The endoscope-assisted supraorbital "keyhole" approach for anterior skull base meningiomas: an updated meta-analysis.

INTRODUCTION: The gold-standard treatment for symptomatic anterior skull base meningiomas is surgical resection. The endoscope-assisted supraorbital "keyhole" approach (eSKA) is a promising technique for surgical resection of olfactory groove (OGM) and tuberculum sellae meningioma (TSM) but has yet to be compared with the microscopic transcranial (mTCA) and the expanded endoscopic endonasal approach (EEA) in the context of existing literature. METHODS: An updated study-level meta-analysis on surgical outcomes and complications of OGM and TSM operated with the eSKA, mTCA, and EEA was conducted using random-effect models. RESULTS: A total of 2285 articles were screened, yielding 96 studies (2191 TSM and 1510 OGM patients). In terms of effectiveness, gross total resection incidence was highest in mTCA (89.6% TSM, 91.1% OGM), followed by eSKA (85.2% TSM, 84.9% OGM) and EEA (83.9% TSM, 82.8% OGM). Additionally, the EEA group had the highest incidence of visual improvement (81.9% TSM, 54.6% OGM), followed by eSKA (65.9% TSM, 52.9% OGM) and mTCA (63.9% TSM, 45.7% OGM). However, in terms of safety, the EEA possessed the highest cerebrospinal fluid leak incidence (9.2% TSM, 14.5% OGM), compared with eSKA (2.1% TSM, 1.6% OGM) and mTCA (1.6% TSM, 6.5% OGM). Finally, mortality and intraoperative arterial injury were 1% or lower across all subgroups. CONCLUSIONS: In the context of diverse study populations, the eSKA appeared not to be associated with increased adverse outcomes when compared with mTCA and EEA and offered comparable effectiveness. Case-selection is paramount in establishing a role for the eSKA in anterior skull base tumours.

How I do it: The expanded trans/supraorbital approach for large space-occupying lesions of the anterior fossa.

BACKGROUND: The supraorbital rim often interferes with the required upward movement of the instruments for resection of large frontal-lobe tumours through a classic supraorbital craniotomy. Here, we present the expanded trans/supraorbital approach to overcome these limitations. METHODS: After an eyebrow skin incision, a one-piece bone flap was created incorporating the orbital rim and roof. Basal extension of the craniotomy allowed for a better intracranial visualisation with improved manoeuvrability and angulation of the instruments without using brain retraction. CONCLUSIONS: This approach poses a feasible alternative to large frontal craniotomies for frontal-lobe tumours, for which a regular supraorbital craniotomy is insufficient.

How I do it: the mononostril endonasal transethmoidal-paraseptal approach.

BACKGROUND: The use of endoscopes in transnasal surgery offers increased visualization. To minimize rhinological morbidity without restriction in manipulation, we introduced the mononostril transethmoidal-paraseptal approach. METHODS: The aim of the transethmoidal-paraseptal approach is to create sufficient space within the nasal cavity, without removal of nasal turbinates and septum. Therefore, as a first step, a partial ethmoidectomy is performed. The middle and superior turbinates are then lateralized into the ethmoidal space, allowing a wide sphenoidotomy with exposure of the central skull base. CONCLUSIONS: This minimally invasive transethmoidal-paraseptal approach is a feasible alternative to traumatic transnasal concepts with middle turbinate and extended septal resection.

The supraorbital keyhole approach: how I do it.

BACKGROUND: Improvements in image guidance, endoscopy, and instruments, have significantly advanced "keyhole" neurosurgery. We describe the concept and technique of the supraorbital keyhole approach. METHODS: The supraorbital keyhole approach is performed through an eyebrow skin incision. Image guidance may be used to define the optimal surgical trajectory. A limited supraorbital craniotomy is fashioned. The frontal lobe is mobilized and the central skull base approached, without the need for brain retractors. Endoscopy is used to enhance visualization, and tube-shaft instruments to improve manipulation through the narrow surgical corridor. CONCLUSIONS: The supraorbital keyhole approach provides a safe method to access selected skull base lesions.

Bilateral subdural hematoma caused by spontaneous intracranial hypotension originating from a discogenic microspur successfully treated with duraplasty: A case report.

Introduction: Discogenic microspurs are calcified outgrowths from the intervertebral disc which can perforate the dura, causing a leak of cerebrospinal fluid (CSF). Spontaneous leaks of the CSF present a recognized cause of spontaneous intracranial hypotension (SIH). Moreover, subdural hematomas (SDH) are a potentially severe complication of SIH. Research question: We present a case of a bilateral subdural hematoma without orthostatic headaches caused by a discogenic microspur protruding from the T1-2 intervertebral disc. The microspur is conjectured to be the culprit of the leak by ventrally perforating the dura and catalyzing the causal chain leading to the formation of the subdural hemorrhage. Material and methods: A 79-year woman noticed a progressive gait disturbance accompanied by a decline of short-term memory over several months without experiencing orthostatic headaches. Magnetic resonance imaging (MRI) showed extensive bilateral subdural fronto-parietal hematoma, signs of CSF hypotension (dilated venous compartments), and computed tomography (CT) myelography revealed a CSF leak originating at the T1-2 level. Results: The leakage site was treated with microsurgical duraplasty leading to a regression of the symptoms and complete resolution of the subdural hematomas within five postoperative months. Discussion and conclusion: Discogenic microspurs can perforate the dura causing a CSF leak, leading to spontaneous intracranial hypotension, finally resulting in a bilateral subdural hematoma. This constellation of symptoms does not necessarily induce orthostatic headaches and can be treated with microsurgical duraplasty.

Three-dimensional structure of the basal lamella of the middle turbinate.

The middle turbinate's basal lamella (3BL) is a variable landmark which needs to be understood in endoscopic transnasal skull base surgery. It comprises an anterior frontal and a posterior horizontal part and appears in its simplest depiction to be "L"-shaped, when viewed laterally. In this study we analyzed its 3D morphology and variations focusing on a precise and systematic description of the anatomy. CBCTs of 25 adults, 19 cadavers and 6 skulls (total: 100 sides) were investigated with the 3DSlicer software, creating 3D models of the 3BL. We introduced a novel geometrical classification of the 3BL's shape, based on segments. We analyzed their parameters and relationship to neighboring structures. When viewed laterally, there was no consistent "L"-shaped appearance of the 3BL, as it is frequently quoted. A classification of 9 segment types was used to describe the 3BL. The 3BLs had in average of 2.95 ± 0.70 segments (median: 3), the most frequent was the horizontal plate (23.05% of all segments), next a concave/convex plate (22.71%), then a sigma plate (22.37%). Further types were rare. We identified a horizontal plate in 68% of all lateral views whilst 32% of the 3BLs were vertical. A sigma-concave/convex-horizontal trisegmental 3BL was the most common phenotype (27%). Globally, the sigma-concave/convex pattern was present in 42%. The 3BL adhered the ethmoidal bulla in 87%. The segmenting method is eligible to describe the 3BL's sophisticated morphology.

The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

BACKGROUND: Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. METHODS: Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RESULTS: RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P < 0.001). Higher PaCO2 induced an increase in mean srvO2 from 50% to 68% (P < 0.001). RvVelo (P < 0.001) and srvO2 (P = 0.007) were higher in 8 compared with 2 mm cerebral depth. RvHb was not influenced by alterations in PaCO2 but positively correlated to sevoflurane concentration (P = 0.005). CONCLUSIONS: Increases in rvCBF and rvVelo by PaCO2 suggest preserved hypercapnic vasodilation under anesthesia with sevoflurane 1.4% and 2.0% end-tidal concentration. A consecutive increase in srvO2 implies that cerebral arteriovenous difference in oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

Virtual reality system for planning minimally invasive neurosurgery. Technical note.

OBJECT: The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. METHODS: Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. RESULTS: After a short period of acclimatization, the system proved easy to operate and is currently used routinely for preoperative planning of difficult cases at the authors' institution. It was felt that working with a virtual reality multimodal model of the patient significantly improved surgical planning. The pathoanatomy in individual patients could easily be understood in great detail, enabling the authors to determine the surgical trajectory precisely and in the most minimally invasive way. CONCLUSIONS: The authors found the preoperative 3D model to be in high concordance with intraoperative conditions; the resulting intraoperative "déjà-vu" feeling enhanced surgical confidence. In all procedures planned with the Dextroscope, the chosen surgical strategy proved to be the correct choice. Three-dimensional virtual reality models of a patient allow quick and easy understanding of complex intracranial lesions.

A case control study of statin and magnesium administration in patients after aneurysmal subarachnoid hemorrhage: incidence of delayed cerebral ischemia and mortality.

OBJECTIVE: To analyse the effect of the implementation of statin and magnesium treatment on delayed cerebral ischemia (DCI) and 14 day mortality in patients with subarachnoid hemorrhage (SAH). METHODS: Retrospective, single-center, observational case control study. One hundred SAH patients received either simvastatin and magnesium, solely statin or no treatment. RESULTS: Eighteen percent (n=5) of patients receiving statin and magnesium treatment developed a DCI whereas 24% (n=5) in the statin group and 16% (n=8) in the control group had DCI. Dead by day 14 was registered in 18% (n=5) of patients in the statin and magnesium group, in 10% (n=2) in the statin group and in 27% (n=14) in the control group. None of the results reached a statistical significance level of 0.05. CONCLUSION: A trend towards a lower mortality within 14 days in patients receiving solely simvastatin and those receiving statin and magnesium as compared with the control group was found. A higher incidence for DCI was found in the statin group, whereas patients without statin and magnesium tended to have less often DCI. None of the results was statistically significant.

Endoscopic endonasal pituitary surgery: surgical and outcome analysis of 50 cases.

OBJECTIVE: Microsurgical transsphenoidal surgery for pituitary tumors has been standard therapy for decades and was established by Harvey Cushing in the early twentieth century. Today, endoscopy is increasingly accepted in the therapy of pituitary lesions. In this retrospective study, we analysed the surgical technique and outcome of 50 patients with pituitary lesions treated with an endoscopic endonasal trans-sphenoidal approach. METHODS: Between January 2004 and July 2005, 50 patients (30 female and 20 male) with pituitary tumors were operated upon using an endoscopic endonasal trans-sphenoidal procedure without nasal speculum or postoperative nasal packing. The follow-up period ranged from 3 to 18 months. RESULTS: All patients had normal airways through both nostrils immediately after extubation. Postoperative discomfort was minimal and hospitalization was 4-5 days. Three patients developed postoperative transient diabetes insipidus, persisting in one for a further 2 months. Among the 50 patients, total tumor removal was achieved in 47 patients (94%), subtotal in two patients (4%). One patient died intraoperatively due to subarachnoid haemorrhage. CONCLUSION: The endoscopic endonasal transsphenoidal approach for removing pituitary lesions is a form of minimally invasive surgery offering excellent postoperative results.

Endoscopic unilateral transethmoid-paraseptal approach to the central skull base.

Objectives: The endoscopic technique in transnasal skull base surgery offers optimal visualization and free manipulation in the surgical field. However, it may cause approach-related sinonasal injury, influencing patients' quality of life (QOL). To minimize rhinological morbidity without restrictions in surgical manipulation and tumor resection, we introduced the unilateral transethmoidal-paraseptal approach. In this article, we analyzed the long-term results and sinonasal outcome of this technique. Study Design: Retrospective analysis of medical records. Methods: Forty-two consecutive patients underwent surgery between June 2010 and March 2014 using the transethmoid-paraseptal approach. Perioperative work-up included neurological, radiological, endocrinological, ophthalmological, and rhinological analysis. Patients' preoperative, 1-month and 1-year postoperative QOL was measured using the Sino-Nasal Outcome Test (SNOT-22). Results: At all individuals, a unilateral transethmoid-paraseptal approach was performed. Removal of the turbinates, posterior septal resection or a conversion to biportal surgery could be avoided in all cases. There were no intraoperative neurovascular complications. All patients had a notable improvement in any disease-related symptoms, as well as by objective criteria. Complete tumor resection was aimed in 39 cases and achieved in 31 of them. The SNOT-22 scores transiently worsened 1 month after surgery and non-significantly improved after 1 year, compared with the preoperative status. A subgroup of 7 patients with preoperative sinonasal disease evidence showed continuous significant improvement (p < .05) of SNOT-22 scores across time. The smell screening tests showed no significant difference across time. Conclusion: The described approach allows safe removal of various skull base lesions without deterioration in sinonasal QOL and smell function. Level of Evidence: 4.

Minimally invasive keyhole approaches in spinal intradural tumor surgery: report of two cases and conceptual considerations.

Despite their predominantly histologically benign nature, intradural tumors may become symptomatic by virtue of their space-occupying effect, causing severe neurological deficits. The gold standard treatment is total excision of the lesion; however, extended dorsal and dorsolateral approaches may cause late complications due to iatrogenic destruction of the posterolateral elements of the spine. In this article, we describe our concept of minimally invasive spinal tumor surgery. Two illustrative cases demonstrate the feasibility and safety of keyhole fenestrations exposing the spinal canal.

Endoscopic fenestration of intraventricular cerebrospinal fluid cysts: the contralateral approach.

OBJECTIVE: The endoscopic fenestration of intraventricular CSF cysts has evolved into a well-accepted treatment modality. However, definition of the optimal trajectory for endoscopic fenestration may be difficult. Distorted ventricular anatomy and poor visibility within the cyst due to its contents can make endoscopic fenestration challenging if approached from the ipsilateral side. In addition, transcortical approaches can theoretically cause injury to eloquent cortex, particularly in patients with dominant-sided lesions. The aim of this study was to examine the value of the contralateral transcortical transventricular approach in patients with dominant-sided ventricular cysts. METHODS: During a 5-year period between 2007 and 2011, 31 patients with intraventricular CSF cysts underwent surgery by the senior author (R.R.). Fourteen of these patients had cysts located on the dominant side. An image-guided endoscopic cyst fenestration via the contralateral transcortical transventricular approach was performed in 11 patients. A retrospective chart review was performed in all these patients to extract data on clinical presentation, operative technique, and surgical outcome. RESULTS: The most common presenting symptom was headache, followed by memory deficits and cognitive deterioration. In all cases CSF cysts were space occupying, with associated obstructive hydrocephalus in 8 patients. Image-guided endoscopic fenestration was successfully performed in all cases, with septum pellucidotomy necessary in 6 cases, and endoscopic third ventriculostomy in 1 case for additional aqueductal occlusion. Postoperative clinical outcome was excellent, with no associated permanent neurological or neuropsychological morbidity. No recurrent cysts were observed over a mean follow-up period of 2 years and 3 months. CONCLUSIONS: The contralateral approach to ventricular cysts can achieve excellent surgical outcomes while minimizing approach-related trauma to the dominant hemisphere. Careful case selection is essential to ensure that the contralateral endoscopic trajectory is the best possible exposure for sufficient cyst fenestration and restoration of CSF circulation.

Aneurysm Surgery with Preoperative Three-Dimensional Planning in a Virtual Reality Environment: Technique and Outcome Analysis.

OBJECTIVE: Aneurysm surgery demands precise spatial understanding of the vascular anatomy and its surroundings. We report on a decade of experience planning clipping procedures preoperatively in a virtual reality (VR) workstation and present outcomes with respect to mortality, morbidity, and aneurysm occlusion rate. METHODS: Between 2006 and 2015, the clipping of 115 intracranial aneurysms in 105 patients was preoperatively planned with the Dextroscope, a stereoscopic, patient-specific VR environment. The outcome data for all cases, planned and performed in 3 institutions, were analyzed based on clinical charts and radiologic reports. RESULTS: Eighty-five incidental, unruptured aneurysms in 77 patients were electively planned and treated surgically. Mortality was 0% and morbidity (modified Rankin Scale score >2) was 2.6%. The rate of complete aneurysm obliteration on postoperative imaging was 91.8%. In addition, 30 aneurysms were treated in 28 patients with previous subarachnoid hemorrhage. Mortality in these cases was 3.6%, morbidity (modified Rankin Scale score >2) 7.1%, and the rate of complete aneurysm clipping was 90%. CONCLUSIONS: Meticulous three-dimensional surgical planning in a VR environment enhances the surgeon's spatial understanding of the individual vascular anatomy and allows clip preselection and positioning as well as anticipation of potential difficulties and complications. VR planning was associated, in this multi-institutional series, with excellent clinical outcomes and rates of complete aneurysm closure equivalent to benchmark cohorts.

Endoscopic aqueductoplasty through a tailored craniocervical approach.

OBJECT: Neuroendoscopy has an essential role in the management of occlusive hydrocephalus due to a membranous obstruction of the sylvian aqueduct. Well-known endoscopic methods include endoscopic third ventriculostomy (ETV) and endoscopic aqueductoplasty through a frontal burr hole. Building on their experience in the endoscopic management of hydrocephalus, the authors realized that not all of their patients with aqueductal obstruction were eligible for the aforementioned lines of treatment. Certain anatomical situations made it impossible to perform ETV or endoscopic aqueductoplasty through a frontal burr hole. Long-term complications of the shunt system led the authors to seek an alternative form of treatment for these patients. In this study, they present a new endoscopic approach to performing aqueductoplasty through the fourth ventricle. METHODS: Endoscopic aqueductoplasty was performed in five patients by using a tailored craniocervical approach. In all patients a caudally located membranous obstruction of the sylvian aqueduct was present, and the authors were able to relieve the membranous obstruction in all patients without complications. All patients experienced improvement, which was demonstrated clinically and on imaging studies. CONCLUSIONS: Caudal endoscopic aqueductoplasty is a safe and effective method of treatment in the management of a caudally located membranous obstruction of the sylvian aqueduct. This should be considered as an alternative endoscopic method when other endoscopic solutions are not suitable.

Stereoscopic neuroanatomy lectures using a three-dimensional virtual reality environment.

INTRODUCTION: Three-dimensional (3D) computer graphics are increasingly used to supplement the teaching of anatomy. While most systems consist of a program which produces 3D renderings on a workstation with a standard screen, the Dextrobeam virtual reality VR environment allows the presentation of spatial neuroanatomical models to larger groups of students through a stereoscopic projection system. MATERIALS AND METHODS: Second-year medical students (n=169) were randomly allocated to receive a standardised pre-recorded audio lecture detailing the anatomy of the third ventricle accompanied by either a two-dimensional (2D) PowerPoint presentation (n=80) or a 3D animated tour of the third ventricle with the DextroBeam. Students completed a 10-question multiple-choice exam based on the content learned and a subjective evaluation of the teaching method immediately after the lecture. RESULTS: Students in the 2D group achieved a mean score of 5.19 (±2.12) compared to 5.45 (±2.16) in the 3D group, with the results in the 3D group statistically non-inferior to those of the 2D group (p<0.0001). The students rated the 3D method superior to 2D teaching in four domains (spatial understanding, application in future anatomy classes, effectiveness, enjoyableness) (p<0.01). CONCLUSION: Stereoscopically enhanced 3D lectures are valid methods of imparting neuroanatomical knowledge and are well received by students. More research is required to define and develop the role of large-group VR systems in modern neuroanatomy curricula.

Surgical technique of the supraorbital key-hole craniotomy.

BACKGROUND: The enormous development of microsurgical techniques and instrumentation together with preoperative planning using the excellent preoperative diagnostic facilities available, enables neurosurgeons to treat more complicated diseases through smaller and more specific approaches. METHODS: The technical details of the supraorbital key-hole craniotomy are described in this article as it has been evolving in our experience for more than 10 years. After an eyebrow skin incision with careful soft tissue dissection and single frontobasal burr-hole trephination, a supraorbital craniotomy is carried out with a diameter of about 1.5 x 2.5 cm. As a real frontolateral approach, the supraorbital craniotomy avoids removal of the orbital rim, the lesser sphenoid wing or the zygomatic arch. RESULTS AND CONCLUSIONS: The supraorbital craniotomy allows wide intracranial exposure of the deep-seated supra- and parasellar region, according to the concept of key-hole approaches. The limited craniotomy requires minimal brain retraction thus significantly decreasing approach-related morbidity. In addition, the short skin incision within the eyebrow, the careful soft tissue dissection, and the single burr hole trephination result in a pleasing cosmetic outcome.

[Endosonographic anatomy of the ventricular system]. / A kamrarendszer endoszonográfiás anatómiája.

A preclinical cadaver study was performed to test a transendoscopic sonographic probe for neurosurgery. In 25 fresh post-mortem adult human cadaver with a total of 39 endo-sonographic dissections in the ventricular system were carried out. A sonograph with an outer diameter of 6 F was used and radial sonograms were made by a real-time image technique. First results showed precise imaging, comparable to a CT in a neighbouring area of 3 cm. In this publication, the authors describe the endo-neurosonographic anatomy of the ventricular system. The sonographic probe was advanced through the working canal of a ventriculoscope, then the endoscopic and sonographic imaging were compared. Results were documented by parallel sonographic and endoscopic photo and video recordings. Based on the authors experience, it is revealed that the additional sonographic view could also be used as a navigation tool.

[Biportal neuroendoscopy of the prepontine cisterns]. / A praepontin ciszternák biportalis neuroendoszkópiája.

INTRODUCTION: While bi- or multiportal approaches have been adopted in different fields of surgery including abdominal and spine surgery, the uniportal access into the skull is a traditional principle in neurosurgery. In this preclinical cadaver study the authors developed combinations of biportal endoneurosurgical dissections in the prepontine subarachnoid space to test the safety of this technique. METHODS: In 34 fresh post-mortem adult human cadavers and 14 formaldehyde-fixed adult human head specimen a total of 48 biportal endoscopical dissections were carried out. 0 degree, 30 degrees, and 70 degrees lens scopes with a diameter of 1.7 and 4.2 mm and trochars with a diameter of 5.0 to 6.5 mm were used. RESULTS: Six different endoscopic routes to the prepontine region and a total of 10 different combinations of this approaches could be described. Useful and safe biportal combinations were: 1. supraorbital on both sides, 2. supraorbital combined with ipsilateral anterior subtemporal, 3. supraorbital combined with contralateral anterior subtemporal, 4. supraorbital combined with ipsilateral posterior subtemporal, 5. supraorbital combined with ipsilateral frontal interhemispheric, 6. supraorbital combined with contralateral frontal interhemispheric, 7. anterior subtemporal combined with ipsilateral frontal interhemispheric, 8. anterior subtemporal combined with contralateral frontal interhemispheric. CONCLUSION: The biportal endomicrosurgical strategy offered effective and safe dissections within the prepontine subarachnoid space.