Extended endoscopic endonasal approaches for cerebral aneurysms: anatomical, virtual reality and morphometric study

Is It Time for a Paradigm Shift in the Surgical Management of Trigeminal Schwannomas? Evaluating the Role of the Transorbital Approach: An Anatomo-Clinical Study and Systematic Literature Review

BACKGROUND

Endoscopic transorbital approach emerged in recent years as an effective, minimally invasive route to access Meckel's cave area. Several case series proved its effectiveness in the surgical treatment of trigeminal schwannomas. This route provides the advantages of a minimally invasive approach associated with low morbidity rates. In this anatomo-clinical study we illustrate the usefulness of the superior eyelid transorbital approach for the surgical treatment of trigeminal schwannoma guiding the clinical applicability of the anatomical findings into real surgical practice.

METHODS

Superior eyelid transorbital endoscopic approach was performed on 8 cadaveric specimens, and the surgical results were confirmed in a retrospective review of all the surgical cases of transorbital surgery performed by the senior authors providing an illustrative case. Finally, we performed a literature review of all the case series of trigeminal schwannomas operated through an endoscopic transorbital approach.

RESULTS

Stepwise dissection was divided in 3 phases: skin, endo-orbital, and endocranial. The illustrative case provided demonstrate gross total resection of a cavernous sinus type trigeminal schwannomas treated through this route. Literature review revealed 68 cases of trigeminal schwannomas that were successfully treated using the transorbital approach.

CONCLUSIONS

The endoscopic transorbital approach may offer a valuable alternative for the surgical treatment of trigeminal schwannomas. This technique provides a minimally invasive, direct and natural "interdural" route to the lateral wall of the cavernous sinus and Meckel's cave.

Application of virtual and mixed reality for 3D visualization in intracranial aneurysm surgery planning: a systematic review

Background

Precise preoperative anatomical visualization and understanding of an intracranial aneurysm (IA) are fundamental for surgical planning and increased intraoperative confidence. Application of virtual reality (VR) and mixed reality (MR), thus three-dimensional (3D) visualization of IAs could be significant in surgical planning. Authors provide an up-to-date overview of VR and MR applied to IA surgery, with specific focus on tailoring of the surgical treatment.

Methods

A systematic analysis of the literature was performed in accordance with the PRISMA guidelines. Pubmed, and Embase were searched to identify studies reporting use of MR and VR 3D visualization in IA surgery during the last 25 years. Type and number of IAs, category of input scan, visualization techniques (screen, glasses or head set), inclusion of haptic feedback, tested population (residents, fellows, attending neurosurgeons), and aim of the study (surgical planning/rehearsal, neurosurgical training, methodological validation) were noted.

Results

Twenty-eight studies were included. Eighteen studies (64.3%) applied VR, and 10 (35.7%) used MR. A positive impact on surgical planning was documented by 19 studies (67.9%): 17 studies (60.7%) chose the tailoring of the surgical approach as primary outcome of the analysis. A more precise anatomical visualization and understanding with VR and MR was endorsed by all included studies (100%).

Conclusion

Application of VR and MR to perioperative 3D visualization of IAs allowed an improved understanding of the patient-specific anatomy and surgical preparation. This review describes a tendency to utilize mostly VR-platforms, with the primary goals of a more accurate anatomical understanding, surgical planning and rehearsal.

Endoscopic endonasal approach for simultaneously treating a pituitary adenoma coexisting with a paraclinoid aneurysm: illustrative case

BACKGROUND

There is a certain incidence of pituitary adenomas coexisting with intracranial aneurysms, but a concurrent therapeutic strategy of tumor removal and aneurysm clipping via endoscopic endonasal approach is rarely reported. The indications and limitations of endoscopic endonasal approach surgery for this type of lesions are worth discussing.

OBSERVATIONS

The case of a pituitary tumor coexisting with a paraclinoid aneurysm was reviewed. Using an endoscopic endonasal approach, the pituitary adenoma was completely excised with extrapseudocapsular separation technique, the aneurysm was clipped at the same time, and the skull base defect was reconstructed in multilayer fashion. No tumor recurrence was found, and aneurysm clipping was complete at the 6-month follow-up after surgery.

LESSONS

For patients harboring a pituitary adenoma with a selected paraclinoid aneurysm, simultaneous tumor resection and aneurysm clipping via endoscopic endonasal approach are feasible. This strategy has the advantages of saving medical resources, promoting the patient’s rapid postoperative recovery, and reducing possible antiplatelet therapy after interventional therapy. However, surgery needs to strictly follow the indications in experienced hands, and the therapeutic effect needs to be verified by more cases and longer follow-up results.

Virtual Reality in the Neurosciences: Current Practice and Future Directions

Virtual reality has made numerous advancements in recent years and is used with increasing frequency for education, diversion, and distraction. Beginning several years ago as a device that produced an image with only a few pixels, virtual reality is now able to generate detailed, three-dimensional, and interactive images. Furthermore, these images can be used to provide quantitative data when acting as a simulator or a rehabilitation device. In this article, we aim to draw attention to these areas, as well as highlight the current settings in which virtual reality (VR) is being actively studied and implemented within the field of neurosurgery and the neurosciences. Additionally, we discuss the current limitations of the applications of virtual reality within various settings. This article includes areas in which virtual reality has been used in applications both inside and outside of the operating room, such as pain control, patient education and counseling, and rehabilitation. Virtual reality's utility in neurosurgery and the neurosciences is widely growing, and its use is quickly becoming an integral part of patient care, surgical training, operative planning, navigation, and rehabilitation.

Anatomic feasibility of endoscopic endonasal intracranial aneurysm clipping: a systematic review of anatomical studies

Clinical studies have suggested the endoscopic endonasal approach (EEA) for aneurysm clipping as a feasible way to treat select intracranial aneurysms. Among neurosurgery, there is not a consensus on the utility of EEA aneurysm clipping. This review aims to define the anatomic feasibility of EEA for aneurysm clipping. Two databases (PubMed, Cochrane) were searched for anatomical studies assessing EEA for intracranial aneurysm clipping. Literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quantitative anatomical studies were included. Eleven studies met inclusion criteria. Vascular exposure and clip placement on vessels of interest were possible, although only one study assessed these parameters with physical aneurysm models. Anterior circulation vessels, although accessible in over 90% of specimens, had low successful clipping rates in a small and large aneurysm models. Small and large model posterior circulation aneurysms were more readily clipped. Proximal and distal controls were readily attainable in posterior circulation aneurysms, but not anterior. This current literature review highlights the relevance of anatomical studies in assessing the feasibility of the EEA for clipping intracranial aneurysms. As such, anterior circulation aneurysms are poor candidates for EEA given difficulties in clip placement and obtaining proximal control and distal control in small and large aneurysms. While our results suggest that clipping of posterior circulation aneurysms is feasible from a technical stand of view, further clinical experience is required to assess its feasibility in terms of safety and efficacy, balancing the indications with endovascular treatment options.

Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Posterior circulation aneurysms are difficult to treat with the current methods of coiling and clipping. To address limitations in training, we developed a cadaveric model to train learners on endoscopic clipping of posterior circulation aneurysms. An endoscopic transclival approach (ETA) and a transorbital precaruncular approach (TOPA) to successfully access and clip aneurysms of the posterior circulation are described. The model has flexibility in that a colored silicone compound can be injected into the cadaveric vessels for the purpose of training learners on vascular anatomy. The other option is that the model could be connected to a vascular perfusion pump allowing real-time appreciation of a pulsatile or ruptured aneurysm. This cadaveric model is the first of its kind for training of endoscopic clipping of posterior circulation aneurysms. Learners will develop proficiency in endoscopic skills, appropriate dissection, and appreciation for relative anatomy while developing an algorithm that can be employed in a real operative arena. Going forward, various clinical scenarios can be developed to enhance the realism, allow learners from different specialties to work together, and emphasize the importance of teamwork and effective communication.

Endoscopic Endonasal Approach for Clipping Anterior Communicating Artery Aneurysms From Cadaver Studies and Three-Dimensional Printed Models to a Clinical Case

OBJECTIVES

Anterior communicating artery (ACoA) aneurysm is one of the most common intracranial aneurysms, and it is also the aneurysm with the highest rupture rate. With the improvement of endoscopic techniques, it is possible to use an endoscopic endonasal approach (EEA) to clip ACoA aneurysms. For further analysis of the EEA for clipping ACoA aneurysms, we used cadaver heads and three-dimensional (3D)-printed models to finish the anatomical study, and we finally selected 1 clinical case to complete the clipping through the EEA.

MATERIALS AND METHODS

We first collected 3 cadaver heads to simulate the EEA. Then, the imaging data of 29 real cases of ACoA aneurysm were collected, and the model of an aneurysm was prepared by 3D printing technology; then, the EEA was used to simulate the clipping of the aneurysm model. Finally, a clinical case with 2 ACoA aneurysms was selected to adopt the EEA for clipping.

RESULTS

Both the cadaver head and 3D-printed aneurysm model could simulate aneurysm clipping with the EEA. The clinical case of the selected ACoA aneurysm can successfully complete the clipping through the EEA.

CONCLUSIONS

3D-printed models are a good method to study the anatomical characteristics of a surgical approach. For specially selected ACoA aneurysms, the EEA is relatively simple method that can be used to clip the aneurysm successfully. The EEA for clipping ACoA aneurysms is a useful complement to the current traditional craniotomy approaches and endovascular embolization.

A Cadaveric Anatomical Study on Anterior Communicating Artery Aneurysm Surgery by Extended Endoscopic Endonasal Approach

Background:

The use of minimally invasive approaches in the management of cerebral aneurysms continues to evolve and a purely endoscopic endonasal approach (EEA) for cerebral aneurysm has its own advantages. The purpose of the present study is to perform a detailed anatomical dissection study to test the usefulness of the extended EEAs for selected anterior communicating artery (ACoA) aneurysm.

Materials and Methods:

Nine human cadaveric heads were used for this study, and all dissections were performed through the endonasal corridor. Endoscopic endonasal surgical dissections were carried out, and surgery was simulated in all specimens to reach the ACoA region. The ACoA complex, its neural and osseous relations, degree of vascular exposure, and the ability to perform clip placement were observed and analyzed.

Results:

The transplanum and transtuberculum approaches exposed the A1 and A2 segments of the anterior cerebral artery and the ACoA in all specimens. This route allowed clip ligation of the distal A1 branches, ACoA and proximal A2 branches to the level of the pericallosal segment. Proximal and distal control was most readily achievable at the level of the ACoA complex.

Conclusion:

The present cadaveric study on nine specimens with bilateral dissection has demonstrated that the endonasal transplanum transtuberculum approach to the ACoA region provides excellent visualization of the vasculature. When selected prudently, such lesions may be favorable targets for an extended endoscopic endonasal (EEA) in comparison to transcranial approaches that may provide a suboptimal exposure.

Anatomical assessment of the endoscopic endonasal approach for the treatment of paraclinoid aneurysms

OBJECTIVE

Endoscopic endonasal approaches (EEAs) are increasingly being incorporated into the neurosurgeon's armamentarium for treatment of various pathologies, including paraclinoid aneurysms. However, few anatomical assessments have been performed on the use of EEA for this purpose. The aim of the present study was to provide a comprehensive anatomical assessment of the EEA for the treatment of paraclinoid aneurysms.

METHODS

Five cadaveric heads underwent an endonasal transplanum-transtuberculum approach to expose the paraclinoid area. The feasibility of obtaining proximal and distal internal carotid artery (ICA) control as well as the topographic location of the origin of the ophthalmic artery (OphA) relative to dural landmarks were assessed. Limitations of the EEA in exposing the supraclinoid ICA were also recorded to identify favorable paraclinoid ICA aneurysm projections for EEA.

RESULTS

The extracavernous paraclival and clinoidal ICAs were favorable segments for establishing proximal control. Clipping the extracavernous ICA risked injury to the trigeminal and abducens nerves, whereas clipping the clinoidal segment put the oculomotor nerve at risk. The OphA origin was found within 4 mm of the medial opticocarotid point on a line connecting the midtubercular recess point to the medial vertex of the lateral opticocarotid recess. An average 7.2-mm length of the supraclinoid ICA could be safely clipped for distal control. Assessments showed that small superiorly or medially projecting aneurysms were favorable candidates for clipping via EEA.

CONCLUSIONS

When used for paraclinoid aneurysms, the EEA carries certain risks to adjacent neurovascular structures during proximal control, dural opening, and distal control. While some authors have promoted this approach as feasible, this work demonstrates that it has significant limitations and may only be appropriate in highly selected cases that are not amenable to coiling or clipping. Further clinical experience with this approach helps to delineate its risks and benefits.

Extended Endoscopic Endonasal Clipping of Intracranial Aneurysms: An Anatomic Feasibility Study

BACKGROUND

Intracranial aneurysms (IAs) located in the midline region represent formidable challenge owing to their deep location. The objective of this study was to assess feasibility and identify the limitations of endoscopic endonasal clipping of IAs. We further aimed to describe the locations and characteristics of aneurysms that may be amenable for endoscopic endonasal clipping; thus outlining the indications of these approaches.

METHODS

Fifteen latex-injected cadaveric heads were used for endoscopic endonasal exposure of anterior and posterior cerebral circulations. An aneurysm simulator model with 2 different sizes was used at the common sites for IAs to emulate a real surgery. Key measured parameters included "exposure of vessels and their respective perforators," "ability to gain proximal/distal control," and "possibility of clip placement" according to the size, direction, and location of the aneurysm model. Maneuverability of instruments and the need for pituitary gland transposition were assessed and recorded as well.

RESULTS

Exposure of the anterior communicating artery complex and the common sites of posterior circulation aneurysms were feasible. The size, location, and direction of the aneurysm model had an impact on obtaining proximal and/or distal control, and the ability of clip placement.

CONCLUSIONS

Clipping of midline aneurysms of the posterior circulation is feasible via endoscopic endonasal approach. Small-sized ventrally and medially directed aneurysm models carried a better probability of getting proximal and/or distal control, as well as better overall ability to place a clip. The endonasal route seems to provide a limited condition for proper management of anterior circulation aneurysms.

Assessment of the endoscopic endonasal approach to the basilar apex region for aneurysm clipping

OBJECTIVE

The expanded endoscopic endonasal approach (EEA) has shown promising results in treatment of midline skull base lesions. Several case reports exist on the utilization of the EEA for treatment of aneurysms. However, a comparison of this approach with the classic transcranial orbitozygomatic approach to the basilar apex (BAX) region is missing.The present study summarizes the results of a series of cadaveric surgical simulations for assessment of the EEA to the BAX region for aneurysm clipping and its comparison with the transcranial orbitozygomatic approach as one of the most common approaches used to treat BAX aneurysms.

METHODS

Fifteen cadaveric specimens underwent bilateral orbitozygomatic craniotomies as well as an EEA (first without a pituitary transposition [PT] and then with a PT) to expose the BAX. The following variables were measured, recorded, and compared between the orbitozygomatic approach and the EEA: 1) number of perforating arteries counted on bilateral posterior cerebral arteries (PCAs); 2) exposure and clipping lengths of the PCAs, superior cerebellar arteries (SCAs), and proximal basilar artery; and 3) surgical area of exposure in the BAX region.

RESULTS

Except for the proximal basilar artery exposure and clipping, the orbitozygomatic approach provided statistically significantly greater values for vascular exposure and control in the BAX region (i.e., exposure and clipping of ipsilateral and contralateral SCAs and PCAs). The EEA with PT was significantly better in exposing and clipping bilateral PCAs compared to EEA without a PT, but not in terms of other measured variables. The surgical area of exposure and PCA perforator counts were not significantly different between the 3 approaches. The EEA provided better exposure and control if the BAX was located ≥ 4 mm inferior to the dorsum sellae.

CONCLUSIONS

For BAX aneurysms located in the retrosellar area, PT is usually required to obtain improved exposure and control for the bilateral PCAs. However, the transcranial approach is generally superior to both endoscopic approaches for accessing the BAX region. Considering the superior exposure of the proximal basilar artery obtained with the EEA, it could be a viable option when surgical treatment is considered for a low-lying BAX or mid-basilar trunk aneurysms (≥ 4 mm inferior to dorsum sellae).

Measurements and Clinical Application of Anatomical Space for Transfrontal Pituitary Surgery Through Magnetic Resonance Imaging Reconstruction

OBJECTIVE

This study aims to clarify the relative position of the normal important structures and anatomical spaces formed by the structures passed through during the transfrontal pituitary surgery, and discuss how to avoid some eloquent structures.

METHODS

A total of 120 cases of magnetic resonance imaging images from normal adult brains were selected as the object of study and divided into male and female groups. The important adjacent structures of the pituitary passed through during the transfrontal pituitary surgery were marked on the reconstructed images. In all planes of the spaces passing through successively during the pituitary surgery, the morphological parameters such as the size, boundary, structure, and spatial extent of the spaces were measured.

RESULTS

The size, boundary, structure, and spatial extent of the space between the 2 optic nerves, the space between the optic nerves and the pituitary stalk, and the space between the tuber cinereum and the interal carotid artery in the plane of the pituitary stalk were measured, the anterior part and the posterior part in male were shorter than those in female (P = 0.021; P = 0.029); no statistically significant difference was found in the measurements of the lengths and angles of these spaces.

CONCLUSIONS

The authors' findings provide the surgeons with the detailed anatomical data and help to provide a morphological basis for intraoperative protection of the pituitary and vital adjacent structures and surgical approach.

Morphometric Analysis of Rat Spinal Cord Angioarchitecture by Phase Contrast Radiography: From 2D to 3D Visualization

STUDY DESIGN

An advanced imaging of vasculature with synchrotron radiation X-ray in a rat model.

OBJECTIVE

To develop the potential for quantitative assessment of vessel network from two-dimensional (2D) to 3D visualization by synchrotron radiation X-ray phase contrast tomography (XPCT) in rat spinal cord model.

SUMMARY OF BACKGROUND DATA

Investigation of microvasculature contributes to the understanding of pathological development of spinal cord injury. A few of X-ray imaging is available to visualize vascular architecture without usage of angiography or invasive casting preparation.

METHODS

A rat spinal cord injury model was produced by modified Allen method. Histomorphometric detection was simultaneously analyzed by both histology and XPCT from 2D to 3D visualization. The parameters including tissue lesion area, microvessel density, vessel diameter, and frequency distribution of vessel diameter were evaluated.

RESULTS

XPCT rendered the microvessels as small as capillary scale with a pixel size of 3.7 μm. It presented a high linear concordance for characterizing the 2D vascular morphometry compared with the histological staining (r = 0.8438). In the presence of spinal cord injury model, 3D construction quantified the significant angioarchitectural deficiency in the injury epicenter of cord lesion (P<0.01).

CONCLUSION

XPCT has a great potential to detect the smallest vascular network with pixel size up to micron dimension. It is inferred that the loss of abundant microvessels (≤40 μm) is responsible for local ischemia and neural dysfunction. XPCT holds a promise for morphometric analysis from 2D to 3D imaging in experimental model of neurovascular disorders.

LEVEL OF EVIDENCE

N/A.

Endoscopic Endonasal Clipping of Anterior Circulation Aneurysm: Surgical Techniques and Results

BACKGROUND

Endoscopic endonasal clipping of intracranial aneurysms may use microsurgical techniques as an alternative to the transcranial approach. Here we report a series of patients who underwent microsurgical clipping of anterior circulation aneurysms via an endoscopic endonasal approach (EEA).

METHODS

This retrospective chart review included all the patients who underwent standard binostril EEA for aneurysm clipping. Surgical outcomes and complications are noted. The rationality and limitations of this procedure are discussed.

RESULTS

Seven patients with 12 aneurysms of the anterior circulation underwent EEA for clipping. These 12 aneurysms consisted of 5 anterior communicating artery (AComA) aneurysms, 4 paraclinoid aneurysms, 1 ophthalmic artery aneurysm, and 2 aneurysm located in the cavernous segment of internal carotid artery (ICA). Nine of the 12 aneurysms were successfully clipped. One giant paraclinoid aneurysm could not be clipped during operation and was coiled in second endovascular stage. The 2 aneurysms located in the cavernous segment of ICA were not clipped intentionally in a single-stage procedure, after weighing the surgical benefit against the difficulty of surgical exposure and feasibility. The proximal control of ICA was achieved in all cases. There was no death, no cerebrospinal fluid leak, or other complications. All patients recovered completely.

CONCLUSIONS

EEA can provide direct access for microsurgical clipping of strictly selected anterior circulation aneurysms. All the principles of cerebrovascular surgery must be followed. These procedures require a long learning curve. Only teams with adequate experience in microvascular and endoscopic skull base surgeries should attempt this approach for treating aneurysms.

A pilot study of a cardiovascular virtual endoscopy system based on multi-detector computed tomography in diagnosing tetralogy of Fallot in pediatric patients

The present study aimed to investigate the capabilities of the cardiovascular virtual endoscopy (VE) system in diagnosing tetralogy of Fallot (TOF) and performing measurements. A total of 37 patients underwent two-dimensional echocardiography (2-DE) and multi-detector computed tomography (MDCT) examinations. The obtained MDCT images were applied to a cardiovascular VE system. Diagnostic time by VE was first studied and compared with MDCT. Subsequently, with surgical findings as the ground truth, the capabilities of VE, 2-DE and MDCT in diagnosing TOF and its complications were investigated. Additionally, measurements on aorta overriding ratio and diameters for the left pulmonary artery, right pulmonary artery and right ventricular outflow tract by 2-DE and VE were analyzed. Diagnostic time by VE was significantly shorter than MDCT (188±42 vs. 303±42 sec, respectively; P<0.0001). VE, MDCT and 2-DE demonstrated comparable diagnostic rates of TOF (35/37 vs. 34/37 vs. 32/37, respectively; P>0.05). Similar findings were demonstrated in diagnosing complications of the muscular ventricular septal defects, patent ductus arteriosus, vagus subclavian artery, right arch, double superior vena cava and pulmonary artery. Furthermore, in diagnosing the atrial septal defect, 2-DE outperformed MDCT and VE (accuracy, 100 vs. 81 vs. 73%, respectively; all P<0.05). In performing relevant measurements, VE outperformed MDCT and 2-DE, particularly in accessing aorta overriding ratios with no intra-operator difference (P=0.3770) and high consistency (r=0.916). In conclusion, cardiovascular VE was demonstrated to have acceptable accuracy in diagnosing TOF, and possess advantages in shortening the diagnostic time and in performing measurements.

Endoscopic Endonasal Transclival Approach versus Dual Transorbital Port Technique for Clip Application to the Posterior Circulation: A Cadaveric Anatomical and Cerebral Circulation Simulation Study

Purpose  Simulation training offers a useful opportunity to appreciate vascular anatomy and develop the technical expertise required to clip intracranial aneurysms of the posterior circulation. Materials and Methods  In cadavers, a comparison was made between the endoscopic transclival approach (ETA) alone and a combined multiportal approach using the ETA and a transorbital precaruncular approach (TOPA) to evaluate degrees of freedom, angles of visualization, and ergonomics of aneurysm clip application to the posterior circulation depending on basilar apex position relative to the posterior clinoids. Results  ETA alone provided improved access to the posterior circulation when the basilar apex was high riding compared with the posterior clinoids. ETA + TOPA provided a significantly improved functional working area for instruments and visualization of the posterior circulation for a midlevel basilar apex. A single-shaft clip applier provided improved visualization and space for instruments. Proximal and distal vascular control and feasibility of aneurysmal clipping were demonstrated. Conclusions  TOPA is a medial orbital approach to the central skull base; a transorbital neuroendoscopic surgery approach. This anatomical simulation provides surgical teams an alternative to the ETA approach alone to address posterior circulation aneurysms, and a means to preoperatively prepare for intraoperative anatomical and surgical instrumentation challenges.

Pure Endoscopic Endonasal Clipping of an Incidental Anterior Communicating Artery Aneurysm

Anterior communicating artery (AcoA) aneurysm is the most common form of intracranial aneurysm. It occurs rarely together with other intracranial lesion. Today, microsurgical techniques and endovascular methods are used in the treatment of these aneurysms. Endoscopic endonasal approach is a useful technique for midline lesions of the skull base and is underpinned with extensive experience. In this article, we present a 72-year-old female patient who underwent endoscopic endonasal transplanum-transtubercular surgery for tuberculum sellae meningioma followed by clipping of the incidental AcoA aneurysm. After complete removal of a tuberculum sellae meningioma via an endoscopic endonasal approach, an anterior and superior projected saccular AcoA aneurysm in the gyrus rectus area was totally clipped successfully via pure endoscopic endonasal transplanum-transtubercular approach, without any damage to parent arteries. The patient was discharged from the hospital within a short period of time without any postoperative complication. Endoscopic endonasal approach is a new paradigm in the treatment of aneurysm. Although this technique cannot be routinely used due to lack of experience, it is an effective and safe method in selected and anatomically appropriate cases. We believe that increased knowledge and experience will create successful results in this approach, and it can offer an alternative method for selected aneurysm cases.

The Expanded Endoscopic Endonasal Approach to Anterior Communicating Artery Aneurysms: A Cadaveric Morphometric Study

OBJECTIVE

The purpose of this study was to explore the endoscopic endonasal approach to the anterior communicating artery complex.

DESIGN

Anatomic, morphometric analysis of human cadaver heads.

SUBJECTS

Fifteen latex-injected adult cadaver heads.

MAIN OUTCOME MEASURES

The anatomic boundaries of the operative field and the dimensions of exposure of the anterior communicating artery (ACoA) complex were measured and clip placement feasibility was assessed.

RESULTS

Exposure of the ACoA and bilateral A1 and A2 segments was accomplished in all 15 cadaver heads. Average length of the exposed ACoA was 3 ± 1 mm, the left A1 was 5 ± 3 mm and right A1 was 5 ± 1 mm, while the A2 segment was 5 ± 2 mm bilaterally. The average distance from the alar floor to the ACoA was 95 mm, while proximal lateral limit measured between the alar floor margins was 36 mm. The distal lateral limit as defined by the distance between the lateral most exposed margins of the chiasm was 19 mm. Clip placement was accomplished for the ACoA and the A1 and A2 segments bilaterally in all specimens.

CONCLUSION

The endoscopic, endonasal transtuberculum, transplanum approach is an anatomically feasible alternative to treating select aneurysms of the ACoA complex.

Using the Endoscopic Endonasal Transclival Approach to Access Aneurysms Arising from AICA, PICA, and Vertebral Artery: An Anatomical Study

Objective To explore the use of the endoscopic endonasal transclival approach (EEA) for clipping anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery (PICA), and vertebral artery (VA) aneurysms. Design Anatomical study. Participants Fifteen adult cadavers. Main Outcome Measures Length of artery exposed and distance from the nasal ala to the arteries. Results The length of the right and left VA exposed were 1.7 ± 0.6 cm and 1.6 ± 0.6 cm, respectively. The distance to the right VA was 11.1 ± 0.9 cm and to the left was 11.1 ± 0.8 cm. Right and left AICA were exposed for an average length of 1.1 ± 0.3 cm and 0.8 ± 0.3 cm, respectively. The distance to the right AICA was 10.3 ± 0.8 cm and to the left was 10.3 ± 0.8 cm. The right PICA was exposed for a length of 0.5 ± 0.2 cm at a distance of 10.9 ± 0.5 cm. The left PICA was exposed for a length of 0.5 ± 0.2 cm at a distance of 11.1 ± 0.9 cm. Conclusion The EEA can provide direct access to AICA, PICA, and VA, making it a potential alternative to the traditional approaches for the clipping of aneurysms arising from those arteries.

Virtual reality cerebral aneurysm clipping simulation with real-time haptic feedback

BACKGROUND

With the decrease in the number of cerebral aneurysms treated surgically and the increase of complexity of those treated surgically, there is a need for simulation-based tools to teach future neurosurgeons the operative techniques of aneurysm clipping.

OBJECTIVE

To develop and evaluate the usefulness of a new haptic-based virtual reality simulator in the training of neurosurgical residents.

METHODS

A real-time sensory haptic feedback virtual reality aneurysm clipping simulator was developed using the ImmersiveTouch platform. A prototype middle cerebral artery aneurysm simulation was created from a computed tomographic angiogram. Aneurysm and vessel volume deformation and haptic feedback are provided in a 3-dimensional immersive virtual reality environment. Intraoperative aneurysm rupture was also simulated. Seventeen neurosurgery residents from 3 residency programs tested the simulator and provided feedback on its usefulness and resemblance to real aneurysm clipping surgery.

RESULTS

Residents thought that the simulation would be useful in preparing for real-life surgery. About two-thirds of the residents thought that the 3-dimensional immersive anatomic details provided a close resemblance to real operative anatomy and accurate guidance for deciding surgical approaches. They thought the simulation was useful for preoperative surgical rehearsal and neurosurgical training. A third of the residents thought that the technology in its current form provided realistic haptic feedback for aneurysm surgery.

CONCLUSION

Neurosurgical residents thought that the novel immersive VR simulator is helpful in their training, especially because they do not get a chance to perform aneurysm clippings until late in their residency programs.

The endonasal approach for treatment of cerebral aneurysms: A critical review of the literature

The last two decades of neurosurgery have seen flourishing use of the endonasal approach for the treatment of skull base tumors. Safe and effective resections of neoplasms requiring intracranial arterial dissection have been performed using this technique. Recently, there have been a growing number of case reports describing the use of the endonasal approach to surgically clip cerebral aneurysms. We review the use of these approaches in intracranial aneurysm clipping and analyze its advantages, limitations, and consider future directions. Three major electronic databases were queried using relevant search terms. Pertinent case studies of unruptured and ruptured aneurysms were considered. Data from included studies were analyzed. 8 case studies describing 9 aneurysms (4 ruptured and 5 unruptured) treated by the endonasal approach met inclusion criteria. All studies note the ability to gain proximal and distal control and successful aneurysm obliteration was obtained for 8 of 9 aneurysms. 1 intraoperative rupture occurred and was controlled, and delayed complications of cerebrospinal fluid leak, vasospasm, and hydrocephalus occurred in 1, 1, and 2 patients, respectively. Described limitations of this technique include aneurysm orientation and location, the need for lower profile technology, and challenges with handling intraoperative rupture. The endonasal approach for clipping of intracranial aneurysms can be an effective approach in only very select cases as demonstrated clinically and through cadaveric exploration. Further investigation with lower profile clip technology and additional studies need to be performed. Options of alternative therapy, limitations of this approach, and team experience must first be considered.