Neuro-otologic Surgery through Minimally Invasive Retrosigmoid Approach: Endoscope Assisted Microvascular Decompression, Vestibular Neurotomy, and Tumor Removal

Applying the Full Endoscopic Keyhole Technique to CPA Lesions: A Single-Center Study

In recent years, endoscopy has become an increasingly common tool used during neurosurgical procedures. However, its application in treating cerebellopontine angle (CPA) lesions has not progressed as rapidly. In this study, the authors present their initial experience with surgically treating CPA lesions using a fully endoscopic keyhole retrosigmoid approach. They conducted a retrospective analysis of clinical data from patients who underwent endoscopic keyhole CPA surgery at their center between May 2017 and April 2022. They provide a comprehensive explanation of this method and an overview of the strategies that have been developed to achieve better clinical outcomes. The study included 107 patients, consisting of 10 cases of vestibular schwannoma, 21 cases of epidermoid cyst, 32 cases of trigeminal neuralgia, and 44 cases of hemifacial spasm. The authors analyzed the clinicodemographic details of the patients. Among the 31 tumor cases, gross total resection was achieved in 25 patients (80.6%), while near-total resection was performed in 6 patients (19.4%). In patients with trigeminal neuralgia, facial pain resolved in 31 out of 32 patients (96.9%). Similarly, facial convulsions disappeared or were relieved in all 44 patients (100%) with hemifacial spasms after the operation. Postoperative complications included facial nerve paresis (n=9, 8.4%), with improvement observed in 6 cases during follow-up, transient facial hypoesthesia (n=3, 2.8%), cerebrospinal fluid rhinorrhea (n=3, 2.8%), transient abducens paresis (n=1, 0.9%), and postoperative hemorrhage (n=1, 0.9%). Endoscopy provides improved deep illumination and, combined with close-up observation, enhances the visualization of structures within the CPA region. The fully endoscopic keyhole technique is a safe and effective method for managing CPA lesions.

Selective Vestibular Neurectomy through the Presigmoid Retrolabyrinthine Approach in the Treatment of Meniere's Disease

BACKGROUND

Meniere's disease (MD) is a disabling disease, especially in patients who are refractory to medical therapy. Moreover, selective vestibular neurectomy (VN), in these selected cases, can be considered a surgical alternative which preserves hearing function and facial nerve.

METHODS

We retrospectively studied 23 patients with MD diagnosis and history of failed extradural endolymphatic sac surgery (ELSS) who underwent combined micro-endoscopic selective VN, between January 2019 and August 2023, via a presigmoid retrolabyrinthine approach. All patients were stratified according to clinical features, assessing preoperative and postoperative hearing levels and quality of life.

RESULTS

At the maximum present follow-up of 2 years, this procedure is characterized by a low rate of complications and about 90% vertigo control after surgery. No definitive facial palsy or hearing loss was described in this series. One patient required reintervention for a CSF fistula. Statistically significant (p = 0.001) difference was found between the preoperative and the postoperative performance in terms of physical, functional, and emotive scales assessed via the DHI questionnaire.

CONCLUSIONS

Selective VN via a presigmoid retrolabyrinthine approach is a safe procedure for intractable vertigo associated with MD, when residual hearing function still exists. The use of the endoscope and intraoperative neuromonitoring guaranteed a precise result, saving the cochlear fibers and facial nerve. The approach for VN is a familiar procedure to the otolaryngologist, as is lateral skull base anatomy to the neurosurgeon; therefore, the best results are obtained with multidisciplinary teamwork.

Bibliometric Analysis of the Top 100 Cited Articles and Author H-Indexes on the Surgical Treatment of Trigeminal Neuralgia

INTRODUCTION

Medically refractory cases of trigeminal neuralgia often require treatment escalation. Surgical options include microvascular decompression and percutaneous ablation. This paper provides a bibliometric analysis of the most influential articles on the surgical management of trigeminal neuralgia.

METHODS

The Web of Science database was queried to identify the top 100 cited articles concerning surgical treatment of trigeminal neuralgia. The search terms used included ALL=(("trigeminal neuralgia" OR "tic douloureux" OR "Fothergill's disease" OR "Trifacial neuralgia") AND ("surgical treatment" OR "surgical management" OR "surgery" OR "neurosurgery") NOT ("radiosurgery" OR "gamma knife")). The extracted variables included the first and senior author names, journal, publication year, institution, and surgical modality.

RESULTS

Our bibliometric search yielded 2104 studies, with 41,502 citations overall. Within the top 100 articles, Zakrzewska had the most first author papers (n = 5), and Burchiel had the most senior author papers (n = 6). The Massachusetts General Hospital was the most represented institution (n = 5). The United States was the most represented country (51%). Microvascular decompression was the most studied surgical strategy (51%), followed by percutaneous radiofrequency coagulation (9%), balloon/nerve compression (7%), and glycerol rhizolysis (7%). Some studies assessed multiple treatment modalities (22%). The types of studies included retrospective articles (58%), prospective articles (26%), reviews (10%), anatomic studies (2%), and basic science (1%). Neurosurgery (35%) and the Journal of Neurosurgery (33%) were the most represented journals.

CONCLUSIONS

The current literature consists of retrospective reviews and mostly describes microvascular decompression for trigeminal neuralgia. Future studies should include further characterization of other surgical modalities such as percutaneous radiofrequency thermocoagulation, glycerol injection, and balloon compression.

Fully Endoscopic Retrosigmoid Approach for Cerebellopontine Angle Tumors

BACKGROUND

Fully endoscopic or endoscope-controlled approaches are essentially keyhole approaches in which rigid endoscopes are the sole visualization tools used during the whole procedure. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Fully endoscopic retrosigmoid approach for cerebellopontine angle tumors is a minimally invasive approach that is not routinely practiced by neurosurgeons, with few series published so far. Unfamiliarity with the technique, steep learning curve, and concerns about inadequate exposure, neurovascular injury, and decreased visibility may explain this fact. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic retrosigmoid approach and present an overview of the published series.

METHODS

From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic retrosigmoid approach for cerebellopontine angle tumors were retrieved and analyzed. The pertinent literature was also reviewed.

RESULTS

The surgical technique of the fully endoscopic retrosigmoid approach was formulated.

CONCLUSION

The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

An Investigation Into Whether the Facial Nerve and Auditory Nerve can be Protected by Removal of the Posterior Wall of the Internal Auditory Canal Under 30° Neuroendoscopy During Vestibular Schwannoma Surgery

The aim of this study was to evaluate the surgical technique of microresection of vestibular schwannoma by removing the posterior wall of the internal auditory canal (IAC) under neuroelectrophysiological monitoring and 30° neuroendoscopy, with respect to the protection of facial and auditory nerve function. Forty-five cases of microscopic resection of auditory neuromas were performed through a posterior approach to the inferior occipital sigmoid sinus using a 30° neuroendoscope to assist in the removal of the posterior wall of the IAC during surgery. Patients underwent cranial enhancement magnetic resonance imaging examination and functional assessment of the facial and auditory nerves before and after surgery, and clinical data were collected for retrospective analysis. All tumors were removed in 41 patients, and most of the tumors were removed in 4 patients. The facial nerve was anatomically preserved in 43 patients (95.6%), and the percentage of facial nerve function preservation (House-Brackmann grade I-II) was 84.4%. Forty patients (88.9%) had anatomical preservation of the auditory nerve, with a 66.7% functional preservation rate. At 3 to 39 months of follow-up, 45 patients were reviewed with 3.0 T-enhanced magnetic resonance imaging, and no tumor recurrence was observed in any of the patients. Microscopic resection of auditory neuroma through the posterior approach of the inferior occipital sigmoid sinus with intraoperative use of 30° neuroendoscopic assistance to abrade the posterior wall of the IAC can eliminate dead space in certain anatomical areas during surgery and minimize surgical damage to the facial and auditory nerves, which is the basis for preservation of facial and auditory nerve function.

Fully endoscopic microvascular decompression for trigeminal neuralgia: technical note and early outcomes

Microscopic microvascular decompression (MVD) has been considered a curative and reliable method for treating classical trigeminal neuralgia (TN) for decades. Endoscopy can provide bright illumination and a panoramic view, which enhances the visualization of the posterior fossa. In view of the above advantages of endoscopy, it gradually became an option for MVD for treating TN. This study was performed to evaluate the advantages of fully endoscopic MVD for treating TN and is presented with a description of our operative technique. From January 2020 to January 2022, 95 classical TN patients underwent fully endoscopic MVD performed by the same surgeon and assistant in our department. The assistant held the endoscope, and the surgeon operated. Brain stem auditory evoked potentials (BEMPs) were routinely monitored. For every patient, the neurovascular conflict was identified, and complete decompression was achieved. The Barrow Neurological Institute (BNI) pain intensity score was used to evaluate the degree of facial pain. The intraoperative findings, postoperative outcomes, and complications were analyzed. Immediately after the operation, 93 patients (97.9%) achieved complete pain relief (BNI score of I). Two patients (2.1%) still had some pain, but it could be adequately controlled with medicine (BNI score of III). During the 12-36 months of follow-up, recurrence was found in 3 patients (3.2%), including one patient (1.1%) with a BNI score of II and 2 patients (2.1%) with a BNI score of III. Complications were found in 5 patients (5.3%), including facial numbness in 3 patients (3.2%), vertigo in one patient (1.1%), and headache in one patient (1.1%). There were no cases of mortality, stroke, hearing impairment, facial paralysis, or other complications. Fully endoscopic MVD is a safe and effective method for treating TN. It provides bright illumination and a panoramic view for surgeons to better observe neurovascular conflicts in deep areas of the cerebellopontine angle (CPA).

Endoscopically-Assisted Percutaneous Trigeminal Rhizotomy for Trigeminal Neuralgia: A Cadaveric Feasibility Study

Objective Trigeminal neuralgia (TN) is a debilitating syndrome characterized by paroxysmal facial pain in one or more divisions of the trigeminal nerve. The etiology and treatment paradigms are still controversial. The endoscopically-assisted procedure has not yet been described in percutaneous procedures for TN. The aim of this study was to assess the utility and feasibility of endoscopic-assisted percutaneous approaches for trigeminal rhizotomy in TN.

Methods This study comprised eight cadaveric sides heads that underwent an endoscopically assisted percutaneous approach using Hakanson's anterior puncture method for targeting the foramen ovale.

Results V3 exiting the foramen ovale was easily visualized with the endoscope on all sides. While approaching the foramen ovale, distal branches of V3 such as the lingual and inferior alveolar nerves were first identified as they traveled between the medial and lateral pterygoid muscles. These branches were then traced proximally to the V3 trunk deep to the lateral pterygoid. Large arteries and veins were easily visualized and avoided in the trajectory to the foramen ovale. No gross injury to any neurovascular structure along the course of the needle insertion was identified.

Conclusion We found that endoscopic-assisted percutaneous approach to the foramen ovale is feasible and allows for accurate canalization and anatomical identification of the precise location for rhizotomy under direct visualization. Such a procedure, after it is confirmed in patients, could offer a new technique for reducing unsuccessful canalization and could improve outcomes.

Case report: Fully endoscopic microvascular decompression for glossopharyngeal neuralgia

With the advances in endoscopic technology, endoscopy is widely used in many neurosurgical procedures, such as microvascular decompression, which is an effective method to treat glossopharyngeal neuralgia, trigeminal neuralgia, and facial spasm. The purpose of this study was to determine the efficacy of fully endoscopic microvascular decompression in the treatment of glossopharyngeal neuralgia. We managed a patient with glossopharyngeal neuralgia in our department, whose main clinical manifestation was recurrent left ear and facial pain for 3 years. The patient underwent a fully endoscopic microvascular decompression. The pain in the left ear and face was significantly relieved postoperatively, and there was no recurrence at the 6-month follow-up evaluation. We describe a case of glossopharyngeal neuralgia that was successfully treated by fully endoscopic microvascular decompression, which showed that endoscopy has advantages in microvascular decompression, and fully endoscopic microvascular decompression is an effective method for glossopharyngeal neuralgia.

Deep Learning Based Real-Time Semantic Segmentation of Cerebral Vessels and Cranial Nerves in Microvascular Decompression Scenes

Automatic extraction of cerebral vessels and cranial nerves has important clinical value in the treatment of trigeminal neuralgia (TGN) and hemifacial spasm (HFS). However, because of the great similarity between different cerebral vessels and between different cranial nerves, it is challenging to segment cerebral vessels and cranial nerves in real time on the basis of true-color microvascular decompression (MVD) images. In this paper, we propose a lightweight, fast semantic segmentation Microvascular Decompression Network (MVDNet) for MVD scenarios which achieves a good trade-off between segmentation accuracy and speed. Specifically, we designed a Light Asymmetric Bottleneck (LAB) module in the encoder to encode context features. A Feature Fusion Module (FFM) was introduced into the decoder to effectively combine high-level semantic features and underlying spatial details. The proposed network has no pretrained model, fewer parameters, and a fast inference speed. Specifically, MVDNet achieved 76.59% mIoU on the MVD test set, has 0.72 M parameters, and has a 137 FPS speed using a single GTX 2080Ti card.

Simultaneous Endoscopic and Microscopic Visualization in Microvascular Decompression for Hemifacial Spasm

BACKGROUND

Hemifacial spasm (HFS) is a socially limiting condition leading to decreased quality of life that can be treated with microvascular decompression (MVD). Endoscopy has been described as an adjunct to traditional microscopy for MVD, although the best visualization technique is debated.

OBJECTIVE

To review the current literature on use of endoscopy in MVD for HFS and to describe the simultaneous microscopic and endoscopic visualization technique along with a video illustration.

METHODS

Patients who underwent MVD for HFS were retrospectively reviewed from January 2011 to December 2019. The first set of patients in the series were done using traditional endoscopic assisted visualization, followed by a change in technique in the subsequent patients using the simultaneous endoscopic technique. The surgical technique is described as well as illustrated with a video.

RESULTS

In total, 21 patients underwent 24 MVDs to treat HFS. The simultaneous endoscopic/microscopic technique was used in 48% of cases for visualization. All but one patient had resolution of their symptoms immediately after the procedure. In total, 7 patients had recurrence of HFS, with 4 (17%) resolving spontaneously and 3 (13%) ultimately undergoing redo MVD. Postoperatively 7 patients (29%) had transient complications that all resolved completely. There was no significant difference between the traditional alternating microscopic and endoscopic technique with the simultaneous endoscopic microscopic technique.

CONCLUSION

Endoscopic assistance during MVD for HFS is beneficial and may be streamlined by using the simultaneous microscope and endoscope visualization technique.

The incidence of postoperative cerebrospinal fluid leakage after elective cranial surgery: a systematic review

Cerebrospinal fluid (CSF) leakage is a major complication after elective neurosurgical procedures. The aim of this systematic literature review is to summarize the incidence rates of postoperative cerebrospinal fluid leakage for neurosurgical procedures, classified by surgical approach. The Pubmed, Cochrane, Embase, and Web of Science databases were searched for studies reporting the outcome of patients undergoing elective neurosurgical procedures. The number of patients, surgical approach, and indication for surgery were recorded for each study. Outcomes related to CSF leakage such as clinical manifestation and treatment were reported as well. One hundred and thirteen studies were included, reporting 94,695 cases. Overall, CSF leaks were present in 3.8% of cases. Skull base surgery had the highest rate of CSF leakage with 6.2%. CSF leakage occurred in 5.9% of anterior skull base procedures, 6.4% of middle fossa, and 5.2% of transpetrosal surgeries. 5.8% of reported infratentorial procedures were complicated by CSF leakage versus 2.9% of supratentorial surgeries. CSF leakage remains a common serious adverse event after cranial surgery. There exists a need for standardized procedures to reduce the incidence of postoperative CSF leakage, as this serious adverse event may lead to increased health care costs.

Cell Transplantation to Restore Lost Auditory Nerve Function is a Realistic Clinical Opportunity

Hearing is one of our most important means of communication. Disabling hearing loss (DHL) is a long-standing, unmet problem in medicine, and in many elderly people, it leads to social isolation, depression, and even dementia. Traditionally, major efforts to cure DHL have focused on hair cells (HCs). However, the auditory nerve is also important because it transmits electrical signals generated by HCs to the brainstem. Its function is critical for the success of cochlear implants as well as for future therapies for HC regeneration. Over the past two decades, cell transplantation has emerged as a promising therapeutic option for restoring lost auditory nerve function, and two independent studies on animal models show that cell transplantation can lead to functional recovery. In this article, we consider the approaches most likely to achieve success in the clinic. We conclude that the structure and biochemical integrity of the auditory nerve is critical and that it is important to preserve the remaining neural scaffold, and in particular the glial scar, for the functional integration of donor cells. To exploit the natural, autologous cell scaffold and to minimize the deleterious effects of surgery, donor cells can be placed relatively easily on the surface of the nerve endoscopically. In this context, the selection of donor cells is a critical issue. Nevertheless, there is now a very realistic possibility for clinical application of cell transplantation for several different types of hearing loss.

Fully endoscopic microvascular decompression for hemifacial spasm

OBJECTIVE

Hemifacial spasm (HFS) is characterized by involuntary tonic and/or clonic contractions of facial nerve muscles. Fully endoscopic microvascular decompression (E-MVD) for HFS has not been widely adopted. This paper aims to illustrate the safety and efficacy of the fully endoscopic technique for HFS treatment.

METHODS

The authors conducted a single-center retrospective study of 27 patients (28 separate E-MVD cases; 1 patient had bilateral E-MVD) diagnosed with HFS who underwent fully E-MVD from January 2013 to October 2016. Intraoperative brainstem auditory evoked potentials and lateral spread resolution were reviewed. Outcome was based on the clinical status of the patient at the last contact point with the senior author. Complications were categorized as facial weakness, hearing loss, ataxia, dysphagia, or any adverse event able to be attributed to the surgical procedure.

RESULTS

HFS was relieved either completely or partially in the majority of cases (24 of 28, 85.7%). Of the 28 separate procedures, 17 (60.7%) resulted in complete resolution of symptoms, 4 (14.3%) resulted in near-complete resolution, 2 (7.1%) resulted in 50% reduction of symptoms, 1 (3.6%) resulted in minimal reduction, and 4 (14.3%) resulted in no relief. Of the 27 patients, 26 (96%) had no permanent postoperative complications. In multivariate logistic regression, the best predictor of greater than 50% resolution of spasm was resolution of intraoperative lateral spread response.

CONCLUSIONS

A fully E-MVD for HFS provides a safe and comprehensive view of the neurovascular conflict. Exclusive use of the endoscope in MVD is both safe and feasible in the treatment of HFS. Attention to lateral spread response monitoring remains an integral part of comprehensive neurosurgical management.

A minimally invasive endoscope assisted retrosigmoid approach for removal of arachnoid cysts in the internal auditory canal: a step by step description

Introduction

Arachnoid cyst in the internal auditory canal is a quite rare pathology but due to its compressive action on the nerves in this district should be surgically removed. Several surgical techniques have been proposed but no surgeons have used the minimally assisted endoscope retrosigmoid approach for its removal.

Objective

To investigate the feasibility of using a minimally invasive endoscope assisted retro-sigmoid approach for surgical removal of arachnoid cysts in the internal auditory canal.

Methods

Minimally invasive endoscope assisted retrosigmoid approach allows to access to the internal auditory canal through a minimally invasive retrosigmoid approach that combines the use of a microscope and an endoscope. It is performed in six steps: soft tissue step, bone step, dura step, cerebellopontine angle step (performed using an endoscope and a microscope), microscope-endoscope assisted arachnoid cysts removal and closure. We tested minimally invasive endoscope assisted retrosigmoid approach for removal of arachnoid cysts in the internal auditory canal on two human cadaveric heads (specimens) of subjects affected from audio-vestibular disorders and with arachnoid cysts in the internal auditory canal confirmed by magnetic resonance imaging.

Results

The mass was completely and successfully removed from the two specimens with no damage to the nerves and/or vessels in the surgical area.

Conclusion

The results of our study are encouraging and support the feasibility of using minimally invasive endoscope assisted retrosigmoid approach for removal of arachnoid cysts in the internal auditory canal. While further clinical in-vivo studies are needed to confirm the accuracy and safety of using the minimally invasive endoscope assisted retrosigmoid approach for this specific surgery, our group has successfully used the minimally invasive endoscope assisted retrosigmoid approach in the treatment of microvascular compressive syndrome, schwannoma removal and vestibular nerve resection.

Vestibular Neurectomy for Intractable Vertigo: Case Series and Evaluation of Role of Endoscopic Assistance in Retrolabyrinthine Craniotomy

Objective  This study evaluates the utility of endoscopy for retrolabyrinthine vestibular nerve section (RLVNS). Design/Setting  This is a retrospective review for RLVNSs by the senior author. The endoscope's utility was assessed and assigned a grade based on operative findings. Participants/Main Outcome Measures  Fifteen patients (eight males and seven females; 53 and 47%, respectively) were identified with mean age 56.7 years. Indications included Ménière's disease (MD) in 12 of 15 patients (80%), uncompensated vestibular neuritis in 2 patients (13%), and other vestibular neuropathy in 1 patient (7%). Vertigo resolved in 14 of 15 patients (93%). Complications included decreased hearing in two patients (13%) and deep venous thrombosis in one patient (7%). There were no facial nerve complications or mortalities. Results  Sectioning vestibular division of the vestibular-cochlear nerve was achieved without perceived benefit of endoscopy in the 80% of cases (grade 0, n  = 12). Endoscopy was helpful in patients with a small mastoid (grade 1, n  = 2, 13.3%), and deemed necessary where the flocculus of the cerebellum was adherent to the eighth nerve arachnoid at the porus acusticus (grade 2, n  = 1, 6.7%). Conclusion  RLVNS is a safe and efficacious procedure for the treatment of vertigo; the surgical endoscope may be a useful adjunct in selected cases. Patients with MD may expect the greatest benefit from surgery.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

A Meta-Analysis of Endoscopic Microvascular Decompression versus Microscopic Microvascular Decompression for the Treatment for Cranial Nerve Syndrome Caused by Vascular Compression

OBJECTIVE

The aim of this study was to compare the efficacy and safety of endoscopic microvascular decompression (E-MVD) and microscopic microvascular decompression (M-MVD) for the treatment for cranial nerve syndrome caused by vascular compression, including primary trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia.

METHODS

A systematic search of the online databases, including PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, China Biology Medicine disc, and China National Knowledge Infrastructure, was performed from January 1966 to March 2018. The language of the included literature was not limited. Relevant outcomes of perioperative safety and postoperative efficacy were considered for meta-analysis. Single-arm and cumulative meta-analyses were also conducted. All the outcomes were calculated as odds ratios (ORs) with 95% confidence intervals using R language.

RESULTS

A total of 9 studies involving 1093 (E-MVD [543] vs. M-MVD [550]) patients were included for analysis in our study. The recent remission rate (92% vs. 86%; OR, 1.71; P = 0.0089), offending vessel discovery rate (99% vs. 95%; OR 2.76, P = 0.0061), and long-term remission rate (97% vs. 87%; OR 4.59, P = 0.0036) were significantly higher in patients who underwent E-MVD than in those who underwent M-MVD, whereas perioperative complications (23% vs. 35%; OR 0.56, P < 0.0001) were significantly lower in patients who underwent E-MVD.

CONCLUSIONS

This meta-analysis confirms that E-MVD is superior to M-MVD both in perioperative and postoperative efficacy (short- and long-term), and therefore it should be considered as an appropriate treatment choice for patients with neuralgia and hemifacial spasm.

Minimally Invasive Endoscopic Retrosigmoid Approach to the Cerebellopontine Angle Using a Novel Surgical Instrument: A Cadaveric Study

OBJECTIVES

In this study, we aimed to describe how endoscopes show the neural and vascular structures at the cerebellopontine angle (CPA) through a minimal craniotomy in a well-described anatomic point in the retrosigmoid region and at the same time, evaluate the endoscopic anatomic exposure and maneuverability. We planned to use the new surgical instrument (endoscope cannula), which we designed on fresh frozen cadavers to simulate a real surgical procedure.

MATERIALS AND METHODS

The surgical procedure was planned to be performed on 20 sides of 10 fresh cadaver heads. The distance between the asterion and mastoid process was determined, and the midpoint was then marked. From this midpoint, a craniotomy 2 cm in size was posteriorly made. The endoscope cannula together with 0° or 30° endoscopes was inserted to capture the panoramic views of the neurovascular structures in CPA. Endoscopic anatomic exposure and maneuverability were evaluated using 0° and 30° endoscopes with/without the endoscope cannula.

RESULTS

The surgeon could easily use both hands during the surgical simulation, and maneuverability was seen to increase in CPA with the use of the endoscope cannula.

CONCLUSION

The surgeon can work actively with both hands when the endoscopes and the endoscope cannula are used together. We believe that owing to this, the surgeon's maneuverability would increase and a more effective minimally invasive endoscopic retrosigmoid surgery would ensue.

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

OBJECTIVE

We describe and quantitatively assess minimally invasive keyhole retrosigmoid approaches targeted to the upper, middle, and lower cranial nerve (CN) complexes of the cerebellopontine angle (CPA).

METHODS

Anatomic dissections were performed on 10 sides of 5 fixed, silicone-injected cadaver heads. Surgical views through various trajectories were assessed in endoscopic videos and 3-dimensional (3D) interactive virtual reality microscope views. Surgical freedom and angles of attack to the proximal and distal areas of CN complexes of the CPA were compared among upper and lower keyholes and conventional retrosigmoid craniotomy using neuronavigation.

RESULTS

Compared with keyholes, the conventional approach had superior surgical freedom to most areas except for the distal CN V, the root of CN VII, and the root of CN IX, where differences were not significant. The conventional retrosigmoid approach provided a larger horizontal angle of attack than either the upper or lower keyholes for all selected areas; however, the vertical angles of attack were not different. Splitting the petrosal fissure resulted in a significant increase in the vertical angle of attack to the root zones of CNs V and VII but not to the distal areas of these nerves or CN IX. Illustrative cases of endoscope-assisted keyhole retrosigmoid approaches for the treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are presented.

CONCLUSIONS

Targeted keyhole retrosigmoid approaches require detailed understanding of the 3D anatomy of the CPA to create appropriate locations of corridors, including skin incisions and keyholes. Endoscope assistance complements the standard microsurgical technique by maximizing the visualization and identification of the delicate neurovascular structures.

Endoscope-assisted decompression of facial nerve for treatment of hemifacial spasm

Microvascular decompression has become the sole method for a curative treatment of primary hemifacial spasm. Finding the responsible conflicting artery is not always easy as its location can be deeply situated within the cerebellopontine/medullary fissure at the facial root exit zone. Sole or additional offending vessel(s) may be at the meatus of the internal auditory canal (5% of the cases). Identifying the compressive vessel(s) and performing decompression is in most cases possible without cerebellar retraction by classical microsurgical techniques. However, in a number of patients the neurovascular conflict may be hidden in spite of the direct illumination of the operative microscope. Therefore, assistance by endoscopy can be useful and contribute as a minimally invasive approach. The author reports his own experience in a series of 553 patients operated on over the past three decades. A total of 93.6% had complete relief of their spasm (11% after repeated surgery). Relief was delayed in 20.8% of these patients. Recurrence was rare (0.3%). There was no mortality and morbidity was low: deafness occurred in 0.6%. There was no permanent postoperative facial palsy. CSF leakage amounted to 1% in the last period of surgery. In conclusion, the author advocates combining the use of both the endoscopy for exploration and the microscope for decompression.

Preoperative evaluation of neurovascular relationship in trigeminal neuralgia by three-dimensional fast low angle shot (3D-FLASH) and three-dimensional constructive interference in steady-state (3D-CISS) MRI sequence

OBJECTIVE

The purpose of the study was to evaluate the value of high-resolution three-dimensional fast low angle shot (3D-FLASH) and three-dimensional constructive interference in steady-state (3D-CISS) MRI sequence solely or the combination of both in the visualization of neurovascular relationship in patients with trigeminal neuralgia (TN).

METHODS

65 patients with unilateral TN underwent 3D-FLASH and 3D-CISS imaging were retrospectively studied. Neurovascular relationship at the intracisternal segment of trigeminal nerve was reviewed by two experienced neuroradiologist, who was blinded to the clinical details. The imaging results were compared with the operative findings in all patients.

RESULTS

The accuracy and positive rates of the 3D-FLASH + CISS imaging (98.46, 92.31%) in judging the symptomatic side according to the presence of vascular contacts were higher than those of 3D-CISS (90.77%, 84.62) or 3D-FLASH (89.23, 83.08%) sequence. In addition, the statistical analysis showed the sensitivity and accuracy of 3D-FLASH + CISS imaging was higher than that of 3D-FLASH (p < 0.05). The 3D-FLASH + CISS imaging was more accurate in determining the type of offending vessel than 3D-CISS or 3D-FLASH imaging.

CONCLUSION

The retrospective study demonstrates that the combination of 3D-FLASH with 3D-CISS sequence well delineates the relationship between intracisternal segment of trigeminal nerve and adjacent vessels in terms of increased positive rates and accuracy. Advances in knowledge: The study firstly dealt with the combination of 3D-CISS and 3D-FLASH imaging in TN.

Long-term surgical results in microvascular decompression for hemifacial spasm: efficacy, morbidity and quality of life

Hemifacial spasm is a condition that may severely reduce patients' quality of life. Microvascular decompression is the neurosurgical treatment of choice. The objective of this work was to describe the efficacy and morbidity of microvascular decompression for hemifacial spasm, evaluate the long-term efficacy on the quality of life and investigate prognostic factors for failure of the procedure. A retrospective study of 446 cases of hemifacial spasm treated by 511 retrosigmoid microvascular decompression over 22 years was conducted. Epidemiological, clinical and imaging findings, treatment modalities and outcomes of patients with pre- and postoperative HSF-8 quality of life questionnaire were studied. Success rate was 82% after first surgery and 91.6% after revision surgery. A low rate of perioperative morbidity was found. Facial palsy was mostly transient (5.5% transient and 0.2% permanent) and cochleovestibular deficit was seen in 4.8% of patients. Revision surgery increased nervous lesions (10.6% to 20.7%). Mean quality of life scores were significantly improved from 18 to 2 over 32, evaluated 7.3 years after surgery. Predictive factors of surgical failure were single conflicts (p = 0.041), atypical vasculo-nervous conflicts involving other vessel than postero-inferior cerebellar artery (p = 0.036), such as vein (p = 0.045), and other compression sites than root exit zone (p = 0.027). Retrosigmoid microvascular decompression is a safe and effective treatment of hemifacial spasm. Revision surgery is not to be excluded in case of failure, but does place patients at risk for more complications. Quality of life is improved in the long-term, indicating objective and subjective satisfaction.

Endoscopic versus microscopic microvascular decompression for trigeminal neuralgia: equivalent pain outcomes with possibly decreased postoperative headache after endoscopic surgery

OBJECTIVE

Endoscopic surgery has revolutionized surgery of the ventral skull base but has not yet been widely adopted for use in the cerebellopontine angle. Given the relatively normal anatomy of the cerebellopontine angle in patients with trigeminal neuralgia (TN), the authors hypothesized that a fully endoscopic microvascular decompression (E-MVD) might provide pain outcomes equivalent to those of microscopic MVD (M-MVD) but with fewer complications.

METHODS

The authors conducted a single-institution, single-surgeon retrospective study with patients treated in the period of 2006–2013. Before surgery, all patients completed a questionnaire that included a validated multidimensional pain-outcome tool, the Penn Facial Pain Scale (PFPS, formerly known as Brief Pain Inventory–Facial), an 11-point scale that measures pain intensity, interference with general activities of daily living (ADLs), and facial-specific ADLs. Using a standardized script, independent research assistants conducted follow-up telephone interviews.

RESULTS

In total, 167 patients were available for follow-ups (66.5% female; 93 patients underwent M-MVD and 74 underwent E-MVD). Preoperative characteristics (i.e., TN classification, PFPS components, and medication use) were similar for the 2 surgical groups except for 2 variables. Patients in the M-MVD group had slightly higher incidence of V3 pain, and the 2 groups differed in the date of surgery and hence in the length of follow-up (2.4 years for the M-MVD group and 1.3 years for the E-MVD group, p < 0.05). There was a trend toward not finding neurovascular conflict at the time of surgery more frequently in the M-MVD than in the E-MVD group (11% vs 7%, p = 0.052). Internal neurolysis was more often performed in the E-MVD group (26% vs 7%, p = 0.001). The 2 groups did not significantly differ in the length of the MVD procedure (approximately 2 hours). Self-reported headaches at 1 month postoperatively were present in 21% of the patients in the M-MVD group versus 7% in the E-MVD group (p = 0.01). Pain outcomes at the most recent followup were equivalent, with patients reporting a 5- to 6-point (70%–80%) improvement in pain intensity, a 5-point (85%) improvement in pain interference with ADLs, and a 6-point (85%) improvement in interference with facial-specific ADLs. Actuarial freedom from pain recurrence was equivalent in the 2 groups, with 80% pain control at 3 years.

CONCLUSIONS

Both the fully endoscopic MVD and the conventional M-MVD appear to provide patients with equivalent pain outcomes. Complication rates were also similar between the groups, with the exception of the rate of headaches, which was significantly lower in the E-MVD group 1 month postoperatively.

Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a sudden, severe, brief, stabbing, and recurrent pain within one or more branches of the trigeminal nerve. Type 1 as intermittent and Type 2 as constant pain represent distinct clinical, pathological, and prognostic entities. Although multiple mechanism involving peripheral pathologies at root (compression or traction), and dysfunctions of brain stem, basal ganglion, and cortical pain modulatory mechanisms could have role, neurovascular conflict is the most accepted theory. Diagnosis is essentially clinically; magnetic resonance imaging is useful to rule out secondary causes, detect pathological changes in affected root and neurovascular compression (NVC). Carbamazepine is the drug of choice; oxcarbazepine, baclofen, lamotrigine, phenytoin, and topiramate are also useful. Multidrug regimens and multidisciplinary approaches are useful in selected patients. Microvascular decompression is surgical treatment of choice in TN resistant to medical management. Patients with significant medical comorbidities, without NVC and multiple sclerosis are generally recommended to undergo gamma knife radiosurgery, percutaneous balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation procedures. Partial sensory root sectioning is indicated in negative vessel explorations during surgery and large intraneural vein. Endoscopic technique can be used alone for vascular decompression or as an adjuvant to microscope. It allows better visualization of vascular conflict and entire root from pons to ganglion including ventral aspect. The effectiveness and completeness of decompression can be assessed and new vascular conflicts that may be missed by microscope can be identified. It requires less brain retraction.

Standardized reporting of adverse events after microvascular decompression of cranial nerves; a population-based single-institution consecutive series

OBJECTIVE

To investigate frequencies of adverse events occurring within 30 days after microvascular decompression (MVD) surgery using a standardized report form of adverse events.

METHODS

We conducted a retrospective review of 98 adult patients (≥16 years) treated with MVD between 1 January 1994 and 1 June 2013. Adverse events occurring within 30 days were classified according to the Landriel Ibanez classification for neurosurgical complications: grade I represents any non-life threatening complication treated without invasive procedures; grade II is complications requiring invasive management; grade III is life-threatening adverse events requiring treatment in an intensive care unit (ICU); grade IV is death as a result of complications. We sought to compare our results with reports from the literature.

RESULTS

Patients' median age was 61 years (range 26-83), and 64 (65 %) were females. Indications for MVD were trigeminal neuralgia (n = 77, 79 %), glossopharyngeal neuralgia (n = 4, 4 %), hemifacial spasm (n = 16, 16 %) and combined trigeminal neuralgia and hemifacial spasm (n = 1, 1 %). The overall 30-day complication rate was 20 %, with 14 % grade I complications, 5 % grade II complications and 1 % grade III complications. The comparison with the literature was hampered by the diverse and unsystematic way of reporting complications.

CONCLUSION

We provide a standardized report of postoperative complications in a consecutive patient series undergoing MVD. Due to the heterogeneous and non-standardized reporting of complications in the literature, it is difficult to know if our 20 % complication rate is low or high. Standardized reporting is a necessity for meaningful and more valid comparisons across studies. The safety of MVD, a fairly standardized neurosurgical procedure, is well suited for comparisons across centers provided that complications are reported in a standardized manner.

Endoscopic-Assisted Middle Fossa Craniotomy for Resection of Vestibular Schwannoma

Background Rates of hearing preservation following surgery via middle fossa craniotomy in patients harboring tumors with unfavorable characteristics are significantly lower than for those patients with “favorable” tumors.

Objectives We will present two cases both with unfavorable conditions, which underwent endoscopic-assisted middle fossa craniotomy (MFC) resection of intracanalicular vestibular schwannomas with preserved postoperative hearing.

Methods Chart reviews were conducted on both patients. Their presentation, intraoperative details, and techniques, pre- and postoperative audiograms, and facial nerve outcomes are presented.

Results Patient A had 5.6 × 6.8 × 13.2 mm intracanalicular tumor with unserviceable hearing (pure tone audiometry [PTA], 41; speech determination score [SDS], 47%; class D) but was blind so hearing preservation was attempted. Postoperative hearing was preserved (PTA, 47; SDS, 60%; class B). Patient B had a 5 mm round intracanalicular tumor immediately adjacent to the vestibule and cochlea without any fundal fluid present. Preoperative audiogram showed serviceable hearing (PTA, 48; SDS, 88%; class B). Postoperatively, aidable hearing was preserved (PTA, 51; SDS, 76%; class C).

Conclusion Hearing preservation surgery via MFC can be enhanced with endoscopic-assisted dissection, especially in the lateral internal auditory canal. The superior optical view allows for preservation of cochlear nerve function and removal of residual tumor not otherwise seen on microscopy.

Fully Endoscopic Retrosigmoid Vestibular Nerve Section for Refractory Meniere Disease

OBJECTIVE

This study aims to report our results and technical details of fully endoscopic retrosigmoid vestibular nerve section.

DESIGN

A prospective observational study was conducted.

SETTING

A single academic, tertiary institution involving neurosurgery and neurotology.

PARTICIPANTS

Previously diagnosed patients with Meniere disease, refractory to medical therapy, who underwent fully endoscopic vestibular nerve section.

MAIN OUTCOME MEASURES

Postoperative improvement in vertiginous symptoms as well as hearing preservation, based on the American Association of Otolaryngology-Head and Neck Surgeons score and the Gardener and Robertson-Modified Hearing Classification. Facial nerve preservation based on the House-Brackman (HB) score.

RESULTS

Symptoms improved or resolved in 38 of 41 (92.2%) patients with only 1 of 41 (2.4%) reporting worsening symptoms. All 41 patients (100%) had a postoperative HB score of 1/6, demonstrating full facial nerve preservation. Hearing was stable or improved in 34 of 41 (82.9%) patients. Three complications took place for a rate of 7.3%, one cerebrospinal fluid leak, and two wound infections.

CONCLUSION

The fully endoscopic approach to vestibular nerve sections is a safe and effective technique for the treatment of medically refractory Meniere disease. This technique also utilizes smaller incisions, minimal cranial openings, and no cerebellar retraction with improved visualization of the cerebellopontine angle neurovascular structures.

Principles of vestibular pharmacotherapy

Ideally, vestibular pharmacotherapy is intended, through specific and targeted molecular actions, to significantly alleviate vertigo symptoms, to protect or repair the vestibular sensory network under pathologic conditions, and to promote vestibular compensation, with the eventual aim of improving the patient's quality of life. In fact, in order to achieve this aim, considerable progress still needs to be made. The lack of information on the etiology of vestibular disorders and the pharmacologic targets to modulate, as well as the technical challenge of targeting a drug to its effective site are some of the main issues yet to be overcome. In this review, my intention is to provide an account of the therapeutic principles that have shaped current vestibular pharmacotherapy and to further explore crucial questions that must be taken into consideration in order to develop targeted and specific pharmacologic therapies for each type and stage of vestibular disorders.

The combined microscopic-endoscopic technique for radical resection of cerebellopontine angle tumors

OBJECT

The combined microscopic and endoscopic technique has shown significant advantages in the management of various lesions through different approaches. Endoscopic-assisted techniques have frequently been applied to cerebellopontine angle (CPA) surgery in the context of minimally invasive craniotomies. In this paper the authors report on the use of the endoscope in the CPA as a tool to increase the extent of resection, minimize complications, and preserve the function of the delicate CPA structures. They also describe a technique of the simultaneous use of the microscope and endoscope in the CPA and dissection of CPA tumors under tandem endoscopic and microscopic vision to overcome the shortcomings of introducing the endoscope alone in the CPA. The reliability of using the microscope alone in dissecting CPA tumors is evaluated, as is the effectiveness of the combined technique in increasing the resectability of various types of CPA tumors.

METHODS

The authors conducted a retrospective analysis of 50 patients who underwent combined microscopic-endoscopic resection of CPA tumors by the senior author over a period of 3 years (February 2011 to February 2014) at Brigham and Women's Hospital, Harvard Medical School. The reliability of the extent of microscopic removal was evaluated with endoscopic exploration. Additional resection was performed with both microscopic and the combined microscopic-endoscopic technique. Endoscopically verified total resection was validated by intraoperative or postoperative MRI. The function of the cranial nerves was evaluated to assess the impact of the combined technique on their function.

RESULTS

A tumor remnant was endoscopically identified in 69% of the 26 patients who were believed to have microscopic total resection. The utilization of the endoscopic visualization and dissection increased endoscopically verified total removal to 38 patients, and 82% of these patients had no sign of residual tumor on postoperative imaging. The technique was most effective with epidermoid tumors. There were a total of 17 new cranial nerve deficits in 10 patients. Preoperative fifth cranial nerve deficits improved in 52% and hearing improved in 29% of patients after surgery.

CONCLUSIONS

This method provides simultaneous microscopic and endoscopic visualization and dissection techniques through skull-base approaches to CPA tumors. It overcomes some of the shortcomings of endoscopic-assisted surgery, further extends the surgical field, and increases the radicality of tumor resection with good functional outcomes.

Pre-operative image-based segmentation of the cranial nerves and blood vessels in microvascular decompression: Can we prevent unnecessary explorations?

OBJECTIVES

This study was conducted to validate the accuracy of image-based pre-operative segmentation using the gold standard endoscopic and microscopic findings for localization and pre-operative diagnosis of the offensive vessel.

PATIENTS AND METHODS

Fourteen TN and 6 HS cases were randomly selected. All patients had 3T MRI, which included thin-sectioned 3D space T2, 3D Time of Flight and MPRAGE Sequences. Imaging sequences were loaded in BrainLab iPlanNet and fused. Individual segmentation of the affected cranial nerves and the compressing vascular structure was performed by a neurosurgeon, and the results were compared with the microscopic and endoscopic findings by two blinded neurosurgeons. For each case, at least three neurovascular landmarks were targeted. Each segmented neurovascular element was validated by manual placement of the navigation probe over each target, and errors of localization were measured in mm.

RESULTS

All patients underwent retro-sigmoid craniotomy and MVD using both microscope and endoscope. Based on image segmentation, the compressing vessel was identified in all cases except one, which was also negative intraoperatively. Perfect correspondence was found between image-based segmentation and endoscopic and microscopic images and videos (Dice coefficient of 1). Measurement accuracy was 0.45 ± 0.21 mm (mean ± SD).

CONCLUSION

Image-based segmentation is a promising method for pre-operative identification and localization of offending blood vessels causing HFS and TN. Using this method may prevent some unnecessary explorations on especially atypical cases with no vascular contacts. However, negative pre-operative image segmentation may not preclude one from exploration in classic cases of TN or HFS. A multicenter study with larger number of cases is recommended.

Effects of microvascular decompression surgery on posture control: A case report in an elderly patient

AIMS OF THE STUDY

We report the case of an 84-year-old woman with neurovascular conflict of the left cochleovestibular nerve. Prior to surgery, the patient complained of positional vertigo and dizziness for the past two years, and marked instability. Hearing loss and tinnitus were reported on the left side. The aim of this study was to investigate the effects of microvascular decompression of the cochleovestibular nerve on posture control.

MATERIALS AND METHODS

Evaluation of cochleovestibular function and posture control was performed before and after surgery. Postural performance was analyzed in static and dynamic conditions, with and without vision, and with optokinetic stimulation. Perception of the static visual vertical (SVV) was recorded in darkness.

RESULTS

Positional vertigo and tinnitus disappeared immediately after the decompression. The SVV remained unchanged one week after the surgery. Speech intelligibility of the left ear was improved (30 dB), and the vestibular deficit on this side was also significantly reduced (54% versus 18%). However, the more spectacular result was the effect on postural control. This elderly patient improved her postural balance in both static and dynamic conditions, and became able to maintain her equilibrium in the more challenging dynamic conditions, with and without vision, as early as one week after the surgery, a postural performance that she had been unable to do preoperatively.

CONCLUSION

This work is the first to show that the postural deficits resulting from neurovascular conflict of the cochleovestibular nerve are strongly improved after microvascular decompression.

Fully endoscopic microvascular decompression for trigeminal neuralgia: technique review and early outcomes

OBJECT

Fully endoscopicmicrovascular decompression (E-MVD) of the trigeminal nerve was initially described more than 1 decade ago, but has not yet gained wide acceptance. The authors present the experience of their first 47 consecutive E-MVDs for trigeminal neuralgia (TN).

METHODS

All surgeries were performed by a single surgeon (J.Y.K.L.) at the Pennsylvania Hospital at the University of Pennsylvania. Patients prospectively completed pain scales before and after surgery by using the Brief Pain Inventory-Facial outcomes tool. All patients were called on the telephone, and the same outcome tool was administered without reference to their preoperative pain status.

RESULTS

Forty-seven patients (17 men) were identified and enrolled. Forty (85%) had Burchiel Type 1 TN. Vascular compression was observed at surgery in 42 patients (89%). No surgery was aborted or converted to microscope. One patient suffered permanent hearing loss, for a permanent neurological morbidity rate of 2%. Overall improvement in pain outcomes was excellent, with a median maximum pain intensity preoperatively of 10 and postoperatively of 0 (p< 0.0001). The mean interference with global function scores were 6.2 preoperatively and reduced to 1.0 at last follow-up (p < 0.0001). The mean interference with facial function was 7.3 preoperatively and reduced to 1.2 at last follow-up (p < 0.0001). The mean follow-up period after surgery was 15 ± 8 months.

CONCLUSIONS

In experienced hands, E-MVD offers superb visualization and illumination and is both safe and effective, at least in the short term. Further longer-term study is needed to compare E-MVD to traditional microscopic MVD.

Microvascular decompression under neuroendoscopic view in hemifacial spasm: rostral-type compression and perforator-type compression

We report microvascular decompression (MVD) under neuroendoscopic view in hemifacial spasm (HFS) patients with rostral- and perforator-type compression of the root exit zone (REZ) of the facial nerve. Using either a wireless iPad Mini as a monitor on the microscope or a high-resolution monitor, microscopic and endoscopic views enabled MVD for complete cure of HFS with rostral-type compression (the offender compressing the REZ on the opposite rostral side to the operative approach) or perforator-type compression (the offender tethered to the REZ by the perforator). MVD under neuroendoscopic view may offer more accurate MVD and complete resolution of HFS.

Endoscopic Resection of Vestibular Schwannomas

Objective To report our results and the technical details of fully endoscopic resection of vestibular schwannomas. Design Prospective observational study. Setting A single academic institution involving neurosurgery and neurotology. Participants Twelve consecutive patients who underwent fully endoscopic resection of a vestibular schwannoma. Main Outcome Measures Hearing preservation, based on the American Association of Otolaryngology-Head and Neck Surgeons (AAO-HNS) score as well as the Gardener and Robertson Modified Hearing Classification (GR). Facial nerve preservation based on the House-Brackmann (HB) score. Results All patients successfully underwent gross total resection. Facial nerve preservation rate was 92% with 11 of 12 patients retaining an HB score of 1/6 postoperatively. Hearing preservation rate was 67% with 8 of 12 patients maintaining a stable AAO-HNS grade and GR score at follow-up. Mean tumor size was 1.5 cm (range: 1-2 cm). No patients experienced postoperative cerebrospinal fluid leak, infection, or cranial nerve palsy for a complication rate of 0%. Mean operative time was 261.6 minutes with an estimated blood loss of 56.3 mL and average length of hospital stay of 3.6 days. Conclusion A purely endoscopic approach is a safe and effective option for hearing preservation surgery for vestibular schwannomas in appropriately selected patients.

Usefulness of the endoscope in microvascular decompression for trigeminal neuralgia and MRI-based prediction of the need for endoscopy

BACKGROUND

Microvascular decompression (MVD) is a documented effective treatment of trigeminal neuralgia (TN). Lately, reports on endoscopy-assisted microvascular decompression (eaMVD) with better outcome and less risk have emerged. This study was undertaken to verify under which circumstances the endoscope proved essential in identifying the neurovascular conflict (NVC) during eaMVD for TN, and to assess the possibility to predict the need for the endoscope on preoperative magnetic resonance imaging (MRI).

METHODS

Retrospective analysis of 97 patients with TN undergoing eaMVD at the Oslo University Hospital - Rikshospitalet, 1999-2009. To assess the NVC and anatomical variations, surgical reports were evaluated. MRI was available in 66 patients. The MRIs were evaluated by a blinded neuroradiologist.

RESULTS

In 27 of the 97 patients (27.8 %), the endoscope was a significant aid in identifying the NVC, due to a bony ridge obscuring the view of the fifth nerve, a very distal vascular compression, or a combination of both. The preoperative MRI over-diagnosed the presence of a bony ridge. However, the MRI-based fraction of microscopically visible trigeminal nerve (FVN) in the cerebellopontine angle cistern proved diagnostic (ROC curve, AUC 0.89, p = <0.001) with an optimal cut-off value of 0.35. Hence, if less than 35 % of the trigeminal nerve is visible on preoperative MRI, the endoscope will be needed to identify the NVC.

CONCLUSIONS

The endoscope is a valuable tool during MVD for TN, especially under anatomical circumstances such as a bony ridge hiding the direct microscopic view of the NVC. These anatomical circumstances can be predicted with good accuracy on preoperative MRI.

Pure endoscopic removal of epidermoid tumors of the cerebellopontine angle

PURPOSE

Epidermoid tumors located in the cerebellopontine angle (CPA) are challenging lesions because they tend to grow slowly in the subarachnoid cisterns around delicate neurovascular structures and often extend into surgical anatomic corners. The aim of this paper is to demonstrate the advantages and limitations of purely endoscopic removal of the CPA epidermoids.

METHODS

Six patients harboring an epidermoid tumor located in the CPA were treated using an endoscope-controlled microsurgical technique. A retrosigmoid suboccipital approach was used in all patients. The cerebellomedullary cistern and the cisterna magna were opened to allow cerebrospinal fluid drainage and cerebellar drop, thus yielding a wide and straight working channel to the CPA. Then, the tumor and its capsule were removed by the modified microsurgical instruments.

RESULT

The symptoms caused by mass effect of the lesion resolved after surgery. There were no deaths, but permanent deficits occurred in one patient whose cranial nerves VII/VIII complex was accidentally lesioned. Tumors and their capsules were totally removed in five cases. All patients were discharged 3-5 days after surgery. To date, no recurrences have been observed (follow-up range 14-50 months).

CONCLUSION

The endoscope-controlled microsurgical technique enables a safe tumor removal even when parts of the lesion are not visible in a straight line in CPA epidermoids. By angled endoscopic lenses, tumor extending into adjacent cranial compartments or surgical anatomic corners can be removed through a single small craniotomy without retracting neurovascular structures.

Transmastoid retrosigmoid approach to the cerebellopontine angle: surgical technique

BACKGROUND

The traditional suboccipital craniotomy in the retrosigmoid approach gives limited exposure to the cerebellopontine angle (CPA) structures and necessitates cerebellar retraction, whereas the addition of drilling of the mastoid process with reflection of venous sinuses offers wider exposure of the CPA and avoids cerebellar retraction. We describe the details of the surgical technique and provide radiological measurements substantiating the advantages of this approach.

OBJECTIVE

To validate the usefulness of partial mastoidectomy in the retrosigmoid approach and to evaluate the complications of this maneuver.

METHODS

Radiological CPA measurements on computed tomography bone window films were made on the last consecutive 20 patients who underwent CPA surgery via the transmastoid retrosigmoid approach. We measured the distance and angle of work by this approach and compared the measurements with those using the traditional retrosigmoid approach if that would have been used in each case. We also reviewed 432 patients from the records of the senior author to evaluate possible complications of this approach.

RESULTS

The mean working distance for the transmastoid approach was 23.06 mm, whereas the working distance in the traditional approach was 46.44 mm. The mean increase in the angle of work after drilling of the mastoid was 25.39 degrees, and the simple average of increased distance in lateral exposure was 26.66 mm.

CONCLUSION

The transmastoid retrosigmoid approach increases the exposure and gives better access to the CPA targets. This approach alleviates cerebellar retraction, facilitates surgery in the supine position, promotes the use of the endoscope, and is associated with negligible complications.

An endoscopic-assisted technique for retrosellar access during the extended retrosigmoid approach: a cadaveric feasibility study and quantitative analysis of retrosellar working area

The retrosigmoid approach has been advocated for certain petroclival tumors but provides limited access to any retrosellar extension of tumor, necessitating a two-stage operation. Our purpose was to demonstrate preliminary feasibility of an endoscopic-assisted technique to provide retrosellar access during the extended retrosigmoid approach and compare microscopic and endoscopic retrosellar working area. Standard retrosigmoid craniectomy and partial petrosectomy respecting inner ear structures were performed on six embalmed cadaveric heads. Two balloons were inflated to simulate a 15 mm petroclival tumor. Retrosellar clival and brainstem working area and ipsilateral oculomotor nerve and posterior cerebral artery (PCA) working distance were measured using the endoscope and microscope. Artificial tumors were implanted and resected using the endoscopic-assisted technique to assess feasibility. The endoscope provided significantly greater mean working area/distance on the clivus (201.6 vs 114.8 mm(2), p < 0.01), brainstem (223.5 vs 121.2 mm(2), p < 0.01), ipsilateral oculomotor nerve (10.8 vs 6.4 mm, p < 0.01), and ipsilateral PCA (13.7 vs 8.9 mm, p = 0.01). Petrous dissection to create a 10 × 10 mm working channel and artificial tumor resection was feasible in all dissections. The superior petrosal vein required ligation in 9 (75%) cases. Air cells were exposed in 1 (8%) case. The described endoscopic-assisted technique can provide retrosellar access during the extended retrosigmoid approach to access petroclival tumors with retrosellar extension. Risks include superior petrosal vein sacrifice, bleeding that can impair visualization, injury to the trigeminal nerve during endoscopic insertion/manipulation or injury to the brainstem while working in the medial limits of exposure. Further work is necessary to determine clinical feasibility, safety, and efficacy.

Closed-suction drainage and cerebrospinal fluid leakage following microvascular decompression : a retrospective comparison study

OBJECTIVE

We performed this study to investigate whether the use of closed-suction drainage following microvascular decompression (MVD) causes cerebrospinal fluid (CSF) leakage.

METHODS

Between 2004 and 2011, a total of 157 patients with neurovascular compression were treated with MVD. MVD was performed for hemifacial spasm in 150 (95.5%) cases and for trigeminal neuralgia in 7 (4.5%) cases. The mean age of the patients was 49.8±9.6 years (range, 20-69). Dural substitutes were used in 44 (28.0%) patients. Ninety-two patients (58.6%) were underwent a 4-5 cm craniotomy using drainage (drainage group), and 65 (41.4%) did a small 2-2.5 cm retromastoid craniectomy without closed-suction drainage (no-drainage group).

RESULTS

Eleven (7.0%) patients experienced CSF leakage following MVD based on the criteria of this study; all of these patients were in the drainage group. In the unadjusted analyses, the incidence of CSF leakage was significantly related with the use of closed-suction drainage following MVD (12.0% in the drainage group vs. 0% in the no-drainage group, respectively; p=0.003; Fisher's exact test). Those who received dural substitutes and the elderly (cut-off value=60 years) exhibited a tendency to develop CSF leakage (p=0.075 and p=0.090, respectively; Fisher's exact test). In the multivariate analysis, only the use of closed-suction drainage was significantly and independently associated with the development of CSF leakage following MVD (odds ratio=9.900; 95% confidence interval, 1.418 to infinity; p=0.017).

CONCLUSION

The use of closed-suction drainage following MVD appears to be related to the development of CSF leakage.

Endoscopic vascular decompression for the treatment of trigeminal neuralgia: clinical outcomes and technical note

OBJECTIVE

This study sought to describe the operative technique and clinical outcomes in a series of 57 patients with trigeminal neuralgia treated with endoscopic vascular decompression (EVD) alone without the use of microscopy at any point.

METHODS

A prospective observational study was performed on 57 consecutive patients treated with EVD alone for trigeminal neuralgia from October 2005 to October 2010. Patient outcomes were evaluated with respect to pain abatement, complication rate, length of hospital stay, and overall operative time. Pain outcome was graded using the Barrow Neurological Institute pain intensity score (BNI), with BNI 1 considered an excellent result and BNI 2 or 3 considered a good result. Follow-up ranged from 12 to 72 months, with a mean of 32 months. In addition to reporting these cases, our operative technique for EVD is described in detail.

RESULTS

All 57 patients reported severe preoperative pain (BNI 5); 100% of patients achieved immediate postoperative pain control or complete pain relief (BNI 1 to 3), with 82% obtaining an excellent result of BNI 1, and 18% of patients reported good results of BNI 2 or 3. At follow-up, 56 of 57 patients (98%) reported complete relief or well controlled pain (BNI 1 to 3), with 75% obtaining an excellent result of BNI 1; 23% of patients obtained a good result of BNI 2 or 3. The complication rate was 4%, with no mortality. Mean length of hospital stay was 1.6 days, with a range of 1 to 5 days; mean operative time was 133 minutes.

CONCLUSIONS

EVD is a safe and highly effective alternative to the more traditional open microvascular decompression or the more recently developed endoscopically assisted microvascular decompression.

Microsurgical endoscopy-assisted presigmoid retrolabyrinthine approach as a minimally invasive surgical option for the treatment of medium to large vestibular schwannomas

BACKGROUND

Treatment of vestibular schwannomas presents many controversial aspects, from the indication to the selection of the best treatment option. In the era of stereotactic radiotherapy, microsurgery has to be competitive in terms of providing the best chances of functional preservation and complete tumor removal. The two most commonly used surgical approaches are the retrosigmoid suboccipital and the presigmoid translabyrinthine. We describe the endoscopy-assisted presigmoid retrolabyrinthine approach (EAPRA) aiming at combining the advantages of the retrosigmoid and translabyrinthine techniques.

METHODS

For 2 years (from May 2009 to June 2011), the EAPRA was used to remove medium to large sporadic vestibular schwannomas in ten patients.

RESULTS

Complete tumor removal was obtained in eight patients, postoperative transient facial nerve function impairment or worsening was observed in two, and one had hearing deterioration postoperatively. No threatening complications occurred after surgery, and the length of hospitalization was usually less than 10 days.

CONCLUSIONS

The EAPRA can provide direct access to the CPA along with labyrinthine complex conservation, allowing hearing function preservation and minimal cerebellar retraction. Endoscopic assistance is a crucial adjunct in the presigmoid retrolabyrinthine approach in order to address the limits imposed by labyrinthine complex preservation. It ensures complete visualization of the intracanalicular portion of the schwannoma, thus improving the rate of a radical tumor resection. The EAPRA could represent a valid surgical option in vestibular schwannoma surgery.

Usefulness of endoscope-assisted microsurgery for removal of vestibular schwannomas

The usefulness of endoscope-assisted microsurgical removal of vestibular schwannomas in the internal auditory canal (IAC) was evaluated. Microsurgical removal using the endoscope was done in 28 procedures and microsurgical removal without an endoscope was done in 43 procedures. A retrosigmoid approach was used. The tumor location in the IAC was classified as grade 1 (located up to the mid-portion), 2, 3, or 4 (located up to the fundus with bony destruction) according to the tumor extent, and residual tumor in the IAC was evaluated as grade A (remnant tumor was not observed), B, C, or D (remnant tumor was observed over the mid-portion) according to the extent of remnant tumor. The residual tumor in the IAC was less in the endoscope-assisted group than in the microsurgery group. There was a significant difference only in grade 2, that is, tumor located beyond the mid-portion of the IAC. There was no significant difference in the results of preservation of useful hearing, facial nerve function, and tumor recurrence between the two groups. The benefit of endoscope-assistance microsurgery was shown for those patients whose tumors extended beyond the mid-portion of the IAC but did not reach the fundus.

Endoscope-assisted neurovascular decompression of the trigeminal nerve: a cadaveric study

Endoscopes are increasingly used to examine cranial nerves in microvascular decompression (MVD) operations. The superior petrosal vein (SPV) is often purposely sacrificed to gain adequate exposure to the trigeminal nerve (TN) during MVD. Recently, the importance of preserving the SPV has been emphasized due to potential complications associated with its sacrifice. Our focus is to study the ability to operate on the TN with preservation of the SPV by using endoscope-assisted microsurgery. We studied both cerebellopontine angles in seven cadaveric heads which vascular system had been injected with colored silicon material. MVD procedures were simulated using the operative microscope (Moeller-Wedel, Cologne, Germany) and two fixed-angled (0°and 30°) rigid endoscopes (Aesculap, PA, USA). To compare the practical advantages of microscopic MVD (MMVD) and endoscope-assisted MVD (EAMVD), we divided the approaches into four subcategories (microscopic without and with SPV sacrifice and endoscope-assisted without and with SPV sacrifice) and compared the maneuverability associated with each category using a numerical grading system. EAMVD scored significantly better than MMVD both without and with cutting of the SPV (p < 0.001). Only in MMVD did cutting of the SPV improve the maneuverability especially in the superior quadrant of the nerve (p = 0.012). Based on the proposed scoring system, use of the endoscope in an assisted mode facilitates visualization and mobilization of the vascular loop associated with the TN without need to sacrifice the SPV. Sacrifice of the SVP may help maneuverability in the superior quadrant of the nerve in MMVD.