Learning Soft Millirobot Multimodal Locomotion with Sim-to-Real Transfer.

With wireless multimodal locomotion capabilities, magnetic soft millirobots have emerged as potential minimally invasive medical robotic platforms. Due to their diverse shape programming capability, they can generate various locomotion modes, and their locomotion can be adapted to different environments by controlling the external magnetic field signal. Existing adaptation methods, however, are based on hand-tuned signals. Here, a learning-based adaptive magnetic soft millirobot multimodal locomotion framework empowered by sim-to-real transfer is presented. Developing a data-driven magnetic soft millirobot simulation environment, the periodic magnetic actuation signal is learned for a given soft millirobot in simulation. Then, the learned locomotion strategy is deployed to the real world using Bayesian optimization and Gaussian processes. Finally, automated domain recognition and locomotion adaptation for unknown environments using a Kullback-Leibler divergence-based probabilistic method are illustrated. This method can enable soft millirobot locomotion to quickly and continuously adapt to environmental changes and explore the actuation space for unanticipated solutions with minimum experimental cost.

Pangolin-inspired untethered magnetic robot for on-demand biomedical heating applications.

Untethered magnetic miniature soft robots capable of accessing hard-to-reach regions can enable safe, disruptive, and minimally invasive medical procedures. However, the soft body limits the integration of non-magnetic external stimuli sources on the robot, thereby restricting the functionalities of such robots. One such functionality is localised heat generation, which requires solid metallic materials for increased efficiency. Yet, using these materials compromises the compliance and safety of using soft robots. To overcome these competing requirements, we propose a pangolin-inspired bi-layered soft robot design. We show that the reported design achieves heating > 70 °C at large distances > 5 cm within a short period of time <30 s, allowing users to realise on-demand localised heating in tandem with shape-morphing capabilities. We demonstrate advanced robotic functionalities, such as selective cargo release, in situ demagnetisation, hyperthermia and mitigation of bleeding, on tissue phantoms and ex vivo tissues.

Magnetic guidewire steering at ultrahigh magnetic fields.

With remote magnetic steering capabilities, magnetically actuated guidewires have proven their potential in minimally invasive medical procedures. Existing magnetic steering strategies, however, have been limited to low magnetic fields, which prevents the integration into medical systems operating at ultrahigh fields (UHF), such as magnetic resonance imaging (MRI) scanners. Here, we present magnetic guidewire design and steering strategies by elucidating the magnetic actuation principles of permanent magnets at UHF. By modeling the uniaxial magnetization behavior of permanent magnets, we outline the magnetic torque and force and demonstrate unique magnetic actuation opportunities at UHF, such as in situ remagnetization. Last, we illustrate the proposed steering principles using a magnetic guidewire composed of neodymium magnets and a fiber optic rod in a 7-Tesla preclinical MRI scanner. The developed UHF magnetic actuation framework would enable next-generation magnetic robots to operate inside MRI scanners.

Heat-Mitigated Design and Lorentz Force-Based Steering of an MRI-Driven Microcatheter toward Minimally Invasive Surgery.

Catheters integrated with microcoils for electromagnetic steering under the high, uniform magnetic field within magnetic resonance (MR) scanners (3-7 Tesla) have enabled an alternative approach for active catheter operations. Achieving larger ranges of tip motion for Lorentz force-based steering have previously been dependent on using high power coupled with active cooling, bulkier catheter designs, or introducing additional microcoil sets along the catheter. This work proposes an alternative approach using a heat-mitigated design and actuation strategy for a magnetic resonance imaging (MRI)-driven microcatheter. A quad-configuration microcoil (QCM) design is introduced, allowing miniaturization of existing MRI-driven, Lorentz force-based catheters down to 1-mm diameters with minimal power consumption (0.44 W). Heating concerns are experimentally validated using noninvasive MRI thermometry. The Cosserat model is implemented within an MR scanner and results demonstrate a desired tip range up to 110° with 4° error. The QCM is used to validate the proposed model and power-optimized steering algorithm using an MRI-compatible neurovascular phantom and ex vivo kidney tissue. The power-optimized tip orientation controller conserves as much as 25% power regardless of the catheter's initial orientation. These results demonstrate the implementation of an MRI-driven, electromagnetic catheter steering platform for minimally invasive surgical applications without the need for camera feedback or manual advancement via guidewires. The incorporation of such system in clinics using the proposed design and actuation strategy can further improve the safety and reliability of future MRI-driven active catheter operations.

Wireless MRI-Powered Reversible Orientation-Locking Capsule Robot.

Magnetic resonance imaging (MRI) scanners do not provide only high-resolution medical imaging but also magnetic robot actuation and tracking. However, the rotational motion capabilities of MRI-powered wireless magnetic capsule-type robots have been limited due to the very high axial magnetic field inside the MRI scanner. Medical functionalities of such robots also remain a challenge due to the miniature robot designs. Therefore, a wireless capsule-type reversible orientation-locking robot (REVOLBOT) is proposed that has decoupled translational motion and planar orientation change capability by locking and unlocking the rotation of a spherical ferrous bead inside the robot on demand. Such an on-demand locking/unlocking mechanism is achieved by a phase-changing wax material in which the ferrous bead is embedded inside. Controlled and on-demand hyperthermia and drug delivery using wireless power transfer-based Joule heating induced by external alternating magnetic fields are the additional features of this robot. The experimental feasibility of the REVOLBOT prototype with steerable navigation, medical function, and MRI tracking capabilities with an 1.33 Hz scan rate is demonstrated inside a preclinical 7T small-animal MRI scanner. The proposed robot has the potential for future clinical use in teleoperated minimally invasive treatment procedures with hyperthermia and drug delivery capabilities while being wirelessly powered and monitored inside MRI scanners.

The Evaluation of Survivin and Bcl-2 Expression on the Medical Radiation Doses for Neural Tube Defect Development.

AIM: To investigate the effects of different radiation doses on the development of the neural tube defect in chick embryos using computed tomography (CT), and assess its correlation with survivin and Bcl-2 expressions. MATERIAL AND METHODS: A total of 150 chicken eggs were used and grouped into five categories. In Group 1 (n=30), the embryos were not exposed to radiation. In Group 2 (n=30), the embryos were irradiated using lung cancer screening chest CT protocol. In Groups 3 and 4 (n=30 each), the abdominopelvic and adult routine head CT protocols, respectively, were used to irradiate the embryos. In Group 5 (n=30), the embryos were irradiated using adult brain perfusion CT protocol. Subsequently, the embryos were examined under a stereomicroscope to assess the presence of neural tube developmental abnormalities. Moreover, immunohistochemical staining was performed to determine the survivin and Bcl-2 expression levels. RESULTS: The risk of developing neural tube defect increased with the amount of exposed radiation. Moreover, no significant correlation was observed between the survivin and Bcl-2 expression levels and the radiation dose. CONCLUSION: Overall, the results of this study indicate that the radiation from CT may cause neural tube defect in chicken embryos.

Transforaminal Epidural Steroid Injection in the Treatment of Pain in Foraminal and Paramedian Lumbar Disc Herniations.

AIM: To compare the effect of fluoroscopically guided transforaminal epidural steroid injections on radicular pain in foraminal and paramedian lumbar disc herniations. MATERIAL AND METHODS: This study included patients who did not benefit from previous medical treatments or are not suitable for surgery. Transforaminal epidural steroid injections for the treatment of foraminal and paramedian lumbar disc herniation were performed in 370 and 1262 patients, respectively. Every group’s preprocedural visual analogue scale (VAS) and 12-week postprocedural VAS scores were recorded, and statistical analysis was performed. The complications noted were also recorded. RESULTS: The preprocedural and postprocedural mean VAS scores for radicular pain in foraminal disc herniation were 67.11 ± 4.28 and 34.78 ± 3.64, respectively. However, the preprocedural and postprocedural mean VAS scores in paramedian disc herniation were 62.16 ± 6.65 and 19.07 ± 4.50, respectively. Statistical analysis of the varying preprocedural and postprocedural VAS scores showed that transforaminal epidural steroid injections were more effective for paramedian disc herniation than for foraminal disc herniation (p < 0.05). CONCLUSION: Transforaminal epidural steroid injections were more effective for paramedian lumbar disc herniation than for foraminal disc herniation, 12 weeks after the procedure.

Spontaneous Resolution of a Sylvian Arachnoid Cyst in a Child: A Case Report.

We report the case of a 7-year-old boy with an incidentally diagnosed left sylvian arachnoid cyst. At a clinical follow-up of 2 years, cranial computed tomography scans found the cyst to be totally resolved. The mechanism of this rare spontaneous resolution of an arachnoid cyst is discussed.

Stepwise Removal of the Fused Midline Parietal Bone to Avoid Superior Sagittal Sinus Injury in Infants with Sagittal Synostosis.

This work describes a simple technique for the safe removal of the midline parietal bone with the synostotic sagittal suture in infants with sagittal synostosis to avoid dural tearing and bleeding from the superior sagittal sinus. The technique consists of stepwise removal of the midline parietal bone in three pieces instead of one piece, starting with the anterior one-third midline bone being safely freed from the underlying dural sinus and then transversely cut using a craniotome. The step is repeated twice for the middle and distal one-third of the bone respectively. Once the midline bone is bilaterally cut along its entire length, the stepwise elevation of the superior sagittal sinus dura using an elevator and removal of the midline bone in three pieces allows a safer, controlled procedure minimizing the risk of tearing the underlying dural sinus and preventing sinus bleeding in infants with sagittal synostosis.

Thalamic abscess caused by a rare pathogen: streptococcus constellatus.

Streptococcus constellatus is a microorganism that lives commensally in the oropharyngeal region, urogenital region, and intestinal tract. However, it can cause infection in patients with certain predisposing factors. Rarely, this microorganism can cause a brain abscess. Thalamic localization of brain abscesses is much rarer than abscesses in other locations of the brain. Brain abscess caused by streptococcus constellatus are very rarely been reported in the literature. We present a rare case of a left-sided thalamic abscess caused by streptococcus constellatus in a 25-year-old male patient who was injured by shrapnel pieces in the head and who was malnourished. The patient was successfully treated by stereotactic aspiration and antibiotherapy.

Impact of 1p/19q codeletion on the diagnosis and prognosis of different grades of meningioma.

BACKGROUND: Meningiomas are one of the most common tumours to affect the central nervous system. Genetic mutations are important in meningeal tumourigenesis, progression and prognosis. In this study, we aimed to examine the effect of 1p/19q deletion on the diagnosis and prognosis of meningioma subtypes using the fluorescence in situ hybridization (FISH) method. METHODS: Twenty-four patients with meningioma were retrospectively studied. Tumour samples were obtained from 10 typical, 11 atypical and three anaplastic malignant meningiomas. The most representative tumour sections were screened for 1p/19q deletion using the FISH method. RESULTS: Of the 24 patients, eight were women (33.3%) and 16 (66.7%) were men. The mean age was 56.6 years. The higher-grade meningioma was usually seen in males and had a higher rate of deletion on 1p (p = 0.001). There was a statistically significant difference between the grades and the rate of deletion on 19q (p = 0.042) and between the grades and the rates of polysomy, monosomy and amplification on 19q (p = 0.002; p = 0.001; p = 0.002, respectively). There was no statistical difference between 1p/19q codeletion and the grades of meningioma (p > 0.05). We detected higher level of Ki-67 in the condition of codeletion but did not find a statistical difference (p = 0.0553). CONCLUSION: Deletion on 1p, as well as deletion, polysomy, monosomy and amplification on 19q, are detected more frequently in high grade meningiomas. This amplification is most likely due to the amplification of oncogenes.

Choroid plexus carcinoma in adults: an extremely rare case.

Choroid plexus tumors are rare intraventricular papillary neoplasms derived from choroid plexus epithelium, which account for approximately 2% to 4% of intracranial tumors in children and 0.5% in adults. Almost all choroid plexus carcinomas are seen in children and are extremely rare in adults. Headache, diplopia, and ataxia are the most common symptoms usually caused by mechanical obstruction of cerebrospinal fluid flow followed by hydrocephalus, regardless of tumor location. We present an illustrative case with 73 years old male patient who was consulted with headache to our neurosurgery department. In cranial computed tomography, there was a mass in 4(th) ventricle and we confirmed the mass with magnetic resonance imaging. After surgery had been performed, pathology specimen was diagnosed as choroid plexus carcinoma which was rarely seen in this age group.

Spinal intramedullary metastasis of breast cancer.

Objective. Breast cancer accounts for approximately one-third of all cancers in females. Approximately 8.5 % of all central nervous system metastases are located in the spinal cord. These patients have rapidly progressing neurological deficits and require immediate examination. The aim of surgery is decompression of neural tissue and histological evaluation of the tumor. In this paper, we present a case of breast cancer metastasis in thoracic spinal intramedullary area which had been partially excised and then given adjuvant radiotherapy. Case. A 43-year-old female patient with breast cancer for 8 years was admitted to our hospital with complaints of weakness in both legs. Eight years ago, she received chemotherapy and radiotherapy. On her neurological examination, she had paraparesis (left lower extremity: 2/5, right lower extremity: 3/5) and urinary incontinence. Spinal MRI revealed a gadolinium enhancing intramedullary lesion. Pathologic examination of the lesion was consistent with breast carcinoma metastasis. The patient has been taken into radiotherapy. Conclusion. Spinal intramedullary metastasis of breast cancer is an extremely rare situation, but it has a high morbidity and mortality rate. Microsurgical resection is necessary for preservation or amelioration of neurological state and also for increased life expectancy and quality.

Spontaneous cervical epidural hematoma with hemiparesis mimicking cerebral stroke.

Aim. Spontaneous cervical epidural hematoma (SCEH) is defined as an epidural hematoma that does not have an etiological explanation. The most common site for SCEH is cervicothoracic area. Early diagnosis and treatment are important for prognosis and good results. In this paper, we aimed to present a case who complains of sudden weakness on right extremities imitating cerebral stroke and that neuroimaging reveals spontaneous cervical epidural hematoma. Case. A 72-year-old woman was admitted to our hospital with acute neck pain and loss of strength on right extremities. On neurological examination, the patient had right hemiparesis. PT, aPTT, and INR results were 50.5, 42.8, and 4.8, respectively. Cranial MRI was in normal limits. Spinal MRI revealed a lesion that extends from C4 to C7 located on the right side and compatible with epidural hematoma. The patient was operated after normalization of INR values. Conclusion. Even though SCEH is a rare condition, it can cause severe morbidity and mortality. Early diagnosis and treatment are quiet important for prognosis. SCEH can easily be mistaken for stroke as with other pathologies and this diagnosis should come to mind especially in patients who have diathesis of bleeding.

A laboratory training model in fresh cadaveric sheep brain for microneurosurgical dissection of cranial nerves in posterior fossa.

A neurosurgical laboratory training model is designed for residents of neurosurgery to handle surgical microscopes and microneurosurgical instruments. The material consists of a one-year-old fresh cadaveric sheep cranium. A four-step approach was designed to simulate microneurosurgical dissection along the posterior fossa cisterns, and to dissect cranial nerves emerging from the brain stem. We conclude that this laboratory training model is useful to allow trainees to gain experience with the general use of an operating microscope, and familiarity with handling cranial nerves.

[Cerebral infarction due to traumatic carotid artery dissection: case report and review of current management]. / Travmatik karotis arter diseksiyonuna bagli serebral enfarkt: Olgu sunumu ve güncel yaklasimin gözden geçirilmesi.

With the advent of improved neuroradiological methods, it has been determined that frequency of traumatic carotid artery dissections is higher than previously observed. Since delayed neurological deficits may develop in some asymptomatic undiagnosed cases, it is essential to consider the possibility of the carotid artery dissection and evaluate it properly in suspicious cases. In this article, a case of internal carotid artery dissection and subsequent cerebral infarction following a motor vehicle accident is presented. Pathogenesis, clinical features, diagnostic method choices and treatments in this rare but severe condition are discussed in light of the relevant literature in order to convey current knowledge.

Neuroprotective effects of N-acetylcysteine on experimental closed head trauma in rats.

N-acetylcysteine (NAC) is a precursor of glutathione, a potent antioxidant, and a free radical scavenger. The beneficial effect of NAC on nervous system ischemia and ischemia/reperfusion models has been well documented. However, the effect of NAC on nervous system trauma remains less understood. Therefore, we aimed to investigate the therapeutic efficacy of NAC with an experimental closed head trauma model in rats. Thirty-six adult male Sprague-Dawley rats were randomly divided into three groups of 12 rats each: Group I (control), Group II (trauma-alone), and Group III (trauma+NAC treatment). In Groups II and III, a cranial impact was delivered to the skull from a height of 7 cm at a point just in front of the coronal suture and over the right hemisphere. Rats were sacrificed at 2 h (Subgroups I-A, II-A, and III-A) and 12 h (Subgroups I-B, II-B, and III-B) after the onset of injury. Brain tissues were removed for biochemical and histopathological investigation. The closed head trauma significantly increased tissue malondialdehyde (MDA) levels (P < 0.05), and significantly decreased tissue superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities (P < 0.05), but not tissue catalase (CAT) activity, when compared with controls. The administration of a single dose of NAC (150 mg/kg) 15 min after the trauma has shown protective effect via decreasing significantly the elevated MDA levels (P < 0.05) and also significantly (P < 0.05) increasing the reduced antioxidant enzyme (SOD and GPx) activities, except CAT activity. In the trauma-alone group, the neurons became extensively dark and degenerated into picnotic nuclei. The morphology of neurons in the NAC treatment group was well protected. The number of neurons in the trauma-alone group was significantly less than that of both the control and trauma+NAC treatment groups. In conclusion, the NAC treatment might be beneficial in preventing trauma-induced oxidative brain tissue damage, thus showing potential for clinical implications.

Microneurosurgical training model in fresh cadaveric cow brain: a laboratory study simulating the approach to the circle of Willis.

BACKGROUND: Residents of neurosurgery need many years to develop microneurosurgical skills, and laboratory training models are essential for developing and refining surgical skills before clinical application of microneurosurgery. A simple simulation model is needed for young residents to learn how to handle microneurosurgical instruments, and to perform safe dissection of intracranial vessels and nerves. METHODS: The material consists of a 2-year-old fresh cadaveric cow cranium. A 4-step approach was designed to dissect the internal carotid artery and its proximal branches, the optic nerve, the optic chiasm, and the pituitary stalk. RESULTS: The model simulates standard microneurosurgery using a variety of approaches to vessels and neural structures in and around the circle of Willis of the human brain. CONCLUSION: The cadaveric cow brain, besides being cost-effective, represents a fairly useful method to accustom residents of neurosurgery, especially junior residents, to dissecting intracranial vessels and nerves, and it simulates intracranial microneurosurgical procedures performed in the human brain.

Nocardial brain abscess: review of clinical management.

Nocardiosis has become a significant opportunistic infection over the last two decades as the number of immunocompromised individuals has grown worldwide. We present two patients with nocardial brain abscess. The first patient was a 39-year-old woman with systemic lupus erythematosus. A left temporoparietal abscess was detected and aspirated through a burr-hole. Nocardia farcinica infection was diagnosed. The patient had an accompanying pulmonary infection and was thus treated with imipenem and amikacine for 3 weeks. She received oral minocycline for 1 year. The second patient was a 43-year-old man who was being treated with corticosteroids for glomerulonephritis. He was diagnosed with a ring-enhancing multiloculated abscess in the left cerebellar hemisphere, with an additional two small supratentorial lesions and triventricular hydrocephalus. Gross total excision of the cerebellar abscess was performed via a left suboccipital craniectomy. Culture revealed Nocardia asteroides, and the patient was successfully treated with intravenous ceftriaxone, then oral trimethoprime-sulfamethoxazole for 1 year. The clinical course, radiological findings, and management of nocardial brain abscess are discussed in light of the relevant literature, and current clinical management is reviewed through examination of the cases presented here.

[Pediatric head injuries: a retrospective analysis of 280 patients.]. / Çocukluk çagi kafa travmalari: 280 olgunun retrospektif degerlendirmesi.

BACKGROUND: To assess etiological factors, clinical features, radiological findings and recovery rates in pediatric head injuries. METHODS: Patients (n =280) with head injuries (age range: 0 - 16 years) hospitalized in Trakya University Department of Neurosurgery between January 1995 and 2004 were analyzed statistically. RESULTS: According to Glasgow Coma Scale (GCS) the patients had minor (GCS: 13- 15 ; 70.1% ), moderate (GCS: 9- 12; 17,1% ), or severe (GCS: 3 to 8; 6,8% ). head injuries The most common etiological factor was fall from a height (34,3%); and the most frequently associated injury was extra-spinal skeletal injury (12,9%). Fifty-one patients (18,2%) underwent neurosurgical operation. 87.5% of them recovered completely, while 12,5% showed partial recovery or died, as graded by Glasgow Outcome Scale (GOS). There was a moderately strong correlation between initial GCS and GOS (r=0,53, p=0,01). CONCLUSIONS: Nearly half of the pediatric head injuries were caused by falls with good prognoses. In the school age, motor vehicle accident (MVA) was the most frequent trauma type. MVA was the most serious type of trauma as demonstrated by its low GCS and GOS scores. Polytraumas, subdural hematomas, cerebral contusions, subarachnoid or intracerebral hemorrhages, cerebral edemas, diffuse axonal injuries, and any cranial lesion which required surgery were found to be related with poor prognosis.