Faculty Bibliography

In recent years, endoscopic endonasal techniques have been applied to the treatment of sinonasal malignancies. Comprehensive anatomical knowledge is essential to preserve oncological principles and minimize surgical morbidity. The bones that form the anterior cranial base are pneumatized and the sinuses provide surgical corridors for the endoscopic endonasal approach to the skull base. During endoscopic endonasal resection of sinonasal malignancies, usually, the intranasal portion of the tumor is first debulked to provide visualization of the margins and assess the extent of the tumor. Afterwards the tumor is completely removed and the margins of resection are defined. In case of dural resection, the reconstruction is done with vascularized tissue (septal flap or pericranial flap). Sinonasal malignant neoplasms that invade the skull base can be resected accordingly to oncological principles using endoscopic endonasal techniques. Profound knowledge of the endoscopic anatomy of the ventral cranial base is paramount in order to perform a safe resection and reconstruction.

Objectives To determine the difference in operative times and associated complications for cases performed solely by attending-level surgeons versus cases assisted by surgeons-in-training for endoscopic endonasal pituitary surgeries. Design Retrospective chart review. Setting Tertiary-care academic medical center. Participants A total of 228 patients having undergone endoscopic endonasal pituitary surgery from 2005 to 2011. Main Outcome Measure Duration of surgery comparing attending only (AO) and trainee-assisted (TA) surgeries. Results Thirty-seven (19%) of 198 cases were identified as AO surgeries, the remaining 161 (81%) were TA. Operative times (minutes) for the AO group were significantly shorter than the TA group (149.1 ± 54.8 vs 219.5 ± 83.7, p < 0.001). The AO group had fewer intraoperative cerebrospinal fluid leaks (30% vs 39%, p = 0.318), decreased estimated blood loss (408 mL vs 523 mL, p = 0.176), fewer postoperative complications (27% vs 37%, p = 0.268), and shorter length of stay (3.5 vs 4.3 days, p = 0.294). Conclusions This is the first study in otolaryngology or neurosurgery to compare operative times and outcomes for AO versus TA cases at a single academic institution. Operative times were significantly decreased and a trend toward a decrease in patient morbidity was noted for cases performed solely by attendings. The valuation of teaching activities in the operating room is a necessary first step toward optimizing the allocation of resources and funding of surgical education.

OBJECTIVES/HYPOTHESIS/OBJECTIVE:The aim of this work was to define the anatomical landmarks, limitations, and difficulties of obtaining internal carotid artery (ICA) exposure via endonasal endoscopic approaches (EEA). STUDY DESIGN/METHODS:Cadaveric descriptive study. METHODS:The ICA was dissected via EEA in 10 cadaveric specimens (20 sides) prepared with intravascular injections of colored silicone. We carried the ICA dissection from the cavernous to the distal parapharyngeal segments through a transpterygoid corridor. RESULTS:The transpterygoid approach provided adequate exposure of the lacerum and horizontal petrous ICA. Additional exposure of the ICA and the infrapetrous area required resection of the eustachian tube (ET) and the fibrocartilaginous tissue of the foramen lacerum after a medial maxillectomy and resection of the pterygoid plates. The main anatomical landmarks to the corresponding ICA segment include: the vidian nerve that points to the lacerum and horizontal segments, the mandibular nerve (V3) that heralds the petrous segment, the foramen ovale and the ET that signal toward the carotid canal, and the posterior trunk of the mandibular nerve (V3) and the ET that mark the parapharyngeal segment. CONCLUSIONS:EEAs provide access to the ICA from its cavernous to the distal parapharyngeal segments. A stepwise approach is critical to its exposure and control. Surgeons must be aware of its frequently tortuous three-dimensional course and the intimate relation of the vessel to the carotid canal and the cartilage of the foramen lacerum.

OBJECT/OBJECTIVE:The aim of this study was to report the results in a consecutive series of patients who had undergone an endoscopic endonasal approach (EEA) for drainage of a petrous apex cholesterol granuloma (CG). METHODS:Seventeen cases with a confirmed diagnosis of petrous apex CG were identified from a database of more than 1600 patients who had undergone an EEA to skull base lesions at the authors' institution in the period from 1998 to 2011. Clinical outcomes were reviewed and compared with those in previous studies of open approaches. RESULTS:Nine patients underwent a transclival approach and 8 patients underwent a combined transclival and infrapetrous approach. A Silastic stent was used in 11 patients (65%), a miniflap in 4 (24%), and a simple marsupialization of the cyst in 3 (18%). All symptomatic patients had partial or complete improvement of their symptoms postoperatively and at the follow-up (mean follow-up 20 months, range 3-67 months). Complications developed in 3 patients (18%) including epistaxis, chronic serous otitis media, eye dryness, and a transient sixth cranial nerve palsy. Two patients (12%) had a symptomatic recurrence of the cyst requiring repeat endoscopic endonasal drainage. There were no instances of internal carotid artery injuries, CSF leaks, or new hearing loss. The mean postoperative hospital stay was 2 days (range 0.7-4.6 days). These results were comparable with those in previous studies of open approaches to petrous apex CGs. There was a strong correlation between the size of the cyst and the type of approach chosen (Rpb [point biserial correlation coefficient] = +0.67, p = 0.003359) and a very strong correlation between the degree of medial extension (defined by the V-angle) and the choice of approach (Rpb = +0.81, p < 0.0001). Based on these observations, the authors developed an algorithm for guiding the choice of the most appropriate route of drainage. CONCLUSIONS:The EEA is a safe and effective alternative to traditional open approaches to petrous apex CGs.

OBJECTIVES/HYPOTHESIS/OBJECTIVE:The aim of this study was to investigate and compare the surgical anatomy of two different routes to access and drain petrous apex (PA) cholesterol granulomas: the expanded endonasal approach (EEA) and the transcanal infracochlear approach (TICA). STUDY DESIGN/METHODS:Anatomic and radiologic study. METHODS:The EEA and TICA to the PA were performed in 11 anatomic specimens with the assistance of imaging guidance. The PA was categorized into three zones: superior PA, anterior-inferior PA, and posterior-inferior PA. The maximum drainage window achieved by each approach was calculated using the imaging studies of each anatomic specimen. RESULTS:The EEA was able to reach superior PA and anterior-inferior PA in all specimens and posterior-inferior PA in 90%. The TICA did not provide access to superior PA in any case. The TICA was suitable to reach anterior-inferior PA in 80% of specimens and posterior-inferior PA in 60%. Based on the radiologic study, the EEA provided a drainage window three times larger than the TICA. CONCLUSIONS:The transnasal approach provides reliable access to the PA when combined with internal carotid artery exposure and allows for large drainage window. The transcanal approach is less versatile and more limited than the transnasal approach but provides access to the most posterior and inferior portion of the PA without Eustachian tube transection. Here we propose a new surgical classification that may help to decide the most suitable approach to the PA according to the location and extension of the lesion.

The authors present the technical and anatomical nuances needed to perform an endoscopic endonasal removal of a tuberculum sellae meningioma. The patient is a 47-year-old female with headaches and an incidental finding of a small tuberculum sellae meningioma with no vascular encasement, no optic canal invasion, but mild inferior to superior compression of the cisternal segment of the left optic nerve. Neuroophthalmology assessment revealed no visual defects. Treatment options included clinical observation with imaging follow-up studies, radiosurgery, and resection. The patient elected to undergo surgical removal and an endonasal endoscopic approach was the preferred surgical option. Preoperative radiological studies showed the presence of an osseous ring between the left middle and anterior clinoids, the so-called carotico-clinoidal ring. The surgical implications of this finding and its management are illustrated. The surgical anatomy of the suprasellar region is reviewed, including concepts such as the chiasmatic sulcus and limbus sphenoidale, medial and lateral optico-carotid recesses, and the paraclinoidal and supraclinoidal segments of the internal carotid artery. Emphasis is made in the importance of exposing the distal dural ring of the internal carotid artery and the precanalicular segment of the optic nerve for adequate intradural dissection. The endonasal route allows for early coagulation of the tumor meningeal supply and extensive resection of dural attachments, and importantly, provides an inferior to superior access to the infrachiasmatic region that facilitates complete tumor removal without any manipulation of the optic nerve. The lateral limit of dural removal is formed by the distal dural ring, which is gently coagulated after the tumor is resected. A 45° scope is used to inspect for any residual tumor, in particular at the entrance of the optic nerve into the optic canal and at the most anterior margin of the exposure (limbus sphenoidale). The steps for reconstruction are detailed and include intradural placement of dural substitute and extradural placement of the nasoseptal flap. The nuances for proper harvesting, positioning, and reinforcement of the flap are described. No lumbar drain was used. The patient had an uneventful recovery with no CSF leak or any other complications. Imaging follow-up at 6 months showed complete removal of the tumor. The patient had no sinonasal or neurological symptoms, and olfaction was fully preserved. The video can be found here: http://youtu.be/kkuV-yyEHMg .

OBJECTIVES/HYPOTHESIS/OBJECTIVE:Demonstrate the endoscopic anatomy of the palatovaginal (PV) canal and artery for identification and dissection of the vidian nerve during endoscopic transpterygoid approaches. Evaluate the length of the PV canal and its relation with the vidian nerve. Show that the traditionally known PV canal is a misnomer and should be renamed. STUDY DESIGN/METHODS:Experimental study: anatomical and radiological. METHODS:Dissection of eight cadaveric heads was performed to demonstrate the endoscopic anatomy of the PV canal. Computed tomography scan analysis of 20 patients was used to evaluate the length of the PV canal, the angle formed between this canal and the vidian nerve, and the distance between the vidian canal and the PV canal. Study of 10 dry skull bases was performed to verify the structures involved in the formation of the PV canal. RESULTS:Anatomic steps and foundations for dissection of the vidian nerve using the PV canal as a landmark were described. The mean length of the PV canal was 7.15 mm. The mean proximal distance between the vidian and the PV canal was 1.95 mm, and the mean distal distance was 4.14 mm. The mean angle between those canals was 48 degrees. The osteology study showed the vaginal process of the sphenoid bone did not contribute to the formation of the PV canal. CONCLUSIONS:Our anatomic investigations, radiologic studies, and surgical experience demonstrate the important anatomic relationship of the PV canal with the vidian canal and the relevance of the PV canal as a surgical landmark in endoscopic endonasal transpterygoid approaches. Anatomically, PV canal is a misnomer and should be replaced with palatosphenoidal canal.

The authors present a fully endoscopic endonasal repair of a spontaneous CSF leak caused by a defect in the anterior fossa floor. Patients were positioned supine in a Mayfield headholder in slight extension. A complete ethmoidectomy was performed to expose the defect. The middle turbinate was removed to increase visualization and allow for more working room. The defect was identified and exposed. A nasoseptal flap was raised and placed over the defect. A free-mucosal graft fashioned from the removed middle turbinate was placed on the nasoseptal donor site. The video can be found here: http://youtu.be/gAN2cvQVXCE .

OBJECTIVES/HYPOTHESIS/OBJECTIVE:Measure the dimensions of the nasoseptal (NS) flap and the anterior skull base (ASB) defect. Verify whether the flap is sufficient to cover the defect. Study the anatomy of the septal artery (SA). STUDY DESIGN/METHODS:Anatomical and radiological study. METHODS:After endoscopic craniofacial resection, sufficiency of the flap to cover the ASB defect was assessed. The SA was dissected. The number of branches in the pedicle and the distance between the artery and the sphenoid ostium were noted. Radiologic study analyzing CT scans of 30 patients for comparison among measurements of the NS flap and the ASB defect was performed. RESULTS:In all cases the flap was sufficient to cover the ASB. Two branches of the SA were found in the pedicle in 71.4%. The distance between the SA and the sphenoid ostium was 9.3 mm. The reconstruction area of the flap (17.12 cm(2) ) was larger than the defect area (8.64 cm(2) ) (P < .001). The difference between the superior length of the flap and the anterior-posterior distance of the defect was ≤ 5 mm in 26.7%. Comparison between the anterior flap width and the anterior defect width revealed that in 33% the difference was ≤ 5 mm. CONCLUSIONS:The dimensions of NS flap are sufficient to cover completely the ASB defect. The anterior edge of the defect presents increased risk for failure in coverage. Additional width adding the nasal floor mucosa to the flap is important to decrease the risk of gap in the anterior orbit-orbit defect. It is more common to find two branches of the SA in the pedicle.