Principles of Pituitary Surgery

Key Points 1. Understand the principles of pituitary surgery including the key-elements of surgical planning and decision-making 2. Identify the technical nuances distinguishing the endoscopic from the microscopic transsphenoidal approach 3. Understand the strategies utilized during the nasal, sphenoidal, and sellar stages of surgery that maximize tumor resection while minimizing complications and preserving sino- nasal anatomy/functio

Endoscopic repair of high-flow cranial base defects using a bilayer button.

OBJECTIVES/HYPOTHESIS: Repair of the skull base still begins with a direct repair of the dural defect. We present a new button closure for primary repair of the dura for high flow defects. STUDY DESIGN: Retrospective review. METHODS: We reviewed our 20 cases of primary button grafts and compared the results to the previous 20 high-flow open-cistern cerebrospinal fluid (CSF) cases. Subjects were excluded if they had no violation of the arachnoid space or potential for low-flow CSF leak. The button is constructed so that the inlay portion is at least 25% larger than the dural defect, and the onlay portion is just large enough to cover the dural defect. The two grafts are sutured together using two 4-0 Neurolon sutures and placed with the inlay portion intradurally and the onlay portion extradurally. RESULTS: The button graft repair of open-cisternal defects had a drop in CSF leak complications to 10% (2/20), and these two leaks were repaired with the button technique as the salvage surgery. This is a significant improvement over the 45% leak rate in the prebutton graft group (P \u3c .03). In our button graft group we used nasoseptal flaps on 16/20 repairs, and 1/2 repairs that leaked in the button group did not have a nasoseptal flap. Lumbar drains were used in approximately 38% in both groups (P = .83). CONCLUSIONS: The button graft can be used in conjunction with the nasal septal flap or as a stand-alone repair with good results reducing the postoperative leak rate to 10% for high-flow CSF repairs

Molecular outflow launched beyond the disk edge

One of the long-standing problems of star formation is the excess of angular momentum of the parent molecular cloud. In the classical picture, a fraction of angular momentum of the circumstellar material is removed by the magneto-centrifugally driven disk wind that is launched from a wide region throughout the disk. In this work, we investigate the kinematics in the envelope-disk transition zone of the Class I object BHB07-11, in the B59 core. For this purpose, we used the Atacama Large Millimeter/submillimeter Array in extended configuration to observe the thermal dust continuum emission ($\lambda_0 \sim$ 1.3 mm) and molecular lines (CO, C$^{18}$O and H$_2$CO), which are suitable tracers of disk, envelope, and outflow dynamics at a spatial resolution of $\sim 30$ AU. We report a bipolar outflow that was launched at symmetric positions with respect to the disk ($\sim$80~AU in radius), but was concentrated at a distance of 90--130~AU from the disk center. The two outflow lobes had a conical shape and the gas inside was accelerating. The large offset of the launching position coincided with the landing site of the infall material from the extended spiral structure (seen in dust) onto the disk. This indicates that bipolar outflows are efficiently launched within a narrow region outside the disk edge. We also identify a sharp transition in the gas kinematics across the tip of the spiral structure, which pinpoints the location of the so-called centrifugal barrier.Comment: 5 pages, 5 figures, Accepted for publication in A&A Letter

Tensile and flexural ultimate strength of fiber-reinforced ceramic-matrix composites

International audienceA constitutive equation has been derived for fiber reinforced ceramic-matrix composites, based on fiber breakage and distributed fiber pull-out. Length-dependent and length-independent regimes, governed by the size of the specimen, are differentiated, The constitutive equation is used to predict the ultimate strength of fiber-reinforced ceramic-matrix composites subjected to tensile and flexural loadings

Is Reconstruction of the Sella Necessary to Prevent Optic Chiasm Prolapse and Cerebrospinal Fluid Leakage Following Endoscopic Resection of Pituitary Macroadenomas?

Visual compromise is a common presentation of pituitary macroadenomas and is related to direct optic nerve and chiasm compression. Although the extent of visual recovery following treatment depends on the duration and severity of the visual compromise, the majority of patients experience gradual improvement in their vision. Delayed visual deterioration following treatment is typically related to either tumor recurrence or radiation-induced optic neuropathy, although visual worsening due to prolapse of the optic apparatus into a secondary empty sella has rarely been reported. In 1968, Guiot reported the first a case of reversible visual deterioration associated with optic chiasm prolapse following resection of a large pituitary macroadenoma (Guiot). Based on their observations, Guiot and collaborators recommended that a “prop” be placed in the sella at the time of transsphenoidal pituitary adenoma resection to prevent progressive herniation of the optic structures. Similarly, Hardy coined the term “preventive chiasmopexy” to describe filling of the sella cavity with autologous tissue such as muscle or fat following resection of large tumors to prevent this herniation phenomenon. While optic chiasm prolapse with associated visual deterioration appears to represent a rare occurrence, its true incidence and pathophysiological basis remain uncertain. Reconstruction of the sella with autologous tissues is also widely employed as a means to prevent postoperative cerebrospinal fluid leakage with these tissues typically harvested from a secondary operative site such as the abdomen. Although not frequently reported in the pituitary literature, complications of abdominal fat graft harvest include hematoma and seroma formation as well as infection with an incidence ranging from 1-7%. At our institution, we do not routinely perform dural reconstruction following transsphenoidal resection of pituitary macroadenomas using adipose tissue to prevent cerebrospinal fluid leakage or optic chiasm prolapse. In this study, we sought to determine the incidence of optic chiasm prolapse into the sellar defect by determining the radiographic position of the optic chiasm following surgery and incidence of delayed visual deterioration. Pages: 13-1

Proteostasis by STUB1/HSP70 complex controls sensitivity to androgen receptor targeted therapy in advanced prostate cancer.

Protein homeostasis (proteostasis) is a potential mechanism that contributes to cancer cell survival and drug resistance. Constitutively active androgen receptor (AR) variants confer anti-androgen resistance in advanced prostate cancer. However, the role of proteostasis involved in next generation anti-androgen resistance and the mechanisms of AR variant regulation are poorly defined. Here we show that the ubiquitin-proteasome-system (UPS) is suppressed in enzalutamide/abiraterone resistant prostate cancer. AR/AR-V7 proteostasis requires the interaction of E3 ubiquitin ligase STUB1 and HSP70 complex. STUB1 disassociates AR/AR-V7 from HSP70, leading to AR/AR-V7 ubiquitination and degradation. Inhibition of HSP70 significantly inhibits prostate tumor growth and improves enzalutamide/abiraterone treatments through AR/AR-V7 suppression. Clinically, HSP70 expression is upregulated and correlated with AR/AR-V7 levels in high Gleason score prostate tumors. Our results reveal a novel mechanism of anti-androgen resistance via UPS alteration which could be targeted through inhibition of HSP70 to reduce AR-V7 expression and overcome resistance to AR-targeted therapies

Prevention and Management of Bleeding During Endoscopic Approaches to Skull Base Pathologies

The rate of serious permanent morbidity and mortality with endonasal approaches has declined secondary to increased knowledge of the pertinent anatomy, advanced neuroimaging and navigation techniques, better surgical instruments, and improved exposure and reconstruction strategies.1-3 Although rare, vascular injury remains a potentially serious complication. However, with limited systematically-collected and reported data, the exact incidence rate of vascular injuries is difficult to determine. In terms of arterial injuries, the incidence based on reported series likely ranges from 0.3%-9% (Table 1),4-11 with higher rates most commonly associated with chordomas and chondrosarcomas involving the clivus. Venous injury is comparatively less severe and easier to manage. As a result, there is a comparatively lower impetus to publish epidemiological data and management strategies for these injuries. The consequences of arterial injury include fatal hemorrhage, vessel occlusion or thromboembolism causing infarction, development of a pseudoaneurysm (PA), carotid-cavernous fistula (CCF), subarachnoid hemorrhage (SAH), and vasospasm.6,7,9 Surgical expertise and detailed knowledge of the neurovascular anatomy is critical to the avoidance and management of vascular injuries. Pages: 20-2

Comprehensive Management of the Paranasal Sinuses in Patients Undergoing Endoscopic Endonasal Skull Base Surgery.

OBJECTIVE: The endonasal route often provides the most direct and safe approach to skull base pathology. In this article we review the literature with regard to management of the paranasal sinuses in the setting of skull base surgery. METHODS: We describe our institutional experience and review the literature of concurrent management of the sinusitis in patients undergoing endoscopic skull base surgery. RESULTS: Patients should be optimized preoperatively to ensure the endonasal route is a safe corridor to enter the intracranial cavity. Often the paranasal sinuses can be surgically addressed at the same time as endoscopic skull base surgery. We describe the technical details of management of the paranasal sinuses when addressing skull base pathology. CONCLUSIONS: Careful management of the paranasal sinuses throughout the peri-operative course is paramount to optimizing sinonasal function and safety

Endonasal Vascularized Flaps For Cranial Base Reconstruction

Since the introduction of extended endoscopic cranial base surgery, postoperative cerebrospinal fluid (CSF) leak has been a formidable and troublesome issue resulting in complications such meningitis, pneumocephalus, and the need for additional surgical interventions. Establishment of a watertight cranial base reconstruction is the most critical step in preventing postoperative CSF leakage. Historically, various free grafts, both synthetic and autologous, were utilized as repair materials for reconstruction of the cranial base defect often in combination with temporary CSF diversion. Free grafts are often sufficient for repair of small low flow, low pressure dural defects. High postoperative CSF leak rates reported in the initial endoscopic skull base literature are evidence that free grafts do not provide a reliably competent repair for large defects or direct high-flow CSF leaks. The introduction of the Hadad-Bassagasteguy vascularized nasoseptal flap has significantly reduced the reported CSF leak rate with a recent meta-analysis reporting that use of the vascularized flap is associated with a 7% rate of postoperative CSF leakage compared to 16% with free grafts alone for large dural defects.6 Since the initial description of the vascularized pedicled nasoseptal flap in 2006, many surgeons have developed a variety of alternative vascularized flaps for endonasal cranial base reconstruction. In this article, we summarize and compare several of the most clinically useful vascularized flaps including their harvest technique, indications and limitations, and potential complications. Pages: 28-3