Clinical and radiological outcomes of one-level cervical corpectomy with an expandable cage for three-column uncomplicated subaxial type «B¼ injures: a multicenter retrospective study.

PURPOSE: To evaluate the clinical and radiological results of the operative management of three-column uncomplicated type «B¼ subaxial injures treated with a one-level cervical corpectomy with an expandable cage. METHODS: This study included 72 patients with a three-column uncomplicated type «B¼ subaxial injures who met the inclusion criteria, underwent a one-level cervical corpectomy with an expandable cage at one of three neurosurgical departments between 2005 and 2020, and were followed up for clinical and radiological outcomes at a minimum 3-yr follow-up. RESULTS: There was a decrease in the VAS pain score from an average of 80 mm to 7 mm (p = 0.03); a decrease in the average NDI score from 62 to 14% (p = 0.01); excellent and good outcomes according to Macnab's scale were 93% (n = 67/72). There was an average change in the cervical lordosis (Cobb method) from -9.10 to -15.40 (p = 0.007), without significant loss of lordosis (p = 0.27). There was no significant degeneration of the adjacent levels by 3 years post-op. The fusion rate, using the Cervical Spine Research Society criteria, was poor: it was 62.5% (n = 45/72), and using the CT criteria, it was 65.3% (n = 47/72). 15.4% patients (n = 11/72) suffered complications. Statistical difference between the fusion and pseudoarthrosis (according to X-ray criteria) subgroups showed that there were no statistically significant differences in the smoking status, diabetes, chronic steroid use, cervical injury level, subtypes of AO type B subaxial injuries and types of expandable cage systems. CONCLUSIONS: One-level cervical corpectomy with an expandable cage, despite a poor fusion rate, can be considered a feasible and relatively safe method for treating three-column uncomplicated subaxial type «B¼ injures, with the benefit of immediate stability, anatomical reduction, and direct decompression of the spinal cord. While no one in our series had any catastrophic complications, we did note a high complication rate.

Visualization of brain microvasculature and blood flow in vivo: Feasibility study using confocal laser endomicroscopy.

OBJECTIVE: Qualitative and quantitative analyses of blood flow in normal and pathologic brain and spinal cord microvasculature were performed using confocal laser endomicroscopy (CLE). METHODS: Blood flow in cortical, dural, and spinal cord microvasculature was assessed in vivo in swine. We assessed microvasculature under normal conditions and after vessel occlusion, brain injury due to cold or surgical trauma, and cardiac arrest. Tumor-associated microvasculature was assessed in vivo and ex vivo in 20 patients with gliomas. RESULTS: We observed erythrocyte flow in vessels 5-500 µm in diameter. Thrombosis, flow arrest and redistribution, flow velocity changes, agglutination, and cells rolling were assessed in normal and injured brain tissue. Microvasculature in in vivo CLE images of gliomas was classified as normal in 68% and abnormal in 32% of vessels on the basis of morphological appearance. Dural lymphatic channels were discriminated from blood vessels. Microvasculature CLE imaging was possible for up to 30 minutes after a 1 mg/kg intravenous dose of fluorescein. CONCLUSIONS: CLE imaging allows assessment of cerebral and tumor microvasculature and blood flow alterations with subcellular resolution intraoperative imaging demonstrating precise details of real-time cell movements. Research and clinical scenarios may benefit from this novel intraoperative in vivo microscopic fluorescence imaging modality.

Proposed definition of competencies for surgical neuro-oncology training.

OBJECTIVE: The aim of this work is to define competencies and entrustable professional activities (EPAs) to be imparted within the framework of surgical neuro-oncological residency and fellowship training as well as the education of medical students. Improved and specific training in surgical neuro-oncology promotes neuro-oncological expertise, quality of surgical neuro-oncological treatment and may also contribute to further development of neuro-oncological techniques and treatment protocols. Specific curricula for a surgical neuro-oncologic education have not yet been established. METHODS: We used a consensus-building approach to propose skills, competencies and EPAs to be imparted within the framework of surgical neuro-oncological training. We developed competencies and EPAs suitable for training in surgical neuro-oncology. RESULT: In total, 70 competencies and 8 EPAs for training in surgical neuro-oncology were proposed. EPAs were defined for the management of the deteriorating patient, the management of patients with the diagnosis of a brain tumour, tumour-based resections, function-based surgical resections of brain tumours, the postoperative management of patients, the collaboration as a member of an interdisciplinary and/or -professional team and finally for the care of palliative and dying patients and their families. CONCLUSIONS AND RELEVANCE: The present work should subsequently initiate a discussion about the proposed competencies and EPAs and, together with the following discussion, contribute to the creation of new training concepts in surgical neuro-oncology.

Tailoring the surgical corridor to the basilar apex in the pretemporal transcavernous approach: morphometric analyses of different neurovascular mobilization maneuvers.

BACKGROUND: The pretemporal transcavernous approach (PTA) provides optimal exposure and access to the basilar artery (BA); however, the PTA can be invasive when vital neurovascular structures are mobilized. The goal of this study was to evaluate mobilization strategies to tailor approaches to the BA. METHODS: After an orbitozygomatic craniotomy, 10 sides of 5 cadaveric heads were used to assess the surgical access to the BA via the opticocarotid triangle (OCT), carotid-oculomotor triangle (COT), and oculomotor-tentorial triangle (OTT). Measurements were obtained, and morphometric analyses were performed for natural neurovascular positions and after each stepwise expansion maneuver. An imaginary line connecting the midpoints of the limbus sphenoidale and dorsum sellae was used as a reference to normalize the measurements of BA exposure and to facilitate the clinical applicability of this technique. RESULTS: In the OCT, the exposed BA segment ranged from - 1 ± 3.9 to + 6 ± 2.0 mm in length in its natural position. In the COT, the accessible BA segment ranged from - 4 ± 2.3 to - 2 ± 3.0 mm in length in its natural position. Via the OTT, the accessible BA segment ranged from - 7 ± 2.6 to - 5 ± 2.8 mm in length in its natural position. In the OCT, COT, and OTT, a posterior clinoidectomy extended the exposure down to - 6 ± 2.7, - 8 ± 2.5, and - 9 ± 2.9 mm, respectively. CONCLUSIONS: This study quantitatively evaluated the need for the expansion maneuvers in the PTA to reach BA aneurysms according to the patient's anatomical characteristics.

[Neurosurgical Outcomes of Intradural Extramedullary Spinal Tumors in 97 cases:Siberian Experience].

We retrospectively investigated the clinical presentation and outcome of patients with spinal intradural extramedullary tumors, which had been surgically treated. A total of 97 consecutive patients(32 males and 65 females;mean age, 48 years;range, 17-79 years)underwent surgery between 2004 and 2014 at Irkutsk State Medical Academy and affiliated hospitals. To determine presentation and outcomes associated with these tumors, we evaluated the waiting period before surgery, neurological symptoms including motor, sensory, urinary, and rectal dysfunction, modified McCormick scale, Macnab's outcome assessment of patient satisfaction, surgical procedure, tumor location, and histological diagnosis. The most frequent preoperative symptom was myelopathy(52.6%)at presentation, followed by radiculopathy(20.6%), and a combination of both(26.8%). Surgical intervention produced highly successful results, in which 77 of 97 cases showed neurological improvement. However, the symptoms were not completely reversed, and there was improvement only the equivalent to one grade in the modified McCormick scale for most patients. Surgical outcomes were not influenced by tumor location, extent of lamina resection, or histological diagnosis, but there was a correlation between greater patient improvement and a shorter waiting period before surgery. As such, we recommend early total resection for symptomatic spinal intradural extramedullary tumors.

Chen Jingrun, China's famous mathematician: devastated by brain injuries on the doorstep to solving a fundamental mathematical puzzle.

Chen Jingrun (1933-1996), perhaps the most prodigious mathematician of his time, focused on the field of analytical number theory. His work on Waring's problem, Legendre's conjecture, and Goldbach's conjecture led to progress in analytical number theory in the form of "Chen's Theorem," which he published in 1966 and 1973. His early life was ravaged by the Second Sino-Japanese War and the Chinese Cultural Revolution. On the verge of solving Goldbach's conjecture in 1984, Chen was struck by a bicyclist while also bicycling and suffered severe brain trauma. During his hospitalization, he was also found to have Parkinson's disease. Chen suffered another serious brain concussion after a fall only a few months after recovering from the bicycle crash. With significant deficits, he remained hospitalized for several years without making progress while receiving modern Western medical therapies. In 1988 traditional Chinese medicine experts were called in to assist with his treatment. After a year of acupuncture and oxygen therapy, Chen could control his basic bowel and bladder functions, he could walk slowly, and his swallowing and speech improved. When Chen was unable to produce complex work or finish his final work on Goldbach's conjecture, his mathematical pursuits were taken up vigorously by his dedicated students. He was able to publish Youth Math, a mathematics book that became an inspiration in Chinese education. Although he died in 1996 at the age of 63 after surviving brutal political repression, being deprived of neurological function at the very peak of his genius, and having to be supported by his wife, Chen ironically became a symbol of dedication, perseverance, and motivation to his students and associates, to Chinese youth, to a nation, and to mathematicians and scientists worldwide.

Monsters and the case of L. Joseph: André Feil's thesis on the origin of the Klippel-Feil syndrome and a social transformation of medicine.

André Feil (1884-1955) was a French physician best recognized for his description, coauthored with Maurice Klippel, of patients with congenital fusion of cervical vertebrae, a condition currently known as Klippel-Feil syndrome. However, little is known about his background aside from the fact that he was a student of Klippel and a physician who took a keen interest in describing congenital anomalies. Despite the relative lack of information on Feil, his contributions to the fields of spinal disease and teratology extended far beyond science to play an integral role in changing the misguided perception shrouding patients with disfigurements, defects, deformities, and so-called monstrous births. In particular, Feil's 1919 medical school thesis on cervical abnormalities was a critical publication in defying long-held theory and opinion that human "monstrosities," anomalies, developmental abnormalities, and altered congenital physicality were a consequence of sinful behavior or a reversion to a primitive state. Indeed, his thesis on a spinal deformity centering on his patient, L. Joseph, was at the vanguard for a new view of a patient as nothing less than fully human, no matter his or her physicality or appearance.

Prospective evaluation of the utility of intraoperative confocal laser endomicroscopy in patients with brain neoplasms using fluorescein sodium: experience with 74 cases.

OBJECTIVE: This study evaluated the utility, specificity, and sensitivity of intraoperative confocal laser endomicroscopy (CLE) to provide diagnostic information during resection of human brain tumors. METHODS: CLE imaging was used in the resection of intracranial neoplasms in 74 consecutive patients (31 male; mean age 47.5 years; sequential 10-month study period). Intraoperative in vivo and ex vivo CLE was performed after intravenous injection of fluorescein sodium (FNa). Tissue samples from CLE imaging-matched areas were acquired for comparison with routine histological analysis (frozen and permanent sections). CLE images were classified as diagnostic or nondiagnostic. The specificities and sensitivities of CLE and frozen sections for gliomas and meningiomas were calculated using permanent histological sections as the standard. RESULTS: CLE images were obtained for each patient. The mean duration of intraoperative CLE system use was 15.7 minutes (range 3-73 minutes). A total of 20,734 CLE images were correlated with 267 biopsy specimens (mean number of images/biopsy location, in vivo 84, ex vivo 70). CLE images were diagnostic for 45.98% in vivo and 52.97% ex vivo specimens. After initiation of CLE, an average of 14 in vivo images and 7 ex vivo images were acquired before identification of a first diagnostic image. CLE specificity and sensitivity were, respectively, 94% and 91% for gliomas and 93% and 97% for meningiomas. CONCLUSIONS: CLE with FNa provided intraoperative histological information during brain tumor removal. Specificities and sensitivities of CLE for gliomas and meningiomas were comparable to those for frozen sections. These data suggest that CLE could allow the interactive identification of tumor areas, substantially improving intraoperative decisions during the resection of brain tumors.

Two bullets to the head and an early winter: fate permits Kutuzov to defeat Napoleon at Moscow.

General Mikhail Kutuzov (circa 1745-1813) brilliantly repelled Napoleon's invasion of Russia. Honored as a national hero and a savior of Russia, Kutuzov has a unique medical story. He was shot in the head twice while fighting the Turks (1774 and 1788) and survived the serious injuries seemingly against all odds. The first bullet "ran through the head from one temple to the other behind both eyes." The second bullet entered the cheek, destroyed upper teeth, traveled through the head, and exited the occiput. Massot, a French surgeon with the Russian army, wrote after treating Kutuzov's seemingly two mortal wounds: "It must be believed that fate appoints Kutuzov to something great, because he was still alive after two injuries, a death sentence by all the rules of medical science." Aided by Massot's expert surgical technique, Kutuzov lived to become intimately engaged in events that altered world history. His health did, however, suffer significant effects due to the bullet wounds. In 1812, as Napoleon's Grande Armée approached, Kutuzov realized he could not confront Napoleon and he strategically retreated from Moscow, submitting the French to the harsh winter and Russian cavalry. Napoleon's devastated army retreated to Paris, and Kutuzov became the personification of Russian spirit and character. Kutuzov's survival of two nearly mortal head wounds created the legends, additional mystery, and drama surrounding him, not the least astonishing of which was the skilled neurosurgical care that probably saved his life.

Intraoperative in vivo confocal endomicroscopy of the glioma margin: performance assessment of image interpretation by neurosurgeon users.

Objectives: Confocal laser endomicroscopy (CLE) is an intraoperative real-time cellular resolution imaging technology that images brain tumor histoarchitecture. Previously, we demonstrated that CLE images may be interpreted by neuropathologists to determine the presence of tumor infiltration at glioma margins. In this study, we assessed neurosurgeons' ability to interpret CLE images from glioma margins and compared their assessments to those of neuropathologists. Methods: In vivo CLE images acquired at the glioma margins that were previously reviewed by CLE-experienced neuropathologists were interpreted by four CLE-experienced neurosurgeons. A numerical scoring system from 0 to 5 and a dichotomous scoring system based on pathological features were used. Scores from assessments of hematoxylin and eosin (H&E)-stained sections and CLE images by neuropathologists from a previous study were used for comparison. Neurosurgeons' scores were compared to the H&E findings. The inter-rater agreement and diagnostic performance based on neurosurgeons' scores were calculated. The concordance between dichotomous and numerical scores was determined. Results: In all, 4275 images from 56 glioma margin regions of interest (ROIs) were included in the analysis. With the numerical scoring system, the inter-rater agreement for neurosurgeons interpreting CLE images was moderate for all ROIs (mean agreement, 61%), which was significantly better than the inter-rater agreement for the neuropathologists (mean agreement, 48%) (p < 0.01). The inter-rater agreement for neurosurgeons using the dichotomous scoring system was 83%. The concordance between the numerical and dichotomous scoring systems was 93%. The overall sensitivity, specificity, positive predictive value, and negative predictive value were 78%, 32%, 62%, and 50%, respectively, using the numerical scoring system and 80%, 27%, 61%, and 48%, respectively, using the dichotomous scoring system. No statistically significant differences in diagnostic performance were found between the neurosurgeons and neuropathologists. Conclusion: Neurosurgeons' performance in interpreting CLE images was comparable to that of neuropathologists. These results suggest that CLE could be used as an intraoperative guidance tool with neurosurgeons interpreting the images with or without assistance of the neuropathologists. The dichotomous scoring system is robust yet simple and may streamline rapid, simultaneous interpretation of CLE images during imaging.

Laminectomy with Laminar Reconstruction for Resection of Intradural Tumors at the Thoracolumbar Junction: A Technical Note.

OBJECTIVE: To introduce a new laminar reconstruction technique to treat primary spinal cord tumors. METHODS: Laminectomy and laminoplasty techniques have been used to treat intradural spinal tumors. The advantage of laminectomy is its superior exposure of the spinal cord, whereas the advantage of laminoplasty is the reconstruction of the dorsal roof of the spine. In this technical note, we present a technique that combines a full laminectomy to maximize exposure, with a reconstructive technique to repair the lamina. This technique restores the posterior ligamentous complex to preserve spinal biomechanics. RESULTS: In this illustrative case, a 55-year-old woman with severe back pain radiating to the right lower extremity was found to have an intradural tumor at the T12-L1 spinal level. Given the transitional level of the spine and potentially high biomechanical stresses on the posterior support structures, we used a T12 laminectomy to resect the tumor, followed by reconstruction using miniplates. The patient tolerated the surgery well, without any complications. She was discharged home and was doing well during the 3 months follow-up visit. Appropriate patient consent was obtained. CONCLUSIONS: Laminectomy and laminar reconstruction allow maximum visualization and manipulation of the tumor, followed by restoration of the dorsal roof of the spinal ring, and is an effective technique for treating spinal cord tumors.

Laminoplasty versus Laminectomy in the Treatment of Primary Spinal Cord Tumors in Adult Patients: A Systematic Review and Meta-analysis of Observational Studies.

The present systematic review and meta-analysis was conducted to compare the safety and efficacy of the two approaches for primary spinal cord tumors (PSCTs) in adult patients (laminoplasty [LP] vs. laminectomy [LE]). LE is one of the most common procedures for PSCTs. Despite advantages of LP, it is not yet widely used in the neurosurgical community worldwide. The efficacy of LP vs. LE remains controversial. Adult patients over 18 years of age with PSCT at the level of the cervical, thoracic, and lumbar spine were included in the study. A literature search was performed in MEDLINE via PubMed, EMBASE, The Cochrane Library, and Google Scholar up to December 2021. Operation time, hospital stay, complications, and incidence of postoperative spinal deformity (kyphosis or scoliosis were extracted. A total of seven retrospective observational studies with 540 patients were included. There were no significant differences between LP and LE group in operation time (p =0.25) and complications (p =0.48). The LE group showed larger postoperative spinal deformity rate than the LP group (odds ratio, 0.47; 95% confidence interval [CI], 0.27-0.84; p =0.01). The LP group had a shorter hospital stay (standardized mean differences, -0.68; 95% CI, -1.03 to -0.34; p =0.0001) than the LE group. Both LP and LE have comparable operative times and total complications in the treatment of PSCT. LP was superior to LE in hospital stay and postoperative spinal deformity rate. However, these findings are limited by the very low quality of the available evidence. Randomized controlled trials are needed for further comparison.

5-aminolevulinic acid, fluorescein sodium, and indocyanine green for glioma margin detection: analysis of operating wide-field and confocal microscopy in glioma models of various grades.

Introduction: Surgical resection remains the first-line treatment for gliomas. Several fluorescent dyes are currently in use to augment intraoperative tumor visualization, but information on their comparative effectiveness is lacking. We performed systematic assessment of fluorescein sodium (FNa), 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX), and indocyanine green (ICG) fluorescence in various glioma models using advanced fluorescence imaging techniques. Methods: Four glioma models were used: GL261 (high-grade model), GB3 (low-grade model), and an in utero electroporation model with and without red fluorescence protein (IUE +RFP and IUE -RFP, respectively) (intermediate-to-low-grade model). Animals underwent 5-ALA, FNa, and ICG injections and craniectomy. Brain tissue samples underwent fluorescent imaging using a wide-field operative microscope and a benchtop confocal microscope and were submitted for histologic analysis. Results: Our systematic analysis showed that wide-field imaging of highly malignant gliomas is equally efficient with 5-ALA, FNa, and ICG, although FNa is associated with more false-positive staining of the normal brain. In low-grade gliomas, wide-field imaging cannot detect ICG staining, can detect FNa in only 50% of specimens, and is not sensitive enough for PpIX detection. With confocal imaging of low-intermediate grade glioma models, PpIX outperformed FNa. Discussion: Overall, compared to wide-field imaging, confocal microscopy significantly improved diagnostic accuracy and was better at detecting low concentrations of PpIX and FNa, resulting in improved tumor delineation. Neither PpIX, FNa, nor ICG delineated all tumor boundaries in studied tumor models, which emphasizes the need for novel visualization technologies and molecular probes to guide glioma resection. Simultaneous administration of 5-ALA and FNa with use of cellular-resolution imaging modalities may provide additional information for margin detection and may facilitate maximal glioma resection.

Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training.

OBJECTIVE: Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity. METHODS: Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)-middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)-PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery-anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey. RESULTS: A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models. CONCLUSIONS: The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

Intraoperative confocal laser endomicroscopy: prospective in vivo feasibility study of a clinical-grade system for brain tumors.

OBJECTIVE: The authors evaluated the feasibility of using the first clinical-grade confocal laser endomicroscopy (CLE) system using fluorescein sodium for intraoperative in vivo imaging of brain tumors. METHODS: A CLE system cleared by the FDA was used in 30 prospectively enrolled patients with 31 brain tumors (13 gliomas, 5 meningiomas, 6 other primary tumors, 3 metastases, and 4 reactive brain tissue). A neuropathologist classified CLE images as interpretable or noninterpretable. Images were compared with corresponding frozen and permanent histology sections, with image correlation to biopsy location using neuronavigation. The specificities and sensitivities of CLE images and frozen sections were calculated using permanent histological sections as the standard for comparison. A recently developed surgical telepathology software platform was used in 11 cases to provide real-time intraoperative consultation with a neuropathologist. RESULTS: Overall, 10,713 CLE images from 335 regions of interest were acquired. The mean duration of the use of the CLE system was 7 minutes (range 3-18 minutes). Interpretable CLE images were obtained in all cases. The first interpretable image was acquired within a mean of 6 (SD 10) images and within the first 5 (SD 13) seconds of imaging; 4896 images (46%) were interpretable. Interpretable image acquisition was positively correlated with study progression, number of cases per surgeon, cumulative length of CLE time, and CLE time per case (p ≤ 0.01). The diagnostic accuracy, sensitivity, and specificity of CLE compared with frozen sections were 94%, 94%, and 100%, respectively, and the diagnostic accuracy, sensitivity, and specificity of CLE compared with permanent histological sections were 92%, 90%, and 94%, respectively. No difference was observed between lesion types for the time to first interpretable image (p = 0.35). Deeply located lesions were associated with a higher percentage of interpretable images than superficial lesions (p = 0.02). The study met the primary end points, confirming the safety and feasibility and acquisition of noninvasive digital biopsies in all cases. The study met the secondary end points for the duration of CLE use necessary to obtain interpretable images. A neuropathologist could interpret the CLE images in 29 (97%) of 30 cases. CONCLUSIONS: The clinical-grade CLE system allows in vivo, intraoperative, high-resolution cellular visualization of tissue microstructure and identification of lesional tissue patterns in real time, without the need for tissue preparation.

Qualitative head-to-head comparison of headlamp and microscope for visualizing 5-ALA fluorescence during resection of glioblastoma.

Fluorescence-guided surgery (FGS) for high-grade gliomas using 5-aminolevulinic acid has become a new standard of care for neurosurgeons in several countries. In this video the authors present the case of a man with glioblastoma who underwent FGS in which similar images of the operative field were acquired alternating between the microscope and a new commercially available headlight, facilitating the comparison of visualization quality between the two devices. The authors also review some of the principles of fluorescence-guidance surgery that may explain the improved brightness and contrast that they observed when using the headlamp versus the microscope. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21181.

Tribute to William Edward Hunt and Robert McDonald Hess Jr.: Pioneers in the Clinical Classification of Ruptured Intracranial Aneurysms.

William Edward Hunt (1921-1999) and Robert McDonald Hess Jr. (1931-2019) were pioneers in revolutionizing the early surgical management of ruptured intracranial aneurysms. Early on in his career as a professor of neurosurgery at Ohio State University, Dr. Hunt adopted a systematic method to identify clinical symptoms of patients presenting with subarachnoid hemorrhage as candidates for either immediate or delayed surgery. As an Ohio State University neurosurgery resident, Dr. Hess was an active key collaborator in Dr. Hunt's aneurysm studies. Described as a modification of the Botterell classification system, the Hunt-Hess scale grading the survival risk of undergoing immediate intracranial aneurysm surgery was implemented and validated across an 18-year consecutive patient series at White Cross Hospital, Columbus, Ohio. Dr. Hunt and Dr. Hess demonstrated that for patients with subarachnoid hemorrhage on admission with Hunt-Hess grades I and II, indicating retained consciousness and minimal neurological deficits, immediate surgical management afforded a <20% mortality rate. In comparison, patients with grade III or higher had a >50% mortality rate, suggesting that conservative management should be instead pursued. As the principal investigator, Dr. Hunt was widely regarded internationally as an expert in the field of treating intracranial aneurysms, eventually serving as a World Federation of Neurosurgical Societies (WFNS) committee member to also publish a universal subarachnoid hemorrhage grading scale. To pay tribute to Drs. Hunt and Hess for their substantial contributions, we present historical vignettes of their lives along with highlighting the role of the Hunt-Hess classification system in transforming management of ruptured aneurysms.

Surgical Anatomy of the Middle Communicating Artery and Guidelines for Predicting the Feasibility of M2-M2 End-to-End Reimplantation.

BACKGROUND: M2-M2 end-to-end reimplantation that creates a middle communicating artery has recently been proposed as a reconstruction technique to treat complex aneurysms of the middle cerebral artery that are not amenable to clipping. OBJECTIVE: To examine the surgical anatomy, define anatomic variables, and explore the feasibility of this bypass. METHODS: Sixteen cadaver heads were prepared for bypass simulation. After the middle cerebral artery bifurcation was approached, the proximal insular (M2) segments and perforators were explored. To define the maximal distance between the M2 segments that allows the bypass to be performed, the M2 segments were mobilized and reimplanted in an end-to-end fashion. RESULTS: Successful reimplantation was performed in all specimens. The mean maximal distance between the M2 segments to create the proposed reimplantation was 9.1 ± 3.2 mm. The mean vessel displacement was significantly greater for the superior (6.0 ± 2.3 mm) M2 segment than for the inferior (3.2 ± 1.4 mm) M2 segment (P < .001). CONCLUSION: In this cadaveric study, the stumps of the M2 segments located at a distance of ≤9.1 mm could be approximated to create a feasible M2-M2 end-to-end anastomosis. Intraoperative inspection of the M2 segments and their perforators could allow further assessment of the feasibility of the procedure before final revascularization decisions are made.

Comparative Analysis of Surgical Exposure among Endoscopic Endonasal Approaches to Petrosectomy: An Experimental Study in Cadavers.

Objectives Endoscopic endonasal approaches (EEAs) for petrosectomies are evolving to reduce perioperative brain injuries and complications. Surgical terminology, techniques, landmarks, advantages, and limitations of these approaches remain ill defined. We quantitatively analyzed the anatomical relationships and differences between EEA exposures for medial, inferior, and inferomedial petrosectomies. Design This study presents anatomical dissection and quantitative analysis. Setting Cadaveric heads were used for dissection. EEAs were performed using the medial petrosectomy (MP), the inferior petrosectomy (IP), and the inferomedial petrosectomy (IMP) techniques. Participants Six cadaver heads (12 sides, total) were dissected; each technique was performed on four sides. Main Outcomes and Measures Outcomes included the area of exposure, visible distances, angles of attack, and bone resection volume. Results The IMP technique provided a greater area of exposure ( p < 0.01) and bone resection volume ( p < 0.01) when compared with the MP and IP techniques. The IMP technique had a longer working length of the abducens nerve (cranial nerve [CN] VI) than the MP technique ( p < 0.01). The IMP technique demonstrated higher angles of attack to specific neurovascular structures when compared with the MP (midpons [ p = 0.04], anterior inferior cerebellar artery [ p < 0.01], proximal part of the cisternal CN VI segment [ p = 0.02]) and IP (flocculus [ p = 0.02] and the proximal [ p = 0.02] and distal parts [ p = 0.02] of the CN VII/VIII complex) techniques. Conclusion Each of these approaches offers varying degrees of access to the petroclival region, and the surgical approach should be appropriately tailored to the pathology. Overall, the IMP technique provides greater EEA surgical exposure to vital neurovascular structures than the MP and the IP techniques.

Characterization of ex vivo and in vivo intraoperative neurosurgical confocal laser endomicroscopy imaging.

Background: The new US Food and Drug Administration-cleared fluorescein sodium (FNa)-based confocal laser endomicroscopy (CLE) imaging system allows for intraoperative on-the-fly cellular level imaging. Two feasibility studies have been completed with intraoperative use of this CLE system in ex vivo and in vivo modalities. This study quantitatively compares the image quality and diagnostic performance of ex vivo and in vivo CLE imaging. Methods: Images acquired from two prospective CLE clinical studies, one ex vivo and one in vivo, were analyzed quantitatively. Two image quality parameters - brightness and contrast - were measured using Fiji software and compared between ex vivo and in vivo images for imaging timing from FNa dose and in glioma, meningioma, and intracranial metastatic tumor cases. The diagnostic performance of the two studies was compared. Results: Overall, the in vivo images have higher brightness and contrast than the ex vivo images (p < 0.001). A weak negative correlation exists between image quality and timing of imaging after FNa dose for the ex vivo images, but not the in vivo images. In vivo images have higher image quality than ex vivo images (p < 0.001) in glioma, meningioma, and intracranial metastatic tumor cases. In vivo imaging yielded higher sensitivity and negative predictive value than ex vivo imaging. Conclusions: In our setting, in vivo CLE optical biopsy outperforms ex vivo CLE by producing higher quality images and less image deterioration, leading to better diagnostic performance. These results support the in vivo modality as the modality of choice for intraoperative CLE imaging.