Value of high-definition imaging in neuroendoscopy

Neuroendoscopic Surgery for Intraventricular Cavernous Malformations: A Review on Indications and Surgical Considerations

BACKGROUND

Intraventricular cavernous malformations (IVCs) are rare vascular lesions of the central nervous system. Surgical resection remains a challenging endeavor, with conventional microsurgical techniques associated with morbidity due to direct brain tissue manipulation. Neuroendoscopic approaches offer a minimally invasive alternative, though their efficacy and safety in treating IVCs remain underexplored.

METHODS

A narrative review was conducted to analyze all documented cases of IVCs treated exclusively with endoscopic transventricular approaches. Reviews, original research papers, and case reports published from 1990 to May 2024 were included. When available, surgical videos were also reviewed.

RESULTS

Seventeen patients with IVCs primarily located in the foramen of Monro were identified. The mean size of the IVCs was 17 mm (range: 7-29 mm). Neuroendoscopic procedures achieved gross total resection in all cases, leading to the resolution of clinical symptoms. Except for one patient who experienced memory impairment postsurgery, no persistent neurological dysfunctions were observed. Intraoperative bleeding, a significant challenge in IVC resection, was managed with continuous warm irrigation and dedicated coagulation instruments. Additionally, 6 cases of neuroendoscopic procedures such as endoscopic third ventriculostomy and septum pellucidotomy were reported for managing hydrocephalus.

CONCLUSIONS

Neuroendoscopic surgery offers several advantages in treating IVCs, including minimally invasive access, precise visualization, and reduced brain tissue manipulation. Our findings support the efficacy and safety of endoscopic transventricular approaches, underscoring its potential as a valuable therapeutic strategy for selected IVCs.

The Future of Neuroendoscopy: Looking Ahead Through a Lens

Neuroendoscopy has progressed remarkably in the past few decades. Ventriculoscopy, skull base endoscopy, and spinal endoscopy are now part of routine practice in the neurosurgical treatment of numerous pathologies. Like other developing fields, however, it faces numerous challenges and obstacles that must be overcome for the field to continue to evolve and expand. This brief review of new and exciting developments in neuroendoscopy describes some of the most interesting directions the field is starting to steer towards.

Neuroendoscopy: history, endoscopes, and instrumentation

INTRODUCTION

Endoscopy was first employed in the surgical treatment of neurosurgical diseases early in the twentieth century, but did not become an established practice for a long time, mainly because of poor technology and clinical results. After a slow re-appearance in the 1980s, the 1990s saw an explosion of techniques and instrumentation. Continuing technological improvement has led to further expansion of surgical techniques and indications for use of neuroendoscopy.

DISCUSSION

The expansion of ventricular endoscopy has led to significant understanding of CSF disorders. Aqueduct stenosis as cause of hydrocephalus and arachnoid cysts are an example of pathologies, the concept and understanding of which now is considerably enhanced, due to the application of neuroendoscopy in their treatment. Management of loculated hydrocephalus has been facilitated considerably with the use of the endoscope. The concepts of aqueductoplasty, septostomy, and foraminoplasty of the foramina of Monro and Magendie emerged, which were previously unknown. Skull base surgery, especially surgery for craniopharyngioma, has seen dramatic improvement in results with the use of the endoscope. Coupling of the endoscope with neuronavigation has expanded technical capabilities even further. Overall, we can do a lot more with the endoscope now in comparison to 30 years ago.

CONCLUSION

We should always remember that the endoscope is only a tool. Its use has indications and limitations related to its design and our ability to extract the maximum, in the context of its shortcomings. Further technological advances will push surgical frontiers even more in years to come.

The endoscopic-assisted approach versus the microscopic only approach in resection of cerebellopontine angle epidermoids: a 5-year retrospective study

Background

The endoscopic-assisted technique has been utilized with various intracranial lesions with many approaches. In the cerebellopontine angle (CPA), the technique has been used to combine the benefits of the operating microscope and the endoscope. In this study, we highlight the use of the endoscopic-assisted technique in resection of CPA epidermoid tumors to ensure a total resection, decrease complications and protect the neurovascular tangles.

Results

In the endoscopic-assisted group, only 18.8% of the patients had post-operative residual in the post-operative MRI. However, in the microscopic only group 56.3% of the patients had post-operative residual. Consequently, there is a statistically significant difference regarding the post-operative residual between the two groups.

Conclusions

The endoscopic-assisted approach is superior to the microscopic only approach in the excision of CPA epidermoids and minimizing the post-operative residual and the recurrence.

Benefits of Endoscopic Sheath in Intraventricular Neuroendoscopy: Technical Note

BACKGROUND

 The usefulness of the endoscopic sheath is underreported in the literature.

OBJECTIVE AND METHODS

 To explain the use of an endoscopic sheath and to highlight its benefits.

RESULTS

 In addition to protecting the surrounding brain parenchyma when inserting the endoscope, the endoscopic sheath is a very useful tool to retract neurovascular structures, achieve hemostasis, and create adequate working space within narrow ventricles. The sheath can be moved within the ventricular system, and the endoscope can be moved independently within the sheath. These movements represent all the advantages of the endoscopic sheath.

CONCLUSIONS

 We used an endoscopic sheath in ∼ 300 intraventricular neuroendoscopic procedures and consider the sheath an essential part of a ventriculoscopic system. Proper use of the sheath can help avoid or manage endoscopic complications.

A 360° Approach to the Craniovertebral Junction in a Cadaveric Laboratory Setting: Historical Insights, Current, and Future Perspectives in a Comparative Study

BACKGROUND

We herein outline the experience matured in our equipped Cranio-Vertebral Junction Laboratory for anatomic dissection.

METHODS

An extreme lateral approach (ELA) was performed on 4 fresh cadavers and submandibular approach was performed on 5. An endoscope and navigation-assisted far lateral approach (FLA) was performed in 5 injected specimens. In these specimens, a transoral approach was also performed, as well as a neuronavigation-assisted comparison between transoral and transnasal explorable distances.

RESULTS

As calculated with neuronavigation, statistically significant differences both in the explored craniocaudal (P = 0.003) and lateral (P = 0.008) distances were observed between the transoral approach and endoscopic endonasal approach. In FLA, neuronavigation facilitated identification and partial removal of the occipital condyle; in one case, during endoscopic intradural exploration, tearing of the emerging roots of the 11th cranial nerve occurred. In ELA, the site where the accessory nerve pierces into the sternocleidomastoid muscle was found at a distance from the tip of the mastoid between 3 and 4 cm.

CONCLUSIONS

During dissections, as in the clinical setting, endoscope and image guidance give the surgeon a constant orientation, increasing the accuracy and the safety of the approach. Nonetheless, the encumbrance of the endoscope could represent a limit in deep and narrow corridors as those running across the craniovertebral junction, especially in "oblique" FLA and ELA, in which the surgical target is often hidden by a delicate tangle of nerves and vessels. Its use appears more suitable and safer in "straight" approaches as transoral and transnasal in which there are no neurovascular structures interposed.

3D Exoscope System in Neurosurgery-Comparison of a Standard Operating Microscope With a New 3D Exoscope in the Cadaver Lab

BACKGROUND

For decades, the operating microscope has been the "gold standard" visualization device in neurosurgery. The development of endoscopy revolutionized different surgical disciplines, whereas in neurosurgery, the endoscope is commonly used as an additional device more than as single visualization tool. Invention of a 3D exoscope system opens new possibilities in visualization and ergonomics in neurosurgery.

OBJECTIVE

To assess the prototype of a 3D exoscope (3D exoscope, year of manufacture 2015, FA Aesculap, Tüttlingen, Germany) as neurosurgical visualization device in comparison to a standard operating microscope.

METHODS

A pterional approach was performed in 3 ETOH-fixed specimens (6 sides). A standard operating microscope was compared to a 3D exoscope prototype. Dimensions like visual field, magnification, illumination, ergonomics, depth effect, and 3D impression were compared.

RESULTS

In all approaches, the structures of interest could be clearly visualized with both devices. Magnification showed similar results. The exoscope had more magnification potential, whereas the visual quality got worse in higher magnification levels. The illumination showed better results in the microscope. Surgeons felt more comfortable with the 3D exoscope, concerning ergonomic considerations. Depth effect and 3D impression showed similar results. None of the surgeons felt uncomfortable using the exoscope.

CONCLUSION

The operating microscope is the gold standard visualization tool in neurosurgery because of its illumination, stereoscopy, and magnification. Nevertheless, it causes ergonomic problems. The prototype of a 3D exoscope showed comparable features in visual field, stereoscopic impression, and magnification, with a clear benefit concerning the ergonomic possibilities.

3-D endoscopy in surgery of pituitary adenomas, prospective evaluation of patient gain using basic outcome parameters

The present prospective cohort study evaluates the effect of three-dimensional (3-D) endoscopy on outcome in transphenoidal endoscopic surgery of pituitary adenomas compared to conventional two-dimensional (2-D) endoscopy. Prospective data was collected from patients undergoing endoscopic surgery for pituitary adenomas before and after the introduction of 3-D endoscopy. Patients, grouped by having 2-D or 3-D endoscopic surgery, were compared in regard to procedure time, intraoperative blood loss, complications, hospital stay, grade of resection and quality of life (QoL). Twenty-six patients having surgery with 2-D endoscopy were compared with 29 patients having surgery with 3-D endoscope. Only primary procedures were included. There were no significant differences in baseline characteristics between the two groups. No statistically significant differences in outcome were noted with 3-D endoscopy. Procedure time, complication rate, hospital stay, rate of gross total resection and post-operative QoL were unaffected by surgical technique though there were non-significant increases in new pituitary insufficiency with 3-D endoscopy and diabetes insipidus with 2-D endoscopy. This prospective cohort study fails to show obvious outcome advantages with 3-D endoscopy in pituitary surgery using basic parameters including post-operative QoL. To our knowledge this is the first prospective study published on the matter, thus corroborating results from previous retrospective studies with similar results on 3-D neuroendoscopy and 3-D endoscopy in general. The main advantage of increased depth perception is more likely found in more complex extended transphenoidal skull base procedure.

Delayed postoperative hyponatremia after endoscopic transsphenoidal surgery for pituitary adenoma

BACKGROUND

Hyponatremia generally occurs after transsphenoidal surgery (TSS) in a delayed fashion. Most patients with delayed postoperative hyponatremia (DPH) are asymptomatic or only express non-specific symptoms; consequently, DPH is associated with prolonged hospitalization. No consensus has been reached on which patients are at greatest risk of developing DPH. We reviewed patients with DPH and evaluated predictive factors for DPH.

METHODS

We retrospectively analyzed 107 consecutive patients who underwent endoscopic TSS for pituitary adenoma (January 2010-December 2016). Patients with DPH (hyponatremia group) and without DPH (normonatremia group) were compared according to their nadir sodium levels on postoperative days 3 to 10. We documented the patients' demographics, clinical features, and postoperative physiological characteristics.

RESULTS

Twenty-five (23.4%) patients developed DPH after endoscopic TSS. The patients' mean age was 54 ± 17 years, and 63.6% of the patients were female. The overall prevalence of DPH was 23.4%. The non-parametric χ2 test and the Mann-Whitney U test revealed statistically significant differences in age, use of antihypertensive drugs, nonfunctioning pituitary adenoma, and higher yet normal preoperative thyroid-stimulating hormone level between the hyponatremia and normonatremia groups (P < 0.05). Logistic regression analysis revealed that only older age was a useful independent predictive factor for DPH (odds ratio, 1.05; 95% confidence interval, 1.01-1.08; P = 0.01). The serum sodium levels on postoperative day 2 were significantly lower in the hyponatremia than normonatremia group (P < 0.01) and were negatively correlated with age (r = - 0.25, P < 0.05). The cut-off age for predicting DPH was 55 years. The hospital stay was significantly longer in the hyponatremia than normonatremia group (P < 0.01).

CONCLUSIONS

Age of more than 55 years was an independent predictive factor for DPH even after adjusting for potential confounders. Older age was negatively correlated with the serum sodium level on postoperative day 2. Preventing early decreases in the sodium level could reduce the risk of DPH.

TRIAL REGISTRATION

1707-027.

[Surgical techniques for treatment of vestibular schwannoma]

BACKGROUND

Microsurgical resection of vestibular schwannomas is demanding, even if not all of these tumors represent a challenge for experienced surgeons. In order to make the right decisions when it comes to balancing the extent of tumor resection with preservation of function, the surgeon must possess detailed knowledge of the surgical techniques and also have mastered these.

OBJECTIVE

The current article describes the state-of-the-art of the three major microsurgical techniques for resection of vestibular schwannomas, their pearls and their perils.

MATERIALS AND METHODS

The literature-based review of the three surgical techniques is complemented by a discussion of operative nuances and weighting of advantages and possible complications based on the authors' own experience.

RESULTS

The translabyrinthine, retrosigmoidal, and subtemporal microsurgical approaches are well documented in the literature regarding their modifications and the achievable surgical results. Hearing preservation is possible with the latter two approaches. The choice of approach and the preservation of neural function depend primarily on the size of the tumor and pre-existing neurologic deficits. Preoperative diagnostics and preparation differ only for semi-sitting patient positioning, where transesophageal echocardiography is required. The classic surgical techniques have been supplemented by fine-tuned electrophysiologic monitoring, endoscopic views, special microinstruments, and intraoperative image guidance.

CONCLUSION

The choice of surgical approach often depends on the personal preference and experience of the surgeon. Preoperative hearing and tumor extension are the main objective selection criteria.

The visualization of the surgical field in tubular assisted spine surgery: Is there a difference between HD-endoscopy and microscopy?

OBJECTIVE

Expert spinal surgeons criticized endoscopic procedures for poor image quality, in comparison to microscopic visualization. The recent introduction of high definition (HD) digital cameras has shown good results in spinal endoscopy. The aim of this study was to assess endoscopic HD image quality in comparison with microscopic visualization.

PATIENTS AND METHODS

All posterior lumbar and cervical spinal surgeries of this study were performed with the EasyGO-system in HD resolution. For each comparison, anatomical structures were predefined intraoperatively. A junior resident was randomly required to enter the operating theatre and to identify those structures either using HD-endoscopic or microscopic visualization through the endoscopic working sheath.

RESULTS

Thirteen lumbar and three cervical procedures were performed. Thirty-four comparisons with a total of 214 predefined anatomical structures were analyzed. The number of predefined structures ranged from 5 to 9 per surgical field. Out of 214 predefined structures, 124 structures (65.8%) were correctly identified under endoscopic view and 88 (41.1%) under microscopic view (p=0.001). Subjective impression of visualization quality were rated 1.25 (very good) for endopscopic images and 1.6 (very good to good) for microscopic view (p=0.02).

CONCLUSIONS

When using a working trocar and live images, endoscopic HD camera imaging accounted for significantly more reliable identifications of anatomical structures compared to the microscopic view. The subjective impression of video quality is significantly better with HD-optics. The goal of further studies should be to evalute if these findings results in improved surgical outcome.

Initial Experience with High-Definition Camera-On-a-Chip Flexible Endoscopy for Intraventricular Neurosurgery

OBJECTIVE

The usefulness of existing neuroendoscopes has been limited by either decreased range of motion or suboptimal image resolution. The flexible high-definition chip-camera endoscope has emerged as a potential solution to the shortcomings of available instruments by combining superior flexibility and image quality in order to better operate within spatially constrained intraventricular operations.

CASE DESCRIPTION

Here we describe a 36-year-old woman who presented with hydrocephalus caused by an obstructive mass arising from the tectum. A high-definition camera-on-a-chip flexible neuroendoscope was used to sample the tectal mass after a traditional neuroendoscope was used to perform a third ventriculostomy.

CONCLUSIONS

As demonstrated by this initial experience, the use of high-definition camera-on-a-chip flexible endoscopy may provide enhanced intraoperative visualization and application for intraventricular neurosurgery.

Endoscopic Endonasal Approach for Craniopharyngiomas

The endoscopic endonasal approach for craniopharyngiomas is increasingly used as an alternative to microsurgical transsphenoidal or transcranial approaches. It is a step forward in treatment, providing improved resection rates and better visual outcome. Especially in retrochiasmatic tumors, this approach provides better lesion access and reduces the degree of manipulations of the optic apparatus. The panoramic view offered by endoscopy and the use of angulated optics allows the removal of lesions extending far into the third ventricle avoiding microsurgical brain splitting. Intensive training is required to perform this surgery. This article summarizes the surgical technique, outcome, and complications.

Comparative effectiveness of 3-dimensional vs 2-dimensional and high-definition vs standard-definition neuroendoscopy: a preclinical randomized crossover study

BACKGROUND:

Although the potential benefits of 3-dimensional (3-D) vs 2-dimensional (2-D) and high-definition (HD) vs standard-definition (SD) endoscopic visualization have long been recognized in other surgical fields, such endoscopes are generally considered too large and bulky for use within the brain. The recent development of 3-D and HD neuroendoscopes may therefore herald improved depth perception, better appreciation of anatomic details, and improved overall surgical performance.

OBJECTIVE:

To compare simultaneously the effectiveness of 3-D vs 2-D and HD vs SD neuroendoscopy.

METHODS:

Ten novice neuroendoscopic surgeons were recruited from a university hospital. A preclinical randomized crossover study design was adopted to compare 3-D vs 2-D and HD vs SD neuroendoscopy. The primary outcomes were time to task completion and accuracy. The secondary outcomes were perceived task workload using the NASA (National Aeronautics and Space Administration) Task Load Index and subjective impressions of the endoscopes using a 5-point Likert scale.

RESULTS:

Time to task completion was significantly shorter when using the 3-D vs the 2-D neuroendoscopy (P = .001), and accuracy of probe placement was significantly greater when using the HD vs the SD neuroendoscopy (P = .009). We found that 3-D endoscopy significantly improved perceived depth perception (P < .001), HD endoscopy significantly improved perceived image quality (P < .001), and both improved participants’ overall impression (P < .001).

CONCLUSION:

Three-dimensional neuroendoscopy and HD neuroendoscopy have differing but complementary effects on surgical performance, suggesting that neither alone can completely compensate for the lack of the other. There is therefore strong preclinical evidence to justify 3-D HD neuroendoscopy.

ABBREVIATIONS:

HD, high definition

SD, standard definition

Ventricular endoscopy in the pediatric population: review of indications

INTRODUCTION

Neuroendoscopy has greatly impacted pediatric neurosurgery over the past few decades. Improved optics and microsurgical tools have allowed neuroendoscopes to be used for a multitude of neurosurgical procedures.

DISCUSSION

In this review article, we present the breadth of intraventricular neuroendoscopic procedures for the treatment of conditions ranging from hydrocephalus and brain tumors to congenital cysts and other pathologies. We critically discuss treatment indications and reported success rates for neuroendoscopic procedures. We also present novel approaches, technical nuances, and variations from recently published literature and as practiced in the authors' institution.

Endoscopic and keyhole endoscope-assisted neurosurgical approaches: a qualitative survey on technical challenges and technological solutions

INTRODUCTION

The literature reflects a resurgence of interest in endoscopic and keyhole endoscope-assisted neurosurgical approaches as alternatives to conventional microsurgical approaches in carefully selected cases. The aim of this study was to assess the technical challenges of neuroendoscopy, and the scope for technological innovations to overcome these barriers.

MATERIALS AND METHODS

All full members of the Society of British Neurosurgeons (SBNS) were electronically invited to participate in an online survey. The open-ended structured survey asked three questions; firstly, whether the surgeon presently utilises or has experience with endoscopic or endoscope-assisted approaches; secondly, what they consider to be the major technical barriers to adopting such approaches; and thirdly, what technological advances they foresee improving safety and efficacy in the field. Responses were subjected to a qualitative research method of multi-rater emergent theme analysis.

RESULTS

Three clear themes emerged: 1) surgical approach and better integration with image-guidance systems (20%), 2) intra-operative visualisation and improvements in neuroendoscopy (49%), and 3) surgical manipulation and improvements in instruments (74%).

DISCUSSION

The analysis of responses to our open-ended survey revealed that although opinion was varied three major themes could be identified. Emerging technological advances such as augmented reality, high-definition stereo-endoscopy, and robotic joint-wristed instruments may help overcome the technical difficulties associated with neuroendoscopic approaches.

CONCLUSIONS

Results of this qualitative survey provide consensus amongst the technology end-user community such that unambiguous goals and priorities may be defined. Systems integrating these advances could improve the safety and efficacy of endoscopic and endoscope-assisted neurosurgical approaches.

Johannes Vermeer of Delft [1632-1675] and vision in neuroendoscopy

Background:

Johannes Vermeer of Delft [1632-1675] was one of the greatest Masters of the Dutch Golden Age who was intensely preoccupied with the behavior of light and other optical effects and was entitled “The Master of Light”. He fastidiously attended to the subtleties of visual expression through geometry, composition, and precise mastery of the rules of perspective. It has been our impression that some visual similarity does exist between neuroendoscopic images and some of Vermeer's paintings. Such a relation could be explained by the fact that optical devices are utilized in producing both types of display.

Methods:

We reviewed the pertinent medical and art literature, observed some video clips of our endoscopy cases, and inspected digital high resolution images of Vermeer's paintings in order to elaborate on shared optical phenomena between neuroendoscopic views and Vermeer's paintings.

Results:

Specific optical phenomena are indeed shared by Johannes Vermeer's works and neuroendoscopic vision, namely light and color effects as well as the rules of perspective.

Conclusion:

From the physical point of view, the possibility that a camera obscura inspired Vermeer's artistic creation makes the existence of a visual link between his paintings and the endoscopic views of the intracranial cavity comprehensible.

Comparison of two algorithms for the application of real-time image mosaicking in neuroendoscopy

OBJECT

Neuroendoscopy is used more and more frequently in neurosurgical procedures and has become an important tool in the neurosurgical armamentarium. However, the main restriction of neuroendoscopy is the limited field of view. A better overview of the area of interest would increase surgical safety and decrease procedure-related morbidity rates. In the present study, the authors aimed to improve this restriction by using and comparing two algorithms to create endoscopic panoramic images, which increase the field of view during neuroendoscopic procedures.

METHODS

Different endoscopic methods with or without a stand and with linear or circular endoscope movements were performed in cadaveric ventricles. Video of the endoscopy was used to create image mosaics of the lateral ventricle with the help of the Kourogi or LogSearch (LS) algorithm. In the LS algorithm, different template sizes were used. Three observers graded the quality of the image mosaic in terms of usefulness in surgery. The fastest frame rate was 3-4 frames/second.

RESULTS

The LS algorithm with a larger template size showed significantly better results for the creation of image mosaics than the Kourogi algorithm in linear endoscopic movement with or without a stand. In circular endoscopic movements, the results seemed to be better with the LS algorithm but were not significantly different from those obtained with the Kourogi algorithm. In summary, image quality in the experimental paradigms was satisfying.

CONCLUSIONS

Results in the study showed that the creation of image mosaics is possible and reliable with the featured algorithms. Image mosaicking is an applicable device for neuroendoscopy and can increase the field of view during endoscopic procedures. Its use can increase the safety and the field of application of neuroendoscopy. However, faster frame rates will be required to create a smooth image for practical use during surgery.

3D Computer graphics simulation to obtain optimal surgical exposure during microvascular decompression of the glossopharyngeal nerve

The affected artery in glossopharyngeal neuralgia (GPN) is most often the posterior inferior cerebellar artery (PICA) from the caudal side or the anterior inferior cerebellar artery (AICA) from the rostral side. This technical report describes two representative cases of GPN, one with PICA as the affected artery and the other with AICA, and demonstrates the optimal approach for each affected artery. We used 3D computer graphics (3D CG) simulation to consider the ideal transposition of the affected artery in any position and approach. Subsequently, we performed microvascular decompression (MVD) surgery based on this simulation. For PICA, we used the transcondylar fossa approach in the lateral recumbent position, very close to the prone position, with the patient's head tilted anteriorly for caudal transposition of PICA. In contrast, for AICA, we adopted a lateral suboccipital approach with opening of the lateral cerebellomedullary fissure, to visualize better the root entry zone of the glossopharyngeal nerve and to obtain a wide working space in the cerebellomedullary cistern, for rostral transposition of AICA. Both procedures were performed successfully. The best surgical approach for MVD in patients with GPN is contingent on the affected artery--PICA or AICA. 3D CG simulation provides tailored approach for MVD of the glossopharyngeal nerve, thereby ensuring optimal surgical exposure.

Observation of the neurohypophysis, pituitary stalk, and adenohypophysis during endoscopic pituitary surgery: demonstrative findings as clues to pituitary-conserving surgery

BACKGROUND

High-definition imaging in endoscopic transsphenoidal pituitary surgery accounts for significantly better identification of anatomic structures. This report presents the clinical images of the adenohypophysis and neurohypophysis under high-definition endoscopic observation, and provides some clues for pituitary-sparing surgery.

METHODS

Ten demonstrative cases of pituitary lesions, including three cases of gonadotropin-producing pituitary adenoma, two cases of somatotropin-secreting pituitary adenoma, and five cases of Rathke's cleft cysts, were entered in this study. From these cases, we extracted helpful intraoperative findings that affected the surgeon's decision about surgical procedures and led to favorable results.

RESULTS

The extracted findings contain the following lessons: (1) to find a boundary plane that separate a lesion from the pituitary; (2) to mark the difference of color between the adenohypophysis and the neurohypophysis; (3) to identify the location of the pituitary stalk connecting to the neurohypophysis; (4) to observe the color change of the pituitary induced by decompression; (5) to know pathological findings of the pituitary surface; (6) to distinguish the parenchyma of the neurohypophysis from pathological tissues; and (7) to recognize the intrasellar findings at the completion of removal. Recognition of these findings led to an excellent result in each case.

CONCLUSIONS

Despite being shown in a limited number of cases, on the basis of HD endoscopic images, accurate identification of the neurohypophysis and the pituitary stalk as well as adenohypophysis during surgery contributes to pituitary-conserving operations.

Value of 3-Dimensional High-Resolution Magnetic Resonance Imaging in Detecting the Offending Vessel in Hemifacial Spasm

BACKGROUND:

High-resolution 3-dimensional (3-D) magnetic resonance imaging (MRI) is widely used to predict the neurovascular anatomy within the cerebellopontine angle.

OBJECTIVE:

To assess the value of 3-D steady-state free precession imaging (SSFP) and time-of-flight magnetic resonance angiography (TOF MRA) in detecting the offending vessels in hemifacial spasm in comparison to intraoperative endoscopic visualization.

METHODS:

42 patients underwent endoscope-assisted microvascular decompression (MVD). All available preoperative 3-D SSFP and TOF MRA images were checked. Intraoperative videos were captured by a high-definition endoscopic camera attached to endoscopes while exploring the area of facial nerve root exit zone (REZ). Evaluation of the 3-D images was performed by 2 independent groups of observers and compared with the operative findings.

RESULTS:

Three-D MRI had an average positive predictive value (PPV) of 89.1% in differentiating between simple and complex compression. Mean accuracy of the images in detection of the offending vessels was 83.3% and 77% according to the first and second groups of observers, respectively. Averaged inter-observer agreement between the 2 groups of observers was substantial, with an averaged Kappa coefficient (K) of 0.56. In the simple compression group, mean accuracy was 97% and 89.4% according to the first and second groups of observers, respectively. Averaged K for agreement was substantial (K = 0.65).

CONCLUSION:

According to endoscopic visualization, 3-D SSFP and TOF MRA images are accurate in detecting the offending vessels in simple compression of the facial nerve, and in predicting presence of a complex compression with variable sensitivity in identifying all offending vessels.

Endoscopic endonasal trans-sphenoid surgery of pituitary adenoma

Endoscopic endonasal trans-sphenoid surgery (EETS) is increasingly used for pituitary lesions. Pre-operative CT and MRI scans and peroperative endoscopic visualization can provide useful anatomical information. EETS is indicated in sellar, suprasellar, intraventricular, retro-infundibular, and invasive tumors. Recurrent and residual lesions, pituitary apoplexy and empty sella syndrome can be managed by EETS. Modern neuronavigation techniques, ultrasonic aspirators, ultrasonic bone curette can add to the safety. The binostril approach provides a wider working area. High definition camera is much superior to three-chip camera. Most of the recent reports favor EETS in terms of safety, quality of life and tumor resection, hospital stay, better endocrinological, and visual outcome as compared to the microscopic technique. Nasal symptoms, blood loss, operating time are less in EETS. Various naso-septal flaps and other techniques of CSF leak repair could help reduce complications. Complications can be further reduced after achieving the learning curve, good understanding of limitations with proper patient selection. Use of neuronavigation, proper post-operative care of endocrine function, establishing pituitary center of excellence and more focused residency and endoscopic fellowship training could improve results. The faster and safe transition from microscopic to EETS can be done by the team concept of neurosurgeon/otolaryngologist, attending hands on cadaveric dissection, practice on models, and observation of live surgeries. Conversion to a microscopic or endoscopic-assisted approach may be required in selected patients. Multi-modality treatment could be required in giant and invasive tumors. EETS appears to be a better surgical option in most pituitary adenoma.

An organic light-emitting diode display for use in neuroendoscopic surgery in the ventricle

The organic light-emitting diode (OLED) display delivers a bright and high-contrast image compared to the liquid crystal display. The first experience of neuroendoscopic surgery using an OLED display was reported and its stereoscopic effect emphasized.

Practical guidelines for setting up an endoscopic/skull base cadaver laboratory

Adequate training based on cadaveric dissection is essential to acquire a practical knowledge of surgical anatomy and microsurgical/endoscopic dissection techniques. Endoscopic procedures for the treatment of pathologies of the skull base are becoming increasingly common. The endoscopic training curve for tool handling and a detailed knowledge of the topographic anatomy of the skull base require intensive training on cadavers before approaching living patients, which is why cadaver laboratory experience should be mandatory for every resident and surgeon preparing to use microsurgical and endoscopic techniques. We describe the basic principles of the philosophy of anatomic dissection and the equipment necessary to set up an endoscopic cadaver laboratory.

Endoscope-assisted microsurgical resection of skull base meningiomas

This study aims to determine the value of endoscope assistance in the microsurgical resection of skull base meningiomas. Fourty-six patients harboring a skull base meningioma underwent an endoscope-assisted microsurgical resection. In 30 patients (65%), tumor parts which could not be visualized under the microscope were detected with the endoscope. In 26 patients (56%), these tumor remnants were removed under endoscopic view. Gross total resection was achieved in 35 patients (76%) and near-total resection in 11 (24%). There was no surgical mortality. The major complication was new cranial nerve deficit. The application of endoscopes was most useful in the small supraorbital craniotomies to look under the ipsilateral optic nerve and internal carotid artery as well as to visualize the diaphragm sellae and olfactory groove. In the retrosigmoid craniotomies, the endoscope was beneficial to inspect the internal auditory canal, to look into Meckel's cave, or to inspect areas hidden behind the jugular tubercle and tentorial edge. There was no obvious complication related to the application of the endoscope. Endoscope assistance is particularly of value when skull base meningiomas are to be removed via small craniotomies to inspect blind corners which cannot be visualized in a straight line with the microscope. In addition, there is a benefit of using endoscopes with various angles of view in standard craniotomies and skull base approaches to look around bony and dural corners or to look behind neurovascular structures, by which the amount of skull base drilling and retraction to expose the tumor can be reduced.

[Conception, realization and analysis of a modern operating theatre workplace for ENT surgery]

BACKGROUND

The requirements of ENT (ear, nose and throat) surgery, i. e. operating theatre, have changed dramatically in recent years, e. g. by high definition video endoscopy, navigation, neuromonitoring, intraoperative imaging, navigated and navigation-controlled instruments and intraoperative imaging and video documentation. For this reason a specialized operating theatre is necessary for ENT. The aim of this work was to compare this operating theatre with the previous standard.

MATERIAL AND METHODS

The scientific basis of this work represents a surgical workflow analysis. Over 200 completely documented operations in conventional operating theatres were available for comparison. In addition the log files of the medical technical devices, software analysis modules of the clinical documentation and ergonomics questionnaires (NASA TLX standard) were available. In the period from 1(st) June 2009 to 31(st) September 2009 a total of 139 standard procedures (9 different ENT surgeons) were analyzed in the new ly integrated operating theatre system "Surgical Deck1-ENT".

RESULTS

In the newly developed operating theatre system four work areas are specified: preparation area, technical cockpit, surgical cockpit and anesthesia cockpit. The medical technical components are permanently installed. The surgical cockpit incorporates five permanently arranged monitors, two main screens, two navigation screens and a surgical dashboard. A suitable high definition video routing system is installed and procedure-specific light profiles are developed. Documentation is automatically carried out in the picture archive and communication system (PACS). The comparison to the conventional operating theatre system the slot time was reduced from 73.8 min to 65.6 min (-11%), the preoperative time was reduced on average by 31% (8 min) per case and the documentation time was decreased on average by 6 min (67%). The interaction steps of the surgeon with the system were reduced by 70% (from 17 to 5 steps). No significant differences in complications could be observed. In the total evaluation of all 16 questions on the ergonomics there was a significant improvement of the workplace layout.

DISCUSSION

The presented operation unit can significantly improve safety and efficiency as well as the ergonomics for ENT surgery and related procedures.

High-Definition Imaging in Endoscopic Transsphenoidal Pituitary Surgery

Background

The transsphenoidal approach to sellar lesions has evolved enormously since its first description in the early 20th century. Endoscopic surgical strategies have become an integral part of the surgical armamentarium. More recently, high-definition (HD) digital cameras with better image resolution were introduced, although their value for the surgical procedure remains equivocal. The purpose of this study was to compare the image quality of a standard-definition (SD) camera with a new HD camera.

Methods

A transsphenoidal pituitary adenomectomy was recorded simultaneously in HD and SD resolution. Eight experienced neurosurgeons were asked to identify predefined as well as not predefined anatomic structures in HD and SD. Additionally, the video quality of three complementary surgical sequences was rated with grades from 1 (“very good”) to 6 (“poor”).

Results

An average of 23.6 ± 2.7 predefined structures (84.38%) were identified in HD versus 17.6 ± 4.4 predefined structures (62.95%) identified in SD. This profound difference in the recognition of anatomic structures reached statistical significance (p = 0.012). Subjective impression of video quality was rated 1.9, 1.9, and 1.4 for the videos in HD and 3.5, 3.3, and 3.5 for the complementary videos in SD. These differences also reached statistical significance (p ≤ 0.005).

Conclusion

HD imaging in endoscopic transsphenoidal pituitary surgery accounts for significantly better identification of anatomic structures in comparison with SD images. Additionally, the subjective impression of video quality is significantly better in HD. This improved intraoperative orientation by better digital image quality might contribute to reduce the gap in intraoperative visual accuracy between microsurgery and endoscopy in pituitary surgery.

Minimally invasive neurosurgery for cerebrospinal fluid disorders

This article focuses on minimally invasive approaches used to address disorders of cerebrospinal fluid (CSF) circulation. The author covers the primary CSF disorders that are amenable to minimally invasive treatment, including aqueductal stenosis, fourth ventricular outlet obstruction (including Chiari malformation), isolated lateral ventricle, isolated fourth ventricle, multiloculated hydrocephalus, arachnoid cysts, and tumors that block CSF flow. General approaches to evaluating disorders of CSF circulation, including detailed imaging studies, are discussed. Approaches to minimally invasive management of such disorders are described in general, and for each specific entity. For each procedure, indications, surgical technique, and known outcomes are detailed. Specific complications as well as strategies for their avoidance and management are addressed. Lastly, future directions and the need for structured outcome studies are discussed.