Vidian Canal as a Transcranial Landmark: Anatomy, Technique, and Illustrative Cases

Objective The vidian nerve can be accessed in transcranial approaches in carefully selected patients to ensure its preservation and to serve as a landmark for sphenoid sinus entry. This report is to review a technique, evaluate it in laboratory settings, and present two illustrative cases. Design The study involves cadaveric dissection and illustrative cases. Setting The study conducted in a cadaveric dissection laboratory. Participants The object of the study is one cadaveric head and two illustrative clinical cases. Main Outcome Measures Two cases using this approach were illustrated, and a cadaver dissection was performed in a step-by-step fashion. Results: The vidian canal can be accessed by drilling the anterolateral triangle. Two illustrated cases were presented; in one, the vidian nerve was used as part of a corridor to access the sphenoid sinus for tumor delivery, and in the other, the technique was used to find and preserve the vidian nerve during transcranial resection. Conclusion Careful identification of the vidian canal in transcranial surgery is a beneficial technique in carefully selected cases which allows identification of the nerve both for its preservation in selected cases and to create the vidian–maxillary corridor for tumor resection. Knowing the anatomy and pneumatization variants is important in the surgical approach.

Simplifying Access to the Lateral Sphenoid Recess: A Modification of the Transpterygoid Approach

Background Meningoencephaloceles originating in the lateral recess of the sphenoid sinus can be difficult to access. Historically, the endoscopic transpterygoid approach was advocated, which carries additional morbidity given the dissection of the pterygopalatine fossa (PPF) contents to provide a direct line approach to the defect. Given our increased facility with angled endoscopes and instrumentation, we now approach this region in a less invasive manner. Methods We describe the endoscopic modified transpterygoid approach (MTPA), a quicker approach to the lateral sphenoid recess which preserves the PPF contents through a single nostril corridor. Results In the MTPA, the face of the sphenoid and anterior junction of the pterygoid plates are removed, allowing for mobilization of the PPF contents with the periosteum intact. Angled instrumentation is then used to resect the meningoencephalocele and repair the skull base defect in the lateral recess. If increased exposure is needed, this can be gained by sacrificing the sphenopalatine artery and even the vidian nerve, although this is rarely required. Conclusions The MTPA obviates the need for PPF dissection and simplifies access to the lateral sphenoid recess while minimizing postoperative morbidity. This approach should be considered for accessing meningoencephaloceles and other benign lesions in this challenging location.

Anatomical Variants of Post-ganglionic Fibers within the Pterygopalatine Fossa: Implications for Endonasal Skull Base Surgery

Objectives The vidian nerve provides parasympathetic innervation to the nasal cavity and the lacrimal gland. Previous anatomic studies have primarily focused on preservation or severance of the vidian nerve proximal to the pterygopalatine ganglion (PPG). This study aimed to assess its neural fibers within the pterygopalatine fossa after synapsing at the PPG, and to explore potential clinical implications for endoscopic endonasal skull base surgery. Methods An endonasal transpterygoid approach was performed on eight cadaveric specimens (16 sides). The PPG and maxillary nerve within the pterygopalatine fossa were divided. The vidian nerve was traced retrograde into the foramen lacerum, and postganglionic fibers distal to the PPG were dissected following the zygomatic nerve into the orbit. Potential communicating branches between the ophthalmic nerve (V1) and the PPG were also explored. Results All sides showed a plexus of neural communications between the PPG and the maxillary nerve. The zygomatic nerve exits the maxillary nerve close to the foramen rotundum, piercing the orbitalis muscle to enter the orbit in all sides. The zygomatic nerve was identified running beneath the inferior rectus muscle toward a lateral direction. In 7/16 sides (43.75%), a connecting branch between V1 and the pterygopalatine ganglion was observed. Conclusion Neural communications between the PPG and the maxillary nerve were present in all specimens. A neural branch from V1 to the PPG potentially contributes additional postganglionic parasympathetic function to the lacrimal gland.

Multimaterial and multicolor 3D-printed model in training of transnasal endoscopic surgery for pituitary adenoma

OBJECTIVEThe aim of the present study was to investigate the practical value of a multimaterial and multicolor 3D-printed model in anatomical teaching, surgical training, and preoperative planning of transnasal endoscopic surgery for pituitary adenoma.METHODSMultimodality neuroimaging data were obtained in a 42-year-old healthy male volunteer and a 40-year-old female patient with an invasive nonfunctional pituitary adenoma. Three 3D-printed models were produced: a monomaterial and monocolor model, a monomaterial and multicolor model, and a multimaterial and multicolor model. The effects on anatomical teaching and surgical training for exposing the vidian nerve were assessed by 12 residents, and the training effect was validated on cadavers. The practical values for preoperative planning were evaluated by 6 experienced neurosurgeons. All evaluations were based on 5-point Likert questionnaires.RESULTSThe multimaterial and multicolor model was superior to the monomaterial models in surgical training for exposing the vidian nerve (Fisher test; p < 0.05). In addition, the multimaterial and multicolor model was superior to the monomaterial models in anatomical teaching and preoperative planning (Friedman test; p < 0.05).CONCLUSIONSMultimaterial and multicolor 3D printing technology makes it convenient and efficient to produce a practical model for simulating individualized and complex anatomical structures in the sellar region. Furthermore, the multimaterial model can provide a more realistic manipulative experience for surgical training and facilitate the preoperative planning.