The role of extended reality in eloquent area lesions: a systematic review.

OBJECTIVE: The surgical approach to lesions near eloquent areas continues to represent a challenge for neurosurgeons, despite all of the sophisticated tools currently used. The goal of surgery in eloquent areas is to maintain a good oncofunctional balance, that is, to preserve neurological function and ensure maximum tumor resection. Among all the available tools, extended reality (used to describe both virtual reality [VR] and mixed reality) is rapidly gaining a pivotal role in such delicate lesions, especially in preoperative planning, and recently, even during the surgical procedure. VR creates a completely new world in which only digital components are present. Augmented reality (AR), using software and hardware to introduce digital elements into the real-world environment, enhances the human experience. In addition, mixed reality, a more recent technique, combines VR and AR by projecting virtual objects into the real world, allowing the user to interact with them. METHODS: A systematic literature review of the last 23.5 years was conducted (January 2000-June 2023) to investigate and discuss all progress related to the emerging role and use of these new technologies (VR, AR, and mixed reality), particularly in eloquent area lesions as a pre- and/or intraoperative tool. RESULTS: Five hundred eighty-four published studies were identified. After removing duplicates and excluding articles that did not meet the inclusion criteria, 21 papers were included in the systematic review. The use of AR or VR was fully analyzed, considering their roles both intraoperatively and for surgical planning. CONCLUSIONS: The increasing use of such innovative technologies has completely changed the way to approach a lesion, using 3D visualization to foster a better understanding of its anatomical and vascular characteristics.

Improving mixed-reality neuronavigation with blue-green light: a comparative multimodal laboratory study.

OBJECTIVE: This study aimed to rigorously assess the accuracy of mixed-reality neuronavigation (MRN) in comparison with magnetic neuronavigation (MN) through a comprehensive phantom-based experiment. It introduces a novel dimension by examining the influence of blue-green light (BGL) on MRN accuracy, a previously unexplored avenue in this domain. METHODS: Twenty-nine phantoms, each meticulously marked with 5-6 fiducials, underwent CT scans as part of the navigation protocol. A 3D model was then superimposed onto a 3D-printed plaster skull using a semiautomatic registration process. The study meticulously evaluated the accuracy of both navigation techniques by pinpointing specific markers on the plaster surface. Precise measurements were then taken using digital calipers, with navigation conducted under three distinct lighting conditions: indirect white light (referred to as no light [NL]), direct white light (WL), and BGL. The research enlisted two operators with distinct levels of experience, one senior and one junior, to ensure a comprehensive analysis. The study was structured into two distinct experiments (experiment 1 [MN] and experiment 2 [MRN]) conducted by the two operators. Data analysis focused on calculating average and median values within subgroups, considering variables such as the type of lighting, precision, and recording time. RESULTS: In experiment 1, no statistically significant differences emerged between the two operators. However, in experiment 2, notable disparities became apparent, with the senior operator recording longer times but achieving higher precision. Most significantly, BGL consistently demonstrated a capacity to enhance accuracy in MRN across both experiments. CONCLUSIONS: This study demonstrated the substantial positive influence of BGL on MRN accuracy, providing profound implications for the design and implementation of mixed-reality systems. It also emphasized that integrating BGL into mixed-reality environments could profoundly improve user experience and performance. Further research is essential to validate these findings in real-world settings and explore the broader potential of BGL in a variety of mixed-reality applications.

Sonodynamic therapy and magnetic resonance-guided focused ultrasound: new therapeutic strategy in glioblastoma.

Glioblastoma (GB) is one of the most aggressive and difficult-to-treat brain tumors, with a poor prognosis and limited treatment options. In recent years, sonodynamic therapy (SDT) and magnetic resonance focused ultrasound (MRgFUS) have emerged as promising approaches for the treatment of GB. SDT uses ultrasound waves in combination with a sonosensitizer to selectively damage cancer cells, while MRgFUS delivers high-intensity ultrasound waves to precisely target tumor tissue and disrupt the blood-brain barrier to enhance drug delivery. In this review, we explore the potential of SDT as a novel therapeutic strategy for GB. We discuss the principles of SDT, its mechanisms of action, and the preclinical and clinical studies that have investigated its use in Gliomas. We also highlight the challenges, the limitations, and the future perspectives of SDT. Overall, SDT and MRgFUS hold promise as novel and potentially complementary treatment modalities for GB. Further research is needed to optimize their parameters and determine their safety and efficacy in humans, but their potential for selective and targeted tumor destruction makes them an exciting area of investigation in the field of brain cancer therapy.

The role of neuronal plasticity in cervical spondylotic myelopathy surgery: functional assessment and prognostic implication.

Cervical spondylotic myelopathy (CSM) is a degenerative disease representing the most common spinal cord disorder in the adult population. It is characterized by chronic compression leading to neurological dysfunction due to static and dynamic injury of the spinal cord in cervical spine. These insidious damage mechanisms can result in the reorganization of cortical and subcortical areas. The cerebral cortex can reorganize due to spinal cord injury and may play a role in preserving neurological function. To date, the gold standard treatment of cervical myelopathy is surgery, comprising anterior, posterior, and combined approaches. However, the complex physiologic recovery processes involving cortical and subcortical neural reorganization following surgery are still inadequately understood. It has been demonstrated that diffusion MRI and functional imaging and techniques, such as transcranial magnetic stimulation (TMS) or functional magnetic resonance imaging (fMRI), can provide new insights into the diagnosis and prognosis of CSM. This review aims to shed light on the state-of-the-art regarding the pattern of cortical and subcortical areas reorganization and recovery before and after surgery in CSM patients, underlighting the critical role of neuroplasticity.

Nuance in Craniovertebral Junction Surgical Approach for Posterior C1-C2 Harms Stabilization: "Window Transposition" of the External Vertebral Venous Plexus for Bloodless C1 Lateral Mass Screw Insertion: Anatomical Aspects and Technical Notes.

Atlas and axis instrumentation may be necessary in cases of several craniocervical junction pathologies. According to the Harms technique, C1-C2 polyaxial screws are inserted respectively in the C1 lateral masses and in C2 pedicles. C1 lateral mass screw insertion requires the careful subperiosteal dissection of the posterior elements of C1, the identification of the screw entry point by the downward distraction of C2 nerve root, and the cautious sparing of the overlying posterior external vertebral venous plexus (peVVP), whose bleeding, obstructing the surgical field, is sometimes barely controlled by hemostatic agents and swabbing. The authors describe in detail the anatomical aspects of an alternative surgical technique developed for the microsurgical transposition of the C1-C2 interposed external vertebral venous plexus in the case of Harms C1-C2 screw stabilization. The longitudinal median incision of the atlantoaxial membrane, followed by bilateral subperiosteal dissection and microsurgical section respectively at the inferior borders of the C1 laminae and at the superior borders of the C2 laminae, allows, as a "window opening," the symmetrical mediolateral transposition of the peVVP. This procedure provides a faster and cleaner anatomical exposition of the posterior surface of the C1 lateral mass and the C2 isthmus, preventing troublesome intraoperative venous bleeding that hinders C1 lateral mass screw insertion.

Pedicle Screw Placement Aided by C-Arm Fluoroscopy: A "Nevermore without" Technology to Pursue Optimal Spine Fixation.

The surgical technique and the intraoperative technology that support spinal pedicle screw placement have consistently evolved over the past decades to decrease the misplacement rate of pedicle screws. We retrospectively evaluated our case series by analyzing the period 2016-2020. Patients undergoing pedicle screw fixation for cervical, thoracic, or lumbar spine degenerative diseases have been included. Surgery was carried out with the aid of intraoperative 3D C-arm fluoroscopy to assess and optimize screw placement and/or correct possible mispositioning. Each patient underwent a postoperative CT scan. Our aim was to evaluate the safety and accuracy of pedicle screw placement and estimate the variation in mispositioning rates. We carried out 329 surgical procedures, as follows: 70 cervical, 78 thoracic spine, and 181 lumbar spine surgeries. An excellent overall pedicle screw positioning was obtained, with slight differences between the cervical (98.6%), thoracic (100%), and lumbar (98.9%) tracts. Accordingly, only three patients required a revision surgery owing to mispositioning (0.91%). In particular, intraoperative C-arm fluoroscopy significatively improved the accuracy of thoracic screw positioning, as shown by postoperative CT scans. Our experience proves the crucial role of intraoperative C-arm fluoroscopy in pursuing optimal technical results and improving patient outcomes at follow-up.

New Trend in Craniovertebral Junction Surgical Strategy: Technical Note for the Treatment of Hangman's Fractures Through a Minimally Invasive Approach.

INTRODUCTION: The reduction, stabilization, and maintenance of alignment are the main goals in the surgical treatment of unstable hangman's fractures. The choice of the surgical strategy remains poorly standardized; anterior and/or posterior fusion could be performed; and none of the available clinical studies in the literature have shown significant differences in outcomes or complication rates. Vertebral anatomy, age, comorbidities, patient factors, and surgical experience may guide the treatment choice. METHODS: We present a case of a polytraumatized young woman with an unstable hangman's fracture type II, according to Levine-Edwards classification. We treated the fracture by using a plate with four holes to fix C2-C3 without discectomy and body fusion. RESULTS: We performed a small incision, such as those used for the fixation of odontoid screws, where the working angle allowed us to easily and quickly position the plate by using a minimally invasive approach. CONCLUSION: The stabilization alone, without discectomy and body fusion with the cage, in the same way favored the natural healing of the bone fracture. In our opinion, in some select cases, fixation of C2-C3 alone through a minimally invasive approach allows for bone healing with fewer risks and an easier surgery.

The Role of Aquaporins in Epileptogenesis-A Systematic Review.

Aquaporins (AQPs) are a family of membrane proteins involved in the transport of water and ions across cell membranes. AQPs have been shown to be implicated in various physiological and pathological processes in the brain, including water homeostasis, cell migration, and inflammation, among others. Epileptogenesis is a complex and multifactorial process that involves alterations in the structure and function of neuronal networks. Recent evidence suggests that AQPs may also play a role in the pathogenesis of epilepsy. In animal models of epilepsy, AQPs have been shown to be upregulated in regions of the brain that are involved in seizure generation, suggesting that they may contribute to the hyperexcitability of neuronal networks. Moreover, genetic studies have identified mutations in AQP genes associated with an increased risk of developing epilepsy. Our review aims to investigate the role of AQPs in epilepsy and seizure onset from a pathophysiological point of view, pointing out the potential molecular mechanism and their clinical implications.

Infratentorial Relapsing Neuroglial Tumors in Adults: Management and Unsolved Issues-A Systematic Review.

(1) Background: Gangliogliomas are rare tumors accounting for about 0.4% of all central nervous system tumors. They are usually located in the temporal lobes of children and young adults, though such tumors in the infratentorial region and adult-age patients rarely reported. (2) Methods: A systematic review on ganglioglioma with infratentorial location in the adult population was conducted in accordance with the PRISMA guidelines. A total of 275 articles were found, and 23 were included. Demographic data, the location and histology of the lesion, pre-operative neurological status, the type of surgery, recurrence, radiotherapy/chemotherapy adjuvant treatments, neurological outcomes and follow-up information were collected. We also presented an illustrative case. (3) Results: A total of 27 patients were included. In 51%, the location was the cerebellum; in 40%, it was the fourth ventricle; in 11%, it was brainstem; and in 4%, it was the cerebellopontine angle. STR was performed in 44%, GTR in 26% and biopsy in 15% of the cases. Adjuvant radiotherapy was found in 22% of cases. Disease recurrence occurred in 15% of patients between 1 and 12 months after surgery with a diagnosis of high-grade ganglioglioma, while in six cases, no disease recurrence was documented. (4) Conclusions: Infratentorial glioneuronal tumors are rare findings in the adult population. Histopathological characterization does not seem to fully reflect their true behavior. Future studies are warranted for better characterizing histopathological findings and treatment.

Corticocortical Evoked Potentials in Eloquent Brain Tumor Surgery. A Systematic Review.

Eloquent brain tumor surgery involves the delicate task of resecting tumors located in regions of the brain responsible for critical functions, such as language, motor control, and sensory perception. Preserving these functions is of paramount importance to maintain the patient's quality of life. Corticocortical evoked potentials (CCEPs) have emerged as a valuable intraoperative monitoring technique that aids in identifying and preserving eloquent cortical areas during surgery. This systematic review aimed to assess the utility of CCEPs in eloquent brain tumor surgery and determine their effectiveness in improving patient outcomes. A comprehensive literature search was conducted using electronic databases, including PubMed/Medline and Scopus. The search strategy identified 11 relevant articles for detailed analysis. The findings of the included studies consistently demonstrated the potential of CCEPs in guiding surgical decision making, minimizing the risk of postoperative neurological deficits, and mapping functional connectivity during surgery. However, further research and standardization are needed to fully establish the clinical benefits and refine the implementation of CCEPs in routine neurosurgical practice.

Preoperative Angiographic Protocol for the Surgical Management of Spinal Dural Arteriovenous Fistulas: A Technical Nuance for Safe Minimally Invasive Surgery.

BACKGROUND: Interruption of the fistulous point is the goal of treatment of spinal dural arteriovenous fistulas (dAVFs). Microsurgery remains a highly efficient treatment in terms of complete occlusion with the lowest risk of recurrence rate. It is reported that the hardest step involves finding the fistulous site itself, potentially extending surgical access and time and increasing potential postoperative surgical-related complications. The accurate preoperative detection of the shunt and spinal level together is crucial for guiding optimal, fast, and safe microsurgical treatment. METHODS: We describe a preoperative angiographic protocol for achieving a safe and simple resection of spinal dural arteriovenous fistulas based on a 6-year institutional experience of 42 patients who underwent minimally invasive procedures. Two illustrative cases are included to support the technical descriptions. RESULTS: The suspected artery associated with the vascular malformation of interest is studied in our angiographic protocol through nonsubtracted selective acquisitions in lateral projection. The resulting frames are reconstructed with three-dimensional rotational angiography. The implementation of the preoperative angiographic protocol allowed 100% of intraoperative identification of the fistulous point in all cases with the use of a minimally invasive approach. CONCLUSIONS: Nowadays, neurosurgeons advocate for minimally invasive procedures and procedures with low morbidity risk for treatment of spinal dural arteriovenous fistulas. Our preoperative approach for accurate angiographic localization of the fistulous point through nonsubtracted and three-dimensional reconstructed angiography allowed us to achieve safe and definitive occlusion of the shunt.

The Use of Intraoperative Microvascular Doppler in Vascular Neurosurgery: Rationale and Results-A Systematic Review.

Surgical treatment of neurovascular lesions like intracranial aneurysms, arteriovenous malformations and arteriovenous dural fistulas is still associated with high morbidity. Several recent studies are providing increasing insights into reliable tools to improve surgery and reduce complications. Inadvertent vessel compromise and incomplete occlusion of the lesion represent the most possible complications in neurovascular surgery. It is clear that direct visual examination alone does not allow to identify all instances of vessel compromise. Various modalities, including angiography, microvascular Doppler and neurophysiological studies, have been utilized for hemodynamics of flow vessels in proper clipping of the aneurysm or complete obliteration of the lesion. We intended to review the current knowledge about the intraoperative microvascular Doppler (iMDS) employment in the most updated literature, and explore the most recent implications not only in intracranial aneurysms but also in neurovascular lesions like arteriovenous malformations (AVMs) and arteriovenous dural fistulas (AVDFs). According to the PRISMA guidelines, systematic research in the most updated platform was performed in order to provide a complete overview about iMDS employment in neurovascular surgery. Twelve articles were included in the present paper and analyzed according to specific research areas. iMDS employment could represent a crucial tool to improve surgery in neurovascular lesions. The safety and effectiveness of the surgical treatment of neurovascular lesions like intracranial aneurysm and other neurovascular lesions like AVMs and AVDFs requires careful and accurate consideration regarding the assessment of anatomy and blood flow. Prognosis may depend on suboptimal or incomplete exclusion of the lesion.

Neurologic and Neuropsychological Outcomes for Treatment of Unruptured Middle Cerebral Artery Aneurysms: Standard Pterional Versus Minipterional Approach in a Retrospective Single-Center Analysis.

BACKGROUND: In accordance with technique advancement and minimal invasiveness surgical approaches, the minipterional has progressively replaced the standard pterional approach for treatment of unruptured middle cerebral artery (MCA) aneurysms. Nowadays, multimodal intraoperative resources including microDoppler and microflow probes, indocyanine green videoangiography, and neurophysiologic monitoring constitute a fundamental prerequisite for increasing the safety of the clipping procedure. Our study investigated and compared in a single-center experience the effect of the evolution of a minimally invasive and multimodal approach in unruptured MCA aneurysm surgery by measuring postoperative complication rate, recovery time, and long-term neuropsychological and functional outcomes. METHODS: One hundred and thirty-one patients who underwent surgical treatment for unruptured MCA aneurysms at our institution were evaluated retrospectively. Patients' clinical, radiologic, and surgical reports were collected. Cognitive evaluation and quality of life were assessed through validated tests in telephone interviews. Patients who met the inclusion criteria were divided into 2 groups: "PT (pterional)" and "MPT (minipterional)." RESULTS: Ninety-two patients were included in the analysis. A significant reduction of postoperative complication rates and new-onset postoperative seizures was recorded in the MPT group (P value = 0.006). Severe cognitive deficits were lower in the MPT group, although without a clear statistical correlation. CONCLUSIONS: Decreased complication rates, faster recovery time, and a trend toward better cognitive and functional performances were documented for the MPT group of patients. In our experience, the minipterional approach with multimodality-assisted microsurgery reduced neurologic complications and recovery time and improved long-term cognitive outcome and quality of life.

Nuclear medicine imaging modalities to detect incidentalomas and their impact on patient management: a systematic review.

PURPOSE: This systematic review aims to investigate the role of nuclear imaging techniques in detecting incidentalomas and their impact on patient management. METHODS: Following PRISMA guidelines, a comprehensive literature search was conducted from February to May 2022. Studies in English involving patients undergoing nuclear medicine studies with incidental tumor findings were included. Data on imaging modalities, incidentaloma characteristics, management changes, and follow-up were extracted and analyzed. RESULTS: Ninety-two studies involving 64.884 patients were included. Incidentalomas were detected in 611 cases (0.9%), with thyroid being the most common site. PET/CT with FDG and choline tracers showed the highest incidentaloma detection rates. Detection of incidentalomas led to a change in therapeutic strategy in 59% of cases. Various radiotracers demonstrated high sensitivity for incidentaloma detection, particularly in neuroendocrine tumors and prostate cancer. CONCLUSION: Nuclear imaging techniques play a crucial role in detecting incidentalomas, leading to significant changes in patient management. The high sensitivity of these modalities highlights their potential in routine oncology follow-up protocols. Future directions may include enhancing spatial resolution and promoting theranostic approaches for improved patient care.

Glomus Cervical Arteriovenous Malformation Presenting with Intracranial Subarachnoid Hemorrhage: Clinical Case and Pial Resection Surgical Technique Description.

Spinal intramedullary arteriovenous malformations (AVMs) can present with spinal hemorrhage. However, some of them occasionally can be the cause of angiographically negative intracranial subarachnoid hemorrhage, thus requiring a more comprehensive diagnostic approach to detect the possible source of bleeding. Nidal or arterial feeder aneurysms are widely considered high-risk rupture portions of the spinal AVM and recognized as a major cause of bleeding. Due to the tight eloquent confines within the thecal sac and the higher annual rupture risk after the initial bleeding, recurrent hemorrhage may have catastrophic outcomes. Hence the goal of management is to obliterate the spinal AVM preserving neurologic function and preventing future hemorrhagic events. Unlike cerebral AVMs, partial treatment of spinal intramedullary AVMs has been documented to be effective to improve the patients' prognosis dramatically. Microsurgical resection with or without adjuvant embolization has been considered the mainstay treatment for symptomatic glomus spinal intramedullary AVMs. The case of a 25-year-old man with acute cerebral subarachnoid hemorrhage caused by intranidal aneurysm rupture of cervical glomus-type AVM is presented here. The patient was surgically treated by C3-C4 laminectomy and AVM excision by pial resection technique. Thereby, the pial resection technique helps in providing subtotal AVM nidus resection, minimizing parenchymal dissection but effectively devascularizing glomus AVMs with satisfactory long-term results.

Flow diversion for indirect carotid-cavernous fistula: Still an off-label indication?

Background: Flow diversion (FD) is an established treatment for large or giant wide-necked unruptured intracranial aneurysms. In the past few years, the use of flow diverter devices was extended to several other "off-label" indications, including solitary or adjunctive treatment to coil embolization for direct (Barrow A type) carotid cavernous fistulas (CCFs). The use of liquid embolic agents still represents the first-line treatment for indirect CCFs. Typically, the ipsilateral inferior petrosal sinus or superior ophthalmic vein (SOV) is the preferred transvenous routes to access CCFs. In some cases, vessel tortuosity or different features make the endovascular access challenging, thus requiring different approaches and strategies. The aim of the study is to discuss rational and technical aspect in treating indirect CCFs referring to the most up-to-date literature. An alternative experience-based endovascular strategy with FD is described. Methods: We report the case of a 54-year-old woman diagnosed with indirect CCF and treated with flow diverter stent. Results: After multiple unsuccessful attempts at transarterial right SOV catheterization, a right indirect CCF fed by a single trunk at the ophthalmic origin from the internal carotid artery (ICA) was treated by ICA stand-alone FD. Blood flow was redirect and successfully reduced through the fistula, with immediately postprocedure improvement of the patient's clinical status (ipsilateral proptosis and chemosis). Ten-months radiological follow-up showed the complete obliteration of the fistula. No adjunctive endovascular treatment was performed. Conclusion: FD appears a reasonable alternative stand-alone endovascular strategy also for selected difficult-to-access indirect CCFs, when all conventional routes are judged unfeasible. Further investigations will be necessary to better define and support this potential lesson-learned application.

The Role of Augmented Reality Neuronavigation in Transsphenoidal Surgery: A Systematic Review.

In the field of minimally invasive neurosurgery, microscopic transsphenoidal surgery (MTS) and endoscopic transsphenoidal surgery (ETS) have been widely accepted as a safe approach for pituitary lesions and, more recently, their indications have been extended to lesions at various skull base regions. It is mandatory during transsphenoidal surgery (TS) to identify key anatomical landmarks in the sphenoid sinus and distinguish them from the lesion. Over the years, many intraoperative tools have been introduced to improve the neuronavigation systems aiming to achieve safer and more accurate neurosurgical interventions. However, traditional neuronavigation systems may lose the accuracy of real-time location due to the discrepancy between the actual surgical field and the preoperative 2D images. To deal with this, augmented reality (AR)-a new sophisticated 3D technology that superimposes computer-generated virtual objects onto the user's view of the real world-has been considered a promising tool. Particularly, in the field of TS, AR can minimize the anatomic challenges of traditional endoscopic or microscopic surgery, aiding in surgical training, preoperative planning and intra-operative orientation. The aim of this systematic review is to analyze the potential future role of augmented reality, both in endoscopic and microscopic transsphenoidal surgeries.