Minimally invasive neurosurgery

Microcatheter tracking in thrombectomy procedures: A finite-element simulation study

BACKGROUND AND OBJECTIVE

Mechanical thrombectomy is a minimally invasive procedure that aims at removing the occluding thrombus from the vasculature of acute ischemic stroke patients. Thrombectomy success and failure can be studied using in-silico thrombectomy models. Such models require realistic modeling steps to be effective. We here present a new approach to model microcatheter tracking during thrombectomy.

METHODS

For 3 patient-specific vessel geometries, we performed finite-element simulations of the microcatheter tracking (1) following the vessel centerline (centerline method) and (2) as a one-step insertion simulation, where the microcatheter tip was advanced along the vessel centerline while its body was free to interact with the vessel wall (tip-dragging method). Qualitative validation of the two tracking methods was performed with the patient's digital subtraction angiography (DSA) images. In addition, we compared simulated thrombectomy outcomes (successful vs unsuccessful thrombus retrieval) and maximum principal stresses on the thrombus between the centerline and tip-dragging method.

RESULTS

Qualitative comparison with the DSA images showed that the tip-dragging method more realistically resembles the patient-specific microcatheter-tracking scenario, where the microcatheter approaches the vessel walls. Although the simulated thrombectomy outcomes were similar in terms of thrombus retrieval, the thrombus stress fields (and the associated fragmentation of the thrombus) were strongly different between the two methods, with local differences in the maximum principal stress curves up to 84%.

CONCLUSIONS

Microcatheter positioning with respect to the vessel affects the stress fields of the thrombus during retrieval, and therefore, may influence thrombus fragmentation and retrieval in-silico thrombectomy.

Minimally Invasive Image-Guided Transgluteal Approach for Resection of a Sciatic Nerve Tumor: A Technical Note

There are a variety of surgical approaches to lesions around the sciatic notch. Historically, peripheral nerve surgeons prefer an infragluteal approach involving a large incision with reflection of the gluteus maximus to better visualize the operative field. This approach was imperative when lesion localization was imprecise. Comparatively, orthopedic surgeons prefer a muscle-splitting, transgluteal approach to operate on the static structures of the posterior hip. The transgluteal approach is significantly less morbid, allowing for same-day discharge and less extensive rehab given preservation of the gluteal muscle. In this article we describe the use of dynamic ultrasound imaging to localize and aid in the resection of three unique tumors around the sciatic notch using a minimally invasive, tissue-sparing, transgluteal technique. We offer a comprehensive description of the benefits, anatomic considerations, and nuances of using a transgluteal approach for the resection of lesions at the sciatic notch.

Postural ergonomics and work-related musculoskeletal disorders in neurosurgery: lessons from an international survey

Background

Work-related musculoskeletal disorders (WMSDs) affect a significant percentage of the neurosurgical workforce. The aim of the current questionnaire-based study was to examine the prevalence of WMSDs amongst neurosurgeons, identify risk factors, and study the views of neurosurgeons regarding ergonomics.

Methods

From June to August 2020, members of the “European Association of Neurosurgical Societies,” the “Neurosurgery Research Listserv,” and the “Latin American Federation of Neurosurgical Societies” were asked to complete an electronic questionnaire on the topics of WMSDs and ergonomics.

Results

A total of 409 neurosurgeons responded to the survey, with a 4.7 male to female ratio. Most of the surgeons worked in Europe (76.9%) in academic public hospitals. The vast majority of the participants (87.9%) had experienced WMSDs, mainly affecting the shoulder, neck, and back muscles. The most common operations performed by the participants were “Craniotomy for convexity/intrinsic tumors” (24.1%) and “Open lumbar basic spine” (24.1%). Neurosurgeons agreed that ergonomics is an underexposed area in the neurosurgical field (84.8%) and that more resources should be spend (87.3%) and training curricula changes should be made (78.3%) in order to alleviate the burden of WMSDs on neurosurgeons. Univariate analysis did not reveal any associations between the development of WMSDs and age, gender, tenure, average duration of operation, operating time per week, type of operation, and surgical approach.

Conclusions

The problem of WMSDs ought to be more closely addressed and managed by the neurosurgical community. More studies ought to be designed to investigate specific ergonomic parameters in order to formulate practice recommendations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-04722-5.

Qualitative and quantitative evaluation of in vivo SD-OCT measurement of rat brain

OCT has been demonstrated as an efficient imaging modality in various biomedical and clinical applications. However, there is a missing link with respect to the source of contrast between OCT and other modern imaging modalities, no quantitative comparison has been demonstrated between them, yet. We evaluated, to our knowledge, for the first time in vivo OCT measurement of rat brain with our previously proposed forward imaging method by both qualitatively and quantitatively correlating OCT with the corresponding T1-weighted and T2-weighted magnetic resonance images, fiber density map (FDM), and two types of histology staining (cresyl violet and acetylcholinesterase AchE), respectively. Brain anatomical structures were identified and compared across OCT, MRI and histology imaging modalities. Noticeable resemblances corresponding to certain anatomical structures were found between OCT and other image profiles. Correlation was quantitatively assessed by estimating correlation coefficient (R) and mutual information (MI). Results show that the 1-D OCT measurements in regards to the intensity profile and estimated attenuation factor, do not have profound linear correlation with the other image modalities suggested from correlation coefficient estimation. However, findings in mutual information analysis demonstrate that there are markedly high MI values in OCT-MRI signals.

Finite element modeling of haptic thermography: A novel approach for brain tumor detection during minimally invasive neurosurgery

Intraoperative Thermal Imaging (ITI) is a novel neuroimaging method that can potentially locate tissue abnormalities and hence improves surgeon's diagnostic ability. In the present study, thermography technique coupled with artificial tactile sensing method called "haptic thermography" is utilized to investigate the presence of an abnormal object as a tumor with an elevated temperature relative to the normal tissue in the brain. The brain tissue is characterized as a hyper-viscoelastic material to be descriptive of mechanical behavior of the brain tissue during tactile palpation. Based on a finite element approach, Magnetic Resonance Imaging (MRI) data of a patient diagnosed to have a brain tumor is utilized to simulate and analyze the capability of haptic thermography in detection and localization of brain tumor. Steady-state thermal results prove that temperature distribution is an appropriate outcome of haptic thermography for the superficial tumors while heat flux distribution can be used as an extra thermal result for deeply located tumors.

A stereotaxic image-guided surgical robotic system for depth electrode insertion

This article constructs a surgical robotic system for the stereotactic insertion of the depth electrodes for stereoelectroencephalogram (SEEG). The purpose is to increase the efficiency of the stereotactic insertion of the electrodes. The registration method of this system is based on the noninvasive fiducial markers. After registration, the robotic system can locate all the preplanned electrode trajectories automatically. The validation of this proposed system has been performed by testing the time consumption of the system workflow and measuring the positioning accuracy on phantoms. From the result, we conclude that this surgical robotic system can assist surgeons in performing the stereotactic insertion of the depth electrodes accurately and efficiently.

Cortical vessel imaging and visualization for image guided depth electrode insertion

To avoid intracranial hemorrhage during minimally invasive depth electrode insertion without craniotomy for epilepsy surgery, precise in vivo imaging of cortical vessel and relevant rendering methods are critical, and should be used in preoperative planning. In this study, a non-invasive phase contrast MR angiography (PC-MRA) method was chosen for cortical vessel imaging. After image pre-processing (registration and segmentation), three visualization methods were implemented to optimize the vessel imaging and brain tissue rendering for surgical planning. The processed results were evaluated by comparing with intraoperative photographs. The results showed occurrences of missing vessels between imaging and photos (18.3%, 6 cases), but these could be compensated by realistic sulci visualization methods. The results showed 3D texture mapping to be the most suitable cortex visualization method for use in surgical navigation. Based on the methods and evaluations, a new surgical planning system and criteria of usage were developed with input from the surgeons' experience using the prototype system. This system could greatly help reduce the risk of the intracranial hemorrhage during electrode insertion and also avoid potential risks caused by contrast agent injections for contrast enhanced MRA or CTA.

Surgical Endovascular Neuroradiology in the 21st Century: What Lies Ahead?

FEW COULD HAVE imagined the tremendous growth of endovascular surgery over the past 40 years. Endovascular therapy has greatly enhanced the care of the patient in neurosurgery, spine surgery, and head and neck surgery. Progress in technology and techniques continue to push forward the boundaries of what is deemed “treatable,” assuming acceptable risk. This article will briefly review the current state of endovascular surgery and speculate about what its role will be in the near and far future. Endovascular therapy provides a minimally invasive approach to the central nervous system and other systems via natural and, at times, highly selective pathways. Maximizing the accessibility of these routes to highly specific regions of the central nervous system provides an elegant and minimalist approach to treating diseases of the central nervous system with almost no “footprints” of ever having accessed the region. In the future, safe, efficient and intelligent delivery systems that may enhance or alter the tissue's response may result in successful treatment of cerebrovascular diseases, as well as other diseases of the craniospinal axis. The growth of nanotechnology, metallurgy, synthetic polymers, imaging, and training will all combine to help grow the technology and the science that is surgical endovascular neuroradiology.

Anesthesia for minimally invasive neurosurgery

Neurosurgerical techniques utilizing minimally invasive approaches will continue to emerge. For some of these future possibilities, anesthesia may not be required. Other types of neurosurgery, whether performed by humans or a machine, will require entry through the cranium and an absolute lack of movement. Anesthesia will keep pace with these innovations by accurately controlling the delivery of anesthetic to achieve optimal conditions. This control will allow for a safer, more comfortable surgical procedure while decreasing blood loss and morbidity associated with neurosurgery.