1,720,975 research outputs found
The Party Wall: Redefining the Indications of Transcranial Approaches for Giant Pituitary Adenomas in Endoscopic Era
No full textThe evolution of endoscopic trans-sphenoidal surgery raises the question of the role of transcranial surgery for pituitary tumors, particularly with the effectiveness of adjunct irradiation. This narrative review aims to redefine the current indications for the transcranial approaches for giant pituitary adenomas in the endoscopic era. A critical appraisal of the personal series of the senior author (O.A.-M.) was performed to characterize the patient factors and the tumor’s pathological anatomy features that endorse a cranial approach. Traditional indications for transcranial approaches include the absent pneumatization of the sphenoid sinus; kissing/ectatic internal carotid arteries; reduced dimensions of the sella; lateral invasion of the cavernous sinus lateral to the carotid artery; dumbbell-shaped tumors caused by severe diaphragm constriction; fibrous/calcified tumor consistency; wide supra-, para-, and retrosellar extension; arterial encasement; brain invasion; coexisting cerebral aneurysms; and separate coexisting pathologies of the sphenoid sinus, especially infections. Residual/recurrent tumors and postoperative pituitary apoplexy after trans-sphenoidal surgery require individualized considerations. Transcranial approaches still have a critical role in giant and complex pituitary adenomas with wide intracranial extension, brain parenchymal involvement, and the encasement of neurovascular structures
Surgical management of symptomatic hemangioma of the geniculate ganglion: fascicular-sparing resection or grafting?
No full textGeniculate ganglion hemangioma (GGH) is rarely presented in the neurosurgical literature. It extends extradurally on the middle fossa floor and displaces the intratemporal part of the facial nerve. Surgical treatment is advisable at early symptoms. Proposed techniques include fascicular-sparing resection or nerve interruption with grafting. No definitive conclusions exist about the superiority of a certain technique in preserving facial nerve integrity and function. Through the description of a surgically managed symptomatic GGH, we herein discuss literature data about the surgical results of fascicular-sparing resection versus grafting. A PRISMA-based literature search was performed on the PubMed database. Only articles in English and published since 1990 were selected and furtherly filtered based on the best relevance. Statistical comparisons were performed with ANOVA. One hundred sixteen GGHs were collected, 56 were treated by fascicular-sparing resection, and 60 were treated by grafting. The facial function was improved, or unchanged, in 53 patients of the fascicular-sparing group and 30 patients of the grafting one. Sixty-five patients achieved a good (House-Brackmann (HB) grade III) postoperative facial outcome, of which 47 and 18 belonged to the fascicular-sparing and grafting group, respectively. Greater efficacy of the fascicular-sparing technique in the achievement of a better facial outcome was found (p = 0.0014; p = 0.0022). A surgical resection at the earliest symptoms is critical to preserve the facial nerve function in GGHs. Fascicular-sparing resection should be pursued in symptomatic cases with residual facial function (I-III HB). Conversely, grafting has a rationale for higher HB grades (V-VI). Broader studies are required to confirm these findings and turn them into new therapeutic perspectives
Fascicular-Sparing Technique for Resection of Cerebellopontine Angle Facial Nerve Schwannoma
No full textSurgery of cerebellopontine angle (CPA) facial nerve schwannoma (FNS) in patients with good facial nerve function is a challenge.(1-10) Video 1 highlights the fascicular-sparing technique for resection of a CPA FNS. A 41-year-old male patient symptomatic with persistent headaches and tinnitus underwent a retrosigmoid approach for a right cystic CPA tumor, presumed vestibular schwannoma. Intraoperatively, the facial nerve was identified as fine multiple strands splayed around the perimetry of the tumor, which elicited a motor response at a low threshold stimulation. This finding led to the intraoperative diagnosis of FNS according to the reported criteria.(5) Neuromonitoring-assisted fascicular-sparing resection technique was performed. It involved the gradual separation of the uninvolved nerve fibers using a fine-stimulating dissector at a threshold of 0.2 mA. Entry into the tumor was at a stimulation silent cyst. The tumor was debulked with preservation of the endoneurium and pulse irrigation hemostasis. A near-total resection was performed. The patient was discharged on the second postoperative day with a House-Brackman III facial nerve deficit. The deficit remained stable during the following annual follow-up visits.Resection of CPA FNS is indicated at the earliest sign of deficit. However, it might be encountered as masquerading at the surgery of an acoustic tumor. The fascicular-sparing technique is critical in avoiding injuries to the endoneurium during the resection and with the ability to preserve function.The sparing of endoneurium avoids collagenization, fibrosis, and ischemia of the nerve, which are known to be the pathologic substrate of worse functional outcomes
Supracerebellar “Flyover” Approach to Dumbbell Falcotentorial Meningioma Encasing the Galenic Venous System
No full textFalcotentorial meningiomas involve the tentorial apex and straight sinus, posing challenges when encasing the galenic venous system.1 Microneurosurgery is considered the best treatment option for large falcotentorial meningiomas because it provides a definitive cure.2 In contrast, Gamma Knife surgery mainly allows the control of smaller or residual tumors after microsurgical resection.3 Approach selection between interhemispheric supratentorial versa supracerebellar transtentorial is dictated by the displacement of the Galen vein.1,4-8 Video 1 describes the critical surgical steps of the supracerebellar "flyover" approach for a Bassiouni type II dumbbell falcotentorial meningiomas encasing the galenic venous system. Preoperative embolization was ruled out due to potential additional morbidity and mortality risks.9,10 A perimedian supracerebellar infratentorial transtentorial approach was performed with the patient in 3/4 prone Concorde position. After early devascularization and division of the tentorium, the meningioma was internally debulked while preserving the arachnoid plane. The posterior choroidal arteries, internal cerebral veins, basal veins of Rosenthal, and vein of Galen were carefully dissected, and the tumor was completely resected. The patient was discharged on postoperative day 3 with no deficits. Postoperative magnetic resonance imaging confirmed a Simpson grade 1 resection. Pathology revealed a grade 2 meningioma. The patient remained asymptomatic with no recurrence at a 10-year follow-up. The reported case demonstrates that the most critical factor in the choice of approach to midline dumbbell falcotentorial meningiomas is the relationship of the tumor to the galenic venous system and its tributaries
The foramen spinosum: a landmark in middle fossa surgery
Get PDFThe foramen spinosum is an easily identifiable landmark in microsurgery of the middle cranial fossa, and knowledge of the variations in its relationship to the surrounding neurovascular structures is important when operating in this area. We studied the anatomical relationship of the foramen spinosum to the foramen ovale, the mandibular branch of the trigeminal nerve, the greater superficial petrosal nerve, and the petrous part of the internal carotid artery in 12 cadaver heads. We also tried to define an external landmark for early identification of the location of the foramen spinosum in ten dry skulls. We found considerable variations in the anatomy around the foramen spinosum. This knowledge may improve the identification and preservation of the neurovascular structures when using approaches to the middle cranial foss
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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