding a precision rate of 97.3%. Ten percutaneous pedicle screws were implanted and well positioned. O-arm scans were performed 3 times/patient, with an average of 20–30 min/time. Screw implantation times were 5–7 min(cervical spine), 8–10 min(thoracic spine), and 6–8 min(lumbar spine). Intraoperative O-arm scans, combined with real-time navigation technology, allow real-time observation of screw angles and depths, improving the accuracy and safety of posterior screw fixations and reducing the radiation dose and frequency experienced by patients and surgeons.

Neurocutaneous melanosis with intraspinal malignant melanoma in adults—an extremely rare clinical entity: A case report with review of literature

Objectives: Neurocutaneous melanosis(NCM) in adult patients was rare, and few cases had been reported. In this report, we summarized the features of NCM in adult patients for providing useful information about this rare clinical entity. Methods: In this report, we present a case of a 41-year-old woman, who was eventually diagnosed with NCM with intraspinal malignant melanoma. The clinical features,treatments, and prognosis of cases of NCM in adults were thoroughly reviewed and discussed. Results: A 41-year-old woman was eventually diagnosed with NCM with intraspinal malignant melanoma. The post-operative course was uneventful and her symptoms significantly improved(VAS: 3 points). However, she developed symptoms of intracranial hypertension and deteriorated rapidly after 11 months of operation, and died 1 month later. To date, only 15 cases of NCM in adults have been reported in the English literature. Analyses showed that the average age was 33.8 years(range19–65 years), and 11 patients(68.8%) were between 20 and 40 years. A slight male predominance(M:F/11:5) was found. For the 12 cases which detailed follow-up information was available, 9 patients(75%) died, with a survival time ranging from 1 day to 29 months post-operation. Death occurred within the first month of operation in 6 cases(46. 2%). The median survival time was 3 months. Conclusions: We presented a rare case of NCM with intraspinal malignant melanoma in an adult patient. Although rare, this clinical entity causes significant mortality and has poor prognosis.

Posterior mediastinal ganglioneuroma: A case report and literature review

Objectives: Ganglioneuroma is a rare, benign neurogenic tumor arising from the sympathetic ganglia. In this report, we reviewed and summarized the clinical features,treatment, and prognosis of a posterior mediastinal ganglioneuroma. Case: Here, we report on a 29-year-old man referred to us with transient pain in the right side of the chest, lasting for three days. Physical examination revealed no abnormalities.The results of routine laboratory tests were within the normal ranges. Thoracic spinal magnetic resonance imaging showed a well-defined, solid mass in the right paravertebral region at the T5-T8 level, measuring 7.5 cm × 4.2 cm × 1.5 cm. To accurately locate the lesion during surgery, O-arm intraoperative imaging was used in conjunction with the Stealth Station navigation system. The tumor was completely excised and no related complications occurred. The tumor was an encapsulated mass with a solid, homogenous, grayish-tan cut surface. Histopathological examinations confirmed that the mass was a ganglioneuroma. Conclusions: Ganglioneuroma is a rare, benign tumor. Prior to treatment, a careful imaging evaluation is necessary in order to obtain an accurate diagnosis. A definitive diagnosis can be made by histological examination. En bloc resection is the preferred treatment for ganglioneuroma as it has an excellent prognosis.

Surgical resection of a cervical intramedullary schwannoma: A case report and literature review

Schwannomas are the most common type of spinal tumor, and they most commonly occur in intradural extramedullary locations. Intramedullary schwannomas of the central nervous system are very rare and are difficult to diagnose using preoperative imaging. Here, we report a rare, tiny cervical intramedullary schwannoma and review the literature regarding the clinical presentation, magnetic resonance imaging, pathology,and surgical experience associated with this rare tumor type.

Fluorescein sodium use during spinal ependymoma resection

Spinal ependymomas(SEs) are common adult intramedullary tumors; however,determining the absolute boundary between the tumor and the tumor residual may be difficult. We assessed outcomes following the use of fluorescein sodium(FS) during surgical removal of SEs. We performed a retrospective analysis of 112 patients with SEs who were treated at Beijing Tsinghua Changgung Hospital between December 2014 and December 2016. Each patient received intravenous FS(3–4 mg/kg) to determine the SE boundaries during surgery. Tumor removal efficiencies and tumor residuals were assessed using magnetic resonance imaging(MRI) at 10 days and 3 months after surgical recovery; McC ormick's spinal function classification was also performed at the 3-month follow-up. The complete tumor removal rate was 92%(103/112). Ninetyfour patients underwent tumor removal under fluorescent light, which provided distinctive tumor fluorescence. Tumor removal under white light was performed in18 patients; fluorescent images were invisible or indistinctive in these 18 patients. At the 3-month follow-up, sensory function(85.8%(91/106)) and movement(84.3%(86/102)) were improved in patients with pre-surgical dysfunction; urination and defecation functions were improved in 66.7%(16/24). The Mc Cormick spinal cord functional classifications, at the 3-month follow-up, showed significant differences in the percentages of patients with disease classified to each grade(I–IV), compared with preoperative classifications(each, P < 0.05). There was no MRI evidence of tumor relapse or residuals at the 3-month follow-up. FS use during the surgical treatment of SE enables complete tumor removal and detection of tumor residuals.