Graepel, Stephen

Abstract Introduction Safe, effective access to the fourth ventricle for oncologic resection remains challenging given the depth of location, restricted posterior fossa boundaries, and surrounding eloquent neuroanatomy. Despite description in the literature, a practical step-by step dissection guide of the suboccipital approaches to the fourth ventricle targeted to all training levels is lacking. Methods Two formalin-fixed, latex-injected specimens were dissected under microscopic magnification and endoscopic visualization. Dissections of the telovelar, transvermian, and supracerebellar infratentorial-superior transvelar approaches were performed by one neurosurgery resident (D.D.D.), under guidance of senior authors. The dissections were supplemented with representative clinical cases to highlight pertinent surgical principles. Results The telovelar and transvermian corridors afford excellent access to the caudal two-thirds of the fourth ventricle with the former approach offering expanded access to the lateral recess, foramen of Luschka, adjacent skull base, and cerebellopontine angle. The supracerebellar infratentorial-superior transvelar approach reaches the rostral third of the fourth ventricle, the cerebral aqueduct, and dorsal mesencephalon. Key steps described include positioning and skin incision, myofascial dissection, burr hole and craniotomy, durotomy, the aforementioned transventricular routes, and identification of relevant skull base landmarks. Conclusion The midline suboccipital craniotomy represents a foundational cranial approach, particularly for lesions involving the fourth ventricle. Operatively oriented resources that combine stepwise neuroanatomic dissections with representative cases provide a crucial foundation for neurosurgical training. We present a comprehensive guide for trainees in the surgical anatomy laboratory to optimize familiarity with fourth ventricle approaches, mastery of relevant microsurgical anatomy, and simultaneous preparation for learning in the operating room.

Arteriovenous malformations (AVMs) are some of the most challenging surgical entities. Like any challenging surgical procedure, AVM surgery is a series of basic but fundamental steps, each with its own nuances. Despite a myriad of published material regarding AVMs, there are few succinct illustrated summaries of these steps with an accompanying elucidation of the most common pitfalls. This paper provides a step-by-step description and illustration of the basic surgical principles of AVM microsurgical resection, focusing on the main key points and addressing the critical issues that surround this surgery. Deep anatomical knowledge and presurgical planning of these basic steps, combined with good contingency management skills, are paramount for an effective and safe AVM surgery.

ObjectiveWhile pedicled intranasal flaps, such as the nasoseptal flap (NSF), successfully reduce postoperative CSF leaks following endoscopic endonasal approaches (EEA) to the skull base, morbidity remains prevalent. This study describes the first cadaveric description and radiographic analysis of the posterior septal nasal floor mucosal flap (PSNF) designed to reduce pedicled nasal flap morbidity. A case series is also detailed.Study DesignCadaveric dissection, radiographic analysis, and case series.MethodsSeven cadaver specimens underwent harvest of the PSNF. PSNF flap dimensions were measured on the thirty deidentified sinus computed tomography (CT) scans. A retrospective case series was performed on the first set of patients who received the PSNF for reconstruction of a sellar base defect. Information concerning complications, symptoms, and the appearance of the flap was recorded from records of the patient's postoperative inpatient stay, 1‐week postop visit, and 1‐month postop visit.ResultsCadaver dissection of the PSNF flap demonstrated good arc rotation along its pedicle with ability to cover both sellar and planum defects. Cadaveric flap measurements and CT‐derived measurements estimated a mean surface area of 16.7 and 18.3 cm2, respectively. 15 patients underwent reconstruction of a sellar or planum defect using the PSNF technique. Only one CSF leak was encountered postoperatively. Minimal crusting of the flap and donor site was seen 1 month postoperatively.ConclusionThe PSNF flap provides a sizeable pedicled region for reconstruction comparable to other pedicled nasal flaps. Our case series demonstrated good postoperative outcomes without reduced donor site morbidity.Level of Evidence4 Laryngoscope, 132:1561–1568, 2022