Endoscopic anatomy of the palatovaginal canal (palatosphenoidal canal)

Objectives/Hypothesis: 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: 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.

An anatomical analysis of the mini-modified orbitozygomatic and supra-orbital approaches

Seven sides of cadaver heads were used to compare the surgical exposures provided by the mini-modified orbitozygomatic (MOz) and supra-orbital (SO) approaches. The Optotrak 3020 computerized tracking system (Northern Digital, Waterloo, ON, Canada) was utilized to evaluate the area of anatomical exposure defined by six points: (1) ipsilateral sphenoid ridge; (2) most distal point of the ipsilateral middle cerebral artery (MCA); (3) most distal point of the ipsilateral posterior cerebral artery (PCA); (4) most distal point of the contralateral PCA; (5) most distal point of the contralateral MCA; and (6) contralateral sphenoid ridge. Additionally, angles of approach for the ipsilateral MCA bifurcation, ipsilateral ICA bifurcation, basilar artery tip, contralateral MCA and ICA bifurcation and anterior communicating artery (AcomA) were evaluated, first for SO and then for MOz. An image guidance system was used to evaluate the limits of surgical exposure. No differences in the area of surgical exposure were noted (p > 0.05). Vertical angles were significantly wider for the ipsilateral and contralateral ICA bifurcation, AcomA, contralateral MCA and basilar tip (p < 0.05) for MOz. No differences in horizontal angles were observed between the approaches for the six targets (p > 0.05). There were no differences in the limits of exposure. MOz affords no additional surgical working space. However, our results demonstrate systematically that vertical exposure is improved. The MOz should be performed while planning an approach to these regions and a wider exposure in the vertical axis is needed. (C) 2012 Elsevier Ltd. All rights reserved.

Giant cell bone lesions in the craniofacial region: a diagnostic and therapeutic challenge

Background: Giant cell tumors of bone (GCTs) are common in the long bones, but rare in the craniofacial region, with only 1% of cases occurring in the latter. Clinical, radiological, and anatomical diagnosis of this locally aggressive disease, which occurs in response to trauma or neoplastic transformation, poses a major challenge in clinical practice. Methods: The present study describes a series of 4 cases and highlights the main features of the differential diagnosis and treatment of these lesions: GCT, giant cell reparative granuloma (GCRG), and the brown tumor of hyperparathyroidism. Results: GCT presents as a benign neoplasm, most typically affecting the knees, and rarely in the temporal and sphenoid bones. It is radiologically indistinguishable from GCRG due to its lytic, poorly defined appearance. The distinction can only be made microscopically, as the presence of multinucleated giant cells scattered throughout the stroma and the absence of a history of trauma favor a diagnosis of GCT. The brown tumor of hyperparathyroidism occurs with rapid, localized osteoclast activity secondary to the effects of increased parathyroid hormone (PTH) levels; parathyroid examination is indispensable. Conclusion: The diagnosis and treatment of these lesions poses a major challenge due to their similar clinical presentation and radiological appearance. Accurate diagnosis is essential for definition of appropriate management, as complete resection is the goal in GCT and GCRG to avoid recurrence, whereas the brown tumor often yields to treatment of the underlying hyperparathyroidism.