Pedro Plou

BACKGROUND AND OBJECTIVES: Anatomic variability and poor mastoid pneumatization increase the risk of facial nerve injury during mastoidectomy by reducing the reliability of conventional anatomic landmarks. Currently, no standardized numerical guidelines define safe drilling depth relative to the facial canal. The objective of this study was to analyze the mastoid segment of the facial nerve on noncontrast head computed tomography (NCCT) to quantify facial nerve depth at 3 reproducible mastoid reference points and to define a practical, imaging-based safe-drilling zone for mastoidectomy. METHODS: We retrospectively reviewed 100 adult NCCT examinations (200 sides; 65 women, 35 men) acquired with bone windows, submillimetric slice thickness (≤0.6 mm), and multiplanar reformations aligned to the orbitomeatal line (Reid's baseline). Bilateral measurements captured the perpendicular cortex–facial canal distance at 3 anatomic landmarks: (1) incus level, (2) midpoint between the incus and the stylomastoid foramen, and (3) stylomastoid level. Distances (mm) were summarized using 2.5th to 97.5th percentiles. RESULTS: Across 200 sides, cortex-facial canal distances were 15.81 to 24.22 mm at the incus level, 11.53 to 20.22 mm at the midpoint, and 10.34 to 19.77 mm at the stylomastoid level (2.5th-97.5th percentiles). For intraoperative usability and safety, we rounded the 2.5th percentiles down to define safe-drilling limits of 15 mm (incus), 11 mm (midpoint), and 10 mm (stylomastoid). CONCLUSION: NCCT-based percentile mapping yielded reproducible thresholds for drill depth relative to the facial canal. Limiting depth to ≤15 mm at the incus, ≤11 mm at the midpoint, and ≤10 mm at the stylomastoid level provides an anatomically grounded reference that may support operative depth awareness and safer mastoid drilling, particularly when conventional landmarks are unreliable.

Background: Few studies have compared different topical hemostatic agents in live models or brain tissue, and their doses are not standardized. Little is known about the combined use of these different elements in terms of efficacy and safety, especially in neurosurgery. The objective of this study was to evaluate the efficacy of different topic hemostatic agents used in daily neurosurgical practice in an experimental animal model study. Methods: A group of 42 Wistar rats was used. A stereotaxic frame was fixed, and coordinates were determined to locate the bregma. A 3 mm hole was drilled with a bone-profile burr on each side of the midline. A stylet was inserted into the brain to create the defect and induce bleeding. The rats were randomly divided into seven groups, with each group assigned a hemostatic agent. Hemostasis time and control time on the opposite side were measured. Results: Hemostasis was achieved after an average of 1 82 s in the group treated with Beriplast, making it the hemostatic agent that stopped the bleeding the fastest. The control time was an average of 40, 14 s. Compared with the negative control, all the agents resulted in significantly better hemostasis (P < 0.05). Conclusion: A reduction in postoperative bleeding positively impacts annual morbidity and mortality rates, hospitalization time, and hospital bed turnover. Understanding the efficacy and safety of different hemostatic agents will enable surgeons to optimize intraoperative hemostasis, thereby achieving better postoperative outcomes and increased patient safety.

Introduction The transbasal approach traditionally uses a bicoronal scalp incision with bifrontal craniotomy to establish an extradural midline skull base working corridor. Depending on additional craniofacial osteotomies, this approach can expand its reach to the nasal cavity and paranasal sinuses and may be employed for the resection of particularly complex sinonasal and midline skull base tumors. Given its discrepancy in nomenclature and differences in interoperator technique, we propose a practical, operatively oriented guide for trainees performing this approach. Methods Three formalin-fixed, latex-injected specimens were dissected under microscopic magnification and endoscopic-assisted visualization. Stepwise dissections of the transcranial-transbasal approach with common modifications were performed, documented with three-dimensional photography, and supplemented with representative case applications. Results The traditional transbasal approach via bifrontal craniotomy affords wide extradural access to the anterior cranial fossa and central skull base. The addition of craniofacial osteotomies further expands access into the sinonasal cavities, clivus, and craniocervical junction. Key steps described include patient positioning, bicoronal skin incision, pericranial graft harvest, bifrontal craniotomy, orbital rim osteotomy, sphenoidotomy, bilateral ethmoidectomies, and microsurgical dissection of the sellar region. Basal superior sagittal sinus ligation and durotomy allow for intradural exposure. Reconstruction techniques are also discussed. Conclusion While the transbasal approach is rich with historical descriptions, illustrations, and modifications, its stepwise performance may be relatively unknown and unclear to younger generations of trainees. We present a comprehensive guide to optimize familiarity with the transbasal approach and its indications in the surgical anatomy laboratory, mastery of the relevant microsurgical anatomy, and simultaneous preparation for learning and participation in the operating room.

Frontal sinus surgery still represents a challenge due to its complex and highly variable anatomy. In this manuscript, we present a detailed anatomical description of an eyebrow approach that allows full exposure of the frontal sinus with a large osteoplastic bone flap and preservation of the supraorbital nerve. Laryngoscope, 2023.

Background: The transorbital approaches (TOAs) have acquired growing notoriety, thanks to their ability to offer alternative corridors to the skull base. However, the limited access and the unfamiliarity with this surgical perspective make recognition of key landmarks difficult, especially for less experienced surgeons. The study wants to offer a detailed description of the anatomy to comprehend the potential and limitations of TOAs. Methods: Measurements of the orbit region and the surrounding areas were performed on two hundred high-resolution CT scans and thirty-nine dry skulls. Five specimens were dissected to illustrate the TOA, and one was used to perform the extradural clinoidectomy. Three clinical cases highlighted the surgical applications. Results: A step-by-step description of the key steps of the TOA was proposed and a comparison with the transcranial anterior clinoidectomy was discussed. The mean work distance was 6.1 ± 0.4 cm, and the lateral working angle increased 20 ± 5.4° after removing the lateral orbital rim. Conclusions: TOAs are indicated in selected cases when tumor involves the lateral portion of the cavernous sinus or the middle skull base, obtaining a direct decompression of the optic nerve and avoiding excessive manipulation of the neurovascular structures. Comprehension of surgical anatomy of the orbit and its surrounding structures is essential to safely perform these approaches.

Meningiomas are slow-growing neoplasms, accounting for 20% of all primary intracranial neoplasms and 25% of all intraspinal tumors. Atypical and anaplastic meningiomas are infrequent, representing fewer than 5% of all meningiomas. Unusually, they can show aggressive behavior, and extracranial metastases are extremely rare, representing approximately 0.1% of all reported cases. Fifty-six-year-old male patient diagnosed with atypical basal frontal meningioma with multiple resections, both endoscopic endonasal and transcranial. After hypofractionated radiosurgery, the patient showed new tumor recurrence associated to right cervical level II ganglionic metastasis. We opted for complete resection of the meningioma and reconstruction with anterior rectus abdominis muscle flap, as well as selective cervical ganglionectomy. Anatomical pathology showed neoplastic proliferation of meningothelial cells in syncytial cytoplasm, oval or spherical nuclei with slight anisocariosis and hyperchromasia, and intranuclear vacuoles, all compatible with anaplastic meningioma. Due to a lack of consensus on how to treat a metastatic malignant meningioma, this pathology requires a multidisciplinary approach, and treatment needs to be adapted to each particular case. Complete resection of the lesion is the primary goal, and this requires complex procedures involving endocranial as well as extracranial surgeries, which result in composite defects difficult to resolve. Microvascular free flaps are considered the gold standard in reconstructions of large skull base defects, with high success rates and few complications.

The anterior cranial fossa (ACF) is a complex anatomical region that can be affected by a broad spectrum of pathology. For the surgical treatment of these lesions, many approaches have been described, each of them with different scope and potential surgical complications, often associated with significant morbidity. Traditionally, tumors involving the ACF have been operated by transcranial approaches; however, in the last two decades, endoscopic endonasal approaches (EEAs) have been gaining popularity. In this work, the authors review and describe the anatomical aspects of the ACF and the technical nuances of transcranial and endoscopic approaches for tumors located in this region. Four approaches were performed in embalmed cadaveric specimens and the key steps were documented. Four illustrative cases of ACF tumors were selected to demonstrate the clinical application of anatomical and technical knowledge, which are essential in the preoperative decision-making process.

Background The pedicled nasoseptal flap has been a key element in advancing the endoscopic transnasal approach (ETA) for the treatment of skull base lesions from the anterior cranial fossa to the occipitocervical junction. To preserve vascular supply, an anatomical knowledge of the location of the posterior septal artery (PSA) is essential. The objective of this work is to establish the relationship between PSA and the superior edge of the choana to define a safety margin during the opening of the sphenoidal rostrum preserving PSA. Methods One hundred and eighty angiotomographies of the brain were assessed. The sphenopalatine artery (SPA) was evaluated in the pterygopalatine fossa and PSA at its entrance into the nasal cavity and on the sphenoidal rostrum. Results PSA was found in all 3 tomographic planes (axial, coronal and sagittal) in 100 patients (200 PSAs). Thirty-five were male and 65 were females. Average age was 62 years with a range of 19–90 years. Total average distance between PSA and the superior edge of the choana was 8.5 mm with a range of 2.5–18 (12.45 90th percentile). Conclusion Although the distance between the choanal edge and PSA is 8.5 mm on average, due to its variability, a distance of at least 12.45 mm for the opening of the sphenoidal sinus in the ETA approach should be considered as a safety margin.