Transcavernous Resection of an Upper Clival Chondrosarcoma: “Cavernous Sinus as a Route”: 2-Dimensional Operative Video

Complete resection of skull base chondrosarcomas offers the potential for a durable, or even lifelong, cure and is best achieved at the first surgery.1,2 When a skull base chondrosarcoma is located at the upper clivus and in the interpeduncular cistern and invading laterally toward the petrous apex and cavernous sinus, the traditional approaches, ie, endonasal endoscopic or middle fossa approaches, are not adequate for the exposure and resection. The transcavernous sinus approach has been utilized to remove tumor from the cavernous sinus and as a corridor to the interpeduncular cistern and upper clivus, originally described for the clipping of basilar apex aneurysms. We present a case of a chondrosarcoma centered in the upper clivus and eroding the right posterior clinoid, analogous to the location of a giant basilar apex aneurysm. Detailed study of the tumor extension, bony invasion, and relationship with neuroanatomy dictated the most effective surgical approach.3,4 Neuronavigation and intraoperative magnetic resonance imaging (MRI) facilitated the gross total resection of the tumor in the Advanced Multimodality Image-Guided Operating (AMIGO) suite. Achieving a gross total tumor removal of this World Health Organization (WHO) grade I chondrosarcoma, adjuvant irradiation can be withheld1 and the patient monitored with serial imaging. The patient did well after the surgery. The patient consented for surgery and the use of photography.

Mapping Solute Clearance From the Mouse Hippocampus Using a 3D Imaging Cryomicrotome

The hippocampus is susceptible to protein aggregation in neurodegenerative diseases such as Alzheimer’s disease. This protein accumulation is partially attributed to an impaired clearance; however, the removal pathways for fluids and waste products are not fully understood. The aim of this study was therefore to map the clearance pathways from the mouse brain. A mixture of two fluorescently labeled tracers with different molecular weights was infused into the hippocampus. A small subset of mice (n = 3) was sacrificed directly after an infusion period of 10 min to determine dispersion of the tracer due to the infusion, while another group was sacrificed after spreading of the tracers for an additional 80 min (n = 7). Upon sacrifice, mice were frozen and sectioned as a whole by the use of a custom-built automated imaging cryomicrotome. Detailed 3D reconstructions were created to map the tracer spreading. We observed that tracers distributed over the hippocampus and entered adjacent brain structures, such as the cortex and cerebroventricular system. An important clearance pathway was found along the ventral part of the hippocampus and its bordering interpeduncular cistern. From there, tracers left the brain via the subarachnoid spaces in the directions of both the nose and the spinal cord. Although both tracers followed the same route, the small tracer distributed further, implying a major role for diffusion in addition to convection. Taken together, these results reveal an important clearance pathway of solutes from the hippocampus.

Prepontine Shunting for Pseudotumor Cerebri in Previously Failed Shunt Patients: A 5-Year Analysis

BACKGROUND Shunting procedures have a high failure rate when used to treat pseudotumor cerebri (PTC) patients who have failed medical therapy. This failure is believed to be attributable to the collapsibility of the ventricular system when exposed to increased differential pressure gradients in the cerebral spinal fluid compartments caused by ventriculoperitoneal shunts (VPS). OBJECTIVE To investigate whether prepontine/interpeduncular cistern shunting may be a reasonable alternative to VPS intervention in PTC patients with history of shunt failure. There have been no large series of cisternal-peritoneal shunt (CPS) patients in the PTC population. METHODS A retrospective review of 49 patients with placement of CPS for PTC with 2 failed prior shunting procedures was performed. Shunt survivability was based on shunt patency and resolution of ophthalmologic symptoms and cranial nerve deficits. All patients were followed for a minimum of 3 yr with serial ophthalmologic and neurosurgical evaluations. RESULTS At 3 yr, 44 of the 49 (88.9%) patients had working CPS. Three patients in this group had infections requiring complete shunt removal. Excluding infections, 44 of 46 (95.5%) shunts were functional at 3 yr. There were 3 small, asymptomatic hemorrhages that did not increase patient length of stay, and there were no catastrophic hemorrhages or strokes. There were also no abdominal complications related to shunt placement. CONCLUSION CPS is a viable alternative to VPS in PTC patients who have failed traditional shunting methods to give these patients a persistent benefit of a working shunt. The procedure provides this solution with low operative and perioperative morbidity.

Microsurgical Clipping of an Unruptured Basilar Apex Aneurysm: 2-Dimensional Operative Video

Aneurysms of the basilar artery apex are generally at an increased risk of rupture compared with aneurysms in other locations, and the risk of rupture increases with increasing aneurysm size. Therefore, these lesions necessitate treatment to decrease the risk of rupture. The location, size, and directionality of dome projection influence the difficulty of microsurgical treatment. The patient presented with an incidental basilar apex aneurysm identified on workup for headaches. The aneurysm projected superoposteriorly into the interpeduncular cistern. The surgical approach involved a wide exposure of the basilar apex complex and meticulous identification and preservation of P1 perforators during clip applications. It was imperative to visualize all perforators on both sides of the clip prior to application, given the severe morbidity associated with a perforator infarct. The patient tolerated the procedure well and remained neurologically intact after the operation. This video is an exemplary demonstration of basilar apex aneurysm clip application for an incidentally discovered aneurysm. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Bilateral coagulation of inferior hypophyseal artery and pituitary transposition during endoscopic endonasal interdural posterior clinoidectomy: do they affect pituitary function?

OBJECTIVEThe endoscopic endonasal transcavernous approach with interdural pituitary transposition provides surgical access to the posterior clinoids and interpeduncular cistern. Prior to posterior clinoidectomy, selective coagulation and transection of the inferior hypophyseal artery (IHA) is recommended to prevent uncontrolled tearing of the artery and its avulsion from the wall of the cavernous carotid artery. The authors’ preliminary experience has shown that unilateral sacrifice of the IHA caused no permanent endocrine dysfunction. In this study, they investigated the pituitary function in the setting of bilateral sacrifice of IHAs and pituitary transposition.METHODSAll patients with normal preoperative pituitary function who underwent endoscopic endonasal bilateral posterior clinoidectomy with bilateral IHA sacrifice between March 2010 and December 2016 were included and retrospectively evaluated. All data regarding pituitary function were collected. The degree of pituitary gland manipulation was estimated based on tumor size on preoperative MRI. An angle between a line from the point where the gland meets the floor of the sella to the highest point of the tumor and the horizontal plane of the sellar floor, or access angle, was also measured. Posterior pituitary bright spots on pre- and postoperative T1-weighted MRI were also reported.RESULTSTwenty patients had bilateral transcavernous posterior clinoidectomies with coagulation of both IHAs. There were 13 chordomas, 3 epidermoid cysts, 2 chondrosarcomas, 1 meningioma, and 1 hemangiopericytoma. The mean follow-up was 19 months (range 13–84 months). Two patients experienced transient diabetes insipidus (DI) requiring desmopressin, which resolved before hospital discharge. One patient (with chordoma) developed delayed permanent DI, and a second patient (with hemangiopericytoma) developed permanent DI and panhypopituitarism. The access angle was higher in the group with pituitary dysfunction (47.25° compared to 33.81°; p = 0.07). Posterior pituitary bright spots were preserved in 75% of cases with normal postoperative endocrine function.CONCLUSIONSThe endoscopic endonasal transcavernous approach to the interpeduncular cistern with pituitary transposition and bilateral sacrifice of the IHAs does not cause pituitary dysfunction in a majority of patients. When endocrine deficit occurs, it appears to be more likely to have been caused by surgical manipulation than loss of blood supply. This finding confirms clinically the crucial concept of interarterial anastomosis of pituitary vasculature proposed by anatomists.