Morphometric Analysis of the Retrolabyrinthine Approach to the Posterior Fossa.

INTRODUCTION: The retrolabyrinthine approach provides shorter working distance and less cerebellar retraction compared with the retrosigmoid approach to the internal acoustic canal (IAC) and cerebellopontine angle cistern. However, exposure of the ventral surface of the brainstem and petroclival region may be restricted. Trautmann's triangle (TT), an area intimately related to this region, demonstrates significant anatomical variability, which may adversely affect the ease of the approach. The aim of this study is to evaluate anatomic parameters of the posterior fossa that may anticipate a challenging situation in approaching the IAC and the petroclival region through the retrolabyrinthine approach. METHODS: It was performed a radioanatomic analysis of 75 cerebral angiotomography exams to identify parameters that could potentially reduce areas of surgical exposure. RESULTS: Large variations were observed in the area of exposure of the TT (553%) and the height of the jugular bulb (234%). Shorter distances from the sigmoid sinus to the posterior semicircular canal and high-riding jugular bulb were associated with smaller areas of exposure. Dominant and laterally positioned sigmoid sinuses and less pneumatized mastoids were associated with potentially unfavorable conditions, including a narrower angle of attack to the IAC. Increased petrous slopes and petroclival angles were associated with smaller petroclival areas and shallower clival depths. CONCLUSIONS: This study of the posterior fossa reveals remarkable anatomic variation in the region. These findings should be taken into consideration during the preoperative planning of retrolabyrinthine approaches in order to offer safer and more effective surgical procedures.

Computed Tomography Assessment of the Retrolabyrinthine Approach.

Introduction This study aimed to evaluate preoperative radiological assessments of the retrolabyrinthine approach to identify and describe anatomical constraints that may anticipate a more challenging situation for neurosurgeons and otolaryngologists specialized in skull base surgery. Materials and methods The study included 75 adult patients who underwent high-resolution computed tomography angiography scans of the head, with the aim of analyzing the side of the dominance of the sigmoid sinus (SS), the level of pneumatization of the mastoid portion of the temporal bone, and the height of the jugular bulb. Results The results showed that dominant SS and type 2 jugular bulbs were more common on the right side, while smaller type 1 bulbs were significantly more common on the left. Conclusions These findings provide valuable information for neurosurgeons and otolaryngologists in predicting the difficulty of the retrolabyrinthine approach based on preoperative radiological assessments.

Brain Metastasis of Follicular Thyroid Carcinoma in Pregnancy: A Case Report and Literature Review.

Brain metastases (BMs) related to cancer are quite common and represent the most common brain cancer. We present a rare case of a 32-year-old female, 36 weeks pregnant, admitted to the emergency with complaints of severe headache, vomiting, and left hemiparesis associated with drowsiness. Cranial tomography showed an image suggestive of an expansive lesion in the right front-temporo-insular region with an important mass effect. The result of biopsy with immunohistochemistry was compatible with metastasis of follicular thyroid carcinoma (FTC). The knowledge of neurological characteristics in the clinical analysis of patients with thyroid carcinoma must be highly valued, both in the correct interpretation of the signs and in the early investigation through skull imaging exams.

Infundibular Epidermoid Cyst: Case Report and Systematic Review.

BACKGROUND: Intracranial epidermoid cysts are benign, congenital, keratinizing, squamous epithelial-lined cysts filled with keratin. They are uncommon and often pose a surgical challenge owing to the adherence to surrounding structures. They are typically found at the cerebellopontine angle or in the parasellar region, where they are associated with abnormal development of the Rathke pouch; involvement of the pituitary stalk is rare. CASE DESCRIPTION: The patient's electronic health record was queried for relevant data. A systematic review of the literature using dedicated search terms for cases of infundibular epidermoid cysts was conducted. We present a unique case of a 55-year-old male who presented with vision changes and was found to have a parasellar epidermoid cyst confined to the pituitary stalk. The patient underwent endoscopic transsphenoidal resection, and gross total resection was achieved. The patient's postoperative course was significant for possible chemical meningitis and the development of panhypopituitarism. The patient's vision subjectively improved after surgery. CONCLUSIONS: Although 3 other cases of epidermoid cysts involving the pituitary stalk were identified, our patient's tumor was unique in that it was confined to the stalk. Our patient's case highlights a surgical approach to parasellar epidermoid cysts and the possible complications associated therewith.

Endoscope-assisted hemispherotomy: translation of technique from cadaveric anatomical feasibility study to clinical implementation.

OBJECTIVEAppropriately chosen candidates with medically refractory epilepsy may benefit from hemispheric disconnection. Traditionally, this involves a large surgical exposure with significant associated morbidity. Minimally invasive approaches using endoscopic assistance have been described by only a few centers. Here, the authors report on the feasibility of endoscope-assisted functional hemispherotomy in a cadaver model and its first translation into clinical practice in appropriately selected patients.METHODSThree silicone-injected, formalin-fixed cadaver heads were used to establish the steps of the procedure in the laboratory. The steps of disconnection were performed using standard surgical instruments and a straight endoscope. The technique was then applied in two patients who had been referred for hemispherectomy and had favorable anatomy for an endoscope-assisted approach.RESULTSAll disconnections were performed in the cadaver model via a 4 × 2-cm paramedian keyhole craniotomy using endoscopic assistance. An additional temporal burr hole approach was marked in case the authors were unable to completely visualize the frontobasal and insular cuts from the paramedian vertical view. Their protocol was subsequently used successfully in two pediatric patients. Full disconnection was verified with postoperative tractography.CONCLUSIONSFull hemispheric disconnection can be accomplished with minimally invasive endoscope-assisted functional hemispherotomy. The procedure is technically feasible and can be safely applied in patients with favorable anatomy and pathology; it may lead to less surgical morbidity and faster recovery.

Endoscope-Assisted Retrosigmoid Approach for Cerebellopontine Angle Epidermoid Tumor.

Objectives Surgical resection is the only effective treatment modality for epidermoid tumors. Complete resection with preservation of neurological function must be pursued whenever possible, because it offers a cure for patients. However, the inability to identify hidden remnants, interdigitating around cranial nerves, especially in larger tumors, may be a contributing factor for incomplete resection. This operative video demonstrates the technical nuances in achieving complete resection of a cerebellopontine angle epidermoid tumor via an endoscope-assisted retrosigmoid approach. Design and Setting Operative video of an endoscope-assisted retrosigmoid, approach for complete resection of a cerebellopontine angle epidermoid tumor. The patient was a 16-year-old female, who presented with 1-year history of worsening headaches and imbalance. Her neurological exam was normal, including normal cranial nerve function, and hearing. Radiological evaluation revealed an epidermoid tumor in the right cerebellopontine angle, extending to the interpeduncular cistern. Surgical resection was recommended. Given extension of the tumor across the midline, an endoscope-assisted procedure was planned to increase the odds of complete resection. Results The video demonstrates the surgical technique applied for tumor resection. The patient's clinical symptoms resolved completely after surgery and she remained neurologically intact. Postoperative magnetic resonance imaging (MRI) confirmed complete tumor resection. There were no postoperative complications. Conclusions The use of endoscopic techniques for resection of cerebellopontine angle epidermoid tumor is safe and effective and may increase the odds of complete resection, especially in larger tumors spreading across the midline, by enabling the surgeon clear visualization of deep-seated and contralateral relevant neurovascular structures, not readily accessible by the surgical microscope. The link to the video can be found at: https://youtu.be/X6YP_7OeQQE .

Quantitative analysis of the safety and efficacy of microvascular decompression for patients with trigeminal neuralgia above and below 65 years of age.

For medically-refractory trigeminal neuralgia (TN), microvascular decompression (MVD) is the first-line treatment, and has demonstrated the greatest efficacy and durability. However, due to potential surgical complications, a bias may exist against performing MVD in elderly patients. We sought to determine through a quantitative analysis whether MVD in the elderly is a safe and effective procedure for TN. We completed a Pubmed/SCOPUS literature search up to 12/2016 for eligible studies on MVD for TN. Only research articles with age stratification of results were included. In this quantitative analysis, we analyzed the data for the six articles identified in the literature comparing MVD for a group of patients ≥65 years with an elderly group <65 years. A total of 1483 were included. 455 patients were ≥65 years (mean 70.8 years, range 65-89 years) and 1028 patients were <65 years (mean 53.4 years, range 19-64 years). Composite mean follow-up time was 51.6 months for the elderly group, and 55.1 months for the young group. Following MVD, each group had 1 mortality (p = 0.43). There were 21 serious morbidities in the elderly group (4.62%) and 32 in the young group (3.11%) (p = 0.11). In addition, 15 patients (1.46%) in the elderly group and 24 patients (1.62%) in the young group experienced a cerebrospinal fluid leak (p = 0.23). TN recurrence rates 9.23% in the young group and 13.33% in the elderly group (p = 0.070). In conclusion, for properly-selected surgical candidates, MVD should not be ruled out on the basis of age ≥65 years.

Endoscopic endonasal surgery for epidermoid and dermoid cysts: a 10-year experience.

OBJECTIVEEpidermoid and dermoid cysts may be found along the cranial base and are commonly resected via open transcranial approaches. The use of endoscopic endonasal approaches for resection of these tumors has been rarely reported.METHODSThe authors retrospectively reviewed the medical records of 21 patients who underwent endoscopic endonasal surgery for epidermoid and dermoid cyst resection at the University of Pittsburgh Medical Center between January 2005 and June 2014. Surgical outcomes and variables that might affect the extent of resection and complications were analyzed.RESULTSTotal resection (total removal of cyst contents and capsule) was achieved in 8 patients (38.1%), near-total resection (total removal of cyst contents, incomplete removal of cyst capsule) in 9 patients (42.9%), and subtotal resection (incomplete removal of cyst contents and capsule) in 4 patients (19%). Larger cyst volume (≥ 3 cm3) and intradural location (15 cysts) were significantly associated with nontotal resection (p = 0.008 and 0.0005, respectively). In the whole series, surgical complications were seen in 6 patients (28.6%). No complications were observed in patients with extradural cysts. Among the 15 patients with intradural cysts, the most common surgical complication was postoperative CSF leak (5 patients, 33.3%), followed by postoperative intracranial infection (4 patients, 26.7%). Larger cysts and postoperative CSF leak were associated with intracranial infection (p = 0.012 and 0.028, respectively). Subtotal resection was marginally associated with intracranial infection when compared with total resection (p = 0.091). All patients with neurological symptoms improved postoperatively with the exception of 1 patient with unchanged abducens nerve palsy.CONCLUSIONSEndoscopic endonasal approaches may be effectively used for resection of epidermoid and dermoid cysts in carefully selected cases. These approaches are recommended for cases in which a total or near-total resection is possible in addition to a multilayer cranial base reconstruction with vascularized tissue to minimize the risk of intracranial infection.

Endoscopic Endonasal Surgery for Cranial Base Chondrosarcomas.

BACKGROUND: Microsurgical resection via open approaches is considered the main treatment modality for cranial base chondrosarcomas (CBCs). The use of endoscopic endonasal approaches (EEAs) has been rarely reported. OBJECTIVE: To present the endoscopic endonasal experience with CBCs at our institution. METHODS: Retrospective review of the medical records of 35 consecutive patients who underwent EEA for CBC resection between January 2004 and April 2013. Surgical outcomes and variables that might affect extent of resection, complications, and recurrence were analyzed. RESULTS: Forty-eight operations were performed (42 EEAs and 6 open approaches). Gross-total resection was achieved in 22 patients (62.9%), near total (≥90% tumor resection) in 11 (31.4%). Larger tumors were associated with incomplete resection in univariate and multivariate analysis ( P = .004, .015, respectively). In univariate analysis, tumors involving the lower clivus and cerebellopontine angle were associated with increased number of complications, especially postoperative cerebrospinal fluid leak ( P = .015) and new cranial neuropathy ( P = .037), respectively. Other major complications included 2 cases of meningitis and deep venous thrombosis, and 1 case of hydrocephalus and carotid injury. Involvement of the lower clivus, parapharyngeal space, and cervical spine required a combination of approaches to maximize tumor resection ( P = .017, .044, .017, respectively). No predictors were significantly associated with increased risk of recurrence. The average follow-up time was 44.6 ± 31 months. CONCLUSIONS: EEAs may be considered a good option for managing CBCs without significant posterolateral extension beyond the basal foramina and can be used in conjunction with open approaches for maximal resection with acceptable morbidity.

Endoscopic Endonasal Approach to the Ventral Jugular Foramen: Anatomical Basis, Technical Considerations, and Clinical Series.

BACKGROUND: Surgical exposure of the jugular foramen (JF) is challenging given its complex regional anatomy and proximity to critical neurovascular structures. OBJECTIVE: To describe the anatomical basis, surgical technique, and outcomes of a group of patients who underwent the endoscopic endonasal approach to the JF. METHODS: Five silicon-injected anatomical specimens were prepared for dissection. Additionally, a chart review was conducted through our patient database, searching for endonasal exposure of the JF. Demographic data, clinical presentation, pathological findings, extent of resection in the JF, and occurrence of complications were analyzed. RESULTS: The endonasal exposure of the JF requires 3 sequential steps: a transpterygoid, a "far-medial," and an "extreme-medial" approach. Mobilization or transection of the cartilaginous portion of the eustachian tube (ET) is necessary. In the clinical series, cranial neuropathies were the presenting symptoms in 16 patients (89%). Eighteen tumors (10 chondrosarcomas, 7 chordomas, 1 adenocarcinoma) extended secondarily into the JF. Total tumor resection was achieved in 10 patients (56%), near total (≥90%) in 6 (33%), and subtotal (<90%) in 2 (11%). ET dysfunction (75% of cases), transient palatal numbness (17%), cerebrospinal fluid leakage (17%), and lower cranial nerve palsy (17%) were the most common postoperative complications. There were no carotid artery or jugular vein injuries. CONCLUSION: The endoscopic endonasal approach to the JF requires mobilization or transection of the cartilaginous portion of the ET. This maneuver provides a safe infrapetrosal surgical route to the JF. It may be considered a valid option, in well-selected cases, for resection of malignant and recurrent cranial base tumors.

Endoscopic endonasal skull base surgery for vascular lesions: a systematic review of the literature.

INTRODUCTION: Endoscopic endonasal skull base surgery for vascular lesions is a controversial topic in neurosurgical practice. Concerns regarding the ability to effectively work through the relatively narrow and deep endonasal corridor and manage serious hemorrhagic complications such as inadvertent internal carotid artery (ICA) injury during endoscopic surgery (EES) are relevant sources of disagreement between neurosurgeons. Nevertheless, following careful preoperative evaluation, EES may be indicated for rare, well-selected cases, including medially-projecting paraclinoid aneurysms and cavernous malformations (CMs) located next to the ventral surface of the brainstem. To date, only small retrospective case series and case reports, attesting the safety, feasibility and technical aspects of the EES for aneurysm clipping, CM resection and arterio-venous malformations (AVMs), have been published in the literature. EVIDENCE ACQUISITION: In this manuscript, we conducted a systematic review of the literature applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines on EES for treatment of intracranial vascular lesions. We discuss the indications, advantages, limitations and technical aspects of EES for vascular lesions. EVIDENCE SYNTHESIS AND CONCLUSIONS: Although rarely indicated, EES may be considered as an alternative treatment and part of the armamentarium of cerebrovascular neurosurgeons dealing with these challenging lesions.

Impact of Dynamic Endoscopy and Bimanual-Binarial Dissection in Endoscopic Endonasal Surgery Training: A Laboratory Investigation.

Objective The lack of a standard technique may be a relevant issue in teaching endoscopic endonasal surgery (EES) to novice surgeons. The objective of this article is to compare different endoscope positioning and microsurgical dissection techniques in EES training. Methods A comparative trial was designed to evaluate three techniques: group A, one surgeon performing binarial two-hands dissection using an endoscope holder (rigid endoscopy); group B, two surgeons performing a combined binarial two- and three-handed dissection with one surgeon guiding the endoscope (dynamic endoscopy); and group C, two surgeons performing a binarial two-hands dissection with one surgeon dedicated to endoscope positioning and the other dedicated to a two-handed dissection. Trainees were randomly assigned to these groups and oriented to complete surgical tasks in a validated training model for EES. A global rating scale, and a specific-task checklist for EES were used to assess surgical skills. Results The mean scores of the global rating scale and the specific-task checklist were higher (p = 0.001 and 0.002, respectively) for group C, reflecting the positive impact of dynamic endoscopy and bimanual dissection on training performance. Conclusions We found that dynamic endoscopic and bimanual-binarial microdissection techniques had a significant positive impact on EES training.

Hemostasis in Endoscopic Endonasal Skull Base Surgery.

William Halsted established the basic principles of modern surgical technique highlighting the importance of meticulous hemostasis and careful tissue handling. These concepts hold true today and are even more critical for endoscopic visualization, making hemostasis one of the most relevant cornerstones for the safe practice of endoscopic endonasal surgery (EES) of the skull base. During preoperative assessment, patients at higher risk for serious hemorrhagic complications must be recognized. From an anatomical point of view, EES can be grossly divided in two major components: sinonasal surgery and sellar-cranial base surgery. This division affects the choice of appropriate technique for control of bleeding that relies mainly on the source of hemorrhage, the tissue involved, and the proximity of critical neurovascular structures. Pistol-grip or single-shaft instruments constitute the most important and appropriately designed instruments available for EES. Electrocoagulation and a variety of hemostatic materials are also important tools and should be applied wisely. This article describes the experience of our team in the management of hemorrhagic events during EES with an emphasis on technical nuances.

Endoscopic Endonasal Clipping of Intracranial Aneurysms: Surgical Technique and Results.

OBJECTIVE: Microsurgical clipping of intracranial aneurysms requires meticulous technique and is usually performed through open approaches. Endoscopic endonasal clipping of intracranial aneurysms may use the same techniques through an alternative corridor. The aim of this article is to report a series of patients who underwent an endoscopic endonasal approach (EEA) for microsurgical clipping of intracranial aneurysms. METHODS: We conducted a retrospective chart review. Surgical outcome and complications were noted. The conceptual application and the technical nuances of these procedures are discussed. RESULTS: Ten patients underwent EEA for clipping of 11 intracranial aneurysms arising from the paraclinoidal internal carotid artery (n = 9) and vertebrobasilar system (n = 2). The internal carotid artery aneurysms projected medially, whereas the vertebrobasilar artery aneurysms were directly ventral to the brainstem with low-lying basilar apices. One patient required craniotomy for distal control given the size and thrombosed nature of the aneurysm. Proximal and distal vascular control with direct visualization of the aneurysm was obtained in all patients. In all cases, aneurysms were completely occluded. Among complications, 3 patients had postoperative cerebrospinal fluid leakage and 2 other patients had meningitis. Two patients suffered lacunar strokes. One recovered completely and the other remains with mild disabling symptoms. CONCLUSIONS: EEAs can provide direct access for microsurgical clipping of rare and carefully selected intracranial aneurysms. The basic principles of cerebrovascular surgery have to be followed throughout the procedure. These surgeries require a skull base team with a neurosurgeon well versed in both endoscopic endonasal and cerebrovascular surgery, working in concert with an otolaryngologist experienced in skull base endoscopy and reconstruction.

Fully endoscopic retrosigmoid approach for posterior petrous meningioma and trigeminal microvascular decompression.

BACKGROUND: Cerebellopontine angle tumor resection and cranial nerve microvascular decompression are usually performed with the aid of the surgical microscope. The endoscope is commonly used as an adjuvant. METHOD: A retrosigmoid craniectomy is done. Upon dural opening, the endoscope is inserted into the operative field along the petrotentorial junction. Cerebrospinal fluid drainage provides a wider space for introduction of the endoscope and surgical instruments. Traditional microsurgical techniques are used during the entire procedure. CONCLUSION: A fully endoscopic retrosigmoid approach is a safe and effective procedure for cerebellopontine angle tumor resection and cranial nerve microvascular decompression. KEY POINTS: • Careful examination of preoperative studies is needed to identify anatomical peculiarities. • Patient positioning: the head must be gently flexed and its vertex gently tilted toward the floor. • Neurophysiologic monitoring and intraoperative navigation. • Craniectomy: partial exposure of the transverse and sigmoid sinuses. • Curvilinear dural incision reflected laterally to minimize the risk of sinus injury. • Opening the cerebellomedullary cistern for CSF drainage and cerebellar relaxation. • Dynamic endoscopy enhances depth perception and must be performed by a team with experience in endoscopic intracranial surgery. • Traditional microsurgical techniques have to be applied during the entire operation. • Multilayer reconstruction, including watertight dural closure. • Meningiomas causing brainstem shift are not suitable for endoscopic resection.

Validation of a chicken wing training model for endoscopic microsurgical dissection.

OBJECTIVES/HYPOTHESIS: To determine if training with a chicken wing model improves performance of endoscopic endonasal surgery (EES) with microvascular dissection. STUDY DESIGN: Randomized experimental study. METHODS: A single-blinded randomized clinical trial of trainees with various levels of endoscopic experience was conducted to determine if prior training on a nonhuman model augments endoscopic skill and efficiency in a surrogate model for live surgery. Medical students, residents, and fellows were randomized to two groups: a control group that performed an endoscopic transantral internal maxillary artery dissection on a silicone-injected anatomical specimen, and an interventional group that underwent microvascular dissection training on a chicken wing model prior to performing the anatomic dissection on the cadaver specimen. Time to completion and quality of dissection were measured. RESULTS: A Mann-Whitney test demonstrated a significant improvement in time and quality outcomes respectively across all interventional groups, with the greatest improvements seen in participants with less endoscopic experience: medical students (P = .032, P = .008), residents and fellows (P = .016, P = .032). CONCLUSIONS: Prior training on the chicken wing model improves surgical performance in a surrogate model for live EES.