Hyperspectral and multispectral imaging in neurosurgery: a systematic literature review and meta-analysis.

INTRODUCTION: The neuro-surgical community is witnessing a rising interest for surgical application of multispectral/hyperspectral imaging. Several potential technical applications of this optical imaging are reported, but the set-up is variable and so are the processing methods. We present a systematic review of the relevant literature on the topic. MATERIALS AND METHODS: A literature search based on the PRISMA principles was performed on PubMed, SCOPUS, and Web of Science, using MESH terms and Boolean operators. Papers regarding intra-operative in-vivo application of multispectral and/or hyperspectral imaging in humans during neurosurgical procedures were included. Papers reporting technologies related to radiological applications were excluded. A meta-analysis on the performance metrics was also conducted. RESULTS: Our search string retrieved 20 papers. The main applications of optical imaging during neurosurgery concern tumour detection and improvement of the extent of resection (15 papers) or visualization of perfusion changes during neuro-oncology or neuro-vascular surgery (5 papers). All the retrieved articles were pilot studies, proof of concepts, or case reports, with limited number of patients recruited. Sensitivity, specificity, and accuracy were promising in most of the reports, but the metanalysis showed heterogeneous approaches and results among studies. CONCLUSIONS: The present review shows that several approaches are currently being tested to integrate hyperspectral imaging in neurosurgery, but most of the studies reported a limited pool of patients, with different approaches to data collection and analysis. Further studies on larger cohorts of patients are therefore desirable to fully explore the potential of this imaging technique.

Profiling of circulating glial cells for accurate blood-based diagnosis of glial malignancies.

Here, we describe a blood test for the detection of glial malignancies (GLI-M) based on the identification of circulating glial cells (CGCs). The test is highly specific for GLI-M and can detect multiple grades (II-IV) and subtypes including gliomas, astrocytomas, oligodendrogliomas, oligoastrocytomas and glioblastomas, irrespective of gender and age. Analytical validation of the test was performed as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Real-world performance characteristics of the test were evaluated in four clinical (observational) studies. The test has high analytical sensitivity (95%), specificity (100%) and precision (coefficient of variation [CV] = 13.7% for repeatability and CV = 23.5% for within laboratory precision, both at the detection threshold) and is not prone to interference from common drugs and serum factors. The ability of the test to detect and differentiate GLI-M from non-malignant brain tumours (NBT), brain metastases from primary epithelial malignancies (EPI-M) and healthy individual donors (HD) was evaluated in four clinical cohorts. Across these clinical studies, the test showed 99.35% sensitivity (95% confidence interval [CI]: 96.44%-99.98%) and 100% specificity (95% CI: 99.37%-100%). The performance characteristics of this test support its clinical utility for diagnostic triaging of individuals presenting with intracranial space-occupying lesions (ICSOL).

Arginine deprivation alters microglial polarity and synergizes with radiation to eradicate non-arginine-auxotrophic glioblastoma tumors.

New approaches for the management of glioblastoma (GBM) are an urgent and unmet clinical need. Here, we illustrate that the efficacy of radiotherapy for GBM is strikingly potentiated by concomitant therapy with the arginine-depleting agent ADI-PEG20 in a non-arginine-auxotrophic cellular background (argininosuccinate synthetase 1 positive). Moreover, this combination led to durable and complete radiological and pathological response, with extended disease-free survival in an orthotopic immune-competent model of GBM, with no significant toxicity. ADI-PEG20 not only enhanced the cellular sensitivity of argininosuccinate synthetase 1-positive GBM to ionizing radiation by elevated production of nitric oxide (˙NO) and hence generation of cytotoxic peroxynitrites, but also promoted glioma-associated macrophage/microglial infiltration into tumors and turned their classical antiinflammatory (protumor) phenotype into a proinflammatory (antitumor) phenotype. Our results provide an effective, well-tolerated, and simple strategy to improve GBM treatment that merits consideration for early evaluation in clinical trials.

Tonsillar Carcinoma Spreading Metastases to Central Nervous System: Case Report and Literature Review.

We present a case report of a 51-year-old left-handed male with a background of human papillomovairus 16-positive tonsil squamous cell carcinoma presenting with tonic-clonic seizure and a radiological diagnosis of secondary metastatic deposits. These were initially treated with stereotactic radiosurgery and subsequently with surgery. Surgical resection was performed under general anesthesia with right-sided temporal and parietal approaches. Both the parietal and temporal deposits were removed, while the intraventricular mass was intentionally left to avoid postoperative deficits. Adjuvant radiotherapy and chemotherapy were administered postoperatively. The patient experienced a satisfactory recovery postoperatively and was reoperated for recurrence 4 months later. He maintained a good quality of life and an excellent performance status throughout, but unfortunately he passed away in November 2018 due to septic complications. This case history stresses the difficulty in managing squamous cell carcinomas (SCC) with brain metastatic deposits. There are no current guidelines about the management of patients presenting with such a rare condition. More data are thus desirable to better define treatment guidelines and protocols when SCC brain metastases are present.

Spinal Nerves Schwannomas: Experience on 367 Cases-Historic Overview on How Clinical, Radiological, and Surgical Practices Have Changed over a Course of 60 Years.

BACKGROUND: Spinal schwannomas are common benign spinal tumors. Their treatment has significantly evolved over the years, and preserving neurological functions has become one of the main treatment goals together with tumor resection. STUDY DESIGN AND AIMS: Retrospective review focused on clinical assessment, treatment techniques, and outcomes. METHODS: A retrospective study on our surgical series was performed. Clinical and operative data were analyzed. In regard to neurophysiologic monitoring, patients were retrospectively divided into two groups comparing the outcomes before and after introduction of routine intraoperative neurophysiology tests. RESULTS: From 1951 to 2010, 367 patients overall were treated. Diagnosis was obtained using angiography and/or myelography (pre-CT era), MRI, or CT scan. A posterior spinal approach was used for most patients; complex approaches were adopted for treatment of giant/dumbbell tumors. A trend of neurophysiology monitoring decreasing the rate of post-op neurological deficits was observed but was not statistically significant enough to draft evidence-based conclusions. CONCLUSIONS: Clinical and radiological assessment of spinal schwannomas has markedly changed over the course of 50 years. Diagnostic tools have improved, and detection of recurrence has become way more sensitive. Neurophysiologic monitoring has become a useful intraoperative tool to guide resection and prevent post-op neurological impairment.

Relevancy of positive trends in mortality and functional recovery after surgical treatment of acute subdural hematomas. Our 10-year experience.

BACKGROUND: Among traumatic brain injuries, acute subdural hematoma (aSDH) is considered one of the most devastating still retaining poor surgical outcomes in a considerable percentage of affected patients. However, according to results drawn from published samples of aSDH patients, overall mortality and functional recovery have been progressively ameliorating during the last decades. METHODS: We present a retrospective analysis of 316 consecutive cases of post-traumatic aSDH operated on between 2003 and 2011 at our institution. RESULTS: Mortality was 67% (n = 212); a useful recovery was achieved in 16.4% cases (n = 52). Age >65 years, a preoperative Glasgow coma scale (GCS) ≤ 8, specific pre-existing medical comorbidities (hypertension, heart diseases) were found to be strong indicators of unfavorable outcomes and death during hospitalization. CONCLUSION: Our results, compared with those of the inherent literature, led the authors to question both the "aggressiveness" of neurosurgical care indications in certain subpopulations of patients being known to fare worse or even die regardless of the treatment administered and the relevance of the results concerning mortality and functional recovery reported by third authors.

Sacrificing the superior petrosal vein during microvascular decompression. Is it safe? Learning the hard way. Case report and review of literature.

BACKGROUND: Venous infarction as a complication of microvascular decompression (MVD) is a recognized but extremely rare occurrence in an otherwise standard neurosurgical procedure. Sacrificing one or more veins is considered safe by majority of experienced surgeons and authors. However, in the recent years, there has been growing debate about the management of venous trigeminal compression and/or superior petrosal complex (separation vs. coagulation and cutting of the vein), with few papers describing mild to severe complications related to venous sacrifice. CASE DESCRIPTION: We report our dramatic experience during re-exploration for MVD on a male who developed massive cerebellar, brainstem, and brain infarction. Extensive analysis of surgical planning and literature debate about this topic is also reported. CONCLUSION: Despite rare, venous infarction after venous sacrifice in MVD is possible and can have catastrophic consequences. We would advise: (1) To try preserving the vein anytime this is possible, especially if it is large in size; (2) if it is decided to sacrifice the vein temporary occlusion while observing changed in the neurophysiology might be safer; (3) when planning an MVD for suspected venous compression, possible alternative forms of treatment should also be considered.

Mini Transsternal Approach to the Anterior High Thoracic Spine (T1-T4 Vertebrae).

Purpose. The anterior high thoracic spine is one of the most complex segments to be accessed surgically due to anatomical constraints and transitional characteristics. We describe in detail the mini transsternal approach to metastatic, infective, traumatic, and degenerative pathologies of T1 to T4 vertebral bodies. We analyse our surgical series, indications, and outcomes. Methods. Over a 5-year period 18 consecutive patients with thoracic myelopathy due to metastatic, infective, traumatic, and degenerative pathologies with T1 to T4 vertebral bodies involvement received a mini transsternal approach with intraoperative monitoring. Frankel scoring system was used to grade the neurological status. Results. Mean follow-up was 40 months. 78% patients improved in Frankel grade after surgery and 22% patients remained unchanged. Average operation time was 210 minutes. There were no intraoperative complications. One patient developed postoperative pneumonia successfully treated with antibiotics. Conclusion. The mini transsternal is a safe approach for infective, metastatic, traumatic, and degenerative lesions affecting the anterior high thoracic spine and the only one allowing an early and direct visualisation of the anterior theca. This approach overcomes the anatomical constraints of this region and provides adequate room for optimal reconstruction and preservation of spinal alignment in the cervicothoracic transition zone with good functional patient outcomes.

Perceptions, misconceptions and review of a neurosurgery on-call service in a university teaching hospital.

BACKGROUND: No published guidelines exist for how receiving unit doctors should manage referrals. Feedback regarding the quality of neurosurgical referral handling in our hospital has, in the past, been poor. We designed a novel means to appraise specialist referral handling, such that service delivery could be improved. We also aimed to identify differences, if any, between doctor perceptions versus actual satisfaction with the on-call neurosurgery service in our centre. METHODS: We first distributed questionnaires to gauge doctors' perceptions of our neurosurgery on-call service ('Perceptions of Neurosurgery Service' or 'PONS' questionnaire). Next we distributed a novel quality-of-service questionnaire ('Neurosurgery Service Assessment Questionnaire' or 'NSAQ') to all referring doctors over the three-month period between 01 March 2014 and 01 June 2014. RESULTS: Of the 57 respondents to the PONS questionnaire, 47.3% perceived the neurosurgical referral service to be 'poor' (36.8%, n = 21) or 'very poor' (10.5%, n = 6). Next the NSAQ was sent via email to the referring doctor of each of the 502 referrals received in the study period. A total of 52 responses were received by referring doctors (response rate = 10.36%). Actual referral handling ratings were overwhelmingly positive; 82.7% rated the handling of their referral as 'good' (21.2%, n = 11), 'very good' (32.7%, n = 17) or 'excellent' (28.9%, n = 15). CONCLUSIONS: We describe a novel method for receiving units to appraise their referral services and demonstrate its usefulness in our tertiary neurosurgical unit. We also demonstrate that most referring doctors are satisfied with the handling of their neurosurgical referrals, despite perceptions to the contrary.

Lumbar Endoscopic Microdiscectomy: Where Are We Now? An Updated Literature Review Focused on Clinical Outcome, Complications, and Rate of Recurrence.

Endoscopic disc surgery (EDS) for lumbar spine disc herniation is a well-known but developing field, which is increasingly spreading in the last few years. Rate of recurrence/residual, complications, and outcomes, in comparison with standard microdiscectomy (MD), is still debated and need further data. We performed an extensive review based on the last 6 years of surgical series, systematic reviews, and meta-analyses reported in international, English-written literature. Articles regarding patients treated through endoscopic transforaminal or interlaminar approaches for microdiscectomy (MD) were included in the present review. Papers focused on endoscopic surgery for other spinal diseases were not included. From July 2009 to July 2015, we identified 51 surgical series, 5 systematic reviews, and one meta-analysis reported. In lumbar EDS, rate of complications, length of hospital staying, return to daily activities, and overall patients' satisfaction seem comparable to standard MD. Rate of recurrence/residual seems higher in EDS, although data are nonhomogeneous among different series. Surgical indication and experience of the performing surgeon are crucial factors affecting the outcome. There is growing but still weak evidence that lumbar EDS is a valid and safe alternative to standard open microdiscectomy. Statistically reliable data obtained from randomized controlled trials (better if multicentric) are desirable to further confirm these results.

Preparation of nasoseptal flap in trans-sphenoidal surgery using 2-µ thulium laser: technical note.

OBJECTIVE: The purpose of this study was to assess the feasibility of the use of the 2µ-thulium laser in harvesting nasal septal flaps. BACKGROUND DATA: Nasal septal flaps are routinely performed in almost every trans-sphenoidal surgery. The preservation of the arterial vasculature is a mainstay of the procedure. However, the margins of the flap should be sufficiently healthy to regenerate faster, reducing the risk of possible complications. MATERIALS AND METHODS: Eight patients underwent trans-sphenoidal surgery and removal of pituitary adenomas. Reparation of the defect was performed with the positioning of a rotational vascularized nasal-septal flap. The flaps were harvested with the aid of the 2µ-thulium laser. Every patient was then monitored for 6 months through seriated endoscopic endonasal controls. RESULTS: There were no complications related to the use of the laser, either intraoperatively, or postoperatively. The operative timing did not significantly differ from that of traditional techniques. CONCLUSIONS: The use of the 2µ-thulium laser for the harvesting of nasal septal vascularized flaps can be considered safe and feasible. The limited number of treated patients could be considered as the only restriction to the study. A larger study might have uncovered possible instrumentation-related complications, which were not observed in the present study.

The Pterional Port in Dual-Port Endoscopy: A 2D and 3D Cadaveric Study.

Objective We propose a novel dual-port endonasal and pterional endoscopic approach targeting midline lesions of the anterior cranial fossa with lateral extension beyond the optic nerve. Methods Ten dual-port approaches were performed on five cadaveric heads. All specimens underwent an endoscopic transtuberculum/transplanum approach followed by placement of a pterional port. The endonasal port was combined with an endoscopic extradural pterional keyhole craniectomy. The pterional port was placed at the intersection of the sphenoparietal and coronal sutures. The extradural space was explored using two-dimensional and three-dimensional endoscopes. Results The superolateral access provided by the pterional port may improve the ability to achieve a gross total resection of tumors with lateral extensions. The complete opening of the optic canal achieved through the dual-port approach may enable resection of the intracanalicular portion of a tumor, a crucial step in improvement of visual function and reduction of tumor recurrence. Conclusion The pterional port may enhance control of midline anterior skull base lesions with lateral extension beyond the optic nerve and optic canal. Dual-port endoscopy maintains minimally invasiveness and dramatically increases the working limits and control of anatomical structures well beyond what is attainable through single-port neuroendoscopy.

Three-dimensional endoscope-assisted surgical approach to the foramen magnum and craniovertebral junction: minimizing bone resection with the aid of the endoscope.

OBJECTIVE: To evaluate objectively the anatomic areas of the cranial base exposed by a three-dimensional (3D) endoscope-assisted far lateral approach. METHODS: A series of far lateral approaches with only condyle resection, with only jugular tubercle resection, with both partial condyle and total jugular tubercle resection, and without occipital condyle and jugular tubercle resection were performed on 10 cadaveric heads (20 sides). To assess properly the exposure of major anatomic and neurovascular structures, the intradural anatomy of the exposed craniocervical junction was divided into 8 compartments, including 3 superior cranial compartments, 3 inferior cranial compartments, and 2 spinal compartments. RESULTS: The anteromedial compartments toward the midline were difficult to explore using the microscope and required the aid of the endoscope. The 3D endoscope provided general circumferential visualization of the anatomic structures, even without resection of the jugular tubercle, and afforded good visualization of the more lateral compartments. Safe and optimal surgical corridors for insertion of the endoscope were also identified. CONCLUSIONS: Use of a 3D endoscope allows for minimal resection of the condyle and jugular tubercle, better visualization of the surgical compartments toward the midline, and better in-depth surgical exploration of each intradural compartment. However, the 3D probe is still too large and restricts surgical maneuverability.

Interhemispheric Endoscopic Fenestration of the Lamina Terminalis through a Single Frontal Burr Hole.

Objective We evaluate the feasibility and safety of performing a novel interhemispheric endoscopic fenestration of the lamina terminalis (IEFLT) through a single frontal burr hole immediately lateral to the superior sagittal sinus. Methods Five cadaveric heads underwent IEFLT. Sequential burr holes were made beginning above the glabella and progressed cranially to caudally until the frontal sinus. An endoscope was inserted, and interhemispheric dissection of the arachnoid membranes was completed with endoscopic instruments in a straight direction from the point of entry to the lamina terminalis (LT). Angled optics (0 and 30 degrees) were used to study the neurovascular structures and surgical landmarks. Results The IEFLTs were successfully completed in all specimens and allowed for good visualization of the inferior portion of the LT. The arachnoid dissections were achieved uneventfully. The endoscope provided good surface control of the LT and excellent stereoscopic visualization of the neurovascular complexes. Improved circumferential visualization of the superior part of the anterior portion of the third ventricle was attained. Conclusion IEFLT is a potential alternative to the classic endoscopic third ventriculostomy and a simpler alternative to the subfrontal EFLT, although surgical maneuverability is still limited due to the size of the probe in relation to the narrow surgical corridor.

Dual-Port 2D and 3D Endoscopy: Expanding the Limits of the Endonasal Approaches to Midline Skull Base Lesions with Lateral Extension.

Objective To investigate a novel dual-port endonasal and subtemporal endoscopic approach targeting midline lesions with lateral extension beyond the intracavernous carotid artery anteriorly and the Dorello canal posteriorly. Methods Ten dual-port approaches were performed on five cadaveric heads. All specimens underwent an endoscopic endonasal approach from the sella to middle clivus. The endonasal port was combined with an anterior or posterior endoscopic extradural subtemporal approach. The anterior subtemporal port was placed directly above the middle third of the zygomatic arch, and the posterior port was placed at its posterior root. The extradural space was explored using two-dimensional and three-dimensional endoscopes. Results The anterior subtemporal port complemented the endonasal port with direct access to the Meckel cave, lateral sphenoid sinus, superior orbital fissure, and lateral and posterosuperior compartments of the cavernous sinus; the posterior subtemporal port enhanced access to the petrous apex. Endoscopic dissection and instrument maneuverability were feasible and performed without difficulty in both the anterior and posterior subtemporal ports. Conclusion The anterior and posterior subtemporal ports enhanced exposure and control of the region lateral to the carotid artery and Dorello canal. Dual-port neuroendoscopy is still minimally invasive yet dramatically increases surgical maneuverability while enhancing visualization and control of anatomical structures.

A combined dual-port endoscope-assisted pre- and retrosigmoid approach to the cerebellopontine angle: an extensive anatomo-surgical study.

The use of the endoscope in the cerebellopontine angle (CPA) has been suggested to minimize cerebellar retraction and reduce the size of the craniotomy. 3D endoscopy combines the benefits of conventional 2D endoscopy with the added benefit of stereoscopic perception, though improved visualization alone does not guarantee improved surgical maneuverability and a better surgical outcome. We propose a new combined dual-port endoscope-assisted pre- and retrosigmoid approach to improve visualization and accessibility of the CPA with shortened distances and increased surgical maneuverability of neurovascular structures. We analyze surgical exposure and maneuverability of this approach and compare it with the surgical microscopic and a conventional single-port endoscope-assisted retrosigmoid approach. This combined pre- and retrosigmoid approach was performed on eight cadaveric heads (16 sides). The endoscopic probe was inserted through the presigmoid surgical port while surgical manipulation was performed through the retrosigmoid corridor. The CPA was divided into three compartments, from medial to lateral, the anteromedial, and the middle and the posterolateral. The microscope provided good visualization of the posterolateral and middle compartments, whereas poor visualization was offered of the anteromedial compartment. The dual-port endoscopic approach dramatically improved visualization and surgical maneuverability of the anteromedial compartments, clivus, and related neurovascular structures. Additionally, the 3D endoscope allowed for a better understanding of the surgical anatomy of the CPA and improved visualization of structures located in the anteromedial compartments towards the midline. This approach allowed for full realization of the benefits of endoscopic-assisted technique by improving surgical access and maneuverability.

Endoscopic extradural anterior clinoidectomy and optic nerve decompression through a pterional port.

Since the first description of the intradural removal of the anterior clinoid process, numerous refinements and modifications have been proposed to simplify and enhance the safety of the technique. The growing use of endoscopes in endonasal and transcranial approaches has changed the traditional management of many skull base lesions. We describe an endoscopic extradural anterior clinoidectomy and optic nerve decompression through a minimally invasive pterional port. Minimally invasive optic nerve decompression, with endoscopic extradural anterior clinoidectomy, through a pterional keyhole craniotomy was performed on five preserved cadaveric heads. The endoscopic pterional port provided a shorter and more direct route to the anterior clinoid region, and helped avoid unnecessary and extensive bone removal. An extradural approach helped minimize complications associated with infraction of the subdural space and allowed for the maintenance of visibility while drilling with continuous irrigation. Adequate 270° bone decompression of the optic canal was achieved in all specimens. Endoscopic extradural anterior clinoidectomy and optic nerve decompression is feasible through a single minimally invasive pterional port.

Awake craniotomy for trapping a giant fusiform aneurysm of the middle cerebral artery.

BACKGROUND: Giant fusiform aneurysms of the distal middle cerebral artery (MCA) are rare lesions that, because of the absence of an aneurysm neck and the presence of calcified walls and partial thrombosis, can be difficult to clip without sacrificing the parent vessel. Moreover, when the aneurysm is located in the dominant hemisphere, it is not possible to test language and cognitive functions during surgical intervention, making the closure of the parent vessel extremely dangerous. CASE DESCRIPTION: A 46-year-old woman presented with a one-year history of frontal headache without neurological deficit. A magnetic resonance imaging and an angiography showed a giant fusiform aneurysm of the left M2 tract. Because of the location and the absence of a neck, the aneurysm was considered difficult to coil and not amenable to preoperative balloon occlusion; thus, the patient was a candidate for surgical treatment. After a preoperative psychological evaluation, patient underwent awake craniotomy with the asleep-awake-asleep technique. A standard left pterional approach was performed to expose the internal carotid artery, the MCA and the aneurysm originating from the frontal branch of the MCA. Neurological examination responses remained unchanged during temporary parent artery occlusion, and trapping was successfully performed. CONCLUSIONS: Awake craniotomy is a useful option in intracranial aneurysm surgery because it permits neurological testing before vessels are permanently clipped or sacrificed. With the asleep-awake-asleep technique, it is possible to perform a standard pterional craniotomy, which allows good exposure of the vascular structures without cerebral retraction.

Assessment of the utility of the 2-µ thulium laser in surgical removal of intracranial meningiomas.

BACKGROUND AND OBJECTIVE: Since the 1960s, lasers have been used in neurosurgery for surgical removal of intracranial tumors. Because of its limited penetration (2 mm) through tissues and its wavelength, which is useful in water medium, the 2-µ thulium laser has been applied primarily in urology. Its features are attractive for application under microscope magnification during neurosurgical procedures. The aim of this study was to evaluate the usefulness of the 2-µ thulium laser during microsurgical removal of intracranial meningiomas. MATERIALS AND METHODS: Twenty patients with a diagnosis of intracranial meningiomas were treated with surgical intervention using a 2-µ thulium laser together with bipolar forceps, cavitron ultrasonic surgical aspirator (CUSA) and traditional microdissection instruments. Surgical removal was divided in four phases: (1) dissection from the external structures; (2) coagulation and debulking; (3) dissection from the deep structures; and (4) coagulation and removal of the basal implant. During all these steps, we evaluated the percentage of usage of the 2-µ thulium laser comparing them with bipolar forceps and ultrasonic aspirator and blunt dissection. RESULTS: Thulium laser was used mainly during phases 2 and 4 for 43% and 48.7% of the total removal, respectively. Although also useful during phases 1 and 3, it was only used for 2.2% and 31.3%, respectively: traditional dissection with scissors and forceps was preferred. CONCLUSIONS: Thulium laser seems to be a useful aid in the surgery of intracranial meningiomas, especially to debulk, shrink, and coagulate the mass and the basal implant.