Claudio Cavallo

Fluorescein-guided surgery for resection of high-grade gliomas: A multicentric prospective phase II study (FLUOGLIO).

Purpose: Sodium fluorescein is a dye that, intravenously injected, selectively accumulates in high-grade glioma (HGG) tissue through a damaged blood–brain barrier. In this article, the final results of a multicentric prospective phase II trial (FLUOGLIO) on fluorescein-guided HGG resection through a dedicated filter on the surgical microscope were reported. Methods: Patients with suspected HGGs considered suitable for removal were eligible to participate in this trial. Fluorescein was intravenously injected at a dose of 5 to 10 mg/kg. The primary endpoint was the percentage of patients with histologically confirmed HGGs, without contrast-enhancing tumor at the immediate postoperative MRI. Secondary endpoints were PFS, residual tumor on postoperative MRI, overall survival, neurologic deficits, and fluorescein-related toxicity. The sensitivity and specificity of fluorescein in identifying tumor tissue were estimated by fluorescent and nonfluorescent biopsies at the tumor margin. The study was registered on the European Regulatory Authorities website (EudraCT 2011-002527-18). Results: Fifty-seven patients aged 45 to 75 years were screened for participation, and 46 were considered for primary and secondary endpoints. Mean preoperative tumor volume was 28.75 cm3 (range, 1.3–87.8 cm3). Thirty-eight patients (82.6%) underwent a complete tumor removal. Median follow-up was 11 months. PFS-6 and PFS-12 were 56.6% and 15.2%. Median survival was 12 months. No adverse reaction related to SF administration was recorded. The sensitivity and specificity of fluorescein in identifying tumor tissue were respectively 80.8% and 79.1%. Conclusions: Fluorescein-guided technique with a dedicated filter on the surgical microscope is safe and enables a high percentage of contrast-enhancing tumor in patients with HGGs. Clin Cancer Res; 24(1); 52–61. ©2017 AACR.

Fluorescein-Guided Resection of Intramedullary Spinal Cord Tumors: Results from a Preliminary, Multicentric, Retrospective Study

BACKGROUND Intramedullary spinal cord tumors (IMSCTs) are rare, heterogenous lesions that are usually enhanced on preoperative magnetic resonance imaging (MRI) because of a damaged blood-brain barrier. Sodium fluorescein is a dye that accumulates in areas of the central nervous system with a damaged BBB. Given the pattern of MRI contrast enhancement of the majority of IMSCTs, the use of this fluorescent tracer could improve tumor visualization and quality of resection. In this article, we present the first experience with the application of fluorescein-guided technique for surgical removal of IMSCTs. METHODS Eleven patients (6 men, 5 women; mean age, 50.1 years), harboring 5 ependymomas, 3 hemangioblastomas, 1 astrocytoma, 1 pilocytic astrocytoma, and 1 glioneuronal tumor forming rosettes were included. Sodium fluorescein (5 mg/kg) was injected immediately after patient intubation. Tumors were removed with microsurgical technique and standard neurophysiological monitoring, under YELLOW 560 filter (Pentero 900) visualization. Surgical reports were reviewed regarding usefulness and grade of fluorescein staining. Postoperative MRI was performed within 72 hours after surgery, and postoperative clinical outcome was registered. RESULTS No adverse events were registered. Fluorescent staining was reported in 9 of 11 cases (82%), all of them enhancing on preoperative MRI (100% of ependymomas, 100% of pilocytic astrocytomas, 100% of hemangioblastomas). No fluorescence was reported in 1 astrocytoma and 1 glioneuronal tumor-forming rosette. Intraoperative fluorescence was considered helpful for tumor resection in 9 of 11 cases (82%). Gross total resection was obtained in 8 of 11 cases (72.7%). CONCLUSIONS Our results suggest that fluorescein-guided surgery is a safe and effective technique that can be used during the surgical resection of IMSCTs presenting with contrast-enhancement on preoperative MRI.

Malleable endoscope increases surgical freedom compared with a rigid endoscope in endoscopic endonasal approaches to the parasellar region.

BACKGROUND: One challenge when performing endoscopic endonasal approaches is the surgical conflict that occurs between the surgical instruments and endoscope in the crowded nasal corridor. This conflict decreases surgical freedom, increases surgeon frustration, and lengthens the learning curve for trainees. OBJECTIVE: To evaluate the impact a malleable endoscope has on surgical freedom for endoscopic approaches to the parasellar region. METHODS: Uninostril and binostril endoscopic transsphenoidal approaches to the pituitary gland and cavernous carotid arteries were performed on 8 silicon-injected, formalin-fixed cadaveric heads using both rigid and flexible 3-dimensional endoscopes. Surgical freedom to targets in the parasellar region was assessed using an established technique based on image guidance. Results are presented as 3 measurements: area of surgical freedom for a point target, area for the surgical field (cavernous carotids and sella), and angular surgical freedom (angle of attack). RESULTS: Point target surgical freedom, exposed area surgical freedom, and angle of attack were all significantly greater in approaches using the malleable endoscope compared with the rigid endoscope (P values .06 to <.001), with values varying between 17% and 28%. The improved surgical freedom noted with the malleable endoscope was due to the minimization of instrument-endoscope conflict at the back end (camera) and front end (tip) of the endoscope. CONCLUSION: This study demonstrates that application of a malleable endoscope to transsphenoidal approaches to the parasellar region decreases instrument-endoscope conflict and improves surgical freedom. ABBREVIATION: ICA, internal carotid artery

Long-term follow-up of surgical resection of microcystic meningiomas

Microcystic meningioma is a rare tumor with myxoid and microcystic features. Our objective was to evaluate the efficacy of surgical resection of microcystic meningioma. Between December 1985 and October 2000 we treated 25 microcystic meningioma patients with surgical resection. We retrospectively analyzed the results including the long-term follow-up of this patient population. We identified 15 women and 10 men with a mean age of 53.8 years (24-76 years) who had microcystic meningiomas treated with surgery. Based on the Simpson grade, we found four Grade I (16%), 16 Grade II (64%), three Grade III (12%) and two Grade IV (8%) resections. The mean preoperative Karnofsky Performance Scale (KPS) score was 80.3 (range 60-100). The mean postoperative KPS score was 90.4 (range 60-100). At a mean follow-up of 101.7 months (range 16-221) the KPS score improved to a mean of 93.8. The recurrence/progression free survival (RFS/PFS) rates at 3 and 5 years were 96% and 88%, respectively. The 3 and 5 year RFS/PFS rates based on the Simpson grade were evaluated. The 3 year RFS/PFS rates for Grade I, II, III and IV were 100%, 100%, 66.6% and 100%, respectively. The 5 year RFS/PFS rates were 66.6%, 90%, 66.6% and 100%, respectively. Microcystic meningioma is a rare tumor, which is characterized by extracellular microcystic spaces filled by edematous fluid and peritumoral edema. Following surgical resection these tumors have a positive prognosis with a benign course. The surgical outcomes seem to be associated with the risks related to the surgical procedure.

Endoscopically-Assisted Targeted Keyhole Retrosigmoid Approaches for Microvascular Decompression: Quantitative Anatomical Study

OBJECTIVE We describe and quantitatively assess minimally invasive keyhole retrosigmoid approaches targeted to the upper, middle, and lower cranial nerve (CN) complexes of the cerebellopontine angle (CPA). METHODS Anatomic dissections were performed on 10 sides of 5 fixed, silicone-injected cadaver heads. Surgical views through various trajectories were assessed in endoscopic videos and 3-dimensional (3D) interactive virtual reality microscope views. Surgical freedom and angles of attack to the proximal and distal areas of CN complexes of the CPA were compared among upper and lower keyholes and conventional retrosigmoid craniotomy using neuronavigation. RESULTS Compared with keyholes, the conventional approach had superior surgical freedom to most areas except for the distal CN V, the root of CN VII, and the root of CN IX, where differences were not significant. The conventional retrosigmoid approach provided a larger horizontal angle of attack than either the upper or lower keyholes for all selected areas; however, the vertical angles of attack were not different. Splitting the petrosal fissure resulted in a significant increase in the vertical angle of attack to the root zones of CNs V and VII but not to the distal areas of these nerves or CN IX. Illustrative cases of endoscope-assisted keyhole retrosigmoid approaches for the treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are presented. CONCLUSIONS Targeted keyhole retrosigmoid approaches require detailed understanding of the 3D anatomy of the CPA to create appropriate locations of corridors, including skin incisions and keyholes. Endoscope assistance complements the standard microsurgical technique by maximizing the visualization and identification of the delicate neurovascular structures.

The Barrow Innovation Center Case Series: A Novel 3-Dimensional–Printed Retractor for Use with Electromagnetic Neuronavigation Systems

OBJECTIVE The Barrow Innovation Center consists of an educational program that promotes interdisciplinary collaboration among neurosurgery, legal, and engineering professionals to foster the development of new medical devices. This report describes a common issue faced during the placement of ventricular shunts for the treatment of hydrocephalus and the solution to this problem that was developed through the Barrow Innovation Center. METHODS Neurosurgery residents involved in the Barrow Innovation Center presented the problem of ferromagnetic retractors interfering with pinless image-guidance systems at a monthly meeting. Potential solutions were openly discussed by an interdisciplinary committee of neurosurgeons, patent lawyers, and biomedical engineers. The committee decided to pursue development of a novel self-retaining retractor made of nonferromagnetic material as a solution to the problem. RESULTS Each retractor design was tested in the cadaver laboratory for size and functionality. A final design was chosen and used in a surgical case requiring ventriculoperitoneal shunt placement. The new retractor successfully retracted the scalp without interfering with the electromagnetic image-guidance system. CONCLUSIONS Through the interdisciplinary Barrow Innovation Center program, a newly designed, 3-dimensional-printed skin and soft-tissue retractor was created, along with an innovative universal shunt retainer. Through this integrated program dedicated to surgical innovation (i.e., the Barrow Innovation Center), the process of developing and implementing new technology at our institution has been streamlined, creating a culture of innovation within the neurosurgery training program.

Right Pretemporal-Transsylvian Approach for Resection of a Midbrain Cavernous Malformation: 3-Dimensional Operative Video

Brainstem cavernous malformations (CMs) account for 15% to 18% of all intracranial CMs1 and 13% of all cerebrovascular pathology in the posterior fossa.1,2 This video demonstrates the resection of a pontomesencephalic CM through a pretemporal approach through the oculomotor-tentorial triangle (OTT).3 A 49-yr-old woman presented with an acute onset of left hemiparesis, diplopia, vertigo, partial oculomotor, and facial palsy. Neuroimaging revealed a 25-mm diameter right pontomesencephalic CM with evidence of prior hemorrhage. Institutional Review Board approval and patient consent were obtained for surgery. A right orbitozygomatic craniotomy was performed, and the lesion was exposed through a pretemporal-transsylvian approach. After a wide Sylvian fissure split, the oculomotor nerve (CN III) was dissected away from the temporal lobe, and the temporal lobe was mobilized posteriorly to access the OTT. The posterior cerebral and superior cerebellar arteries were visualized in this triangle, and the cerebral peduncle and the CM were accessed deep to these arteries. After hematoma evacuation, the CM was resected in a piece-meal fashion using an intracapsular technique. Postoperative imaging confirmed the gross total resection of the lesion. The patient had persistent right CN III palsy and a slight worsening of left hemiparesis, which had resolved completely at the 6-mo follow-up. The OTT provides access to the upper ventrolateral pontomesencephalic area.3 This triangular surgical workspace is entered through a pretemporal-transsylvian corridor and widened with posterior temporal lobe retraction. The OTT is an important working space for accessing midbrain and upper pontine CMs posterolateral to CN III.

The Barrow Biomimetic Spine: Comparative Testing of a 3D-Printed L4-L5 Schwab Grade 2 Osteotomy Model to a Cadaveric Model

Introduction The Barrow Biomimetic Spine project is an ongoing effort to develop a three-dimensional (3D)-printed synthetic spine model with high anatomical and biomechanical fidelity to human tissue. The purpose of this study was to evaluate the biomechanical performance of an L4-L5 3D-printed synthetic spine model in a lordotic correction test after Schwab grade 2 osteotomies as compared to human cadaveric spines that have undergone the same osteotomies and lordotic correction. Methods Ten different L4-L5 synthetic spine models were 3D printed. Each print varied in either the material used for the soft tissue components, the infill density of the bony and soft tissue structures, the pre-correction disc height, or the model orientation on the print bed. Each print was instrumented with pedicle screws and underwent a Schwab grade 2 osteotomy. Changes in disc height measurements and end-plate angle were compared against cadaveric data acquired using the same study method. Results A simple linear correlation analysis demonstrated that for horizontally printed models using PolyFlex (Polymaker, New York, NY, USA)(models 1-3, 8, 10), the pre-correction posterior disc height and lordotic correction were moderately correlated (r = 0.56), but this correlation did not achieve statistical significance (P = 0.12). Regression analysis demonstrated a very strong correlation between lordotic correction and change in posterior disc height (r = 0.92, P < 0.001). Models printed either vertically (models 4-6) or with low bone density and high soft tissue density (model 10) appeared to perform the most similarly to the cadaveric tissue. Discussion The 3D-printed synthetic spine models demonstrated predictable and reliable performance in a lordotic correction test based on their respective material qualities and print densities. The print variables tested further demonstrated that this model is capable of achieving high biomechanical fidelity to cadaveric tissue when subjected to the same lordotic correction test after Schwab grade 2 osteotomies.